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BIO 202: Endocrine System Review Guide: Exam 1
Terms in this set (65)
Discuss the way in which hormones promote body homeostasis.
They coordinate and regulate the activities of cells, tissues, organs, and systems through release into the bloodstream. They regulate sleep, body temperature, hunger, and stress as well as long-term processes like growth, development, and reproduction.
Compare and contrast the endocrine system and the nervous system. Make sure you understand the differences between a neurotransmitter and a hormone, addressing the importance of receptor specificity.
- Uses electricity and chemicals to send a fast message
- Has a specific effector organ
- Neurons release neurotransmitters (which demonstrate receptor specificity)
- Directs crisis management
- Uses action potentials propagated along axons
- Uses hormones
- Effects many effector organs
- Slower and longer-lasting than nervous system
- Endocrine glands release hormones (hormone demonstrates receptor specificity)
- Directs gradual, coordinated processes
- Uses bloodstream
Define negative feedback and describe its role in regulating blood levels of the various hormones. Use an example!
Negative feedback = Response to changed body condition (deviation from homeostasis). If the level of something is too high or low, a signal will tell the body to make certain changes that will bring about a return to homeostasis. Once the level is normal, the signal wil be turned off.
Example: If the blood glucose level is high, the pancreas will secrete insulin and the glucose level will be reduced to normal.
List and describe the four types of intercellular communication pathways that enable the body to maintain homeostasis.
- Exchange of ions/ molecules between adjacent cells across gap junctions
- Occurs between two cells of the same type
- Chemical signals transfer info from cell to target cell within a signal tissue
- Most common form of intercellular communication
- Endocrine cells release hormones into bloodstream
- Alters metabolic activities of many tissues and organs simultaneously (long-distance)
- Between dendrites of one neuron and axon terminal of another
- Releases neurotransmitters
Define hormone and target organ.
Hormone = Chemical messengers released in one tissue and transported via the bloodstream to alter the activities of specific in other tissues
Target cell/ organ = Specific locations that possess receptors needed to bind and "read" hormonal messages
What does the "lock and key" system refer to?
A hormone receptor is specific to only one type of hormone. Therefore, if the hormone doesn't fit in a particular receptor, it won't affect the cell/ organ.
What are the three ways in which hormones are classified?
*Three groups based on chemical structure
Amino Acid Derivatives:
- Small molecules structurally related to amino acids
- Tyrosine derivitives (thyroid hormones, catacholamines)
- Tryptophan derivative (melatonin)
- Amino acid chains; most are synthesized as prohormones (inactive molecules that are converted to active hormones before/ after they're secreted)
- Short polypeptides/ small proteins
- Two classes: eicosanoids and steriod hormones
- Eicosonoids (leukotreins, prostaglandins)
- Steriod hormones (estrogens and progestins, androgens, corticosteriods, calcitriol)
Compare and contrast the functionality of free vs. bound hormones in the plasma (bloodstream).
- Functional for less than one hour
- Diffuse out of bloodstream and bind to target receptors
- Broken down and absorbed by liver and kidney cells
- Broken down by enzymes in plasma or interstitial fluid
- Thyroid and steroid hormones
- Remain in circulation much longer than free hormones
- Enter bloodstream and become attached to special transport proteins
- Bloodstream contains substantial reserve of bound hormones
Diagram the general mechanism of action of lipid-soluble hormone. Then, compare and contrast a steroid hormone vs. thyroid hormone mechanism of action. Yes, they are both lipid-soluble hormones, but they have slightly different mechanisms of action.
Lipid-soluble: Diffuse across plasma membrane to reach receptor proteins on inner surface of membrane (intracellular receptors).
Steroid hormones: Bind to receptors in the cytoplasm or nucleus. Hormone-receptor complexes then activate or deactivate specific genes. By this mechanism, steroid hormones can alter the rate of DNA transcription in the nucleus and the pattern of protein synthesis (directly affects metabolic activity and structure of target cell).
Thyroid hormones: Cross membrane by transport mechanism and bind to receptors within nucleus and on mitochondria. The hormone-receptor complexes in the nucleus activate specific genes or change the rate of transcription, which affects the metabolic activities of the cell (increase/decrease concentration of specific enzymes). The hormones bound to mitochondria increase the rate of ATP production.
Diagram the mechanism of action of a lipid-insoluble hormone. Make sure to show the second messenger systems and the role of G-proteins.
1. Hormone (1st messenger) binds receptor
2. Receptor activates G protein
3. G protein activates adenylate cyclase
4. Adenylate cyclase converts ATP to cAMP (2nd messenger)
5. cAMP activates protein kinases
6. Triggers responses of target cell (activates enzymes, stimulates cellular secretion, opens ion channel, etc)
Sketch and explain the process of amplification in regards to the effects of hormones.
Amplification = when a small number of hormones binds to a membrane receptor and thousands of second messengers appear in the cell, which magnifies the hormone's effects on the target cell.
Compare and contrast the process of down-regulation vs. up-regulation. Use an example discussed in class to support your response.
- Presence of hormone triggers decrease in number of hormone receptors
- When levels of particular hormone are high, cells become less sensitive
- Receptors are all filled up
- Some receptors are broken down by target cells
* Example: insulin receptors may be downregulated in type 2 diabetes
- Absence of hormone triggers increase in number of hormone receptors
- When levels of particular hormone are low, cells become more sensitive
- Receptors are available
* Example: there is an increase in uterine oxytocin receptors in the third trimester of pregnancy, promoting the contraction of the smooth muscle of the uterus
If you didn't already do so, diagram the intracellular response of a steroid hormone.
1. Diffusion through membrane lipids
2. Attachment to either cytoplasmic receptor or nuclear receptor
3. Binding of hormone receptor complex to DNA
4. Gene activation
5. Transcription and mRNA production
6. Translation and protein synthesis > Alteration of cellular structure or activity > Target cell response
List and describe the three ways that endocrine reflexes can be triggered. Provide examples.
Endocrine reflexes: stimulus triggers production of hormone that reduces intensity of stimulus (negative feedback)
- Changes in composition of extracellular fluid triggers endocrine reflex
ex: low concentration of calcium in capillary blood stimulates PTH secretion by parathyroid glands (raising blood Ca2+ level)
- Arrival/ removal of specific hormone triggers endocrine reflex
ex: hypothalamus secretes hormones that stimulate other endocrine glands (thyroid, gonads, etc) to secrete hormones
- Arrival of neurotransmitters at neuroglandular junctions triggers endocrine reflex
ex: Preganglionic sympathetic fibers stimulate adrenal medulla cells to secrete catacholamines (E and NE)
Review the locations of the organs of the endocrine system.
Diagram the three ways in which the hypothalamus can interact with the endocrine or nervous system.
1. The hypothalamus stimulates the release of ADH and oxytocin from the posterior pituitary
2. Secretion of regulatory hormones to control activity of the anterior lobe of the pituitary gland
3. Control of sympathetic output to adrenal medulla which leads to the secretion of E and NE
Draw and label the major regions of the pituitary gland
Another word for anterior pituitary
Another word for posterior pituitary
Compare and contrast the roles of releasing hormones and inhibiting hormones in the hypothalamus.
Releasing hormones (RH): Stimulate synthesis/ secretion of one or more hormones at anterior lobe
Inhibiting hormones (IH): Prevent synthesis/ secretion of hormones from anterior lobe
Do whatever it takes to really understand the functional relationship between the hypothalamus and the pituitary gland. Focus on the portal system.
Hypothalamic-hypophyseal portal system:
1. Neurons manufacture ADH and oxytocin which are released by synaptic terminals in the posterior pituitary
2. Neuroseceitory neurons in the hypothalamus secrete RH's and IH's which travel down to the anterior pituitary
3. Before leaving the hypothalamus, the capillary network unite to form a series of larger vessels that spiral around the infundibulum to reach the anterior lobe
4. The vessels between the median eminance and the anterior lobe carry blood from one capillary network to another. These are called "portal vessels" because they link two capillary networks
5. Within the anterior lobe, these vessels form a secondary network that branches among endocrine cells
*When stimulated, hypothalamic neurons secrete RH or IH into the primary capillary plexus
*Hypothalamic hormones travel through portal veins to the anterior pituitary where they stimulate/ inhibit release of hormones made in the anterior pituitary
*In response to releasing hormones, the anterior pituitary secretes hormones into the secondary capillary plexus. This empties into general circulation.
What are neurosecretory cells? Where exactly are they found?
Neurosecretory cells are found in the hypothalamus, but their axons and axon terminals travel to the anterior pituitary. They secrete RH's and IH's that travel to the posterior pituitary.
List the two hormones of the posterior pituitary gland and their target tissues.
Oxytocin --> mammary glands, uterine muscles
- Stimulates uterine contraction during labor
- Causes milk ejection from breast tissue
ADH (vasopressin) --> kidney tubules
- Decreases urine production
- In large amounts, causes vasoconstriction (high BP)
ADH and oxytocin are produced in the ______ and stored in the ______.
Hypothalamus, neurohypophysis (posterior pituitary)
ADH is also known as "_________"
Draw out the major hormones of the anterior pituitary and their target tissues/ organs.
TSH = thyroid stimulating hormone
- Stimulates thyroid gland to release thyroid hormones (T3- triiodothyronine, T4- thyroxine)
GH = growth hormone
- Stimulates liver to secrete somotomedins which causes bone and muscle growth
PRL = prolactin
- Stimulates milk production from mammary glands
FSH = follicle stimulating hormone/ LH = luteinizing hormone
- Stimulates testes to release inhibin or testosterone
- Stimulates ovaries to release estrogin, progesterone, inhibin
MSH = melanocyte stimulating hormone
- Stimulates melanocytes to produce melanin
Describe the anatomical location of the thyroid gland.
It lies inferior to the thyroid cartilage (adam's apple) of the larynx.
List and describe the products of the follicular cells and the parafollicular cells of the thyroid gland.
Thyroglobulin (follicular product)
- Transport proteins
- Attach to most T3 and T4 molecules in bloodstream
Thyroxine (T4) (follicular cell product)
- Contains 4 iodine molecules
Triiodothyronine (T3) (follicular cell product)
- Contains 3 iodine molecules
Calcitonin (parafollicular (C-cell) product)
- Lowers blood calcium
TRH is made in the __________
TSH is made in the __________
T3/T4 are made in the ___________
Diagram the negative feedback loop involved with thyroxine blood level regulation. Be able to predict what will happen to the levels of TRH, TSH, and T3/T4 if any of these hormones rises or falls!
top half of picture
List and describe the major metabolic effects of thyroid hormone. Make sure to inclue which tissues are being affected!
- Increased rate of O2 consumption and energy consumption
- In children: Increased body temperature
- Increased heart rate and force of contraction (ionotropy)
- Increased blood pressure
- Increased sensitivity to sympathetic stimulation
- Maintains normal sensitivity of resp. centers to changes in O2 and CO2 concentrations
- Stimulates RBC formation (enhanges O2 delivery)
- Stimulates other endocrine activity
- Accelerates mineral turnover in bone
What is a cause of hyperthyroidism discussed in class? What are some symptoms? Why do these symptoms result?
Graves Disease symptoms
- Increased body temperature, heart rate, metabolic rate, blood pressure, weight loss
- Calorigenic effect (cells consume more energy resulting in increase in heat generation)
- Ophthalmopathy (protrusion of eyes) -- inflammation and other immune system events affect muscles and other tissues around the eyes
Hypothesize some other causes of hyperthyroidism. Think about what else could cause thyroxine levels to be chronically elevated! Hint: don't focus on the thyroid gland.
Hashimoto's Disease- thyroid inflammation due to attacks from the body's own immune system on the thyroid gland. The thyroid gland thus gradually decays and impacts the thyroid's ability to produce hormones.
Sarcoidosis- Abnormal growths that invade the thyroid and take the place of healthy tissue. Inflamed tissue forms throughout the body and thyroid hormone production is inhibited.
Pituitary gland problem- A tumor or similar problem in the pituitary gland might impact its ability to produce TSH, so the thyroid won't secrete hormones.
Using hypothyroidism as an example, compare and contrast primary, secondary, and tertiary disease.
Primary: From the gland producing the hormone itself. In hypothyroidism, this means the cause is the failure of the thyroid to produce adequate hormone amounts.
Secondary: From gland stimulating gland to stimulate hormone. In hypothyroidism, this means the cause is the pituitary's failure to produce enough TSH
Tertiary: In hypothyroidism, this means it is due to hypothalamic dysfunction.
What would be the result of an iodine deficiency in an individual's diet?
Low T3 and T4 -- so hypothyroidism (primary type).
What anatomical structure in the neck would be affected by a goiter?
Goiters compress the trachea and esophogus, which leads to symptoms such as coughing, waking up from sleep feeling like you can't breathe, sensations of food getting stuck in the upper throat.
Why does an individual who is HYPOthyroid develop a goiter?
The thyroid cannot make T3/T4, but the pituitary gland is stilltrying to stimulate it by secreting TSH. This stimulation causes the thyroid to grow and a goiter to develop.
What are the other names for parafollicular cells of the thyroid gland?
C-cells (clear cells) that are chief cells which produce PTH.
Describe the anatomical location of the parathyroid glands.
Tiny masses on the posterior of the thyroid gland.
PTH = _____________
What are the 4 effects of PTH?
1. Stimulates osteoclasts (accelerates mineral turnover and releases calcium from bone)
2. Inhibits osteoblasts (reduces rate of calcium deposition in bone)
3. Enhances reabsorption of calcium at kidneys, reducing urinary loss.
4. Stimulates formation/ secretion of calcitriol at kidneys
Diagram and label the regulation of blood calcium levels.
number 44 in notebook
Describe the anatomical location of the adrenal glands.
Along the superior border of each kidney.
What are the major hormones (and their associated functions) of the adrenal cortex? List the hormones and their effects.
*Makes mineralcorticoids (ALDOSTERONE)
- Stimulates conservation of sodium and eliminates potassium
- Increases sensitivity of salt receptors on taste buds
- Secretion responds to drop in sodium, blood volume, or blood pressure or rise in blood potassium concentration
*Makes glucocorticoids under stimulation by ACTH (CORTISOL & HYDROCORTISONE)
- Accelerates glucose synthesis and glycogen formation (lowers blood glucose)
- Anti-inflammatory effects (inhibits WBC and other components of immune system)
- After stimulated by ACTH, produces androgens
What are the major hormones (and their associated functions) of the adrenal medulla?
1. Epinephrine (75-80% of secretions)
2. Norepinephrine (20-25% of secretions)
Both increase cardiac activity, BP, glycogen breakdown, blood glucose levels; releases lipids by adipose tissue
Diagram the negative feedback loop involved with hormones of the adrenal gland. Focus on ACTH and cortisol.
Elevated cortisol inhibits release of CRH (corticotropin releasing hormone) by hypothalamic neurosecretory cells
Elevated cortisol inhibits release of corticotropin by anterior pituitary
Compare and contrast the effects of acute and chronic stress on the body.
Acute (short-term) stress: [catecholamines]
- Glycogen broken down into glucose > increased blood glucose
- Increased blood pressure
- Increased resp. rate
- Increased metabolic rate
- Change in blood flow patterns, leading to increased alertness and decreased digestive and kidney activity
Chronic (long-term) stress: [mineralcorticoids and glucocorticoids]
- Retention of sodium ions and water by kidneys
- Increased blood volume and blood pressure
- Proteins and fats broken down and converted to glucose; leading to increased blood glucose
- Immune system may be suppressed
What hormone does the pineal gland produce? What are its effects?
Melatonin = inhibits reproductive functions, protects against damage by free-radicals, sets circadian rhythms (sleep-wake cycles)
Describe the anatomical location of the pancreas.
Lies between the inferior border of the stomach and proximal portion of the small intestine.
Compare and contrast endocrine and exocrine glands.
Endocrine glands: release secretions into extracellular fluid
Exocrine glands: excrete products onto epithelial surfaces (usually by way of ducts)
Describe in detail the cells of the Islets of Langerhans. Is this the endocrine or exocrine pancreatic tissue?
The Islets of Langerhans are endocrine cells. The islets contain alpha cells which secrete glucagon, beta cells which secrete insulin, delta cells which secrete somatostatin (GHIH), and F cells which secrete pancreatic polypeptides.
Compare and contrast the roles of insulin and glucagon. Which cells make what?
- Lowers blood glucose
- Produced by beta cells
- Stimulates glucose uptake by cells of the liver and skeletal muscles
- Enhances ATP production
- Stimulates glycogen formation
- Stimulates amino acid absorption and protein synthesis
- Stimulates triglyceride formation in adipose tissue
- Raises blood glucose
- Produced by alpha cells
- Promotes conversion of glycogen in liver to glucose and release into bloodstream
- Stimulates breakdown of triglygerides in adipose
- Stimulates production of glucose in liver
Diagram the endocrine system control of blood sugar.
Number 55 in notebook
Explain the difference between type I and type II diabetes mellitus. Make sure you understand the difference between receptor cells insensitivity and Islet cell burnout when talking about type II.
- Autoimmune disorder
- In a healthy body, beta cells in the pancreas make insulin. In type I diabetes, the immune system mistakes beta cells for invaders and attacks them
- Type I diabetes symptoms show when enough beta cells are destroyed
- 5~10% of diabetes cases
- Beta cells still produce insulin
- Either the cells don't respond to the insulin properly (insulin receptor insensitivity), and/or the insulin produced naturally isn't enough to meet the needs of the body (islet cell burnout)
- Common causes: obesity, inheritance
- Treatment: Improved diet and exercise
Explain the pathophysiology of Diabetes Insipidus.
- Chronic pituitary or hypothalamus disorder
- Result of deficiency of vasopressin (ADH)
- Inadequite ADH secretion reduces kidney's ability to conserve water
- Also may be caused by trauma/ tumors
What occurs to the mother and developing fetus during gestational diabetes?
The placenta supports the growing baby and hormones from the placenta help with development. However, these hormones block the mother's insulin from performing its proper action in her body (insulin resistance). As a result, the mother may need 3x as much insulin as normal.
What is another name for growth hormone? Where is it produced?
GH = somatotropin
It is produced in the anterior pituitary gland.
What are the major effects/ target tissues of growth hormone?
Target: skeletal muscle, bone, liver, adipose tissue, epithelia, etc
Glucose sparing effect
- Growth of skeletal muscles and long bones
- Amino acids built into proteins
- Fats broken down for energy source
- Breakdown of glycogen reserves in liver
- Increase in blood glucose
What would happen if someone took human growth hormone from an exogenous (outside) source? Use a negative feedback diagram to support your answer.
If GH goes up, blood glucose, and carilage, bone, and tissue growth will increase as well. This causes GHRH to be decreased and GHIH to be increased in hopes of causing GH to decrease as well.
What is acromegalic giantism?
Oversecretion of GH after epiphyseal plate closure (occurs in adults). Bones of hands, face, feet are enlarged.
What causes dwarfism?
Undersecretion of GH during childhood
Summarize the GAS (general adaptation syndrome)/ stress response. Use a personal example.
All Red Salmon Ride Streams East
Stage 1: Alarm Reaction (AR)
- Immediate short-term response to crisis
- "Fight or flight" response prepares body for physical activity
- Decreases effectiveness of immune system
Stage 2: Stage of Resistance (SR)
- Body adapts to stressor
- Change at many levels take place to reduce effects of stressor
- Mobilization of energy reserves, conservation of glucose, conservation of sodium and water, etc
Stage 3: Stage of Exhaustion (SE)
- Stress has been continued for a long time
- Body's resistance to stress is reduced (may quickly collapse)
- Immune system may be almost completely eliminated
AR: working out (stressing); "feel the burn"
SR: muscles start to build to deal with stress
SE: overtraining; injury/ muscle breakdown
Briefly list and describe the endocrine tissues of other systems.
Intestines (digestive system)
- Produce hormones important to digestive activity coordination
Kidneys (urinary system)
- Produce calcitriol and erythropoitin and resin (enzyme)
Heart (cardiovascular system)
- Produces natriuretic peptides when there is an increase in blood volume; opposes angiotensin II; results in decrease of blood volume and pressure
Thymus (lymphatic system)
- Produces thymosins that help develop/ maintain immune defenses
Gonads (reproductive system)
- Produce androgens in interstitial cells; secrete inhibin in nurse cells (support differentiation/ maturation of sperm)
- Produce estrogens; follicle cells form corpus luteum and release estrogens and progesterone
Breast Tissue (reproductive system)
- Responds to prolactin; stimulates/ maintains milk production
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Laboratory Manual for Holes Human Anatomy & Physiology Fetal Pig Version
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