Wednesday, 11 September 2024

4:55 PM

A- detrusor muscle

B- right ureter

C- trigone

D- urethra

MALE REPRO

Spermatogonium (46):

• Male germ cell

• Always in contact with the seminiferous tubule basement membrane

Primary spermatocyte (46/diploid):

• Product of mitotic division of spermatogonium

• Divides via meiosis I

Secondary spermatocyte (23):

•  divides via meiosis II

Spermatid:

• Differentiates into sperm cells through spermiogenesis

• Formed from second meiotic division

• In contact with the luminal membrane of seminiferous tubule while it undergoes differentiation

Spermatozoa/zoon:

• Head, midpiece and tail

• Within lumen

Dartos muscle: Thin layer of muscle in connective tissue surrounding the scrotum; responsible for skin of scrotum becoming wrinkled and reducing surface area

Cremaster  Muscle: An extension of the abdominal muscles into the scrotum; pulls the testes closer to the body when outside temp drops.

An erection occurs due to the activation of the parasympathetic nervous system. This causes vasodilation of the penile arteries as a result of smooth muscle relaxation in their tunica media. Increased blood flow in the arteries results in an engorgement of the corpora cavernosa and the corpus spongiosum due to an increase in the blood volume within their sinusoids.

The pampiniform plexus is a network of 10 - 12 veins which surround the testicular artery. This forms a counter-current heat exchange system so that warm blood in arteries leaving the body heat cooler blood in the veins leaving the testes. The arterial blood entering the testis is now less than 37⁰C. The pampiniform plexus works with the dartos and cremaster muscles to 

thermoregulate the testes and keep them at a constant cooler temperature than body temperature.

Hormones

GnRH

• Origin: hypothalamus

• Target: anterior pituitary

FSH

• Origin: anterior pituitary

• Target: sustentacular/Sertoli cells of seminiferous tubules

• Stimulates production of androgen binding protein (ABP)

LH

• Origin: anterior pituitary

• Targets: interstitial/Leydig cells

• Stimulates production of testosterone

Testosterone

• Stimulates spermatogenesis

• Increases metabolism

• Regulates secondary sexual characteristics

ABP

• Binds to testosterone

• Increases testosterone levels

• Origin: sertoli cells

Inhibin

• Inhibits the release of GnRH and FSH

• Released when sperm count is high

• Origin: Sertoli cells

Glands (makes up 95% of seminal fluid, other 5% from sperm)

Bulbourethral gland (Cowper's):

• 5% of semen

• Produces an alkaline mucus = lubricant and neutralises pH in the urethra during intercourse

Seminal vesicles

• 60% of semen

• Produces fructose, other nutrients and citric acid to nourish sperm

• Produces fibrinogen (fibrin) = semen coagulation (stickiness)

• Produces prostaglandins = uterine contractions to transport sperm

Prostate gland

• 30% of semen

• Produces fibrinolysin to dissolve coagulated sperm

• Contains seminal plasmin = antimicrobial

Average volume of ejaculation = 2-5mL

spermatogenesis vs Spermiogenesis

• spermatogenesis : the entire process which forms spermatozoa

• Spermiogenesis:  the differentiation of a spermatid to form a spermatozoon is Correct

The section of the urethra which travels through the penis is called: spongy urethra

Path of sperm to the vas deferens:

1. Seminiferous tubules

2. Straight tubules (tubulus rectus)

3. Rete testis

4. Efferent ductules

5. Head of epididymis

6. Body of epididymis

7. Tail of epididymis

8. Vas deferens

Why do spermatogonia divide into 'A' and 'B' cells?

A replenishes stem cell pool, B becomes primary spermatocyte

What branches of the nervous system stimulate emission/ejaculation and erection?

• Erection: parasympathetic

• Emission: sympathetic

What is the name of the thickened layer of white fibrous tissue surrounding the corpora cavernosa; and its role? Tunica albuginea. Allows compression of veins during erection