Ch. 28 - Male reproductive system

Question 1

primary reproductive organs male

Answer 1

testes

Question 2

accessory reproductive organs male

Answer 2

ducts and tubules leading from testes to penis, male accessory glands, penis

Question 3

Testes

Answer 3

relatively small organs housed within scrotum that produce sperm and androgens. Covered anteriorly and laterally by a serous membrane called tunica vaginalis.

Question 4

tunica vaginalis

Answer 4

a serous membrane that covers the testes. It is derived from abdominal peritoneum and has outer parietal layer and inner visceral layer that are separated by each other by a cavity filled with serous fluid

Question 5

Tunica albuginea

Answer 5

thick fibrous capsule covering testis; deep to visceral layer of tunica vaginalis

Question 6

mediastinum testis

Answer 6

thickening of tunica albuginea projecting into interior testis. Blood vessels, lymph vessels, and nerves enter or leave through here.

Question 7

Septa

Answer 7

internal projections of tunica albuginea, subdivide internal space into 250 lobules.

Question 8

seminiferous tubules

Answer 8

convoluted and elongated tubes that contain nondividing support cells called sustentacular cells. There are up to 4 tubules in each lobule. The cells nourish developing sperm, release inhibin when sperm count is high, and inhibits FSH secretion and regulates sperm production. Tubules also contain dividing germ cells continuously producing sperm

Question 9

blood-testis barrier

Answer 9

protects developing sperm from material in blood, including leukocytes. Formed from tight junctions between sustentacular cells.

Question 10

interstitial spaces

Answer 10

spaces surrounding seminiferous tubules

Question 11

interstitial cells

Answer 11

reside in interstitial spaces. Stimulated to produce androgens by LH; particularly testosterone. Majority of testosterone is released from interstitial cells; small amounts through adrenal cortex.

Question 12

Hormonal regulation of Spermatogenesis

Answer 12

1. Hypothalamus secretes GnRH which stimulates pituitary to secrete FSH and LH.
2. FSH and LH stimulate spermatogenesis and androgen production. LH stimulates interstitial cells while FSH stimulates sustentacular cells
3. Increased testosterone facilitates spermatogenesis, inhibits GnRH and pit. sensitivity to GnRH and negative feedback effect
4. Sustentacular cells release inhibin to inhibit FSH due to rising sperm.
5. Testosterone stimulates libido and secondary sex characteristics

Question 13

role of FSH in spermatogenesis

Answer 13

stimulates sustentacular cells to secrete androgen-binding protein. This binds to testosterone and ensures high levels in testes.

Question 14

role of LH in spermatogenesis

Answer 14

stimulates interstitial cells to secrete testosterone.

Question 15

spermatogenesis

Answer 15

process of sperm development; occurs in seminiferous tubule. Begins during puberty with significant levels of FSH and LH

Question 16

Spermatogonia

Answer 16

primordial germ cells from which all sperm develop. They are diploid cells near base of seminiferous tubule; surrounded by cytoplasm of sustentacular cell. Divide by mitosis into new spermatogonium and primary spermatocyte.

Question 17

Primary spermatocyte

Answer 17

diploid cells that undergo meiosis

Question 18

Secondary spermatocytes

Answer 18

two cells produced by primary spermatocyte from meiosis I. Haploid cells, 23 chromosomes only. Relatively closer to seminiferous tubule lumen.

Question 19

Spermatid

Answer 19

formed when secondary spermatocytes complete meiosis II. Haploid cell near seminiferous tubule lumen with circular appearance.

Question 20

spermiogenesis

Answer 20

final stage of spermatogenesis where spermatid becomes mature spermatozoa (sperm). excess cytoplasm shed and nucleus elongates. Acrosome cap forms over nucleus that contain digestive enzymes to help penetrate secondary oocyte. Tail forms from organized microtubules in cell and attach to midpiece region containing mitochondria and centriole.

Question 21

acrosome cap

Answer 21

forms over sperm nucleus and contains digestive enzymes to help penetrate secondary oocyte.

Question 22

tail

Answer 22

forms from microtubules in sperm

Question 23

midpiece

Answer 23

contains mitochondria and centriole. mitochondria produces energy to move tail

Question 24

female vs. male gametogenesis

Answer 24

single viable secondary oocyte produced in females while 4 produced in males. female oocytes arrested in meiosis prior to birth while male spermatogonia starts spermatogenesis at puberty. Females can only reproduce until menopause while men can forever.

Question 25

Semen

Answer 25

formed from seminal fluid and sperm. Called ejaculate when released during intercourse. Ejaculate contains 200 to 500 million spermatozoa and transit time from seminiferous tubules to ejaculate is about 2 weeks.

Question 26

Rete testis

Answer 26

meshwork of interconnected channels in mediastinum testis. Receive sperm from seminiferous tubules. It is lined by simple cuboidal epithelium with short microvilli covering luminal surface. Merge to form efferent ductules.

Question 27

efferent ductules

Answer 27

connect rete testis to epididymis. lined with ciliated columnar to propel sperm towards epididymis and nonciliated columnar to absorb excess fluid secreted by seminiferous tubules.

Question 28

epididymis

Answer 28

comma-shaped structure. Composed of internal duct and external covering of CT. Has a head, body, and tail. It contains a 4-5 meter long duct of the epididymis. Stores sperm until mature. If it is ejected too early it is not motile and if too late, it degenerates and is reabsorbed.

Question 29

ductus (vas) deferens

Answer 29

sperm enters here after leaving epididymis. This thick-walled tube is located within spermatic cord, extending through inguinal canal. Separates from other cord components in pelvis. Enlarges and eventually forms ampulla that unites with proximal seminal vesicle to form ejaculatory duct.

Question 30

ductus wall

Answer 30

inner mucosa lined by pseudostratified ciliated columnar. The middle muscularis has 3 layers of smooth muscle: inner longitudinal, middle circular, and outer longitudinal that is necessary for moving sperm through vas deferens. sperm is not motile until ejaculation from penis. It also has an outer adventitia.

Question 31

ejaculatory duct

Answer 31

each duct is between 1-2 cm long. pseudostratified ciliated columnar epithelium that conducts sperm and a component of seminal fluid towards urethra.

Question 32

urethra

Answer 32

transports semen from ejaculatory ducts to outside of body. has 3 components prostatic urethra, membranous, and spongy urethra.

Question 33

male sexual response

Answer 33

excitement phase: erectile bodies of penis composed of venous space that fills and becomes rigid. Parasympathetic innervation causes local release of nitric oxide responsible for increased blood flow and erection. increases hr, bp, and resp. rate.
Orgasm: intense pleasure, tension release, expulsion of semen. ductus deferens moves sperm towards urethra and gland secretions combine to form semen. internal urethral sphincter contracts to prevent urine entry into urethra
Ejaculation: end of orgasm where semen is expelled from contraction of muscles in urethra due to sympathetic innervation.
Resolution: sympathetic division stimulated to contract central artery of penis to help expel engorged blood. Followed by refractory period (minutes to hours)

Question 34

Male climacteric

Answer 34

decrease in testosterone levels in 50s. Due to decreased number of interstitial cells and declines more gradually than women’s hormones drop. Most men have few symptoms but can have hot flashes, mood swings, and decreased sex drive.

Question 35

Prostate enlargement

Answer 35

experienced by most men with age; can interfere with sexual and urinary functions

Question 36

Erectile dysfunction

Answer 36

inability to achieve or maintain erection associated with aging and other risk factors.