Lecture 14: The Genital (Reproductive) System

Question 1

what is the reproductive system

Answer 1

-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

Question 2

what are the 4 common functions of both male and female reproductive systems

Answer 2

gametogenesis, copulation, fertilization, and development of fetus

Question 3

what is gametogenesis

Answer 3

formation of specialized cells (gametes) for sexual reproduction
-sperm: gametes in males
-ova (eggs): gametes in females

Question 4

what is copulation (coitus)

Answer 4

brings male and female gametes together through sexual intercourse

Question 5

what is fertilization

Answer 5

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

Question 6

what is gestation and parturition

Answer 6

the reproductive system support the development of fetus (gestation) and birth of baby (parturition)

Question 7

what are the two types of reproductive organs

Answer 7

gonads & accessory reproductive organs

Question 8

describe the gonads

Answer 8

primary sex organs
-testes: males
-ovaries: females
-produce two products: gametes, and sex hormones

Question 9

describe gametes produced by gonads

Answer 9

-sperm: male
-ova: female
gamete formed by cell division is called meiosis

Question 10

describe the sex hormones produced by gonads

Answer 10

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

Question 11

describe accessory reproductive organs

Answer 11

ducts, glands, and external genitalia

Question 12

what are the functions of the male reproductive system

Answer 12

1. testes (gonads): produce sperm and testosterone
2. ducts: transport, storage, and maturation of sperm
3. accessory glands: secrete liquid protion of semen
4. penis: urethra within, passageway for semen ejaculation

Question 13

describe the scrotum

Answer 13

-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

Question 14

what is the midline septum of the scrotum

Answer 14

divide scrotum into two compartments, one for each testiw

Question 15

what is the raphe of scrotum

Answer 15

raised thickening in scrotal surface

Question 16

how is the scrotum affected by temp changes

Answer 16

when cold, testes are pulled closer to warm body wall

Question 17

what does the dartos muscle do

Answer 17

smooth muscle layer that wrinkles the skin

Question 18

what do the cremaster muscles do

Answer 18

skeletal muscles that elevate testes

Question 19

describe testes

Answer 19

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)

Question 20

what are the two tunics of the testes

Answer 20

tunica vaginalis & tunica albuginea

Question 21

explain the histology of the testes

Answer 21

-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

Question 22

describe the histology of the testes, more specifically the seminiferous tubules

Answer 22

-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

Question 23

what are the effects of testosterone

Answer 23

-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

Question 24

what is the role of sustentocytes (Nurse/ sustenticular cells) of seminiferous tubules

Answer 24

-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

Question 25

what is the blood-testis barrier

Answer 25

-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

Question 26

what is the path of sperm and fluid

Answer 26

straight tubule-> rete testis-> efferent ductules-> epididymis

Question 27

accessory ducts that carry sperm from testes to body exterior

Answer 27

epididymis, ductus deferens, ejaculatory duct, urethra

Question 28

what is the epididymis

Answer 28

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

Question 29

what are the functions of the epididymis

Answer 29

-Monitor and adjust composition of fluid produced by seminiferous tubules
-Recycle damaged sperm
-Store and protect sperm and facilitate their functional maturation

Question 30

describe the ductus (vas) deferens

Answer 30

-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

Question 31

what is the spermatic cord

Answer 31

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

Question 32

what are the contents of the spermatic cord

Answer 32

ductus deferens, testicular artery, veins draining the testes, autonomic nerves, lymphatic vessels, and the cremaster muscle

Question 33

what is the ejaculatory duct

Answer 33

-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

Question 34

describe the male urethra

Answer 34

-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)

Question 35

describe the seminal vesicles (glands)

Answer 35

secrete an alkaline,
viscous fluid containing fructose, prostaglandins
and clotting proteins; Produces majority of semen

Question 36

describe the prostate

Answer 36

a single gland that secretes a milky, slightly acidic fluid containing citric acid, proteolytic enzymes, acid phosphatase, and seminal plasmin

Question 37

describe the bulbo-urethral (Cowper’s) glands

Answer 37

secrete an alkaline fluid during sexual arousal to neutralize urinary acids in urethra, and mucus for lubricating tip of penis

Question 38

describe semen (ejaculate)

Answer 38

-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

Question 39

describe characteristics of semen (pt. 2)

Answer 39

-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

Question 40

describe the penis

Answer 40

-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

Question 41

describe the foreskin (prepuce)

Answer 41

-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

Question 42

what are the two erectile tissues of the penis

Answer 42

corpora cavernosa and corpus spongiosum

Question 43

describe the corpora cavernosa

Answer 43

-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

Question 44

describe the corpus spongiosum

Answer 44

-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

Question 45

describe the male perineum (same as the female)

Answer 45

-Diamond-shaped region btw pubic symphysis, coccyx (anus), and ischial tuberosities
-Suspends scrotum
-Contains root of penis and anus

Question 46

describe testicular cancer

Answer 46

-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

Question 47

what is prostatitis

Answer 47

inflammation of the prostates

Question 48

describe prostate cancer

Answer 48

-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

Question 49

what are inguinal hernias

Answer 49

-protrusions of visceral tissues into inguinal canal
-Fairly common in males
-Spermatic cord creates weak point in abdominal wall