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Physiology Test 4
Terms in this set (184)
Pulmonary ventilation (is/is not) normally the most limiting factor during exercise.
Our maximal breathing capacity is about ___ greater than what we need during maximal exercise.
During typical exercise your ventilation rate will increase to ensure that Hb is always near maximal saturation (near _____) as it leaves lungs.
_____ and ______ of blood are the most limiting factors during exercise (i.e. the lungs are usually not the limiting factor).
Cardiac output and oxygen carrying capacity
Hyperventilation ________ amount of CO2 and H+ in blood
Hyperventilation causes pH to.....
increase (become more basic)
During hyperventilation, oxygen levels...
stay approximately the same (97.5% bound or slightly greater).
Why do you feel lightheaded when you hyperventilate? (1/2)
It is the opposite of Bohr effect on oxygen-Hb curve.
Hyperventilation decreases CO2 and increases pH.
It shifts oxygen/Hb dissociation curve to the left, so less oxygen is given off to tissues including the brain.
Why do you feel lightheaded when you hyperventilate? (2/2)
It can also cause a decrease in blood flow the CNS.
CNS senses low CO2, so it assumes that there is no lack of oxygen
CNS will generally increase overall amount of vasodilation in body which can result in slight decrease in blood flow to brain.
Hyperventilation before diving into water when you are snorkeling or swimming ________ your urge to breath and "psychologically" allows you to stay under longer (but this is dangerous).
Hyperventilation before diving into water greatly _______ carbon dioxide levels, however it has little or no effect on oxygen levels (because Hb is normally 97.5% saturated as it
leaves the lungs even without hyperventilation).
Why do you have a decreased urge to breathe when you hyperventilate before diving into water?
decreased carbon dioxide levels
Why is "shallow water blackout" dangerous?
The snorkeler can blackout because they stay under too long and oxygen levels become too low if they hyperventilate before diving into the water.
The kidneys (are/ are not) extremely important to homeostatis
Kidneys normally receive a (little/large) amount of blood flow.
How much blood flow do the kidneys receive when you are at rest?
What percentage of total cardiac output do the kidneys receive?
The kidneys produce a minimum of ____ ml of urine per day.
The kidneys help maintain ____ and _____ balance, and _____ volume
water, electrolyte, plasma
The kidneys compensate for ingested _____ and ______ and for abnormal water ______ (from excessive sweating, diarrheas, hemorrhage, etc).
water, salts, loss.
The kidneys help maintain a constant osmolarity of ______ in body tissues.
The kidneys help maintain a proper pH (average of _____) in blood and body fluids.
The kidneys help excrete waste products and foreign compounds such as:
urea, uric acid, artificial food additives, and other waste products.
The kidneys are an endocrine gland that produce the hormone ______.
erthropoietin (stimulates RBC production).
The kidneys convert vitamin ____ into its active form.
Vitamin D is a cholesterol0 like compound produced in skin in response to _____.
sunlight (but can also be obtained from dietary sources).
Vitamin D has to be activated by chemical reactions that occur in the _____ and _____.
liver and kidney
Active Vitamin D3 promotes the absorption of _______ and _____ from the intestines.
calcium and phosphate.
Vitamin D3 deficiency results in an impaired ability to absorb Ca++, so the hormone _____ stimulates mobilization of Ca++ from the _____ to maintain ECF and ICF Ca++ levels.
Vitamin D3 deficiency causes the bones to become ______
soft and weak (called rickets in children and osteomalacia in adults).
The kidneys produce ______, which is an enzyme involved in the renin-angiotensisn-aldosterone system that affects ____ retention by the kidneys.
The functional unit of the kidney that is responsible for urine formation
How many nephrons are in each kidney?
Each nephron has ____ components (blood vessels) and _____ components (tubules that hold filtrate that eventually forms the urine).
What are the vascular components of the kidney?
afferent arteriole, glomerulus, efferent arteriole, and the peritubular capillaries.
What is the function of the afferent arteriole?
carries blood from the renal artery to the glomerulus (afferent means conducting toward something).
What is the function of the the glomerulus, a ball of capillaries with relatively large pores?
plasma filters through these capillaries into the tubular components of the nephron (glomerular filtration). However, blood cells and large proteins are too big so they stay in the blood.
How many time greater in the permeability of the glomerulus as compared to normal capillaries?
Glomerular filtration is the ___ step in urine formation.
During glomerular filtration: of the blood that enters the glomerulus, about ____% of its plasma is filtered into the "tubular" component of the nephron.
What is the glomerular filtration rate (GFR)?
about 125ml of filtrate per minute (equal to about 180 liters of filtrate produced per day).
Caffeine can _____ urine production by ______ GFR.
Filtrate has the same constituents as plasma except it lacks _____.
plasma proteins (some small proteins do enter filtrate but are usually reabsorbed by proximal tubule, so urine is usually protein free).
What is the function of the efferent arteriole?
It carries blood from the glomerulus to peritubular capillaries (efferent means conducting away from something).
What is the function of the peritubular capillaries?
They supply the renal tissue with blood (blood from the peritubular capillaries eventually flows into venules then into the renal vein).
The peritubular capillaries (are/are not) closely associated with the tubular components of the nephron.
are; this allows for exchange of materials between vascular and tubular components of the nephron.
The ____ is a specialized portion of the peritubular capillaries that lies in close association with an important tubular component, the Loop of Henle.
What are the tubular components (ones that contain the filtrate) of the nephron?
Bowman's capsule, proximal tubule, Loop of Henle, Distal tubule, and the collecting tubule.
What is the function of Bowman's capsule?
it collects filtrate from the glomerulus and connects with the proximal tubule.
What is the function of the proximal tubule?
it is very important in the reabsorption or important substances (certain materials in tubule are reabsorbed back into the blood. this is the opposite of secretion, which in the movement of substances from the blood into the tubule).
The proximal tubule has both passive and active reabsorption.
Actively reabsorbed: Na+, K+, glucose & amino acids (unless levels get really high in plasma and reach renal threshold, so they will start appearing in urine).
Passively reabsorbed: Cl- (because its follows Na+ due to electrical charge), urea, and 65% of filtered water (follows the ions due to osmosis).
What is the most common endocrine disorder?
Diabetes mellitus, causes high blood glucose levels that are greater than the renal threshold, causing glucose to appear in the urine. This will also include increased water loss since water follows the glucose osmotically.
What is type 1 diabetes mellitus?
due to inadequate insulin production
what is type 2 diabetes mellitus?
tissues become nonresponsive to insulin (also called adult-onset diabetes).
Renal threshold of many ions such as phosphate and calcium are ____ to their normal plasma concentration.
_____% of urea in filtrate is actually reabsorbed passively back into the blood from the proximal tubules due to concentration gradient.
50%, the urea becomes concentrates in the filtrate as water is reabsorbed so urea concentration in filtrate increases. It is not advantageous to reabsorb urea, but it is not enough to cause problems in healthy individuals with a normal GFR, since 50% of the urea normally stays in the filtrate and leaves the body.
_______ is a characteristic of renal failures and indicates that have a decreased GFR, so you are not filtering enough urea.
High blood urea (referred to as BUN/blood urea nitrogen).
The proximal tubule secretes ___ when needed.
H+ (if blood is too acidic, H+ is secreted into the tubule).
Where is the loop of Henle?
It dips from outer portion of kidney (cortex) down into the inner portion of the kidney (medulla).
The descending loop of Henle (is/is not) permeable to water, but (does, does not) have active pumping of Na+ or Cl-.
Is permeable to water, has no active pumping of Na+ or Cl-
The ascending loop of Henle (is/is not) permeable to water, but (does, does not) have active pumping of Na+ or Cl-.
is not permeable to water, has active pumping of Na+ and Cl- out of tubules and into ECF (primary active transport of Na+ out of tubules and secondary transport of Cl- out of the tubules).
Osmotic pressure ______ in the ECF of the kidney medulla and _____ within the ascending loop of Henle.
As the fluid in tubule reaches the top of the ascending loop it is dilute (100 mOsm).
The high NaCl levels in the interstitial fluif of the kidney medulla attracts water out of the descending loop of Henle, increasing osmolarity in the tubule at the bottom of the loop of Henle (1200 mOsm).
What is the osmotic gradient in the kidneys?
blood osmolarity= 300mOsm
kidney cortex = normal osmotic pressure: 300 mOsm
Kidney inner medulla= high osmotic pressure: 1200 mOsm
The osmotic gradient allows the kidneys to concentrate or dilute the urine when necessary.
The vasa recta supplies blood to loop of Henle (with/without) disrupting the osmotic gradient.
without, it follows the loop of henle and forms a "counter current" exchange system, so it does not disrupt the concentration gradient that has been set up by the loop of Henle in the medulla.
The distal tubule is important for what REABSORPTIONS?
-Na+ when needed, controlled by aldosterone
-passive reabsorption of water when needed, controlled by antidiuretic hormone/ADH/vasopressin.
The distal tubule is important for what SECRETIONS?
-active secretion of K+ when needed, controlled by aldosteronoe (stimulating Na+/K+ pump so that Na+ is reabsorbed and K+ is secreted).
-active secretion of H+ when needed.
The collecting tubule/duct travels from the cortex (normal osmotic pressure) down through the medulla (high osmotic pressure) and functions to:
reabsorb and secrete as necessary (same as distal tubule). Both aldosterone and ADH act on the collecting tubule in the same fashion as they act on the distal tubule.
ADH/vasopression is produced in brain (________) and released from _______ in response to increased osmolarity of body fluids, or decrease in the amount
of fluid volume in the body.
hypothalamus, posterior pituitary
What does ADH do?
increases water permeability of the distal tubules and collecting tubules by attaching to receptor on the cells lining the distal and collecting tubules. This causes the production of secondary messenger cAMP which causes an increase in the number of water channels in membranes.
If there is high ADH then...
-the distal and collecting tubules are permeable to water
-water is drawn out of tubules osmotically due to high concentration of solutes in the ECF of the kidney medulla
-fluid in tubules becomes concentrated and results in highly concentrated urine (up to 1200 mOsm).
If there is low ADH then...
-tubules are not permeable to water (no water channels in membranes)
-fluid in tubules stays dilute (as low and 100 mOsm)
-ethanol in beverages decreases levels of ADH thus increasing the production of dilute urine, resulting in more fluid being lost than is consumed= dehydration.
What is diabetes insipidus?
due to a pathological decrease in the production of ADH, causes an inability to produce concentrated urine and can result in an excess loss of body fluid (5-10 liters of urine per day).
-typically treated with synthetic ADH via a nasal spray.
______ is an enzyme produced by cells in the "juxtaglomerular apparatus" in the kidneys.
The juxtaglomerular apparatus is a combination of tubular and vascular components. ________ in juxtaglomerular apparatus produce renin.
renin, granular cells
Renin is produced in response to ______ NaCl concentration, blood pressure, and/or fluid volume in the body.
Renin converts _______ to _______.
angiotensinogen to angiotensin I (angiotensinogen is a plasma protein produced by liver).
Angiotensin 1 is converted to _______ by ________.
angiotensin II by ACE (ACE is produced in lungs)
(ACE = angiotensin-converting enzyme)
Angiotensin II stimulates to release of _____ from the ______.
aldosterone (steroid hormone) from the adrenal cortex.
Angiotensin II also stimulates vaso(constriction/dilation) of blood vessels
Aldosterone stimulates distal and collecting tubules of nephron for
reabsorption of Na+ by...
increasing the number of Na+ channels and Na+/K+ pumps (Cl- passively follows Na+). This also stimulates the secretion of K+.
In the typical person who consumes about 2.3g of salt per day, how much salt is excreted?
-absence of aldsoterone: up to 20g of NaCl
-during maximal aldosteron production: no NaCl is given off in urine.
What do ACE inhibitors do?
Block the action of ACE, thereby blocking production of angiotensin II and preventing the release of aldosterone.
What are ACE inhibitors used for?
lowering blood pressure by:
-preventing Na+ reabsorption and thus decreasing water retention and blood volume
-decreasing vasoconstriction because angiotensin II is also a vasoconstrictor.
Endurance athletes acclimated to warm weather produce relatively high amounts of aldosterone causing....
Na+ reabsorption by the kidney.
-aldosterone has the same effect on sweat glands.
-can increase K+ secretion via Na+/K+ pumps b/c aldosterone increases K+ secretion.
-athletes can compensate for K+ loss by drinking gatorade-like drinks that contain K+ and Na+.
Why do we have a nervous system and an endocrine system?
Endocrine system is slower than the nervous system, but it has a more prolonged effect. Endocrine system can also affect multiple locations in the body.
For example, it could stimulate the gradual growth of a tissue (.e.g. reproductive organs in an animal during the spring to prepare
animal for reproduction).
Hormone ("to excite") was first coined by a physiologist in 1905 to describe the intestinal hormone ____.
secretin; first hormone to be identified in 1902.
-produced by the duodenum in response to acid and stimulates the pancreas to produce bicarbonate.
A hormone is a ____ substance.
organic 1) (contains carbon molecules, i.e. carbon-based
Hormones are released into the blood by a ________ (i.e. endocrine gland) and move into capillaries in the gland (i.e. hormone moves into the blood).
ductless glandular tissue
Hormones travel some distance in the blood and elicit a biological response in a target tissue (regulatory effect) by...
binding to a receptor (therefore target tissues have receptors that are specific for particular hormones).
The definition of a hormone has gradually expanded as we learn more about diversity in the endocrine system.
-some hormones are released by neurons (often referred to as neurohormones)
-some hormones do not have to travel in the blood to their target tissue (paracrine= hormones that affect nearby cells; autocrine= hormones that affect the same cell that produced the hormone).
Some hormones are amino acid derivatives:
Derivatives of the amino acid tyrosine:
-thyroxine (produced by the thyroid gland and is important in the control of metabolic rate)
-epinephrine (adrenaline from the adrenal medulla)
Derivatives of the amino acid tryptophan:
Some hormones are peptides/proteins, depending on the hormone it can range form just a few amino acids to several hundred amino acids.
-they are chains of amino acids.
-the specific sequence of the amino acid gives the hormone a unique shape so that it can fit into a receptor.
-peptide and protein hormones are water soluble so they travel easily in the blood.
Examples of hormones that are peptides/proteins
Small: TRH (thyrotropin releasing hormone) is 3 amino acids
Large: insulin is 51 amino acids (2 subunits)
Large "glycoprotein": can have several hundred amino acids with carbohydrate groups attached, can contain subunits that attach to one another (ex: follicle stimulating hormone/FSH, Lutenizing homrone/LH, Thyroid Stimulating Hormone/TSH
-derivatives of cholesterol
-lipid soluble so they need to be carried by carrier proteins in the blood (specific types of plasma proteins such as globulins and albumins carry steroids in the blood), once they arrive at the target cell they can diffuse directly through cell membranes.
-ex: testosterone, estrogen, progesterone, cortisol, aldosterone
Peptide/protein/glycoprotein mechanism of hormone action
-act through receptors located in/on the cell membrane (integral proteins)
-once the hormone binds, the receptor affects other membrane proteins on the inner surface of the cell membrane (peripheral proteins) (ex: G proteins)
-when stimulated, these proteins can regulate enzymes (ex: adenylate cyclase) which then stimulate the production of second messengers such as cAMP.
-cAMP activates cAMP-dependent protein kinases that phosphorylate specific proteins in the cell.
-phosphorylation can activate or inactivate a specific protein, resulting in altered cellular physiology.
Is there an advantage to using a second messenger system?
It can result in an "amplification" effect of the signal.
(e.g. The binding of a single hormone molecule can turn on a thousand or more enzymes molecules.)
Binding of protein hormones to receptors in some systems can also increase the levels of intracellular Ca++
-by increasing Ca++ influx and increasing Ca++ release from the cell organelles, such as the E.R.
-Ca++ then acts as an intracellular messenger to alter cellular physiology.
Steroid hormone mechanism of action:
-normally travel in the blood bound to a carrier molecule such as albumins or globulins
-dissociate and diffuse directly through the cell membrane because they are lipid soluble.
-attach to an intracellular recptor
-hormone/receptor complex then binds to a specific location on DNA (such as a hormone response element/HRE)
-in many cases, 2 hormone/receptor complexes have to bind to an HRE and form a dimer simultaneously to get a response.
-this alters DNA transcription, thus controlling protein synthesis (ex: it might turn on a specific gene that will then produce mRNA resulting the production of a protein).
Thyroid hormones (ex: thyroxine) act in a similar fashion to steroid hormones
-they are carried proteins in the blood
-they attach to intracellular receptors that will then bind to HREs on the DNA.
The pituitary gland was considered the "master endocrine gland" because it controlled a variety of endocrine glands and is involved in the control of many, but not all, endocrine functions. The release of pituitary hormones is...
controlled by the hypothalamus and by feedback from hormones in the blood.
What are the two primary divisions of the pituitary gland?
Anterior and Posterior.
The posterior pituitary is...
-an outgrowth of the brain (composed of neural tissue)
-contains neurosecretory neurons (the cell bodies are in the hypothalamus of the brain so the hormones released from the posterior pituitary are produced in the hypothalamus of the brain)
-axons of these neurons extend down the stalk of the pituitary and the hormones are transported down the axon the axon terminals and released in the blood.
2 hormones released by the posterior pituitary (each composed of 9 amino acids)
-ADH: stimulates retention of water by the kidneys
-oxytocin: stimulates contraction of uterus during childbirth via a positive feedback system that causes more oxytocin to be released the more the uterine muscle contracts. it also stimulates contraction of smooth muscle in the mammary glands to promote milk ejection during breastfeeding.
The anterior pituitary is made of...
tissue that originated from tip of mouth cavity during embryonic development (oral ectoderm) NOT neural tissue.
The anterior pituitary contains a variety of cell types:
-each cell type is controlled by specific releasing and/or inhibiting hormones which are produced by the hypothalamus.
-these cells also respond to feedback from hormones in the blood coming from the body.
Releasing and inhibiting hormones in the posterior pituitary:
-given off by hypothalamus into the blood vessels that travel down the stalk of the pituitary to the anterior pituitary
-releasing hormones attach to receptors on specific pituitary cells and stimulate the release of specific pituitary hormones
-inhibiting hormones bind to receptor and inhibit the release of a pituitary hormone.
GnRH (gonadotropin-releasing hormone) if the hypothalamic-pituitary-gonadal axis system
-produced in hypothalamus
-stimulates release of LH and FSH from anterior pituitary
-FSH and LH then stimulate gonads for steroid production and gamete production
-steroid hormones provide negative feedback to the pituitary and the hypothalamus.
TRH (thyrotropin-releasing hormone) of the hypothalamic-pituitary-thyroid axis system
-stimulates release of TSH (thyroid stimulating hormone) from anterior pituitary
-TSH stimulates the thyroid to produce thyroxine
-thyroxine can provide negative feedback to the pituitary
-thyroxine is important in controlling metabolic rate
-thyroxine is also important in early development, particularly for the nervous system (low thyroid hormone levels during embryonic development can result in congenital hypothyroidism which was historically known as cretinism which includes mental deficiencies and dwarfism)
-thyroxine contains iodine (lack of iodine in diet can result in low thyroxine levels which can result in a goiter. Lack of thyroxine results in no negative feedback to pituitary and causes increased TSH production, enlarging the thyroid due to overstimulation).
-"Graves" disease in the most common form
-autoimmune disease that stimulates an increase in thyroid hormone production.
-symptoms: increased metabolic rate, poor tolerance to heat, increased anxiety, exopthalmos (bulging of the eyes).
treatment of hyperthyroidism:
-surgical removal of some of the thyroid
-injection of radioactive iodine (131I) which destroys thyroid cells.
CRH/corticotropoin-releasing hormone) of the hypothalamic-pituitary-adrenal axis
-produced by the hypothalamus and travels down blood vessels to anterior pituitary
-CRH is produced in response to stress
-CRH stimulates release of adrenocorticotropic hormone (ACTH) which stimulates the adrenal cortex to produce cortisol
liver, muscles, and fat tissue to increase blood glucose, amino acids, and fats in response to stress
-mobilizes energy molecules to help prepare you to deal with stressful situations
Cushing's Syndrome: ____ cortisol is produced
-can be due to excessive CRH, ACTH, or due to an adrenal gland tumor.
-excess cortisol causes high glucose levels in blood and increased fat deposits in the face and on the back of the neck.
GHRH (growth hormone-releasing hormone)
-produced and released by the hypothalamus
-stimulate release of growth hormone (GH)
-GH stimulates production of insulin-like-growth-1 (IGF-1) from liver which directly stimulates growth of tissues.
Inadequate production of GH results in:
excessive production of GH starting in childhood results in:
excessive production of GH in adulthood results in:
-includes thickening of skin and some bones (enlargement of hands, feet, forehead, nose, lips, and ears).
-in adults, long bones will no longer lengthen in response to GH/IGF-1 stimulation to the person does not grow taller.
What can genetically engineered GH be used for?
-clinically in GH deficient children
-anti-aging in the elderly b/c GH production decreases with age
-illegally as a performance-enhancing/muscle-building drug by some athletes b/c GH stimulates an increase in muscle mass and a decrease in fat.
GHIH (growth hormone-inhibiting hormone/somatostatin)
-inhibiting hormone produced by the hypothalamus that inhibits the release of GH
PIH (prolactin-inhibiting hormone, dopamine)
-inhibiting hormone produced by the hypothalamus that inhibits the release of prolactin
-prolactin is the only anterior pituitary hormone that is primarily under inhibitory control.
-important for mammary gland development and milk production in mammals
-may also have effect on gonads in male mammal (may increase number of LH receptors on testes)
Prolactin can have a wide variety of functions in animals
-acts on kidneys to help regulate water and electrolyte balance in many animals (important in osmoregulation in fishes)
-can stimulate specific parental behaviors in many animals (parental care, nest building and egg incubation in birds, etc).
Genetic sex is determines at ____ in mammals.
-sperm will either have an X or a Y chromosome which it donates to the ovum.
Genetic sex determines ______ (through the production of hormones) which determines _____.
gonadal sex, body sex
The male is the _____ sex.
heterogametic, has two different chromosomes (heteromorphic sex chromosomes, one X and Y chromosome).
Male has been referred to as the "induced sex". Although males have an X chromosome, the presence of the Y chromosome induces embryonic gonads to...
differentiate into tests
-testis-determining gene (SRY) was identified on the Y chromosome in 1990.
The Y chromosome appears to have degenerated overtime because...
it can no longer pair up completely with the X chromosome during meiosis.
-the Y currently has a smaller number of genes (less than 100 actually code for proteins) compared to the X chromosome (which has about 2000 genes)
-however, many of the Y genes are male sepcific
The SRY gene
-sex-determining region of the Y gene
-considered the "testis-determining gene" in mammals
-initiates formation of the testes
-mutations of tis gene can result in male-to-female sex reversal (ex: XY females)
-translation of SRY onto an X chromosome can result in female-to-male sex reversal (ex: XX males).
Both males and females develop in a similar fashion until the SRY gene becomes active. They develop both male and female progenitor ducts simultaneously:
-Mullerian ducts can develop into female ducts
-Wolffian ducts can develop into male ducts.
-the proliferation or degeneration of these ducts in controlled by hormones
In normal males, the gonad develops into a testis and begins to produce several male hormones:
-testis produce antimullerian hormone (AMH) that causes teh mullerian ducts to degenerate in males (which would have otherwise produced the fallopian tubes and uterus)
-testis also produce androgens (testosterone and dihydrotestosterone/DHT) which are important in the development of males
-testosterone stimulate the development of male reproductive ducts from wolffian ducts.
DHT stimulates the development of male external genitalia (i.e. penis).
Some males have a genetic deficiency in the enzyme that converts testosterone to DHT:
-due to a deficiency in this enzyme, testes and internal male ducts develop normally, but external genitalia initially appear ambiguous.
-at puberty, testosterone is produced in large quantities and it stimulates the DHT receptor, causing individuals to develop external male phenotype.
-males with this condition did not develop male-pattern baldness
DHT is the one factor that stimulates:
male-pattern baldness (if the male is genetically predisposed to such)
-antibaldness drugs such as Propcia block the production of DHT.
Female is often referred to as the default sex because the body appears programmed to become female in the absence of SRY, androgens, and AMH.
-with 2 X chromosomes, female has no SRY gene, causing the gonads to develop as ovaries.
-ovaries do not produce androgens or antimullerian hormone during development, causing the mullerian ducts to develop into fallopian tubes and the uterus.
-lack of androgens result in the development of female external genitalia and degeneration of Wolffian ducts.
In males, GnRH from hypothalamus stimulates the release of 2 gonadotropins from the pituitary:
LH and FSH, which travel in the blood to the testes.
The testes is composed of ______.
What is the function of the "Setoli Cells" that line the seminiferous tubules?
They control cells in the environment of the developing sperm (sperm maturation).
What is the function of the "Leydig Cells" between the seminiferous tubules?
-they produce androgens (exL testosterone)
What happens when LH stimulates the Leydig cells in the testes to produce androgens?
-secondary sexual characteristics such as facial hair growth, deep voice, and increased musculature are stimulated
-the CNS is affected via the development of libido/sexual drive at puberty (also occurs in females)
-provide negative feedback to hypothalamus and pituitary gland to control GnRH and LH levels.
-needed for the production of sperm
What happens when FSH from pituitary and testosterone from the testis stimulate the Sertoli cells?
-sperm maturation is facilitated
-sertoli cells line the seminiferous tubules and form the blood-testis barrier that regulates the environment of the developing sperm.
-both FSH and testosterone are needed for sperm maturation (i.e. for the production of spermatozoa)
Sertoli cells produce and release _____ that provides negative feedback to inhibit FSH release from the pituitary.
inhibin, a glycoprotein hormone.
Androgens from Leydig cells provide _____ feedback to pituitary and hypothalamus which inhibit _____ release.
Once formed, sperm moves into the ______ and _______ where it is stored and matures.
epididymus and ductus deferens (tubular structures that lead away from the testis)
The _____ and _____ produce secretions which enhance the survival of the sperm.
prostate gland and seminal vesicles.
The female reproductive cycle/_____ refers to the cyclical growth and then sloughing off of the endometrium of the uterus.
Length of the menstrual cycle is about 28 days and includes 2 cycles:
an ovarian cycle (production of ovum, a secondary oocyte) and a uterine cycle (prepares uterus for possible implantation of developing embryo) that occur simultaneously
Early in the ovarian cycle, there is a slight increase in ____ from the pituitary that causes ____ to develop.
FSH, follicles (oocyte and surrounding cells)
As follicles develop, they produce _____.
Initially there are low levels of estrogen which provides _____ feedback to the pituitary gland and cause LH and FSH levels to _____
negative, be low (so pituitary is not very sensitive to GnRH from hypothalamus)
Estrogen levels then increase and cause _____ feedback on pituitary causing _____.
positive, preovulatory surge of FSH and LH (high estrogen causes pituitary to become very sensitive to GnRH stimulation from the hypothalmus).
FSH/LH surge causes a single dominant follicle to rapidly grow and burst, releasing _____.
the ovum during ovulation (normally occurs halfway through the 28 day cycle).
after ovulation, the remaining portion of the follicle forms a ______.
corpus luteum that produce both estrogen and progesterone (luteum refers to the yellowish color due to increases storage of cholesterol).
Progesterone stimulates _____.
slight increase in body temperature after ovulation (about 0.3 C or about 1 F).
Progesterone also provides _____ feedback to pituitary and hypothalamus.
negative, prevents any further LH or FSH surges during the latter half of the menstrual cycle.
During the uterine cycle, development of ______ occurs simultaneously with the ovarian cycle.
The ______ phase occurs during the first 1/2 of the cycle.
-increased production of estrogen from the ovary stimulates growth and vascularization of the endometrium in preparation for possible pregnancy.
The ____ phase occurs during the 2nd 1/2 of the cycle, following ovulation.
During secretory phase, corpus luteum produces progesterone and estrogen which are needed to:
-help maintain the endometrium (estrogen)
-stimulate endometrium to secrete fluids which provide nutrition for young embryo (progesterone)
-progesterone also provides negative feedback to hypothalamus and pituitary to prevent another LH or FSH surge during the 2nd half of the menstrual cycle.
Corpus leutum ceases production of progesterone and estrogen toward end of cycle if:
fertilization does not occur.
Corpus leuteum is programmed to generate after _____ days.
Without steroids, the endometrium tissue breaks down and:
is sloughed off along with blood from adjacent blood vessels (menstruation).
Fertilization normally occurs in the ____
oviduct (fallopian tubes), which contain cilia that move the ovum toward the uterus.
Ovum only survives for ______.
approximately 24 hrs or less, so fertilization normally occurs within approximately 24 hrs after ovulation.
Sperm normally survive for:
about a day, but some stay viable for up to 5 days in the female reproductive tract.
Developing embryo will implant in uterus about _____ week(s) after fertilization.
Developing embryo and placenta will begin secreting _____ shortly after implantation.
hCG (human chorionic gonadotropin) which is similar to LH and stimulates the corpus luteum to prevent it from degenerating and to continue producing steroids that maintain the endometrium and prevent it from breaking down.
The developing placenta will also take over the production of ______.
estrogen and progesterone, becoming an endocrine organ.
What do home pregnancy kits test for?
hCG in urine
What do birth control pills do?
-many contain combos of synthetic estrogen and progesterone (agonists)
-levels of these hormones are high enough that they inhibit the preovulatory surge of LH and PSH, preventing ovulation
-growth of endometrium can still be cyclical (steroids are taken for the first 3 weeks which causes a gradual build up of endometrium and no steroids are taken for the fourth week, resulting in menstruation).
In addition to being an endocrine organ, the _____ is also a respiratory organ.
placenta, fetus obtains oxygen from it during development.
Fetal hemoglobin has a ____ affinity for oxygen than adult hemoglobin.
-developing embryo is able to obtain oxygen efficiently across the placenta from the maternal hemoglobin.
During sickle cell anemia:
the adult hemoglobin
becomes sickle shaped, embryonic RBC do not sickle.
Researchers at UAB are using this fact to try and cure
Sickle cell anemia.
The _____ carries the oxygenated blood from the placenta to the
fetal venous circulation (it connects to inferior vena cava).
The oxygenated blood enters the right atrium heart (right atrium).
fetal circulation is distinctly different than adult circulation because:
the circulation is shunted so that most blood bypasses the lungs.
-blood coming from placenta is already oxygenated when it enters the right atrium.
There is no air in fetal lungs so:
alveoli and associated capillaries are collapsed
-very little surfactant produced by type 2 alveolar cells during most embryonic development, helping to keep the alveoli collapsed.
The collapsed alveoli create large amounts of:
resistance to blood flow to the lungs and greatly reduces the amount of blood travelling through the lungs and returning the left atrium.
2 structures that help shunt blood away from the lungs:
foramen ovale and ductus arteriosus.
What is the forman ovale?
-an opening with a flap-like valve between right and left atrium.
-as atria contract, blood is shunted from right to left atrium
-valve opens easily because there is little pressure in the left atrium due to very little blood coming from lungs to left atrium.
What is the ductus arteriousus?
-connects the pulmonary artery to aorta
-blood entering right ventricle is pumped into pulmonary artery and then most is shunted into aorta, bypassing pulmonary circulation.
At birth, breathing...
inflates the alveoli which greatly reduces resistance to blood flow in the lungs, increasing blood flow through the lungs and back to the left atrium.
Increased blood pressure in the left atrium closes the flap over the foramen ovale....
ceasing blood flow between the two atria and causing the flap to eventually grow shut.
-if it does not shut, there is a hole in the heart: "patent formen ovale".
The ductus arteriousus between the pulmonary artery and the aorta constricts as a reflex associated with birth so that:
blood no longer travels from the pulmonary artery to the aorta.
During late pregnancy, the placenta gradually increases production of ______, a hormone that is normally produced by the hypothalamus.
corticotropin-releasing hormone (CRH).
CRH directly stimulates the fetal production of _____ and indirectly results in _____.
cortisol, placental production of higher levels of estrogen.
High levels of cortisol and estrogen result in:
an increased sensitivity of the uterus to oxytocin.
As sensitivity to oxytocin increased, the uterus becomes sensitives enough to respond to circulating levels of oxytocin and:
contractions begin, and a positive feedback loop begins, eventually leading to childbirth.
Sets with similar terms
Endocrine Glands and Hormones
The Endocrine System
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