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U5: Male Repro Sys
Male Reproductive System
| Question | Answer |
|---|---|
| Male & female reproductive systems | consist of gonads & the accessory reproductive organs |
| Gonads | in males are the testes; in females are the ovaries; both produce sex cells (gametes) and hormones. |
| Gametes | sex cells |
| Male gametes | sperm |
| Androgens | male hormones made and secreted by the testes; main one is testosterone |
| Estrogens & progesterone | main hormones produced and secreted by ovaries |
| Zygote | a fertilized egg; the first cell of a potentially new individual; receives 23 chromosomes from egg and 23 chromosomes from sperm to equal 46 |
| Male reproductive system | includes gonads, testes, in scrotum; accessory organs include ducts that transport sperm and some glands, whose secretions enhance sperm activity |
| Male ducts | epididymis, vas/ductus deferens, ejaculatory duct, urtethra |
| Male accessory glands | seminal vesicles, prostate gland, Copwer’s/bulbourethral glands |
| Scrotum | contains testes; divided into left and right via middle septum; provides temperature slightly cooler (about 5 degrees) than core body temp, which is necessary for adequate sperm cell production; responds to external temperature to maintain optimum temp. |
| Dartos muscle | under cold conditions, wrinkles and thickens the scrotal skin thus reducing heat loss; under hot conditions will relax |
| Cremaster muscles | will pull testes up toward warm abdominopelvic wall in cold conditions; relaxed in hot conditions |
| Testes/Testicles | divided into lobules, each containing 1-4 seminiferous tubules |
| Seminiferous tubules | specific sites of sperm cell production in testes; walls consist of spermatogenic cells embedded in sustentacular/sertoli cells |
| Spermatogenesis | sperm cell production |
| Interstitial/Leydig cells | found between seminiferous tubules; produce and secrete masculinizing hormones known as androgens (the main such being testosterone) |
| Pampiniform plexus | venous network from which each testicular vein arises; helps provide a cooling effect for the testes |
| Varicocele | a varicose vein in the pampiniform vein |
| Hydrocele | swelling in scrotum causes by an excessive accumulation of fluid in a space around the testis. |
| Testicular cancer | curable if detected early enough; men advised to regularly examine their testicles for lumps; however, most lumps are relatively harmless varicoceles and hydroceles |
| Form in abdominopelvic cavity; descend into scrotum about two months before birth | fetal development of testes |
| Cryptorchidism | congenital condition in males characterized by failure or one or both testes to completely descend into scrotum prior to birth; testis remaining in abdominal cavity for too long will become sterile due to higher temperature |
| Meiosis | cell division by which testes/ovaries produce sex cells/gametes/sperm/eggs; 2 consecutive divisions of nucleus—results in production of cells with only half the # of chromosomes (23), thus only half as much genetic material/DNA |
| Sperm Cell Anatomy | three parts – head, midpiece, tail |
| Head of sperm | part of sperm; contains sperm’s nucleus, thus bears its genetic material/DNA/chromosomes; anterior part of head consists of acrosome |
| Acrosome | anterior part of sperm head which contains digestive enzymes that are released when a sperm in in contact with an egg; help sperm penetrate egg to accomplish fertilization |
| Midpiece of sperm | part of a sperm; contains many mitochondria that produce ATP needed to supply energy required for sperm to use its tail swimming |
| Tail of sperm | part of sperm; flagellum that provides for sperm motility |
| Sustentacular/sustentocyte/sertoli/nurse cells | surround spermatogenic cells in wall of seminiferous tubules; provide physical & chemical assistance to immature sperm cells; tight junctions b/t these form blood-testes barrier |
| Blood-testes barrier | formed by junctions b/t sustentacular cells; prevents protein antigens that occur in differentiating sperm from entering bloodstream & activating immune system; if breached, male’s body will attack own sperm |
| Epididymis | located in scrotum on lateral & posterior surface of testis; highly coiled duct several feet long; where sperm cells temporarily stored & become mature; sperm ejaculated from this site thru vas/ductus deferens; stored too long = phagocytized & degraded |
| Vas/ductus deferens | receives/transports ejaculated sperm from epididymis to ejaculatory duct; runs upward from scrotum w/in spermatic cord, thru inguinal canal, into pelvic cavity, along then behind bladder, where it joins duct from seminal vesicle to form ejaculatory duct |
| Vasectomy | procedure in which small incision is made into each side of scrotum to sever each ductus deferens; cut ends are tied off, fused shut, or plugged; prevents sperm cells from leaving body; reduces volume of semen by about 5% |
| Spermatic cord | composite structure consisting of sheath of connective tissue & enclosed structures; components include ductus/vas deferens, testicular arteries, veins, nerves, and the cremaster muscle; inferior lies in scrotum, superior through inguinal canal |
| Inguinal canal | slit-like passageway through anterior pelvic wall that courses just deep & inferior to aponeurosis of external oblique muscle |
| Inguinal hernia | condition in which small portion of small intestine protrudes into, and sometimes through, the inguinal canal; often caused by lifting heavy objects/strenuously straining; forms a bulge below skin in groin |
| Ejaculatory duct | formed by union of a seminal vesicle w/ end of vas deferens; specifically located w/in prostate gland; propels ejaculated sperm into prostatic urethra |
| Male urethra | has three portions—prostatic, membranous, spongy/penile |
| Prostatic urethra | first portion of male urethra; runs through and is surrounded by prostate gland below urinary bladder |
| Membranous urethra | second portion of male urethra; courses through urogenital diaphragm in floor of pelvic cavity |
| Spongy/penile urethra | terminal portion of male urethra; runs through and surrounded by corpus sponginosum of penis; opening at tip is called external urethral orifice |
| Male accessory sex glands | 5 total—seminal vesicles, prostate gland, cowper’s/bulbourethral glands; secretions of these account for about 95% of semen volume |
| Semen | secretions of accessory glands + sperm; relative alkalinity of semen enhances motility of sperm and protects them from acidic environment of female’s vagina |
| Seminal vesicles | paired glands on posterior surface of male bladder; secretion makes up ~60% of semen; has chemicals to enhance sperm function; has yellow pigment that fluoresces under UV light; joins w/ end of ductus/vas deferens to form an ejaculatory duct w/in prostate |
| Prostate gland | about size/shape of chestnut; immediately below bladder, surrounds first portion of urethra; secretion makes up 1/3 volume semen, chems enhance sperm function; enzyme PSA helps screen for cancer |
| Prostate-specific antigen (PSA) | enzyme in prostate secretion; measuring the level of this enzyme in a man’s blood is the most important method of screening for prostate cancer |
| Benign prostatic hyperplasia | non-cancerous enlargement of prostate gland that occurs in most elderly men; urination becomes increasingly difficult due to prostate presses against prostatic urethra; can be detected via digital rectal exam |
| Bulbourethral/Cowper’s glands | paired, pea-sized glands below prostate gland w/in urogenital diaphragm; produce clear mucus that drains into penile/spongy urethra when male becomes sexually excited; small amount of mucus tends to accumulate at tip of penis prior to ejaculation |
| Penis | most of length consists of shaft; ends in glans penis |
| Two corpora cavernosa, one corpus sponginosum | three columns (bodies) or erectile tissue |
| Prepuce/foreskin | loose cuff of skin surrounding tip of penis; generally removed via circumcision shortly after birth |
| Erection | results from filling/engorgement of three bodies of erectile tissue with blood; during arousal, parasympathetic innervation dilates arteries supplying erectile bodies, thereby increasing flow of blood to those tissues |
| Ejaculation | results from peristaltic contractions of smooth muscle in the walls of the male ducts, all the way from epididymis through urethra |
| Epididymis—ductus/vans deferens—ejaculatory duct—urethra | pathway of ejaculated sperm cell |
| Male perineum | area between base of scrotum and anus |
| Testosterone | androgen; produced by interstitial/Leydig cells of testes; responsible for sex drive, development of secondary sex characteristics |
Created by:
mbtrimm
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