Testicular Function Flashcards
What are the two major functions of reproductive organs?
Gametogenesis
Secretion of hormones
Which hormones are released by the male and female reproductive organs?
Male: testosterone from Leydig cells
Female: oestrogen and progesterone from theca and granulosa cells
When does spermatogenesis begin in the male?
Puberty
Describe spermatogenesis?
Describe what happens in the mitotic stage of spermatogensis?
Spermatogonium > mitotic division > 2 spermatogonia
One remains a spermatogonium (maintain germ cell line)
One becomes a primary spermatocyte (produce speramtozoa)
Describe what happens in the meiotic stage of spermatogenesis?
Primary spermatocyte > first meiotic division > secondary spermatocyte > second meiotic division > spermatids
Descrinbe what happens in the packaging stage of spermatogenesis?
Spermatids mature into spermatozoa (not fully mature yet)
Describe the process of oogenesis?
Describe the mitotic stage of oogenesis?
Oogonium > mitotic division prior to birth > primary oocytes
Describe the stages of oogenesis that have occurred prior to birth?
OOgonium > mitoitc division > primary oocytes
All primary oocytes present at birth
Arrested in first meiotic division
What happens to the primary oocytes?
At puberty, one reaches maturity > enlarged primary oocyte > first meiotic divison completed > secondary oocyte (ovulated) and polar body
Describe what happens to the secondary oocyte and polary body?
Secondary oocyte > fertilisation > second meioptic division > mature ovum and second polar body
First polar body > meoitic division > second polar bodies > degenerate
When do the first and second meitoic divisions occur in oogenesis?
First: prior to ovulation
Second: after fertilisation
Describe thre hormonal regulation of reproduction?
Hypothalamus: GnRH > Anterior pituitary: LH and FSH > Gonads: sex steroids, inhibin and activin
Describe the anatomy and function of the seminiferous tubules?
Sertoli cells: surround and support sperm
Spermatogoina > sperm
Leydig cells: produce testosterone
Capillaries
Describe the hormonal regulation of spermatogenesis?
GnRH > LH > Leydig cells > testosterone > sex characteristics
GnRH > FSH > Sertoli cells > spermatocyte maturation
Inhibin feedback
Describe the effects of testosterone before birth?
Masculinises reproductive tract and exteral genitalia
Promotes descent of testes into scrotum
Describe the effects of testosterone in sex-specific tissues?
Promotes growth and maturation of reproductive system
Spermatogenesis
Describe the secondary sexual effects of testosterone?
Hair growth
Deep voice
Muscle growth
Body configuration
Describe the non-reproductive actions of testosterone?
protein anabolic effects
Bone grwoth
Closure of epiphyses
Sebaceous gland secretions
Describe the composition of semen?
Sperm
Mucous from bulbourethral glands
Water
Buffers from prostate and bulbo-urethral glands
Fructose from seminal vesicles
Citric acid from prostate
Vitamin C from seminal vesicles
Carnitine from epididymis
Enzymes from seminal vesicles and prostate
Zinc
Prostaglandins from seminal vesicles
What is the function of each of the following components of semen:
a) mucous?
b) buffers?
c) enzymes?
d) prostaglandins?
a) Mucous: lubricant
b) Buffers: neutralise acidic vaginal environment
c) Enzymes: clot semen in vagina, then liquefy clot
d) Prostaglandins: smooth muscle contraction
Describe the negative feedback in the male reproductive system?
Testosterone inhibits hypothalamus (GnRH) and anterior pituitary (LH)
Inhibin inhibits anterior pituitary (FSH)
What is andropause?
Lower levels of testosterone in old age
Affects about 50% men over 50
