reproductive system Flashcards
the organs of the male reproductive system include:
· testes (gonads), which produce sperm & secrete hormones
· a system of ducts that receive, store, and transport sperm (epididymis, ductus deferens, ejaculatory ducts, urethra)
· accessory sex glands that provide secretions (seminal vesicles, prostate, bulbourethral glands)
· supporting structures (scrotum & penis)
what is the scrotal septum?
divides the scrotum into 2 sacs, each containing a single testis
what are the dartos and cremaster muscles?
· found in scrotum
· contraction of its muscle fibers regulate the temperature of the testes
· e.g. in response to cold temperatures, the cremaster & dartos muscles contract to move testes closer to body, where they can absorb body heat
normal sperm production requires what temperature?
about 2 to 3 degrees celsius BELOW body temperature
what is the function of seminiferous tubules? what kind of cells do they contain?
· tightly coiled tubules within the testes where sperm are produced
· contain 2 types of cells: spermatogenic cells that form sperm, and Sertoli cells which support sperm formation
list the layers of tissue around the scrotum and testes:
from superficial to deep: · skin of scrotum · dartos muscle · external spermatic fascia · internal spermatic fascia · tunica vaginalis (peritoneum) · tunica albuginea (of testis)
Sertoli cells (or sustencaular cells) are embedded among the spermatogenic cells in the seminiferous tubules. what is the function of Sertoli cells?
· form the blood-testis barrier, which isolates developing gametes from the blood
· nourish spermatocytes, spermatids, and sperm
· phagocytize excess spermatid cytoplasm as development proceeds
· control movements of spermatogenic cells & the release of sperm into the lumen of the seminiferous tubule
· produce fluid for sperm transport
· secrete the hormone inhibin
· regulate the effects of testosterone & FSH
in the spaces between adjacent seminiferous tubules are clusters of cells called Leydig (interstitial) cells. what is the function of Leydig cells?
secrete testosterone
describe the anatomy of a sperm:
major parts are head & tail:
· the flattened, pointed head contains a nucleus with 23 highly condensed chromosomes
· covering anterior 2/3 of nucleus is the acrosome, a cap-like vesicle filled with enzymes to help sperm penetrate the secondary oocyte
· tail is divided into 4 parts:
1. neck - contains centrioles
2. middle piece - contains mitochondria arranged in a spiral, which provide ATP/energy
3. principal piece - largest portion of the tail
4. end piece - terminal, tapering portion of tail
briefly describe hormonal control of testes:
· hypothalamus secretes GnRH, which stimulates anterior pituitary to secrete LH & FSH
· LH stimulates Leydig cells to secrete testosterone
· FSH acts indirectly to stimulate spermatogenesis
· FSH & testosterone act synergistically on Sertoli cells to stimulate secretion of androgen-binding protein (ABP), which binds to testosterone and keeps its concentration high
· testosterone stimulates the final steps of spermatogenesis
· Sertoli cells release inhibin
list the ducts that sperm pass through on its way out of the seminiferous tubules in the testes:
from seminiferous tubules to:
· straight tubules
· rete testes (a network of ducts)
· efferent ducts (coiled ducts in the epididymis)
· ductus epididymis (single tube that efferent ducts empty into)
describe the anatomy of the epididymis:
· a comma-shaped organ that lies along the posterior border of each testis
· consists mostly of tightly coiled ductus epididymis
· efferent ducts from the testis join the ductus epididymis at the larger, superior portion of the epididymis called the head
· the body is the narrow midportion
· the tail is the smaller, inferior portion
· at its distal end, the tail of the epididymis continues as the ductus (vas) deferens
what is the function of the epididymis?
· the site of sperm maturation (sperm acquire motility & ability to fertilize an ovum), which occurs over a period of about 14 days
· helps propel sperm into the ductus (vas) deferns during sexual arousal
· stores sperm, which remain viable here for up to several months
describe the anatomy of the ductus deferens (or vas deferens):
· a less convoluted continuation of the ductus epididymis
· ascends along the posterior border of the epididymis through the spermatic cord, and then enters the pelvic cavity where it loops over the ureter and passes over the side and down the posterior surface of the URB
· the dilated terminal portion of the ductus deferens is the ampulla
what is the function of the ductus deferens (or vas deferens)?
· conveys sperm during sexual arousal from the epididymis toward the urethra by peristaltic contractions
· can store sperm for several months
the spermatic cord is the supporting structure of the male reproductive system that ascends out of the scrotum. describe the anatomy of the spermatic cord:
· contains: the ductus (vas) deferens as it ascends through the scrotum, the testicular artery, veins that drain the testes and carry testosterone into circulation, autonomic nerves, lymphatic vessels, and the cremaster muscle
· the spermatic cord & ilioinguinal nerve pass through the inguinal canal
describe the anatomy of the ejaculatory ducts:
· each ejaculatory duct is 2cm long and is formed by the union of the duct from the seminal vesicle & the ampulla of the ductus (vas) deferens
· the ejaculatory ducts form just superior to the base (superior portion) of the prostate and pass inferiorly and anteriorly through the prostate
· they terminate in the prostatic urethra, where they eject semen & seminal vesicle secretes just before the release of semen from the urethra to the exterior
describe the anatomy of the male urethra:
· about 20cm long, the male urethra passes through the prostate, the deep muscles of the perineum, and the penis
· it is subdivided into 3 parts:
1. prostatic urethra, which passes through the prostate
2. membranous urethra, where it passes through deep muscles of perineum
3. spongy (penile) urethra, where it passes through the corpus spongiosum of the penis
· the spongy urethra ends at the external urethral orifice
what is the function of the male urethra?
· shared terminal duct of the reproductive & urinary systems
· passageway for both semen & urine
where are the seminal vesicles located?
the paired seminal vesicles are convoluted pouchlike structures lying posterior to the base of the urinary bladder & anterior to the rectum
what is the function of the seminal vesicles?
secrete an alkaline, viscous fluid that contains:
· fructose - for ATP production by sperm
· prostaglandins - contribue to sperm motility & vitality
· clotting proteins - help semen coagulate after ejaculation
where is the prostate located? does the prostate grow?
· about the size of a golf ball, the prostate lies inferior to the urinary bladder and surrounds the prostatic urethra
· slowly increases in size from birth to puberty, then expands rapidly until age 30, after which time its size typically remains stable until about age 45, when further enlargement may occur
what is the function of the prostate?
secretes a milky, slighly acidic fluid (pH ~6.5) that contains:
· citric acid - for ATP production by sperm via Krebs cycle
· proteolytic enzymes - eventually break down the clotting proteins from the seminal vesicles
· seminalplasmin - an antibiotic
· acid phosphatase - function unknown
where are the bulbourethral glands (or Cowper’s glands) located?
· about the size of peas, the paird bulbourethral glands are located inferior to the prostate on either side of the membranous urethra within the deep muscles of the perineum
· their ducts open into the spongy urethra
what is the function of the bulbourethral glands?
· secrete an alkaline fluid into the urethra that protects the passing sperm by neutralizing acids from urine in the urethra
· also secrete mucus that lubricates end of penis & lining of urethra, decreasing the # of sperm damaged during ejaculation
describe the constitution of semen and its pH:
· a mixture of sperm & seminal fluid (which contains the secretions of the seminiferous tubules, seminal vesicles, prostate, and bulbourethral glands)
· seminal vesicles contribute 60% of fluid
· prostate contributes 25% of fluid
· slighly alkaline pH of 7.2 - 7.7
what is the volume of semen in a typical ejaculation? what # indicates that the male is likely infertile?
· 2.5 - 5 mL of semen, with 50-150 million sperm per mL
· infertility is below 20 million sperm per mL
describe the anatomy of the body of the penis:
body of penis is composed of:
- corpora cavernosa penis - two dorsolateral masses
- corpus spongiosum penis - smaller midventral mass which contains the spongy urethra & keeps it open during ejaculation
- tunica albuginea - fibrous tissue surrounding the above two structures
erectile tissue encloses the above
what is the function of the penis?
contains urethra and is passageway for ejaculation of semen and excretion of urine
describe the anatomy of the distal end of the penis:
· glans penis - a slightly enlarged, acorn-shaped region at the distal end
· corona - margin of the glans penis
· external urethral orifice - terminal end of urethra within the glans penis
· foreskin (or prepuce) - covering of skin over an uncircumcised penis
describe the anatomy of the base of the penis:
· bulb of the penis - the expanded portion of the base of the corpus spongiosum penis
· crura of the penis - two separated & tapered portions of the corpora cavernosa penis
· the bulb of the penis is attached to the inferior surface of the deep muscles of the perineum & is enclosed by bulbospongiosus muscle, a muscle that aids ejaculation
· each crus of the penis bends laterally away from thh bulb of the penis to attach to the ischial & inferior pubic rami & is surrounded by ischiocavernosus muscle
what are the ligaments that support the weight of the penis?
· fundiform ligament - arises from the inferior part of the linea alba
· suspensory ligament - arises fro the pubic symphysis
erection is maintained by sympathetic or parasympathetic fibers from the sacral portion of the spinal cord?
parasympathetic
ejaculation is a sympathetic or parasympathetic reflex coordinated by the lumbar portion of the spinal cord?
sympathetic
the organs of the female reproductive system include:
· ovaries (female gonads)
· uterine (fallopian) tubes, or oviducts
· uterus
· vagina
· external organs (collectively called vulva, or pudendum)
· mammary glands (also considered part of the integumentary system)
describe the general anatomy of the ovaries:
· paired glands that resemble unshelled almonds in size & shape (homologous to testes) and lie on either side of uterus
· broad ligament of the uterus (part of the parietal peritoneum) attaches to the ovaries via the mesovarium
· ovarian ligament anchors the ovaries to the uterus
· suspensory ligament attaches ovaries to the pelvic wall
what is the function of the ovaries?
ovaries produce:
· gametes, secondary oocytes that develop into mature ova after fertilization
· hormones, including progesterone & estrogen
· inhibin
· relaxin
describe the layers of tissue in each ovary:
from superficial to deep:
· germinal epithelium - simple epithelium
· tunica albuginea - dense irregular connective tissue
· ovarian cortex - consists of ovarian follicles surrounded by dense irregular connective tissue containing collagen fibers & stromal cells
· ovarian medulla - more loosely arranged connective tissue (blood vessels, lymphatic vessels, nerves)
what is the difference between an ovarian follicle, a mature (graafian) follicle), a corpus luteum, and a corpus albicans?
· ovarian follicles - are in the ovarian cortex and consists of oocytes in various stages of development, plus the cells surrounding them
· mature (graafian) follicle - is a large, fluid-filled follicle that is ready to rupture & expel its secondary oocyte (aka ovulation)
· corpus luteum (“yellow body”) - contains the remnants of a mature follicle after ovulation
· corpus albicans (“white body”) - fibrous scar tissue that is the result of degeneration of the corpus luteum
what is the function of the corpus luteum ?
produces progesteron, estrogens, relaxin, and inhibin
describe the anatomy of the uterine (fallopian) tubes, or oviducts:
· pair of tubes about 10 cm (4 in) long lie b/w folds of broad ligaments of the uterus
· infundibulum is the funnel-shaped portion, which is close to the ovary but open to the pelvic cavity
· fimbriae are fingerlike projections at the end of the infundibulum, one of which is attached to the lateral end of the ovary
· from the infundibulum, the uterine tube extends medially & eventually inferiorly and attaches to the superior lateral angle of the uterus
· ampulla is the widest, longest portion, making up about 2/3 of its length
· isthmus is the more medial, short, narrow, thick-walled portion that joins the uterus
what is the function of the uterine tubes?
· provide a route for sperm to reach the ovum
· transport secondary oocytes & fertilized ova from the ovaries to the uterus
what features of the uterine tubes help to move the oocyte or fertilized ovum toward the uterus?
· peristaltic contractions of the smooth muscle
· ciliary action of the mucose
where and when does fertilization occur?
· fertilization suually occurs in the ampulla, although it can happen in the pelvic cavity
· can occur at any time up to about 24 hours after ovulation
where is the uterus located? how is it positioned?
· between the UB and the rectum
· normally projects anteriorly & superiorly over the UB (anteflexion)
· about the size & shape of an inverted pear
describe the anatomical sub-divisions of the uterus:
· fundus is the dome-shaped portion superior to the uterine tubes
· body is the tapering central portion
· cervix is the inferior narrow portion that opens into the vagina
· isthmus is between the body of uterus & the cervix
· uterine cavity is the interior body of uterus
· cervical canal is the interior of the cervix, which opens into the uterine cavity at the internal os and into the vagina at the external os
name & describe the ligaments that maintain the position of the uterus:
· broad ligaments are double folds of peritoneum attaching uterus to either side of pelvic cavity
· paired uterosacral ligaments lie on either side of rectum & connect uterus to sacrum
· cardinal (lateral cervical) ligaments are located inferior to the bases of the broad ligaments & extend from the pelvic wall to the cervix & vagina
· round ligaments extend from a point on the uterus just inferior to the uterine tubes to a portion of the labia majora
the endometrium is the inner layer of the uterus and is highly vascularized. what are the two layers of the endometrium?
· stratum functionalis (functional layer) - lines the uterine cavity & sloughs off during menstruation
· stratum basalis (basal layer) - is deeper and permanent, and gives rise to a new stratum functionalis after each menstruation
describe cervical mucus and its function:
· produced by secretory cells of the mucosa of the cervix
· a mixture of water, glycoproteins, lipids, enzymes, and inorganic salts
· during their reproductive years, females secrete 20-60 mL per day
· more hospitable to sperm at or near time of ovulation because it is then less viscous and more alkaline (pH 8.5)
· supplements the energy needs of sperm
· together with cervix, protect sperm from phagocytes and the hostile environment of the vagina & uterus
where is the vagina located?
· between the urinary bladder & the rectum
· directed superiorly & posteriorly, where it attaches to the uterus
