The Male Reproductive Sytem

Question 1

What is the basic structure of the male gonads

Answer 1

Epididymis, ductus deferens and testes

Question 2

What is the dual function of the male gonads

Answer 2

-Testes secrete large amounts of androgens and small amounts of oestrogens
- Gametogenesis (spermatogenesis in males) to produce gametes

Question 3

Describe the basic anatomy of the male reproductive system

Answer 3

Testis, epididymis, vas deferens, seminal vesicle, prostate, ejaculatory duct, bulbourethal gland, penis

Question 4

What is the role of the testes

Answer 4

Contains globules where spermatogenesis will occur

Question 5

What is the role of the epididymis

Answer 5

Sperm produced are deposited here and travel as they mature

Question 6

What is the role of the vas deferens

Answer 6

Inactive sperm produced are stored here for up to. 3 months

Question 7

What is the role of the seminal vesicle

Answer 7

Produces some of the components that make up the semen that dilutes the sperm to form the ejaculate

Question 8

What is the role of the prostate

Answer 8

Prostate gland creates remaining component of semen, mostly muscle providing switch between urinary tract and ejaculatory tract

Question 9

What is the role of the ejaculatory duct

Answer 9

Everything is mixed to form semen and expelled

Question 10

What is the intratubular compartment

Answer 10

Component of testes that contains stem cells involved in sperm production

Question 11

What is the peritubular compartment

Answer 11

Component of testes that contains leading cells e.g. hormale cells, muscle cells and blood vessels to support spermatogenesis

Question 12

What are spermatids

Answer 12

Small round cells that undergo spermaiogenesis to form spermatozoa (sperm)

Question 13

What is a spermatozoom

Answer 13

Matured spermatids with a smaller nucleus, little cytoplasm and prominent tail

Question 14

How do sperm propel themselves

Answer 14

Micro tubular structures within their tail

Question 15

What is the acrosome

Answer 15

Membrane covering head of sperm that acts as a lysosome and contains hydrolytic enzymes to digest the egg membrane

Question 16

Why are the hydrolytic enzymes in the acrosome only activated during the acrosomal reaction in the fallopian tube

Answer 16

Enable fertilisation and prevents digestion of other cell membranes that aren’t the egg

Question 17

How many days does spermatogenesis take

Answer 17

72

Question 18

How often do groups of spermatogonia enter spermatogenesis

Answer 18

Every 16 days

Question 19

Why are spermatogenesis cycles consistent

Answer 19

To ensure that not all spermatogonia enter spermatogenesis at the same time along the entire length of the seminiferous tubule

Question 20

What type or types of cell division does spermatogenesis involve

Answer 20

Mitosis and meiosis

Question 21

Describe the 6 steps in spermatogenesis

Answer 21

1) spermatogonial stem cells (SSC) divide by mitosis to produce daughter spermatogonia (2n)
2) at least one spermatogonium remains in the stem cell population
3) majority id spermatogonia migrate away from basal laminate (in testes) and differentiate into primary spermatocytes (2n)
4) primary spermatocytes enter meiosis 1 to form 2 secondary spermatocytes (n)
5) each secondary spermatocyte enters meiosis 2 within 20 minutes to form spermatids (n)
6) Initial products of meiosis 1 and 2 are four spermatids linked with cytoplasmic bridges

Question 22

Describe the development of a spermatogonial stem cell to a mature sperm

Answer 22

Spermatogonial stem cells, spermatogonium, primary spermatocytes, secondary spermatocytes, spermatids, mature sperm cell

Question 23

What are the 5 main functions of the Sertoli cells

Answer 23

1) guide sperm towards lumen by forming and re-forming junctions
2) Blood testes barrier as tight junctions to provide immunologically safe environment
3)Secrete fluid to move immobile sperm to epididymis
4) transfer nutrients
5) phagocytosis of residual cytoplasm and dead sperm

Question 24

What are Sertoli cells

Answer 24

Companion cells that surround the dividing cells

Question 25

Where do sperm undergo further maturation after spermatogenesis

Answer 25

Epididymis

Question 26

Why do spermatozoa undergo decapacitation in the epididymis

Answer 26

To prevent spermatozoa undergoing the acrosome reaction before coming into contact with an oocyte (egg)

Question 27

Where are sperm stored

Answer 27

Vas deferens

Question 28

What happens in the vas deferens upon stimulation of the penis

Answer 28

Undergoes peristaltic contractions to propel sperm into urethra during intercourse for ejaculation

Question 29

What does the epididymis epithelium secrete and what is the function of this

Answer 29

Seminal fluid, enables spermatozoa to become increasingly motile/tail activation

Question 30

What controls spermatozoa decapacitation in the epididymis

Answer 30

Testosterone-ABP complexes and testosterone from the blood

Question 31

Describe the composition of semen

Answer 31

Sperm (10%) and seminal fluid (90%)

Question 32

What is the pH of seminal fluid

Answer 32

6.5

Question 33

What buffers seminal fluid

Answer 33

Phosphate and bicarbonate ions

Question 34

What percentage of semen volume is secreted by the seminal vesicles

Answer 34

60-70%

Question 35

What secretes fructose and why

Answer 35

Seminal vesicles, for sperm motility

Question 36

What secretes semenogelins and why

Answer 36

Seminal vesicles, and to induce semen coagulation after ejaculation so no sperm has advantage for fertilisation

Question 37

What percentage of semen volume is secreted by the prostate gland

Answer 37

20-30%

Question 38

What is PSA

Answer 38

prostate specific antigen that is a protease that liquefies coagulated sperm after a few minutes and can be used as an indicator of prostate health

Question 39

Where is PSA secreted from

Answer 39

Prostate gland

Question 40

What else does the prostate gland secrete and why

Answer 40

Citrate, zinc, spermine and acid phosphatase to form thin milky fluid

Question 41

What are the Bulbourethral glands/cowpeas glands

Answer 41

Peas sized gland embedded in urethral sphincter that emptied the penile urethra in response to sexual excitement/ prior to emission and ejaculation of semen

Question 42

How does the bulborethral gland prepare for ejaculation

Answer 42

Secretes mucus to lubricate, cleanse and buffer the urethra

Question 43

What is the average sperm count

Answer 43

60-100 x10^6 /ml of semen

Question 44

What is the average ejaculate volume

Answer 44

1.5-5 ml

Question 45

What three factors may mean someone is considered infertile

Answer 45

- sperm count <20x10^6 /ml semen - less than 50% motile sperm - <60% normally conformed sperm

Question 46

What is internal insemination

Answer 46

Separation of vaginal wall and deposition of semen at the distal end of the vaginal lumen near the cervix by the penis

Question 47

Describe how erection is neurovascular event

Answer 47

During flaccid state blood flow to corpus cavernous is vasoconstricted (via helicine arteries), sexual arousal stimulated parasympathetic nerves innervate vascular muscle of HA to release nitric oxide, which activates cGMP, decreasing Ca2+ and causing vasodilation/relaxation enabling blood flood to CC/ erection

Question 48

What are the Leydig cells

Answer 48

Steriodogenic stromal cells that synthesis androgens

Question 49

What is DHT

Answer 49

Dihydrotestosterone, which is testosterone converted by 5alpha-reductase

Question 50

What is the function of DHT

Answer 50

Masculination of external genitalia in utero, puberty

Question 51

What is the function testosterone

Answer 51

Regulate Sertoli cell function, effects on fat metabolism and deposition of abdominal adipose tissue, promote bone growth and protein anabolism