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Phys Spring 5: Lec 1
Male Repro
| Question | Answer |
|---|---|
| Where are the sperm produced? | Seminiferous tubules |
| Where are the sperm stored? | Vas deferens & epididymis |
| Where are the sperm matured? | Epididymis |
| Trace the path of sperm | Seminiferous tubules --> rete tubules --> epididymis --> vas deferens --> abdomen (inguinal canal) --> behind the bladder --> urethra --> out |
| Where does the ejaculatory duct of the seminal vesicle join the vas deferens (and ultimately the urethra)? | Within the prostate |
| What parallels the vas deferens? | The testicular artery |
| What is the order of developing cells from the wall of the seminiferous tubule to the lumen? | 1. Wall of the tubule 2. Spermatogonia; 3. Sertoli cells connected by tight jxns creating the blood-testis barrier, creating a barrier between the lumen, the spermatogonia, and the wall; 4. Primary and secondary spermatocytes; 5. Sperm in the lumen |
| Discuss spermatogenesis | Spermatogonia surround the seminiferous tubules --> divide via mitosis, remain germ cells --> divide via meiosis --> are now spermatocytes --> pass thru the blood-testis barrier of the Sertoli cells --> develop into sperm |
| How many sperm are produced each day? | ~100 million |
| When do sperm become capable of motility? | After 18-24 hours in the epididymis |
| Why are the sperm incapable of motility within the epididymis? | Inhibitory proteins prevent movement |
| How long can sperm live within the vas deferens? | ~1 month |
| What do the paired seminal vesicles produce? | fructose & prostaglandins in a mucus base |
| What is the fxn of the fructose in the seminal fluid? | to feed the sperm |
| What is the volume of sperm vs. seminal secertions vs. prostate secretion within the ejaculate? | 10% sperm, 60% seminal secretions, 30% prostate secretion |
| What are the (2) fxns of prostaglandins in the seminal fluid? | 1. inhibits woman's immune response to the sperm; 2. cause reverse peristalsis in the uterus & fallopian tubes |
| What is the prostate gland? | A spongy, golf ball-sized gland surrounding the urethra just below the bladder |
| What sort of neurons stimulate the penis for erection, and what do these neurons release? | Parasympathetic neurons, NO |
| What is the fxn of NO in penile erection? | NO causes vasodilation of the local arteries, and relaxation of the smooth muscle fiber mesh-work of the spongy areas, increasing arterial input and restricting venous drainage |
| What is the molecular effect of NO on the penis? | Inc cGMP levels, causing vasodilation |
| What type of neurons cause ejaculation of semen? | Sexual reflex impulses by sympathetic neurons from T12-L2 |
| How does erectile tissue respond to sympathetic stimulation? | Initiates rapid peristaltic contractions of the vas deferens, seminal vesicles, prostate gland, and muscles at the base of the penis |
| What is the volume of semen in ejaculation? | 2-4mL |
| TRUE OR FALSE: sperm are capable of fertilization at ejaculation | FALSE - they are incapable of fertilization at ejaculation |
| What is the fxn of sperm hyaluronidase? | Cuts the extracellular matrix that surrounds the egg |
| What does the anterior membrane of the sperm bind to? | binds to receptors on the zona pellucida of the egg surface? |
| What does binding of sperm to the zona pellucida trigger? | Release of the sperm's acrosomal enzymes, which cut into the egg surface, initiating Ca channel opening, causing a microskeletal rxn to prevent entry of more than 1 sperm |
| How many sperm are within each ejaculate? | 50-100 million |
| Why are so many sperm required to fertilize an egg? | Some are killed by vaginal acid, helping to neutralize the acid; some are killed by the woman's immune system |
| What happens to the woman's immune system after previous intercourse? | Immune tolerance to the sperm |
| What surrounds the egg? | Follicular cells and glycoproteins |
| TRUE OR FALSE: One acrosome has enough enzymes to break thru the follicular cells and glycoproteins surrounding the egg | FALSE - more enzymes are required than one acrosome can provide |
| How long is the head of a sperm? | 10um |
| How long is the tail of a sperm? | 60-70um |
| Where is testosterone produced? | Interstitial/Leydig cells of the testes |
| Where are interstitial/Leydig cells located? | in the spaces between the seminiferous tubules |
| Where is the primary source of androngens for the male body? | Interstitial/Leydig cells |
| What are the (2) fxns of testosterone during fetal development? | 1. directs development of gender-specific organs; 2. controls descent of testes into the scrotal sac |
| What are the (7) fxns of testosterone in puberty & adulthood? | 1. devel. of male sex organs; 2. growth of male-specific body hair patterns; 3. deepens voice; 4. inc muscle mass; 5. thickens & bone directs bone growth; 6. Inc basal metabolic rate; 7. Inc RBC concentration |
| What are the peak ages of testosterone? | During second trimester of pregnancy, between birth and 1yo, then after ~age 13yo to 40yo, then begins to slowly decrease |
| What are the 2 current types of male contraception? | Condoms & vasectomy |
| What are the fxns of the condom? | Physical barrier b/n sperm & egg, reduce spread of HIV & STDs |
| Discuss a vasectomy | Cuts/seals vas deferens; 30 min operation, high success rate |
| What happens to sperm after a vasectomy? | Sperm are produced, stored, and die in epididymis |
| TRUE OR FALSE: Circulating testosterone levels decrease after a vasectomy | FALSE - there is no change in circulating testosterone levels |
| What is the immune response after a vasectomy? | A transient inc in ABs to sperm, but no immune complex disease or immune response to testicular tissue |
| What are the 10 possible future male contraceptive methods? | 1. Injections of testosterone derivatives; 2. Depo-provera injections; 3. RISUG; 4. GnRH agonists; 5. GnRH antagonists; 6. ABs to GnRH, sperm protease, etc. 7. Adjudin; 8. Alpha-blockers; 9. Ca-channel blockers; 10. Gossypol |
| How do injections of testosterone derivatives work as male contraception? | Because it triggers the negative feedback loop of testosterone(?) |
| What are exogenous anabolic steroids? | testosterone, or a derivative |
| How are exogenous anabolic steroids applied? | with an added side-chain for solubility or injected |
| What is the 1 good side effect of anabolic steroids? | Inc muscle mass |
| What does exogenous anabolic steroids do to sperm count and the testes? | lowers sperm count and causes testicular atrophy |
| TRUE OR FALSE: Men taking exogenous anabolic steroids have increased aggressive behavior | TRUE |
| What happens to the heart and blood with exogenous anabolic steroid use? | Valve damage and L ventricle hypertrophy, inc plasma cholesterol & BP, water retention (via aldosterone cross-over effect), and inc RBC production |
| What happens to the liver with exogenous anabolic steroid use? | liver damage occurs via reduced detoxification, hepatocytes fill with steroid dehydrogenase, causing higher blood cholesterol and jaundice |
| What happens to the immune system with exogenous anabolic steroid use? | Suppresses it (via corticoid cross-over effect) |
| TRUE OR FALSE: exogenous anabolic steroid use can cause migraines | TRUE |
| TRUE OR FALSE: exogenous anabolic steroid use can cause severe acne? | TRUE |
| TRUE OR FALSE: There is no way exogenous anabolic steroid use can cause anaphylactic shock. | FALSE - can occur from shared needles |
| What happens to women who use exogenous anabolic steroids? | Everything that happens to males, plus male-pattern body hair, deeper voice, blocked ovulations, miscarriage and fetal damage |
| How long does it take for a spermatogonia to become a mature sperm? | ~ 10 weeks, and occurs throughout a man's life |
| What stimulates the Sertoli cells? | FSH from the pituitary and testosterone from adjacent Leydig/interstitial cells |
| What forms the blood-testis barrier? | Tight jxns between Sertoli cells |
| What is the fxn of inhibin, and where is it released from? | Secreted by Sertoli cells, inhibits FSH release |
| What do the Sertoli cells do to the developing spermatocytes? | fold them into their surface, translocates the to the lumen, and consumes the excess cytoplasm |
| What does the head of the sperm contain? | Acrosome, surface membrane, vacuole, anterior & posterior head cap |
| What are the general parts of a sperm? | Head, neck, body, chief piece of tail, and end piece of tail |
| What does the neck & body of the sperm tail contain? | Lots of mitochondria |
| What does the acrosome contain, and what is its fxn? | Contains enzymes (HA, proteases) for penetrating the cellular and protein barriers around the egg |
| What is the structure & fxn of the sperm tail? | Contains microtubules, provides motive force for sperm swimming |
| What is the speed of sperm motility? | 1-4 mm/min |
| What is the prostate gland secretion composed of? | It is an alkaline secretion containing bicarb, citrate, Ca, and a high concentration of zinc |
| What is the fxn of the prostate gland secretion? | Helps protect the sperm from vaginal acid |
| What is the fxn of zinc in the prostate gland secretion? | Stabilizes the chromatin in the sperm head |
| How does Viagra work? | Blocks PDE5, which prevents cGMP break-down, which maintains vasodilation and erection |
| What breaks down cGMP? | Phosphodiesterase 5 (PDE5) |
| What is capacitation? | The process of sperm becoming capable of fertilization |
| How does capacitation occur? | Inhibitory factors that suppressed sperm activity in vas deferens are diluted by vaginal/uterine fluids, uterine secretions of steroid-binding albumin removes cholesterol from acrosome surface, and there is an influx of Ca from uterine fluids into sperm |
| What are the (2) actions of Ca from the uterine fluids? | 1. Ca moves into the flagellum, causes more rapid motion; 2. Ca moves into the acrosome, enhancing acrosomal enzyme secretion |
| TRUE OR FALSE: Testosterone is secreted into blood and freely circulates | FALSE: Testosterone is secreted into blood and binds to sex hormone-binding globulin and some plasma albumin |
| Which tissues absorb testosterone? | target tissues (?) or liver hepatocytes |
| What is the fxn of liver hepatocytes to testosterone? | liver hepatocytes process testosterone and excrete it into bile & urine |
| What do the adrenal glands secrete? | DHEA and androstenedione |
| What is DHEA converted to? | DHEA --> Androstenedione --> testosterone --> estradiol |
| What are the peak ages of sperm production | ~15yo to ~80yo, then begins to slowly decrease |
| What hormone is the fxn of GnRH, and from where is it released? | Controls sperm development, released from the hypothalamus |
| How does GnRH control sperm development? | GnRH enters the portal system --> anterior pituitary --> causes anterior pituitary to release LH & FSH |
| What is the role of LH in sperm development? | Stimulates interstitial/Leydig cells of the testes to secrete testosterone |
| What is the role of FSH in sperm development? | Stimulates Sertoli cells of the seminiferous tubules to develop the sperm |
| Do testosterone and inhibit provide negative or positive feedback? | Provide negative feedback (feedback inhibition) to hypothalamus & pituitary |
| How do Depo-provera injections work as male contraception? | Blocks LH-FSH |
| What is the route of administration of Depo-provera? | Androgen gel or patch |
| What is RISUG? | A reversible injection of styrene gel into the vas deferens, being developed as a form of male contraception |
| How do GnRH agonists work as male contraception? | Bind to and inactivate receptors (indirectly) by down-regulation |
| How do GnRH antagonists work as male contraception? | bind to and directly inactivates receptors |
| How does Adjudin work as male contraception? | blocks cell adhesion b/n Sertoli cells and spermatocytes |
| How do alpha-blockers work as male contraception? | Inhibits ejaculation |
| How do Ca-channel blockers work as male contraception? | Block sperm movement |
| How does Gossypol work as male contraception? | blocks an enzyme (?) in spermatogenesis |
| What is the risk of using Adjudin? | It is similar to chemotherapy agents, requires high doses and can cause liver damage |
| What is the risk of using Gossypol? | blocking the enzyme is not always reversible, causes a high % of permanent infertility, inducing hypokalemia, and is occasionally fatal |
| What is phenoxybenzamine? | An example of an alpha-blocker contraceptive |
Created by:
hclark86
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