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BIOL 320 EXAM 1 TAMU TAYLOR
Terms in this set (451)
What is cheating?
Intentionally using or attempting to use unauthorized materials, information, study aids, or other devices or materials in any academic exercise
What is fabrication?
Making up data or results, and recording or reporting them
What is falsification?
Manipulating research materials, equipment, or processes, or changing or omitting data or results such that the research is not accurately represented in the research record
What is multiple submissions?
Submitting substantial portions of the same work (including oral reports) for credit more than once without authorization from the instructor of the class for which the student submits the work
What is plagiarism?
The appropriation of another person's ideas, processes, results, or words without giving appropriate credit.
What is complicity?
Intentionally or knowingly helping, or attempting to help, another to commit an act of academic misconduct.
What is endocrinology?
Study of hormones and endocrine glands
What is autocrine signaling?
Secreted by cells in a local area, influences the activity of the same cell from which it was secreted.
Example would be eicosanoids or WBCs signaling to itself to replicate
What is paracrine signaling?
Cells will secrete chemical messenger into interstitial fluid and effect other tissue that neighbors the secreting cell.
NOT IN BLOODSTREAM.
For example histamines that stimulate vasodilation in nearby blood vessels
What is neurotransmitter signaling? Between autocrine, paracrine, and endocrine which type of signaling does this fall under?
Chemical messengers secreted by neurons that activate an adjacent cell (neuron, muscle, gland) by traveling across a synaptic cleft.
Technically under paracrine but is also its own division of signaling
What is endocrine signaling?
Cell secretes chemical messenger into bloodstream and influences target tissue with appropriate receptor to hormone
The testes secrete testosterone that act on itself. Is this still an example of endocrine?
The hormone enters the blood stream and travels body wide, even though it may act on itself
What does the cortex of the adrenal glands make?
steroids (cortisol, aldosterone)
What does the medulla of the adrenal glands make?
catecholamines (epinephrine and norepinephrine)
What are the 5 major endocrine glands that have only endocrine function?
Pituitary gland, Pineal gland, Thyroid gland, Parathyroid gland, Adrenal gland
What are some organs containing endocrine cells?
Hypothalamus, Skin, Thymus, Heart, Liver, Stomach, Pancreas, Small intestine, Kidney, Gonads
What are the differences between endocrine and nervous system communication?
In both cases, cells release a chemical that acts on other cells.
Endocrine secretes hormones into bloodstream while nervous system uses neurotransmitters.
Nervous system is much faster than endocrine system (ms vs s).
Nervous system acts very shortly while endocrine system tends to have longer- lasting effects
Are hormones amplitude or frequency modulated?
amplitude modulated, meaning more hormone released and bound to target tissue means stronger response
Are action potentials amplitude or frequency modulated?
frequency modulated, meaning amount of signal each time is same, but more signals leads to a stronger response
What is chronic secretion? Give an example
relatively constant blood levels of hormone over long periods of time (think thyroid hormone)
What is acute secretion? Give an example
hormone concentrations change suddenly and irregularly (think epinephrine)
What is cyclic secretion? Give an example
hormones are secreted at predictable intervals and concentrations (think hormones involved in periods)
Between water and lipid soluble hormones, would each exhibit chronic, acute, or cyclic secretion?
Chronic and cyclic = lipid as it can last longer Acute = water as it has short half life
What is humoral control?
Response to blood levels of some chemical
For example, if blood sugar is below a certain level, then glucagon will be released
What is hormonal control? What terms are common for hormonal control?
A hormone induces the secretion of another hormone (positive and negative feedback)
Usually has "tropin" or "tropic" term = acts on other hormones
What is neural control?
ANS will stimulate release of hormone based on situation
Fight or Flight for example
A neuron releases a neurotransmitter at a synapse to stimulate a hormone's secretion. What kind of control is this?
A neuron releases a neuropeptide hormone into the blood, which then stimulates another hormone's secretion. What kind of control is this?
True or False: Many hormones inhibit the secretion of itself.
True, this is an example of negative feedback
Usually, the hormone's secretion is inhibited by the hormone itself once blood levels have reached a certain point
What three factors influence whether a target cell is influenced by a hormone or not?
Hormone levels in the bloodNumber of receptors on target tissueAffinity of hormone for receptors (does it need low or high concentrations)
What is up-regulation? When is this common?
Hormone binds to receptor, which initiates formation of more receptors so it can bind to more hormone.
Usually occurs if there is too little hormone in bloodstream or may be due to positive feedback loop
What is down regulation? When is this common? How is this related to type II diabetes?
Hormone binds to receptor, which de-sensitizes receptors and less receptors bind to hormone
Usually happens if there is too much hormone in bloodstream Think type 2 diabetes - down-regulation of insulin receptors
What are some actions of hormones? Which events are only excitatory?
1. Alter plasma membrane permeability (open and close ion channels) 2. Stimulate protein synthesis
3. Activate and deactivate enzymes.
Which hormonal events are only excitatory?
Induce secretory activity & Stimulate mitotic activity
What are all steroid hormones derived from?
Which glands usually produce steroid hormones?
Produced from gonads (testosterone and estrogen) and adrenal cortex (cortisol and aldosterone)
What are biogenic amines?
Derived from amino acids that are modified (catecholamines). Example would be norepinephrine
Are biogentic amines water soluble?
yes except for thyroid hormone
What are the three most common catecholamines?
True or False: Thyroid hormone is rare example of a hormone that looks water soluble but isn't.
Thyroid hormone is derived from tyrosine which is aromatic and has some lipophilic nature, allowing it to directly diffuse across membrane
What enzyme breaks down cAMP?
Describe the PIP2 signaling mechanism. Which hormones use this mechanism?
Hormone binds and activates G protein
G protein activates phospholipase C enzyme, which splits phospholipids into diacylglycerol (DAG) and IP3 DAG activates protein kinases while IP3 releases Ca2+ Ca2+ can alter enzymes or bind to calmodulin Hormones include oxytocin, ADH, and epinephrine
How do lipid soluble hormones and thyroid hormones act on cells?
Hormone diffuses through membrane and binds to intracellular receptor
Receptor-hormone complex (chaperone complex) enters nucleus and binds to specific sequence of DNA
mRNA directs protein synthesis
What are some ways to administer steroid based hormones?
No injection needed
Ingested, topical cream, etc.
What two factors influence hormone concentration?
The rate of release
The speed of inactivation
Would water soluble or fat soluble hormones have a shorter half life?
Water soluble because the enzymes that digest the hormone are already present in the bloodstream
Also, water soluble hormones usually are involved in amplification as they rely on secondary messengers, so we need to remove them faster so we don't get over-response
What is conjugation? What is it used for?
Conjugation is the process of removing lipid soluble hormones by having specific water soluble molecules to the hormones, marking them for removal
What three ways can we inactivate hormones? What are the primary ways to do so?
EnzymesKidneys and filtration into urine (primary method)
Liver and detoxification of blood (primary method)
What is the difference between synergism and antagonism?
Synergism = hormones work together (leads to amplification)
Antagonism = hormone causes opposite effect of other
What is a permissive hormone?
A hormone allows the action of another hormone
What is a chylomicron?
Hormone protein unit
What is another name for the pituitary gland?
What connects the pituitary gland to the hypothalamus?
What is the precursor for the anterior pituitary gland? How does this influence the nature of secretion?
hypophyseal pouch from part of oral cavity called pituitary diverticulum (hormonal secretion in nature)
What is the precursor for the posterior pituitary gland? How does this influence the nature of secretion?
continuous with hypothalamus, neurohypophyseal bud from gray matter (neural secretion in nature)
What part of the pituitary secretes neuropeptides?
What part of the pituitary secretes traditional hormones?
What is the pathway of secretion of the anterior pituitary?
Neurons in ventral hypothalamus secrete hormone into primary capillary plexus
Hormone travels through hypophyseal portal system (bloodstream)
Hormones reach anterior pituitary, which stimulate specific cells of the anterior pituitary to release or inhibit hormones
Anterior pituitary hormones are secreted into secondary capillary plexus
What is the pathway of secretion of the posterior pituitary?
Neurons in paraventricular or supraoptic nuclei in hypothalamus induce action potential which carries neurohormones along hypothalamic-hypophyseal tract
AP travels along axons and reaches axon terminals in posterior pituitary, where hormone is stored in axon terminals until needed to be released
What two nuclei in the hypothalamus are important in this pathway?
paraventricular or supraoptic nuclei
What is another name for the anterior pituitary?
What is another name for the posterior pituitary?
What path carries hormones to the anterior pituitary?
Hypothalamohypophyseal portal system
What path carries hormones to the posterior pituitary?
Which two hormones are used in the posterior pituitary?
oxytocin and Antidiuretic hormone aka vasopressin
What part of the hypothalamus is oxytocin synthesized in?
What part of the hypothalamus is vasopressin synthesized in?
What is the role of oxytocin?
stimulates contraction of uterus and milk expulsion from mammary glands
What is the role of vasopressin?
increases water volume of blood and blood pressure
What kind of regulation is used in the posterior pituitary?
What does oxytocin do?
Stimulates labor or menstruation by causing smooth muscle contraction in uterus. Also responsible for milk letdown in breastfeeding women by promoting contraction of smooth muscle like cells surrounding milk ducts
Why do we usually say its good for moms to breastfeed?
Stimulating nipples stimulates nerves that releases oxytocin, which allows expulsion of milk
What is antidiuretic hormone? What is another name for this hormone?
A water conservation hormone that prevents the output of large amounts of urine by promoting reabsorption of water. Aka vasopressin because it constricts blood vessels and raises BP
What is osmolality?
the concentration of solutes in a solution
How does osmolality relate to ADH?
If osmolality increases, more ADH is secreted so more water is retained, which reduces osmolality.
If osmolality decreases, less ADH is secreted so there is more urine, which increases osmolality
What does diabetes insipidus mean?
Diabetes = overflow Insipidus = no taste
What usually causes diabetes insipidus? What is happening to ADH?
Damage to the brain or brain trauma leads to decrease in secretion of ADH, leading to excessive urination due to imbalance of salt and water
Also can be due to kidney not recognizing ADH
What does "breaking the seal" mean? Why does this usually happen after you drink alcohol? With this in mind, what really is a hangover?
ADH is inhibited by alcohol.
Once you go to the restroom once, you have to keep going and going as it takes the endocrine system time for it to start making ADH and flushing out alcohol.
A hangover is really just the symptoms of dehydration (so technically you can get a hangover without even drinking).
What seven hormones are secreted by the ventral hypothalamus to act on the anterior pituitary?
Growth Hormone Releasing Hormone (GHRH)
Growth Hormone Inhibiting Hormone (somatostatin) (GHIH)
Thyrotropin RH = acts on thyroid to release its hormones
Corticotropin RH = acts on adrenal cortex via ACTH
Gonadotropin RH = acts on gonads via FSH and LH
Prolactin Inhibiting Hormone (dopamine)
What is another name for GHIH?
Growth Hormone Inhibiting Hormone
What six hormones are secreted by the anterior pituitary?
Thyrotropin aka thyroid stimulating hormone
Follicle stimulating hormone (sperm production and follicle maturation)
Luteinizing hormone (ovulation, gonadal hormone production)
Adrenocorticotropic hormone (ACTH)
Growth hormone aka somatotropin
What is another name for growth hormone?
Are the hormones from the anterior pituitary gland water or lipid soluble hormones?
What is the role of FSH?
sperm production and follicle maturation
What is the role for LH?
ovulation, gonadal hormone production
What kind of regulation is used in the anterior pituitary?
Are CRH and ACTH the same hormone?
CRH goes to anterior pituitary, which releases ACTH (adrenocorticotropic hormone) and acts on adrenal cortex
What does growth hormone do?
Tells tissues to use fat instead of glucose for cellular respiration (so it can save it for the brain)
How does growth hormone affect fat reserves, amino acids and proteins, and glucose?
Increases uptake of amino acids and protein synthesis Increases breakdown of lipids
How is growth hormone hormone related to exercise?
Involved in recovery after working out
What does growth hormone do to sulfur?
Uptake of sulfur by cartilage matrix
What are direct effects of GH?
increased breakdown of lipids and the decreased use of glucose as an energy source
What are indirect effects of GH?
increase protein synthesis and growth of bone, muscles, etc.
What stimulates the secretion of GH?
Low blood glucose levels, stress, and rising amino acid levels
What inhibits the secretion of GH?
High blood glucose levels decrease secretion
What is gigantism caused by?
increased GH before bone ossification (childhood)
What is acromegaly caused by?
increased GH after bone ossification (adulthood)
What is dwarfism caused by?
How does GH fluctuate based on the time of day?
Rises during early stages of normal sleep cycle and peaks during deep sleep so you have most growth to occur during sleep
How does stress influence GH release?
In children, it can cause a decrease in GH release
True or False: All of the hormones released by the pituitary are peptide hormones.
All the hormones released by both pituitary glands are peptide hormones, while steroid hormones are typically synthesized in the gonads and in the adrenal medulla.
What three hormones does the thyroid gland secrete? Which one is secreted most?
Triiodothyronine (T3) = 10% of all secretions Tetraiodothyronine aka thyroxin (T4) = 80% of all secretions Calcitonin = 10% of all secretions
What is a thyroid follicle?
structural and functional unit of thyroid gland
What is found in the thyroid follicles?
thyroglobulin & an iodinated glycoprotein, which is an inactive storage form of thyroid hormone.
What is follicular cells in the thyroid in regards to location?
close to thyroid follicles that contain colloid
What is parafollicular cells in the thyroid in regards to location?
far away from thyroid follicles
What is follicular cells in the thyroid in regards to function?
regulated by thyrotropin, secretes thyroxine (T4) and triiodothyronine (T3) precursor thyroglobulin
What is parafollicular cells in the thyroid in regards to function?
secretes calcitonin (important in kids, humoral regulation)
What is T4?
thyroxine = tetraiodothyronine = inactive form, two tyrosines + 4 iodines and is precursor to T3
What is T3?
triiodothyronine = active form, two tyrosines + 3 iodines
Describe the biosynthesis of thyroid hormone. What key enzyme is involved in this process?
Iodide is active transported into thyroid follicle cells by Na+/I- symporter.
Iodide is transported into colloid and thyroperoxidase converts I- to I.
Thryoglobulin (Tg) foundation is synthesized in thyroid follicle cells. Tg is exocytosed into follicle lumen.
Tyrosines within Tg are iodinated by thyroperoxidase to form either T1 or T2.
Two iodinated tyrosines within Tg come together to form T4 or T3.
Endocytosis of iodinated Tg into thyroid follicle cells.
Tg is digested by lysosomal enzymes into individual amino acids and T3 and T4.
T3 and T4 diffuse out of thyroid follicle and enter blood stream
What two things cause release of TRH?
Stress and hypothermia
What inhibits the release of TRH?
How is T3 and T4 involved in negative feedback?
Release of T3 and T4 has an inhibitory effect on secretion of TRH from ventral hypothalamus and TSH from anterior pituitary
What does thyroid hormone do?
1. Regulates basal metabolic rate and body temperature
2. Regulates heart rate and blood pressureInvolved in muscle function
3. Involved in development and function of nervous system
4. Regulates bone growth (permissive for GH)
5. Regulates gastrointestinal motility
6. Involved in functioning of female reproductive system
7. Involved in various skin conditions
What are some symptoms of hypothyroidism?
1. Decreased metabolic rate
2. Low body temperature
3. Weight gain and reduced appetite
4. Reduced heart rate, BP
5. Weak bones and muscles
6. If thyroid hormone levels are low during development, can lead to neurodevelopment disorders
What are some symptoms of hyperthyroidism?
1. Increased metabolic rate
2. High body temperature
3. Weight loss and increased appetite
4. Increased heart rate, BP
6. Goiter (enlargement of thyroid)
What is myxedema? Is this a result of hypothyroidism or hyperthyroidism? How can we treat this?
Having too little thyroid hormone or iodide, leading to mucous swelling
Leads to decrease in basal metabolic rate, chills, constipation, puffy eyes
Feel mentally sluggish
Just treat with synthetic thyroid hormone, often caused by insufficient iodine uptake (can't use iodine)
What is a goiter?
Buildup of Tg as more and more TSH is secreted yet the Tg cannot be iodinated. Leads to enlargement of thyroid
What is Grave's Disease? Is this a result of hypothyroidism or hyperthyroidism? How can we treat this? What is exophthalmos?
Too much thyroid hormone
High basal metabolic rate, excess sweating, eyeball protrusion (exophthalmos)
Most likely autoimmune as body produces antibody that mimics action of TSH
Treatment involves removal of thyroid and give synthetic thyroid hormone
Why was it that many people who had thyroidectomies eventually died at first (think parathyroids)?
Removal of thyroid also lead to removal of parathyroids
Removal of parathyroids meant patients could not properly regulate calcium levels in the blood, leading to death
What are the three effects of PTH?
Increase osteoclast activityIncrease Ca2+ absorption in kidneysIncrease calcitriol levels from kidneys to increase Ca2+ absorption in the gut
Is the cortex glandular in nature or neural?
Is the medulla glandular in nature or neural?
neural - contain chromaffin cells
What cells secrete epinephrine and norepinephrine?
What are the three layers of the adrenal cortex from superficial to deep?
Zona glomerulosa, Zona fasciculata, Zona reticularis
What does the zona glomerulosa secrete?
cells appear to be in clusters, produces aldosterone and other mineralocorticoids
What does the zona fasciculata secrete?
What does the zona reticularis secrete?
Which hormones does ACTH induce the release of?
Cortisol, aldosterone, and gonadocorticoids
What does aldosterone do?
Balances Na+, bicarbonate, Cl-, K+, and H+
Influences fluid balance, water movement, blood pressure
Targets kidney tubules and drives reabsorption of Na+ or excretion of K+, which increases blood volume and blood pressure as water follows sodium
How can too much aldosterone lead to alkalosis?
Aldosterone leads to excretion of H+ into urine, so too much H+ loss leads to elevated pH in fluids
What are the four stimuli to release aldosterone? What is renin and angiotensin II?
Decreases Na+ or increase K+ in blood directly stimulates zona glomerulosa
Decreases Na+ or increase K+ in blood stimulates kidney to release renin which initiates a cascade that produces angiotensin II that stimulates zona glomerulosa
Decreased blood volume and or blood pressure stimulates kidney to release renin which initiates a cascade that produces angiotensin II that stimulates zona glomerulosa
ACTH can stimulate zona glomerulosa
What inhibits aldosterone release?
Increased blood pressure or blood volume causes to secrete atrial natriuretic peptide (ANP) from the heart which inhibits zona glomerulosa
Which is more dangerous = high or low blood pressure?
Low blood pressure.
If blood pressure is too low, then the blood cannot circulate throughout the body, leading to tissue death
This explains why we have more ways to stimulate aldosterone compared to inhibiting it
What does cortisol do? What does it do to sugar levels and fat usage? How is this related to proteins? Immune function and inflammation? Stress?
Responsible for sugar balance (what forms of fuel are available) to optimize brain function
Promotes gluconeogenesis (production of sugar from fats and amino acids) Mobilize fat from adipose for use as energyBreak down muscles to form protein to form ATP or new protein formation Resistance to stress
Depresses immune function (why people who are really stressed get sick easily)
Describe the negative feedback loop of cortisol.
CRH from ventral hypothalamus induces secretion of ACTH in anterior pituitary. ACTH causes cortisol release from zona fasciculata. Cortisol can inhibit ACTH and CRH release. ACTH can also inhibit CRH release
What is Addison's disease? Is it a response to low or high corticoids? What is a defining symptom of this disease? What treatment is there?
Low levels of cortisol and aldosterone
Leads to sodium not being removed from urine and keeping it in blood stream, so water leaves with urine leading to dehydration
Leads to hypotension, weight loss, bronze skin (defining symptom)
Just supplement corticosteroid to treat disease
What is Cushing's disease? Is it a response to low or high corticoids? What is a defining symptom of this disease? What treatment is there?
High levels of cortisol most likely due to tumor in adrenal cortex, ventral hypothalamus, or anterior pituitary
Leads to high levels of glucose in the bloodMuscle and bone wasting due to breakdown by cortisol. Moon face (round face) and fat buffalo hump are defining symptoms
Depresses immune function
Treatment is to remove tumor
What is the general adaptation syndrome? Who founded this?
Founded by Hans Selye (father of stress)
While people may respond to stress differently, everyone follows the same physical paths (controlled mainly by hypothalamus)
What are the three stages of the GAS? Which step is neural and which step is hormonal?
Alarm = initial fight or flight (neural response by sympathetic NS to release epinephrine)
Resistance = long term stress reaction (hormonal response as cortisol is released)
Exhaustion = adrenal glands wear out, leads to many problems like diabetes mellitus, muscle breakdown, etc.
What is a stressor?
Any disturbance to the body
Emotional, financial, physical (temperature, pH, toxin, sleep deprivation, bleeding, etc.)
What is our short term response to stress? Which hormones are involved? Is this an example of neural, hormonal, or humoral response?
NEURAL response as hypothalamus recognizes increased sympathetic NS activity and will stimulate action potentials to spinal cord
We will have reflex in spinal cord that will stimulate adrenal medulla to release catecholamines (epinephrine and norepinephrine)
Increased heart rate, increased BP, convert glycogen to glucose, dilation of bronchioles, increased metabolic rate, increased blood flow to brain to increase alertness and decreased blood flow to digestive and urine activity
What is our long term response to stress? Which hormones are involved? Is this an example of neural, hormonal, or humoral response?
Ventral hypothalamus releases corticotropin releasing hormone which stimulates corticotrope cells of anterior pituitary to release adrenocorticotropin hormone, which causes adrenal cortex to release mineralocorticoids and glucocorticoids (HORMONAL RESPONSE)
We have retention of water and sodium to due release of aldosterone, leading to increased blood volume and blood pressure
Release of cortisol leads to proteins and fats being converted to glucose, increased blood sugar, suppression of immune system
Why would it make sense to suppress the immune system during long term stress?
If you need to survive in the moment, it doesn't need to worry about diseases like the common cold
We don't want to waste resources on the immune system, so we funnel it to other systems that can help us survive in the moment (until stress is over)
What is the difference between homeostasis and stress response?
Homeostasis is constantly working, maintaining controlled conditions in the body
Stress response is temporary, resets controlled conditions in the body so you can survive in the moment (essentially creating our new normal)
What are some artificial corticoids? What are they mainly used for?
Predisolone acetate, dexamethasone
Used to suppress the immune system in autoimmune diseases or organ transplants
What does iatrogenic mean?
What is iatrogenic Addison's disease?
If you add synthetic cortisol, body will decrease ACTH and CRH due to negative feedback, leading to Addison's disease
What is congenital adrenal hyperplasia? Describe the levels of CRH, ACTH, and cortisol with this disease. How can this lead to virilization (development of male
characteristics in females)?
Missing one or more enzymes needed for cortisol synthesis
A decrease in cortisol levels due to inability to properly make it will lead to increase in ACTH levels from the anterior pituitary, stimulating growth of adrenal cortex (can enlarge adrenals)
However, we will only have an increase in cortisol precursors like ACTH and no actual increase in cortisol, leading to conversion of these precursors into testosterone
Can lead to virilization (a lot of testosterone in the body, especially in female
How much of the pancreas is exocrine in nature and how much is endocrine?
99% exocrine (digestive enzymes) and only 1% endocrine
What cells make glucagon and what cells make insulin?
Alpha cells in islet of Langerhans produces glucagon while beta cells produce insulin
What is the effect of insulin?
leading to oxidation of glucose to ATP to give energy, taking extra glucose to convert it into glycogen, and also converting excess glucose to fat
What is the effect of glucagon?
travels to liver to induce glycogenolysis and gluconeogensis to
release glucose into blood
What would we expect the body to do during short term exercise? What two hormones would be important here?
Increase epinephrine and glucagon. Epinephrine increases glycogenolysis. Glucagon increases blood glucose levels by activating gluceoneogensis. Break down fat from adipose. MAINTAIN BLOOD GLUCOSE LEVELS FOR THE BRAIN
What would we expect the body to do during long term exercise? What two hormones would be important here?
Increase ACTH and GH (for recovery and buildup of fuel) release
Increased cortisol secretion to maintain blood sugar levels
Cortisol breaks down proteins to amino acid and increase glucose synthesis
GH slows breakdown of proteins and increase dependence on fats as energy source
What is diabetes mellitus?
A disease in which the body does not produce or respond properly to insulin
What does diabetes mellitus roughly translate to?
"Overflow of honey" - due to insulin imbalance (either secretion or inability to respond to it)
What are the three "poly" symptoms of diabetes mellitus?
Signs are polyuria (too much urine), polydipsia (increased thirst), and polyphagia (increase hunger)
What is type I diabetes?
where you cannot secrete insulin in beta cells (usually found early on)
What is type II diabetes?
where there is too little insulin or little receptors (adult onset)
What is gestational diabetes?
pregnant women are diabetic because human placental lactogen desensitizes insulin receptors, but once baby is born it is gone as HPL levels decrease
What is diabetic ketoacidosis?
is where people do not get treated as they do not get insulin, so body starts burning ketones, leading to acidic pH
What is sugar shock?
Leads to starvation as glucose stays in blood, leading to weight loss and breakdown of muscle, and is source of physiological stress (leading to more glucose in blood - sugar shock)
How can obesity lead to diabetes?
could lead to diabetes as eventually body can give up as it down regulates due to perpetually high glucose levels in blood
What is hypoglycemia?
Chronically low blood sugar
Why do hypoglycemic people tend to be "jumpy"?
because the body will release a lot of glucagon and epinephrine
How can we treat hypoglycemia?
True or False: We would expect to see high levels of glucagon in people with diabetes.
If insulin is low, then glucagon will not be inhibited and will be produced at higher levels than normal
What is type II insulin resistance?
normal levels of insulin but you can't use it
What is type II insulin deficiency?
low levels of insulin due to overworked beta cells
What is the pineal gland? What two substances does it secrete? What part of the brain is this gland located in?
part of epithalamus
Secretes melatonin and arginine vasotocin in response to light and act on hypothalamus and gonads
Melatonin and arginine vasotocin are both involved in GnRH inhibition, which may inhibit reproductive function
What is melatonin? Would we expect melatonin to be higher in kids or adults? In what cases may melatonin be prescribed?
Inhibits GnRH secretion from hypothalamus (can possibly get gonads to shrink)
Regulates sleep cycles by enhancing the tendency to sleep
We would expect melatonin to be higher in kids because they need to recover/sleep more
Can give small doses of melatonin to reset daily rhythms (after jet lag or night shifts)
Propose why animals that breed in the spring may have larger, more active reproductive systems.
During the spring when the days are longer and there is more sunlight, pineal secretions decrease
Pineal secretions like melatonin and arginine vasotocin inhibit GnrH, so less of these secretions means more GnRH
What is seasonal affective disorder?
Overproduction of melatonin during the winter due to very little light throughout the day
Treatment is full spectrum phototherapy (give them "fake" sunlight)
What two hormones does the thymus secrete? Do we expect thymosin to be higher in adults or children?
Thymosin - stimulate and govern production of immune system cells
Thymopoietin - involved in rate at which skin ages
Expect to be largest in kids because this is when you are exposed to environment for the first time, so you need immune system to be very active
What do adipose cells secrete?
Leptin (sends signal to hypothalamus and tells brain to stop eating)
Resistin (antagonizes insulin)
What is cholecalciferol? What is it secreted by?
Hormone secreted by skin that then moves to kidney to become calcitriol Modified by liver and then send to kidney to form active vitamin D3
What is erythropoietin? What is it secreted by?
Acts on bone marrow to lead to red blood cell growth (erythropoiesis) Secreted by kidney
What hormones does the placenta secrete?
Human chorionic gonadotropinHuman placental lactogen. Human chorionic somatomammotropin
What is atrial natriuretic peptide? What is it secreted by?
Hormone released by heart in response to high blood pressure and blood volume
Tells zona glomerulosa to stop making aldosterone, which allows BP and blood volume to drop
Which glands secrete steroids?
How do scientists check if chemicals disrupt endocrine function?
Frogs with exposure to chemicals lead to gender-confused frogs We find clumps of testicular and ovarian tissue inside frogs
True or False: Over one's lifespan, endocrine function largely remains the same unless there are massive structural changes.
How does GH secretion change as you age? Why is exercise important?
GH secretion decreases and is even greater if you don't exercise, whereas if you exercise GH levels may not change at all
Explains why bone mass and muscle mass may decrease as you age
What is the average age of menopause?
Why do people tend to gain weight as you grow?
Thyroid hormone decreases so metabolism rate decreases
How does parathyroid hormone change with age? How does this relate to osteoporosis?
Does not change or may even increase in activity
Parathyroid hormone increases blood calcium levels by increasing osteoclast activity, hence why osteoporosis is more common is older people
This is why it is recommended you exercise so GH is released to increase bone density
How do adrenals change with age?
Cortex decreases while medulla remains the same
How does insulin release change with age?
Hormone release slows with age
Receptors become less sensitive
Blood glucose therefore remains higher for longer, making diabetes mellitus more common
What is blood? What kind of tissue is it? About how much of our body weight is blood?
Live sustaining fluid of bodyConnective tissue but not of fully living cells About 8% of our BW is blood
What are 6 functions of blood?
1. Transport of gases, nutrients, and waste products
2. Transport of processed and regulatory molecules like hormones
3. Maintenance of body temperature
4. Protection against foreign substances
5. Clot formation
6. Regulation of of pH and osmosis
What is the normal pH range of the blood?
What are the three components of blood? How much does each component make up?
55% is plasma
<1% is buffy coat
44% is erythrocytes
What do we usually find in the plasma?
Water, small water soluble proteins, ions
What is the difference between serum and plasma?
Serum is plasma with the clotting factors removed
What do we usually find in the buffy coat?
Platelets and WBCs
What is the total volume of blood in males?
5 to 6 L
What is the total volume of blood in females?
4 to 5 L
About how many platelets mL^3?
About how many WBC mL^3?
4.5 to 11 thousand
About how many RBC mL^3?
4.2 to 6.1 million
How many RBCs do women have?
4.25 to 5.25 million cells per mL^3 of blood
How many RBCs do men have?
5 to 5.75/6 million cells per mL^3 of blood
Do men or women have more RBCs? Why?
men have more due to testosterone stimulating erythropoietin
What happens if we have too few or too many RBCS?
If RBC count is too low, then blood is thin and if blood is thick it is not viscous enough
About how many RBCs do we have in our body? How many do we replace per second?
We have about 25 trillion RBCs. We replace 2.5 million RBCs per second (replace about 1% each day)
About how large are RBCs?
7.5 um in diameter
What benefit is there with RBCs being biconcave?
Increases surface area to volume ratio for gas exchange
A thicker edge than center allows for more gases to move in and out of the RBC
Biconcavity also allows RBCs to bend or fold around thin center to pass through capillaries
What is spectrin? Why is this important?
Protein in cell membranes that provide shape and elasticity for RBCs so they can fit in narrow blood vessels
Capillaries are often the width of only an RBC
What is a benefit of RBCs having no organelles and nucleus?
You have more space for Hb in the cell
No organelles like mitochondria means you have to rely on anaerobic respiration, so you don't waste O2 for oxidative phosphorylation
How many Hb are found in an RBC?
250 million (1/3 of RBC mass)
So 1 billion O2 molecules per RBC
How many grams of Hb are found per CC of blood in males?
13-18 g of Hb per CC of blood
How many grams of Hb are found per CC of blood in females?
12-15 g of Hb per CC of blood
How does Hb change when it is bound to oxygen and when it is not in regards to color?
Oxyhemoglobin is bright red while deoxyhemoglobin is usually dark red or purplish
Deoxyhemoglobin can bind to CO2 to give carbaminohemoglobin
What is carbaminohemoglobin?
hemoglobin bound to carbon dioxide
About how much CO2 is carried to the lungs as carbaminohemoglin?
True or False: Carboxyhemoglobin is Hb bound to CO, which is much more likely to bind to heme than O2.
What is the role of NO being bound to hemoglobin?
Hb transports NO by binding to cysteine residueNO induces relaxation of smooth muscle of blood vessels
What is hematopoiesis? Where does this happen?
The production of blood cellsOccurs in red bone marrow
What is the progenitor cell of all blood cells?
One daughter cell remains a hemocytoblast while one becomes a myeloid or lymphoid stem cell
What is the myeloid and lymphoid stem cell lineage?
Two lineages possible from the division of hemocytoblasts
Which cells come from the myeloid lineage ?
RBCs, platelets, and all but 1 WBC
Which cells come from the lymphoid lineage?
What are the four classes of "blast" cells that myeloid stem cells can differentiate into?
1. Proerythroblast → RBC
2. Megakaryoblast → platelet
3. Myeloblast → basophils, eosinophils, neutrophils
4.Monoblast → monocytes
What are colony-stimulating factors?
Factors that regulate the development of different types of formed elements Erythropoietin is an example that stimulates RBC production
How long does erythropoiesis take?
How do RBCs form? What are the 7 stages?
Early erythroblasts have nuclei and ribosomes to make Hb and spectrin
Accumulation of Hb and ejection of the nucleus, forming a biconcave cell
Proerythroblast → early and late erythroblast → normoblast → reticulocyte → erythrocyte
When is erythropoietin released? What other hormone can influence EPO secretion? What secretes erythropoietin?
Presence of decreased blood oxygen levelsTestosterone releases erythropoietin, which is released from kidneys
What happens if RBCs become too old? Why is this dangerous? How long do RBCs last?
RBCs last about 4 months (120 days) and so WBCs will kill RBCs after so we don't run into risk of RBC explosion, releasing toxic iron. Iron from Hb is stored so it can be reused again while bilirubin is
How are RBCs broken down?
1. Hb is split into heme and globin.
2. Globin gets converted into amino acids which can be recycled.
3. Iron of heme gets attached to transferrin protein and is stored for future use in spleen.
4. The heme pigment (bilirubin) is used in bile production and is excreted.
What is anemia? Is this really a disease?
Low O2 carrying capacity of the blood. Not a disease but a symptom as there are multiple causes for anemia
What are symptoms of anemia?
Pale, Shortness of breath, Chills, Tiredness
What is hemorrhagic anemia?
Loss of O2 capacity because of low RBC count due to blood loss from trauma, ulcers, or chronic stuff
What is hemolytic anemia? What causes this?
Premature lysis of RBCs. Caused by malaria or other blood parasites
What is aplastic anemia? What is this caused by?
Inability of red bone marrow to produce RBCs. Usually damage to stem cells from toxins, cancers, chemotherapy, etc.
What is iron deficiency anemia? How common is this form of anemia?
Insufficient intake or absorption or by excessive iron loss, leads to reduced Hb production
Most common form of anemia
What is pernicious anemia? What is this a sign of?
Reduction in cell division of RBCs leads to reduced number of RBCs
Caused by lack of Vitamin B12 in diet or lack of intrinsic factor to uptake of Vitamin B12
What is nascobal?
a medication where you apply Vitamin B12 in lining of nose for absorption
What is sickle cell anemia? How can we fix this?
Substitution in amino acid leads to abnormal Hb, causing RBCs to change shape, leading to hypoxia
Genetic disease (heterozygous advantage with malaria)
Conduct transfusion to replace cells
What is thalassemia? In which type of people is this common in? What part of the hemoglobin is in question?
Common of people from Mediterranean descent. Globin chains tend to be thinner so lack of functional Hb Conduct transfusion to replace cells
What is polycythemia? How is this involved in doping?
High RBC cell count, leading to very thick blood and heart has to work harder
Can be a result of cancers, low O2 from high altitudes, chronic dehydration, tumor causing too much erythropoietin
Involved in doping as increase in RBC leads to better O2 capacity
How does jaundice happen? Why is this common in premature infants? How can we treat this?
Build up of bilirubin in the body, leading to yellow skinCommon in premature infants as livers are not fully developed yet Exposure to sunlight speeds up bilirubin breakdown ("bili-lights")
What is ameboid movement?
WBCs move by putting out irregular cytoplasmic projections, allowing for directed movement
What is chemotaxis?
"Following the trail" of damaged tissue by leukocytes
What is diapedesis?
Squeezing through endothelial tissue to reach area of damage by leukocytes
Describe the characteristics of leukocytes? What is their common size? What is the ratio of WBCs to RBCs? Are they nucleated and have organelles?
Big size difference (2 to 24 microns) 1 leukocyte per every 800 RBCs Are nucleated and have organelles
Q: Rank the leukocytes in order of prevalence. What is the abundance of each?
Which leukocytes are granulocytes?
neutrophils, eosinophils, basophils
Which leukocytes are agranulocytes?
lymphocytes and monocytes
What are two main differences between granulocytes and agranulocytes?
Granulocytes have large cytoplasmic granules and lobed nuclei while agranulocytes have very small granules that cannot be seen and have un-lobed nuclei
Q: How are neutrophils, eosinophils, and basophils named?
Neutrophils = stain with acidic and basic dyes
Eosinophils = stain red with acidic dyes
Basophils = stain purple with basic dyes
What is leukopoiesis?
production of WBCs
What usually stimulates leukopoiesis?
Macrophages release cytokines that can hormonally cause stimulation of WBCs
What are colony stimulating factors?
Different colony stimulating factors causes the creation of different WBCs in bone marrow
What are interleukins?
Cytokines that stimulate the growth of B and T lymphocytes
What cell do all granulocytes originate from?
Myeloblast → Promyelocyte
These promyelocytes can differentiate into the different granulocytes
What are the two main classes of leukemia?
Myelocytic leukemia = involves myelocytes
Lymphocytic leukemia = involves lymphocytes
What is the difference between acute and chronic leukemia? How fast do they progress? For which type would we expect blast cells to be involved? For which type would we expect myelocyte and band cells to be involved? Which one is common in youth and which one is common in elders?
Acute = rapid onset, involves "blast" cells so you produce immature blood cells, common in youth
Chronic = slower progression, involves myelocytes and band cells, common in elders
What are common characteristics of leukemias? What can it lead to? What is it treated by?
Immature, non-functional WBCs in blood stream Anemia and hemorrhagingBone marrow full of cancerous leukocytesCan lead to internal hemorrhage and infection Treated by radiation, chemo, bone marrow transplant
What is a differential count? Why is this important?
A count of the different mature WBCs in blood
Make sure it follows distribution we mentioned above (NLMEB) otherwise there is a problem
What is leukopenia? What does this commonly lead to?
Reduced numbers of WBCs
Risk of infection because they can't respond
What is leukocytosis? Why does this usually happen?
Increased number of WBCs due to any recent challenge or infection to the body
What is mononucleosis? What is another name for this? What is it caused by?
"Kissing disease" - caused by Epstein-Barr virus that infects salivary glands and lymphocytes.
High and atypical WBCs.
No cure, just runs its course
What are the symptoms of mononucleosis?
Tired, achy, low level sore throat Low grade feverSwollen lymph nodes
How big are platelets?
About 3 um in diameter
Describe the development of platelets.
Hemocytoblast → megakaryoblast → promegakaryocyte with granules →
megakaryocytes with many proplatelets → proplatelets break off to give platelets
How long do platelets last?
Last anywhere from 5 to 9 days
What is a proplatelet? What do platelets granules contain?
Proplatelets contain serotonin, calcium, enzymes, ADP, platelet derived growth factors
What is the abundance of platelets?
Quarter to half a million platelets per mL^3 of blood
What is the function of platelets?
Causes blood clotting by forming platelet plugs and promoting formation/contraction of clots
How are platelets inhibited?
Inhibited by prostaglandins and nitrous oxide (NO) that vasodilate blood vessels. Only become sticky when needed
What is hemostasis?
The process of clotting and stopping bleeding
What are the three steps of hemostasis?
First, blood vessel undergoes spasms (constriction of blood vessels), Platelet plug formation, Coagulation (clot forming)
What is a vascular spasm? What compounds cause constriction?
The immediate but temporary constriction of a blood vessel.
Constriction caused by thromboxanes and endothelin closes vessels to stop flow and blood loss
What is a platelet plug?
Accumulation of platelets that stick to each other and to connective tissue to seal off lesion in blood vessel
Describe the formation of a platelet plug.
Damage to blood vessels releases von Willebrand factors that allow platelets to stick to collagen fibers of vessels
Platelets become activated and undergo platelet release reaction where they release chemicals like ADP, serotonin, calcium, PDGFs, thromboxane via exocytosis
Platelets are activated either through binding to collagen or activation by other platelets via ADP and thromboxane
Fibrinogen connects platelets to each other, creating platelet plug
What is coagulation? What is the main component of a clot?
Formation of a blood clot, which is a network of threadlike fibrins that traps blood cells, platelets, and fluids
Which platelet factor is related to phospholipids?
Platelet factor III
Main role of the extrinsic pathway?
initiation of coagulation
Main role of the intrinsic pathway?
amplification of cascade
What is the extrinsic coagulation pathway? What activates this pathway?
Damage to tissue outside of blood vessels releases thromboplastin (platelet factor III)
Factor VII, thromboplastin, and calcium form a complex that activates factor X that activates common pathway
What is the intrinsic coagulation pathway? What activates this pathway?
Damage to only blood vessel, causing platelets to come in contact with collagen.
Factor XII comes in contact with collagen and is activated, and this activates Factor XI.
Factor XI with calcium activates Factor IX.
Factor IX with calcium, platelet phospholipids, and Factor VIII leads to activation of Factor X which activates common pathway
True or False: The extrinsic and intrinsic pathways are distinct.
Thromboplastin/factor VII complex from extrinsic pathway can activate IX in the intrinsic pathway
What is the common coagulation pathway?
Factor X, Factor V, platelet phospholipids, and Ca2+ form prothrombinase.
Prothrombinase activates thrombin from prothrombin.
Thrombin and calcium activates soluble fibrinogen to insoluble fibrin.
Thrombin also activates Factor XIII and other previous factors, leading to positive feedback loop.
Fibrin along with activated factor XIII creates fibrin clot
What factors can thrombin activate and create a positive feedback loop?
What mechanisms limit clot growth or formation?
Blood contains anticoagulants preventing clotting factors from initiating clot formation in normal blood vessels. Swift removal and dilution of clotting factors (if below a critical condition of clotting factors, clotting won't happen)
What are anticoagulants?
factors that inhibit clotting
What prevents random platelet adhesion?
Smooth endothelial lining of blood vessels prevents platelets from binding
What is prostacyclin?
Anti-thrombic substances like nitrous oxide and prostacyclin secreted by endothelial cells
What is quinine?
Vitamin E quinine acts as anticoagulant
What is disseminated intravascular coagulation? How can this lead to too much yet too little clotting? When is this common?
Disseminated Intravascular Coagulation (DIC).
Widespread random clotting blocks intact blood vessels (too much clotting).
Leads to severe hemorrhage in other areas of the body as platelets are used up in unnecessary clots (too little clotting).
Common in pregnancy, septicemia, incompatible blood transfusions
How does the body react to blood loss? Where is most blood redirected after blood loss? About how much blood can you lose and still maintain constant blood pressure?
If you lose more than 10% of blood, sympathetic ANS will lead to heart contracting harder and vessels will constrict to maintain BP
You really only need blood in heart and brain so blood is redistributed here
Works to maintain BP up to 40% blood loss
How do we remove a clot?
Clot retraction leads to formation of scab as clot shortens via actin and myosin and serum is squeezed out in about first hour
Which substances allow for the rebuilding of blood vessels? What protein dissolves a clot?
Platelet derived growth factor (stimulates growth), fibroblasts, and vascular endothelial growth factors allows rebuilding of blood vessel
Thrombin also activates plasminogen to form plasmin, which dissolves clot by breaking fibrin
What is thrombus?
stationary blood clot
How can a thrombus lead to tissue damage?
Occlusive clots can lead to damage to tissues in the general vicinity as it has lower blood flow
What is an embolus?
moving blood clot
How can an embolus lead to severe disorders like stroke and heart attack?
If a large clot gets into a small vessel, it can block the vessel Can lead to heart attack, stroke, pulmonary embolism
What are some anticoagulants?
heparin, warfarin, aspirin
Which anticoagulant is commonly used during heart surgeries?
Which anticoagulant is also known as rat poison?
What is thrombocytopenia? What usually leads to this? What is the main treatment for this?
Too little platelets in the blood (less than 50000 per mL^3) Usually due to suppression or destruction of bone marrow. May be a result of cancer treatment that attacks bone marrows. Can also be a result of overdosing on anticoagulants. Main treatment is full blood transfusion to add platelets
How does liver failure lead to clotting failure?
The liver is where the clotting factors are synthesized
What is hemophilia? Which factors are involved? Is this autosomal or sex linked? What do we mean when we say this is not an all or none disease? What is the main issue of all hemophilias?
Deficiency of factors VIII, IX, and XI.
Even a 5% increase in one of these factors can lead to improvement, meaning hemophilia is not an all or none disease.
Tends to be sex linked. Inability to form prothrombin activator in the common pathway
What is von Willebrand disease? What does this prevent?
Lack of von Willebrand factors prevents formation of platelet plug
What makes blood during early fetal development?
Yolk sac, Liver, Spleen
About what month of development does bone marrow start making blood?
What are "blood islands" and what do they form from?
Bone marrow develops from mesenchyme cells called "blood islands".
Blood islands are clusters of mesodermal cells that become blood vessels on outside and blood cells on side
What is HbF? Why is it important that HbF have a higher affinity?
Fetal hemoglobin. Has higher affinity for O2 so it can take O2 from mother and get it first
What is hemopoiesis? How does this change from kids to adults?
Formation of blood cells.
In children it occurs in all bones but as red bone marrow is replaced with yellow it becomes confined to epiphyses of long bones
How does aging affect blood?
Leukemias, anemias, clotting disorders are more common as body starts to wear down and bone marrow is replaced with fat
Why are leukemias, anemias, and clotting disorders more common?
As vessels age and roughen up, unnecessary clots are more likely
What are the "two pumps" of the heart?
pulmonary circulation and systemic circulation
What pump is the right side of the heart is related to?
What pump is the left side of the heart is related to?
What are four main functions of the heart?
1. Generate blood pressure via contractions
2. Route blood through pulmonary and systemic circulations
3. Ensure one-way blood flow via valves in the heart and blood vessels
4. Regulate blood supply by modifying the rate of contraction
Between what ribs is the heart found? Describe the orientation (centering and angling).
Between ribs 2-5 in the mediastinum deep to the sternum. Oriented on a diagonal instead of vertical with base directed posteriorly and
slightly superiorly to apex.
Centered off to the left to where about 2/3 of the mass lies to the left of the midline
What is the apex and base of the heart?
Apex = blunt, rounded point of the heart/ top
Base = larger, flat part at the opposite end of the heart/ bottom
What all does the mediastinum contain?
Trachea, Esophagus, Thymus, Heart
Where is the location of the great vessels in regards to the ribs and vertebrae?
At the level of the sternal angle close to the second ribFrom the back, find the T4-T5 intervertebral disc
What is the pericardium?
double-walled sac that encloses the heart
What are the 2 layers of the heart?
fibrous pericardium and inner serous pericardium
What is the role of the fibrous pericardium?
tough and prevents over-filling of heart and anchors to mediastinum and is continuous with great vessels
What is the role of the serous pericardium?
includes parietal and visceral layers with pericardial cavity filled with serous fluid to prevent friction
What is another name for the visceral pericardium?
What are the three layers of the heart wall?
What kind of tissue is endocardium made of?
simple squamous epithelium
which layer of the heart is impermeable to O2?
endocardium is impermeable
What is pericarditis?
inflammation of the pericardial sac
What can pericarditis lead to?
pericardial effusion and cardiac tamponade
What is cardiac tamponade?
compression of the heart by an accumulation of fluid in the pericardial sac
What is the function of valves?
Ensure one way flow of blood
What are atrioventricular valves?
Allows blood to go down ventricle and prevent back flow to atrium
Which side of the AV valve is convex and which side is concave?
Convex on side facing atrium and concave on side facing ventricles
What are the two atrioventricular valves?
1. Tricuspid between RA and RV
2. Bicuspid or Mitral between LA and LV
What are chordae tendinae?
Filaments connecting the tips of the AV valves to the papillary muscles in the ventricles - prevents backflow of blood into the atrias
What are papillary muscles?
Small muscles that anchor the heart strings or cords.
What are semilunar valves?
pulmonary and aortic valves. Valves that allow blood to go through pulmonary artery or aorta and prevent back flow into ventricles.
Which side of the SL valve is convex and which side is concave?
Convex side faces ventricles and concave side faces vessels
Describe the orientation of the AV and SL valves during relaxation of the atria, contraction of the atria, contraction of the ventricles, and relaxation of the ventricles.
Relaxation of atria = gravity drains blood from veins into atria and ventricles, so AV valves open and SL valves closed
Atria contraction = squeeze pushes blood into ventricles, so AV valves remain open and SL valves are still closed
Ventricle contraction = AV valve closes, papillary muscles contract, and SL valves open
Relaxation of ventricles = cusps of SL valves catch blood and close
If you have hypertension, how does opening and closing of the valves change?
It takes more effort to open and close valves.
After-load on SL valves increases, influencing amount of blood heart can pump out
True or False: Most blood from atria to ventricles is sent through contraction of the atria.
Most blood leaks into ventricle via gravity, while atrial contraction finishes off blood transfer
What is auscultation?
Listening to sounds from the heart with a stethoscope
What is the "lub"? Is it high pitched or low pitched?
Lub = AV valves shut and blood hits valves.
First heart sound, low pitched.
Occurs at beginning of ventricular systole and is caused by shutting and vibration of AV valves
What is the "dub"? Is it high pitched or low pitched?
Second heart sound, high pitched.
Occurs at beginning of ventricular diastole and is caused by shutting and vibration of SL valves
What is systole in regards to "lub" and "dub"?
time between "lub" and "dub"
What is diastole in regards to "lub" and "dub"?
time between "dub" and "lub"
True or False: Some people have a third heart sound due to blood flowing in very fast into the ventricles.
What is heart murmur?
abnormal heart sounds
What is valvular insufficiency?
the reflux of blood back through valves as valves cannot fully close, leading to swishing sound after valves close
What is valve stenosis? What usually leads to this? Which valve most commonly gets this?
Stiffening or narrowing of heart valves, reducing amount of blood that can flow. Can be due to accumulation of salts or inflammation. Tends to happen most in aortic semilunar valve as this is what feels most force
How can someone who has had valve stenosis and has had their valve replaced feel better after surgery?
Body adapts to hypoxic conditions due to reduced blood flow from valve stenosis.
Once a functional valve is set in place, blood flow is back to optimal levels, so person's tissues receive a lot of oxygen and they feel much better
Describe the pathway of blood through the heart.
IVC/SVC -> right atrium -> tricuspid valve (AV) -> right ventricle -> Pulmonary semilunar valve -> pulmonary truck/arteries -> LUNGS -> pulmonary veins -> left atrium -> aortic semilunar valve -> aorta -> body
What are the three main branches of the left coronary artery? What parts of the heart do they supply blood?
Circumflex artery - supplies blood to posterior of heart.
Anterior interventricular artery - supplies blood to most of anterior of heart. Left marginal artery - supplies blood to lateral wall of LV
What are the two main branches of the right coronary artery? What parts of the heart do they supply blood?
Right marginal - supplies blood to lateral wall of right ventricle. Posterior interventricular - supplies blood to posterior and inferior part of heart
What is an anastomosis? Why is it important that we have these?
Junction between coronary vessels that allow them to communicate, gives alternate pathways in case one artery is blocked
What are the three coronary veins? What are all three vessels connected to? What parts of the heart do they take blood? What do they all drain into?
Small - right side of heart. Middle - posterior side of heart. Great - left side of heart. All drain into coronary sinus which goes into right atrium
Describe the skeleton of the heart. What are fibrous rings? What is the electrical importance of this fibrous tissue?
Consists of plate of fibrous connective tissue between atria and ventricles
Fibrous rings around AV and SL valves for solid support, reinforcing valve openings
Electrical insulation between atria and ventricles as both contract at different times
Attachment site for cardiac muscles
What are intercalated discs?
junctions between cells that anchor cardiac cells
What are desmosomes?
A type of junction in which cells are fastened together in strong sheets (like rivets)
What are gap junctions?
Small tunnels that connect cells, facilitating the movement of small molecules and ions between the cells.
What is a functional syncytium?
All the cells are connected via gap junctions, so they act like one massive cell All atrial cells fire at once and all ventricle cells fire at once
What does it mean to for the heart to be autorhythmic?
Spontaneous and regular contract of the heart muscles. Even when heart is removed from the body, it can beat on its own as long as it has proper needs.
How many of our heart cells are autorhythmic?
1% of our cardiac cells are autorhythmic
What is a node?
Lumps of modified cardiac muscle cells
What ions contribute to the heart's resting membrane potential? What is the permeability of each?
Low permeability to Na+ and Ca2+.
Higher permeability to K+
What is the pacemaker? What is the formal name for this? Where is it located? What all does it innervates?
Sinoatrial node innervates right and left atria, as well as AV node. SA node connects to atrioventricular node where there is a little pause. Signal goes to apex of heart and then causes ventricles to contract
What are the two nodes of the heart? What are their locations? Which chamber are both nodes found in?
Sinoatrial node = medial to the opening of superior vena cava. Atrioventricular node = medial to tricuspid valve. Both nodes are found in RA
What is another name for the Bundle of His?
Passes through a small opening in fibrous skeleton to reach inter-ventricular septum where it divides into right and left bundle branches
What are Purkinje fibers?
Modified cardiac muscle cells that conduct action potentials that spread throughout the entire ventricles
How long do action potentials of cardiac muscle last? How does this compare to skeletal muscle?
200 to 500 ms. Skeletal muscle APs take less than 2 ms
What are the four phases of a cardiac muscle AP?
1. Rapid depolarization phase
2. Slow early repolarization
3. Prolonged period of slow repolarization (plateau phase)
4. Rapid final repolarization
What causes rapid depolarization?
Voltage gated Na+ channels open, so Na+ diffuses into the cell until potential is about +20 mV.
Ca2+ voltage gated channels open up slowly.
K+ voltage gated channels close
What causes early re-polarization? At what potential does this start?
Voltage gated Na+ channels close at +20 mV and some voltage gated Ca2+ channels close.
Some K+ voltage gated channels open
What causes the plateau stage?
Voltage gated Ca2+ channels remain open, counteracting potential change produced by K+ moving out of cell
What causes rapid re-polarization?
Voltage gated Ca2+ channels close and K+ channels fully open
What is calcium induced calcium release?
Ca2+ movement into the cell stimulates the release of more Ca2+ from the sarcoplasmic reticulum.
This Ca2+ released then leads to muscle contraction
How do the action potential of skeletal and cardiac muscle cells differ in regards to connections between cells and speed?
Cardiac muscle cell action potentials occur from cell to cell via gap junctions whereas skeletal muscle APs occur in one cell.
Cardiac muscle AP is slower as cells are thinner and gap junctions slow down AP
Why is tetanus not possible in cardiac muscle cells?
Plateau phase leads to extended refractory period, allowing cardiac muscle to contract and relax completely before the next AP.
In skeletal muscle, the refractory period is where the skeletal muscle contracts but doesn't relax yet, so we can build APs on top of each other
Describe the AP of pacemaker cells. What is a pacemaker potential? What is primarily responsible for for the depolarization phase?
Small number of non-gated Na+ channels open and Ca2+ slowly open while K+ permeability decreases, leading to slow increase in potential (pacemaker potential is spontaneously developing local potential).
Once we reach threshold, Ca2+ open and K+ channels remain closed (depolarization).
Eventually Ca2+ close and K+ open (re-polarization).
KEY IS THAT THE PACEMAKER POTENTIAL IS LEAKY AND NOT CONSTANT AS NA+ CHANNELS ARE OPEN LITTLE BY LITTLE
What causes depolarization in normal cardiac muscle and in pacemaker cells?
Cardiac muscle = movement of Na+ into the cell. Pacemaker cells = movement of Ca2+ into the cell
What is the difference between an absolute and relative refractory period?
Absolute = cardiac muscle is completely insensitive to further stimulation. Relative = cell is sensitive to stimulation, but greater stimulation is needed
Does cardiac muscle or skeletal muscle have a longer refractory period? Why might this be important?
Cardiac muscle has longer refractory period.
This prevents tetanic contraction and ensures each heart contraction is of the same strength to ensure constantly pumping
Describe the conduction system of the heart. What all does the SA node innervate? How much does the signal between the SA and AV node delay? Why is there a delay? What is the only electrical connection between the atria and ventricles?
SA node has auto-rhythmic cells that fire 70 to 75 times per minute and innervates the RA and LA while also relaying signal to AV node.
Signal from SA to AV node delays about 0.1 sec as it is smaller and also serves as backup node (much slower than SA node). From AV node, signal goes through Bundle of His down to apex of heart, from there it is carried through bundle branches and Purkinje fibers that go to papillary muscles (close flaps).
AV bundle is only electrical connection between atria and ventricles
Why is it important that the AV node delays?
Pacemaker innervates both atria so we need them to contract to release as much fluid as possible for ventricles to pump.
If there was no delay, ventricle would not fully contract all possible blood.
Ventricles need to work together to create a constant pulse
How fast of an HR does the SA node produce?
70 to 80 beats per minute.
This generates action potential faster than other potential pacemaker cells, which is why the SA node is the pacemaker
How fast of an HR does the AV node produce?
40 to 60 bpm
What is an ectopic focus?
Any part of the heart other than the SA node that produces a heartbeat
What is the difference between intrinsic and extrinsic regulation?
Intrinsic = heart's normal functional characteristics change (heart can be regulated in the body or outside under proper conditions).
Extrinsic = neural and hormonal control
Does the PSNS or SNS play a bigger role in affecting the heart?
SNS can increase cardiac output by 50-100%, while PSNS can only decrease by 10-20%
What is the cardioacceleratory center? Which nerves are involved? What neurotransmitter is involved? Do nerves that inhibit the heart innervate all of the heart or just specific parts?
Speeds up heart rate.
Sympathetic ANS - pre-ganglionic fibers innervate upper thoracic sympathetic chain, while post ganglionic nerves are called cardiac nerves.
Innervates nodes of heart, coronary blood vessels, and cardiac muscle so that you can have a quick reaction to speeding up heart beat.
Norepinephrine NT increases permeability to Ca2+
True or False: There comes a point where the heart can beat too fast and cardiac output can actually decrease.
If HR becomes too fast, ventricular diastole decreases as there is not enough time between contractions for the ventricles to fill up. Also, if heart beats too fast the strength of contraction can decrease as waste metabolites build up
What is the cardioinhibitory center? Which cranial nerve is involved? What neurotransmitter is involved? Do nerves that inhibit the heart innervate all of the heart or just specific parts?
Slows down heart rate.
Takes time and only innervates nodes (you don't need to slow down immediately like when you need to when you have to speed up).
Vagus X is involved.
ACh NT causes cell to become more permeable to K+, hyperpolarizing the cells
True or False: Slowing down the heart rate always leads to a decrease in cardiac output.
If venous return stays the same, slowing down the heart rate actually increases cardiac output because there is more time between contractions for the ventricles to fill up
What is the bainbridge reflex?
Baroreceptors in carotid arch and atrial muscles relay pressure info to cardioacceleratory center that trigger the SA node to speed up so we can increase pressure in vessels
What is the difference between epinephrine and thyroxin in regards to effect on HR?
Epinephrine = short term increase, released by adrenal medulla. Thyroxin = gradual, long term increase, released by thyroid
True or False: EKGs detect individual action potentials.
They detect the summation of all action potentials transmitted by cardiac muscle cells through heart
What is the P wave of an EKG?
atrial depolarization (contraction)
What is the QRS wave of an EKG?
ventricular depolarization (contraction)
What is the T wave of an EKG?
ventricular repolarization (relaxation)
What is the PR interval?
interval between P and QRS waves = about 0.16 seconds = atria contract and start to relax
What is the QT interval?
interval between QRS and T waves = about 0.36 seconds = ventricles contract and start to relax
What is a complete heart block?
Aka third degree heart block. There are more P waves than QRS complexes due to conduction block
What does it mean to have an "unfollowed" P?
P and QRS waves are not coordinated and delay is visible, so PR interval is longer
What may be some reasons for an "unfollowed" P?
Delay due to damage of atrial muscle. Delay to due dilated atrium. Delay due to AV node or Bundle of His transmission errors
What is a premature ventricular contraction (PVC)? How does it look on an EKG?
QRS waves without any P waves. There is not enough time for the ventricles to fill completely
What is a bundle branch block? How does it look on an EKG?
Prolonged QRS complex due to delays or blockage in bundle branches
What is fibrillation? What makes this dangerous?
Rapid disorganized firing of the heart chambers. Can lead to no blood movement
What is atrial fibrillation? Is this life threatening? How does it look on an EKG?
No clear P waves and rapid QRS complexes
Not as dangerous as atrial contractions are not that crucial for life and is more about efficient heart beating
What is ventricular fibrillation? Is this life threatening? How does it look on an EKG?
No P, QRS, or T wavesVery dangerous as blood is not being fully pumped out throughout the body
What is arrhythmia? What are some drugs that can cause this?
Irregular uncoordinated heartbeat. Caused by nicotine and caffeine
What is defibrillation?
Reseting the conduction system by sending a huge electrical pulse
What is usually the backup for the SA node as a pacemaker? What is an issue with this?
AV node can produce a heart rate of 40-60 bpm, but this is not as fast as the 70-80 bpm of the SA node
What is bradycardia? What is it caused by? What can this be a sign of?
Very low HR (<60 bpm), leading to decreased body temperature.
Can be caused by drugs, overactive parasympathetic ANS to cardioinhibitory center, athlete (high stroke volume). If HR slows too much, can be sign of swelling of parasympathetic ANS in brain.
What is tachycardia? What is it caused by? What can it lead to?
Rapid HR (>100 bpm), may lead to ventricular fibrillation. Can be caused by high body temperature, stress, drugs, and heart disease
What three factors influence stroke volume?
Preload = amount of stretch of heart at the end of diastole. Contractility = how much the tissue contracts. Afterload = amount of pressure ventricles need to overcome to open valves
What is cardiac output?
heart rate x stroke volume
What is the average cardiac output?
What is the total blood volume?
What is the formula for cardiac output?
CO = heart rate * stroke volume (volume per beat)
What is the formula for stroke volume?
End diastolic volume - end systolic volume
What is venous return? How does this influence stroke volume?
The amount of blood returning to the heart from systemic circulation.
An increase in venous return increases diastolic volume and decreases systolic volume (increasing stroke volume)
What is cardiac reserve? Is it good to have a large or small cardiac reserve?
The difference between cardiac output when a person is at rest and maximum cardiac output.
Greater cardiac output means greater capacity for exercise and ability to respond to stress
What factor directly influences the force of contraction by cardiac muscle?
Degree of stretch of cardiac muscle cells
What is preload? How does this relate to cardiac output?
The extend to which the ventricular walls are stretched. Increased preload means increased cardiac output
What is the Starling law of the heart?
There is a positive relationship between the venous return and preload
What is after-load?
The pressure the LV must produce to overcome pressure in the aorta and move blood into aorta (think force needed to open door).
Can also be thought of as pressure of aortic blood causing semilunar valves to close.
The larger the after-load, the lower the cardiac output
Describe how blood vessel diameter, venous return, preload, stroke volume, and cardiac output change during and after exercise.
During = blood vessels dilate allowing more blood to flow from and to heart, increasing venous return, increasing preload, causing an increased force of cardiac muscle contraction due to extra stretch, increasing stroke volume and cardiac output.
After = blood vessels constrict, decreasing venous return, pre-load, contraction strength, stroke volume, and cardiac output
What is contractility? How can we change this?
Intrinsic strength of ventricles. Influenced by amount of calcium and hormones like epinephrine and thyroxine
What is isovolumetric contraction?
The quick period in time where the AV and SL valves are closed (volume is constant) but pressure quickly builds up in ventricles
What is isovolumetric relaxation?
The quick period in time where the AV and SL valves are closed (volume is constant) but pressure quickly decreases in ventricles
What is the baroreceptor reflex? What are baroreceptors?
Changes in blood pressure can lead to changes in heart rate and force of contraction.
Stretch receptors found in certain large arteries measure blood pressure by detecting degree of stretch of blood vessel walls
Where is the cardioregulatory center located?
Medulla oblongata. Contains the cardioacceleratory center and cardioinhibitory center
What happens to SNS and PSNS when BP increases or decreases?
Increase = reduce SNS and increase PSNS. Decrease = reduce PSNS and increase SNS
What is the chemoreceptor reflex?
Changes in blood CO2, O2, or pH can lead to a change in heart rate and respiration rate
What happens to heart rate if blood pH is acidic?
Increase blood flow to get more CO2 out of blood. Leads to increase in heart rate
What happens to heart rate if blood pH is basic?
Means that CO2 levels are too low, so we see an increase in PSNS and decrease in SNS, leading to decreased HR (so that blood can pick up more CO2 from respiring tissue)
What does the heart start off as?
Two endothelial tubes that are fused together (Day 20).
This "heart" will start rhythmically pumping (Day 22).
Heart continues to elongate and starts to bend (dextral looping) to form arterial end and ventricles (Day 24).
Heart continues to bend as ventricle starts to move caudally and atrium starts to move cranially (Day 28).
Bending is complete with formed vena cava, aorta, ventricles, and atria (Day 35)
What is the foramen ovale? What does this become?
Hole between left and right atria.
There is no functioning pulmonary circuit, so we bypass RV and send blood from RA to LA.
Becomes fossa ovalis
What is the ductus arteriosus? What does this become?
Connection between pulmonary trunk and aorta so blood in pulmonary trunk drains directly into aorta.
Becomes ligamentum arteriosus
What is ASD? How can this lead to a stroke?
Hole between left and right atrium leads to blood flowing from left to right atrium instead of LA to LV.
Higher stroke defect because blood from lungs that pools in LA will just leak back into RA and lungs
What is VSD? How can this be fixed?
Ventricular septal defect. There is a hole between RV and LV. Blood ends up going from LV to RV as there is a hole and LV is stronger than RV.
Reduces circulation body-wide and can lead to stroke, blood in lungs, congestive heart failure.
Can put in occluder patch via catheter to clear up hole and get tissue to grow in region
What is coarctation of the aorta?
Aorta is narrowed, increasing workload of left ventricle as pressure in aorta is higher.
Can led to hypertrophy of the left ventricle
What is tetralogy of fallot?
Occurs about 1 in every 2000 births.
Pulmonary trunk is too narrow.
Pulmonary valve is stenosed, pushing blood back into RV, leading to hypertrophied RV.
Also have ventricular septal defect so we have blood flowing from LV to RV. Aorta opens from both ventricles. PUMPING EFFICIENCY IS VERY BAD
Why is hypertrophy of ventricles bad? What is a parachute procedure?
Muscles get stretched out so they are not as effective in contraction.
Parachute procedure is where a device is placed inside the ventricle to help with contraction (blocks out part of the heart to prevent too much contraction)
What is a blue baby operation?
Used to relieve cyanotic babies.
Merge an artery leaving the heart with the pulmonary trunk to give blood another way to the lungs
Which valve is most prone to sclerosis and thickening?
Mitral valve. As a result, you can heart murmur (you can hear back-flow)
What is cardiac reserve?
The heart's ability to respond to a sudden stress (fight or flight).
Reduces with age as sympathetic control center becomes more random/variable.
Leads to an overall decline in heart rate
What is fibrosis of cardiac muscle?
Cardiac cells die and are replaced with connective tissue instead of muscle.
This leads to reduced stroke volume.
Nodes can also degrade and be replaced with connective tissue, which leads to an increased incidence of arrhythmias
What is atherosclerosis?
Caused by inactivity, smoking, stress, high cholesterol. Buildup of plaque in blood vessels.
Leads to hypertensive heart disease, coronary artery occlusion, heart attack, stroke
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