Reproductive physiology Flashcards
Describe the daily production rate of testosterone in males.
The daily production rate of testosterone in males is 5-15mg.
What percentage of total testosterone circulates as free biologically active hormone?
2-4% of total testosterone circulates as free biologically active hormone.
Which proteins is testosterone bound to?
Testosterone is bound to proteins, particularly albumin (~38%) and SHBG (~60%).
What is the affinity of testosterone to albumin compared to SHBG?
Testosterone is bound to albumin with lower affinity than to SHBG.
What is the ‘bioavailable’ form of testosterone?
Albumin-bound testosterone can also be regarded as ‘bioavailable’.
What is the percentage of SHBG-bound androstenedione?
Androstenedione is only about 6% SHBG-bound.
Describe the daily production rate of estradiol in females.
The daily production rate of estradiol in females is 40-400 micrograms.
What percentage of free estradiol is biologically active?
2-3% of free estradiol is biologically active.
What is the main enzyme responsible for the conversion of testosterone to DHT?
The enzyme 5α-reductase, specifically type 2, is responsible for the conversion of testosterone to DHT.
What is the main enzyme responsible for the conversion of testosterone to DHT?
The enzyme 5α-reductase, specifically type 2, is responsible for the conversion of testosterone to DHT.
What is the main enzyme responsible for the conversion of testosterone to DHT?
The enzyme 5α-reductase, specifically type 2, is responsible for the conversion of testosterone to DHT.
Where is the aromatase enzyme found in greatest quantities?
The aromatase enzyme is found in greatest quantities in the testes and adipose tissue.
Where is the aromatase enzyme found in greatest quantities?
The aromatase enzyme is found in greatest quantities in the testes and adipose tissue.
Where is the aromatase enzyme found in greatest quantities?
The aromatase enzyme is found in greatest quantities in the testes and adipose tissue.
What effects previously attributed to testosterone are now known to be mediated by estrogen?
Many effects previously attributed to testosterone are now known to be mediated by estrogen, especially closure of epiphyses and maintenance of bone density.
What effects previously attributed to testosterone are now known to be mediated by estrogen?
Many effects previously attributed to testosterone are now known to be mediated by estrogen, especially closure of epiphyses and maintenance of bone density.
What effects previously attributed to testosterone are now known to be mediated by estrogen?
Many effects previously attributed to testosterone are now known to be mediated by estrogen, especially closure of epiphyses and maintenance of bone density.
How are testosterone and its metabolites inactivated and excreted?
Testosterone and its metabolites are inactivated in the liver and excreted in the urine.
How is estradiol conjugated in the liver?
Estradiol is conjugated in the liver to sulphates and glucuronates.
What are the two types of receptors that oestradiol binds to?
Oestradiol binds to α receptors (reproductive tissues) and β receptors (bone, brain, heart, etc.).
What are the functions of progesterone?
Progesterone is involved in ovulation, implantation, pregnancy, regulation of uterine function, smooth muscle relaxation, and CNS effects.
What are the actions of testosterone and DHT mediated by?
Both testosterone and DHT exert their activity by binding to androgen receptors.
What are the actions of estradiol mediated by?
The actions of estradiol are mediated by binding to α and β receptors.
What is the role of progesterone in the menstrual cycle?
Progesterone regulates uterine function during the menstrual cycle, controlling cyclical changes in proliferation and decidualization.
