Male Reproductive System Flashcards
At puberty the hypothalamus begins secreting more GnRH and the ant. pituitary secretes LH and FSH in response.
Which cells do LH and FSH bind to in the testes and what is the response?
LH binds LHCG receptors on Leydig cells - induces leydig cells to produce testosterone (binds androgen receptors)
FSH binds receptors on Sertoli cells - activates >300 genes including expression of more androgen receptors, stimulates inhibin and androgen binding protein (ABP) production
What does inhibin do
suppresses FSH production from anterior pituitary
What is testosterone bound to in testicular fluid
androgen binding protein (ABP)
What negative feedback does testosterone give
inhibits hypothalamus secreting GnRH
inhibits pituitary secreting LH
Maturation of sperm occurs in the epididymis. What happens to the sperm at the head (caput), body (corpus) and tail (cauda) of the epididymis?
caput - sperm gains motility
corpus - sperm gains fertilizing ability
tail - storage of sperm (not a big storage area so some also stored in vas deferens)
What is capacitation of sperm and where does it occur?
Female tract.
Molecules in uterine secretions hyperactivate sperm, changing their motility (tail has more thrust), and gives them the ability to undergo the acrosome reaction
Where does pre-ejaculate (mucus) come from and what is its function?
bulbourethral gland aka Cowper’s gland
lubrication and neutralisation of acidic urine in urethra so sperm not damaged
What secretions are emitted from the prostate during copulation?
alkaline secretion high in zinc
enzymes for ejaculate clotting
Prostate-specific antigen (PSA) - an enzyme to break down/liquefy seminal coagulum in vagina
Where is the majority of ejaculate secreted from
seminal vesicles
What do seminal vesicles secrete
semenogelin
fibrinogen-like substrate for ejaculate clotting
fibrinogen for clotting of ejaculate
fructose for nutrition of sperm
Describe the course of sperm through the male tract from production to ejaculation
- > Begin in the seminiferous tubules (mitosis, meiosis, differentiation)
- > Rete testis
- > Epididymis (maturation and storage)
- > Vas deferens (storage)
- > Vas deferens joins the seminal vesicle duct to form the ejaculatory duct where secretion is added from the seminal vesicle
- > Ejaculatory duct passes through the prostate where secretions are added
- > Ejaculatory duct opens into the urethra and sperm move out through urinary meatus
Which cells secrete testosterone in the testes
leydig cells
What is the effect of testosterone on sertoli cells
stimulates to make more sperm
what do leydig cells synthesise testosterone from
cholesterol
During spermiogenesis (differentiation) what does the acrosome form from?
the golgi
During spermiogenesis (differentiation) what happens to the centrioles?
distal centriole forms the axoneme (main unit of the flagellum)
proximal centriole is donated to the egg to form the spindle for the embryos first mitotic division
During spermiogenesis (differentiation) what does the round spermatids?
they become elongated spermatids and finally mature spermatozoa
What happens to the sperms cytoplasm during spermiogenesis?
It is shed as a resdiual body which is phagocytosed by sertoli cells
What are the 3 functions of sertoli cells?
“nurse cells to the sperm”
- Phagocytosis
- Gives nutrition & physical support to sperm
- Releases androgen binding protein (ABP)- concentrates testosterone in the seminiferous tubules enabling spermatogenesis
What happens to the DNA in the nucleus of the sperm during spermiogenesis (differentiation)?
histones are condensed to protamines which are more compact
It carries a sex-determining X or Y chromosome
Where are the mitochondria in the sperm after spermiogenesis (differentiation)?
arranged helically around the midpiece of the flagellum
