Lecture 14: The Genital (Reproductive) System Flashcards
what is the reproductive system
-Does not function continuously like other organ systems
-Does not become active until puberty
-Male and female reproductive organs are quite different, but perform four functions in common
what are the 4 common functions of both male and female reproductive systems
gametogenesis, copulation, fertilization, and development of fetus
what is gametogenesis
formation of specialized cells (gametes) for sexual reproduction
-sperm: gametes in males
-ova (eggs): gametes in females
what is copulation (coitus)
brings male and female gametes together through sexual intercourse
what is fertilization
combine genetic information contained within gametes through fertilization
-zygote: formed when sperm and egg fuse
-first cell of new individual and all body cells arise from it
what is gestation and parturition
the reproductive system support the development of fetus (gestation) and birth of baby (parturition)
what are the two types of reproductive organs
gonads & accessory reproductive organs
describe the gonads
primary sex organs
-testes: males
-ovaries: females
-produce two products: gametes, and sex hormones
describe gametes produced by gonads
-sperm: male
-ova: female
gamete formed by cell division is called meiosis
describe the sex hormones produced by gonads
sex hormaones are steroid hormones
-testosterone= males
-estrogen & progesterone= females
-vital in development and function of reproductive organs and other organs/tissues, sexual behavior, sexual drives
describe accessory reproductive organs
ducts, glands, and external genitalia
what are the functions of the male reproductive system
- testes (gonads): produce sperm and testosterone
- ducts: transport, storage, and maturation of sperm
- accessory glands: secrete liquid protion of semen
- penis: urethra within, passageway for semen ejaculation
describe the scrotum
-A sac of skin and superficial fascia
-Hangs outside abdominopelvic cavity
-Anterior to anus; inferior to base of penis
-Contains paired testes
-2 – 3°C lower than core body temperature
-Lower temperature is necessary for
sperm production
what is the midline septum of the scrotum
divide scrotum into two compartments, one for each testiw
what is the raphe of scrotum
raised thickening in scrotal surface
how is the scrotum affected by temp changes
when cold, testes are pulled closer to warm body wall
what does the dartos muscle do
smooth muscle layer that wrinkles the skin
what do the cremaster muscles do
skeletal muscles that elevate testes
describe testes
paired, oval glands within the scrotum (scrotal cavity) surrounded by two tunics:
-Tunica vaginalis: outerlayer derived from peritoneum (releases fluid into cavity to allow movments of testes in scrotum)
-Tunica albuginea: inner layer forms fibrous capsule (support erection)
what are the two tunics of the testes
tunica vaginalis & tunica albuginea
explain the histology of the testes
-Septa divide testis into ~250 lobules, each containing 1-4 seminiferous tubules
-Site of sperm production (spermatogenesis); Each is about 80 cm long
-Connect to rete testis, a network of interconnected straight tubules
-Efferent ductules connect rete testis to epididymis
describe the histology of the testes, more specifically the seminiferous tubules
-surrounded by CT capsules
-Areolar tissue fills spaces b/w tubules
-Within those spaces, there are:
* Blood vessels
* Large interstitial endocrine cells
→ Leydig cells: Produce androgens, dominant male sex hormones. Testosterone is most important androgen
what are the effects of testosterone
-Stimulates spermatogenesis
-Maintains libido (sexual drive) and related behaviors
-Stimulates bone and muscle growth
-Establishes and maintains male secondary sex characteristics
-Maintains accessory glands and organs of male reproductive system
what is the role of sustentocytes (Nurse/ sustenticular cells) of seminiferous tubules
-Provide nutrients and signals to dividing cells
-Move spermatocytes and spermatids along to lumen
-Secrete testicular fluid (rich in androgens and
metabolic acid) into lumen for sperm transport
-Phagocytize faulty germ cells and excess cytoplasm
-Produce 2 mediators to regulate spermatogenesis:
1. Androgen-binding protein (ABP): keeps
testosterone levels high to stimulate spermatogenesis
2. Inhibin: inhibits spermatogenesis by inhibiting FSH
release by anterior pituitary
what is the blood-testis barrier
-Isolates seminiferous tubules from general circulation
-Nurse cells maintain the barrier: joined by tight junctions that divide seminiferous tubule into
compartments. Outer basal compartment contains spermatogonia. Inner luminal compartment is where meiosis and spermiogenesis (spermaties become motile and become spermatocytes, then sperm)
occur
what is the path of sperm and fluid
straight tubule-> rete testis-> efferent ductules-> epididymis
accessory ducts that carry sperm from testes to body exterior
epididymis, ductus deferens, ejaculatory duct, urethra
what is the epididymis
Start of the male reproductive tract
-Bound to posterior border of each testis
-Consists of head, body, and the tail
Head – Largest part; Receives sperm from efferent ductules
Body – On posterior surface of testis
Tail - Begins near inferior border of testis
- Ascends to connect with ductus deferens
- Primary storage location of sperm until ejaculation
what are the functions of the epididymis
-Monitor and adjust composition of fluid produced by seminiferous tubules
-Recycle damaged sperm
-Store and protect sperm and facilitate their functional maturation
describe the ductus (vas) deferens
-Exits epididymal tail, and ascends through the spermatic cord into the pelvis
-Loops over ureters, passes over and down the posterior surface of urinary bladder
-Expands to form ampulla; Joins duct of seminal vesicle to form ejaculatory duct
-Smooth muscle in walls propels sperm from epididymis to urethra
- Vasectomy: ~ 100% effective form of birth control
what is the spermatic cord
emerges from the scrotum
-spermatic cord and ilioinguinal nerve pass through the inguinal canal: originates at the deep ingional rings and ends at the superficial inguinal rings
-content of spermatic cord: ductus deferens, testicular artery, veins draining the testes, autonomic nerves, lymphatic vessels, and the cremaster muscle
what are the contents of the spermatic cord
ductus deferens, testicular artery, veins draining the testes, autonomic nerves, lymphatic vessels, and the cremaster muscle
what is the ejaculatory duct
-Short passageway from the junction of the duct of seminal vesicle and the ampulla of ductus deferens
-Penetrates wall of prostate, and empties into prostatic urethra
describe the male urethra
-Duct shared by both reproductive and urinary systems: channel for both semen and urine
-Extend from urinary bladder to tip of penis
-Three regions: passes through the prostate gland (prostatic urethra), deep muscles of
the perineum (intermediate/membranous urethra), and the penis (spongy urethra)
describe the seminal vesicles (glands)
secrete an alkaline,
viscous fluid containing fructose, prostaglandins
and clotting proteins; Produces majority of semen
describe the prostate
a single gland that secretes a milky, slightly acidic fluid containing citric acid, proteolytic enzymes, acid phosphatase, and seminal plasmin
describe the bulbo-urethral (Cowper’s) glands
secrete an alkaline fluid during sexual arousal to neutralize urinary acids in urethra, and mucus for lubricating tip of penis
describe semen (ejaculate)
-Milky-white mixture of sperm, seminal fluid and enzymes
-Contains fructose for ATP production, protects and activates sperm, and facilitates sperm movement
-pH is 7.2–7.7 (alkaline) – neutralizes acidity of male urethra and female vagina, and enhance motility
-Volume of average ejaculate is 2.5-5 ml, with 50–150 million sperm/ml
-Sperm count – taken of semen collected after 36 hours of sexual abstinence
describe characteristics of semen (pt. 2)
-Contain prostaglandins that decrease viscosity of mucus in cervix and stimulate reverse peristalsis in uterus
-Contains hormone relaxin, and other enzymes that enhance sperm motility
-Can suppress female immune response
-Antibiotic chemicals (seminalplasmin) destroy some bacteria
-Clotting factors coagulate semen initially to prevent draining out, then liquefy it by fibrinolysin so sperm can finish journey
describe the penis
-Male copulatory organ; Contains urethra and is a passageway for semen and urine
1. Root – fixed portion that attaches penis to body wall inferior to pubic symphysis
2. Body (shaft) – tubular, movable portion of penis
- Composed of 3 cylindrical masses: 2 corpora cavernosa, and 1 corpus spongiosum
3. Glans Penis (Head) – expanded distal end, surrounds external urethral orifice
describe the foreskin (prepuce)
-Fold of skin surrounding tip of penis
-Attaches to neck and continues over glans penis
-Preputial Glands: In skin of neck and inner surface of foreskin. Secrete waxy material (smegma) that can
support bacteria
-Circumcision: Surgical removal of foreskin. Can help prevent infections and penile cancer
what are the two erectile tissues of the penis
corpora cavernosa and corpus spongiosum
describe the corpora cavernosa
-Two cylindrical masses, separated by thin septum
-Under anterior surface of flaccid penis
-Diverge at their bases, forming crus of penis
-Each crus is bound to ramus of ischium and pubis: By tough CT ligaments
-Extend to neck of penis
describe the corpus spongiosum
-Relatively slender erectile body that surrounds
distal portion of urethra -Extends to tip of penis and expands to form glans
penis
-Erectile tissue contains a pair of small arteries
describe the male perineum (same as the female)
-Diamond-shaped region btw pubic symphysis, coccyx (anus), and ischial tuberosities
-Suspends scrotum
-Contains root of penis and anus
describe testicular cancer
-rare, but most common cancer in men age 15–35
-Mumps that lead to orchitis (inflammation of testis) – risk factor
-Cryptorchidism – most common risk factor
-Non-descent of testes; Sign – painless, solid mass in testis
-90% cured by surgical removal of testis and often radiation or chemotherapy
what is prostatitis
inflammation of the prostates
describe prostate cancer
-3rd most common cause of cancer death in males
-Treated with surgery and sometimes radiation
-Metastatic prostate cancer treated with drugs that block testosterone synthesis or action
what are inguinal hernias
-protrusions of visceral tissues into inguinal canal
-Fairly common in males
-Spermatic cord creates weak point in abdominal wall
