Male sex hormones Flashcards
Actions of testosterone: enlargement
Stimulates enlargement of testes and male accessory organs
What is sexual development programmed by?
Genome
Which gene determines sex?
23
Is there a defined sex at 6 weeks of development?
No
What does Gonad (cortex) form for females?
Ovary
What does Gonad (cortex) form for males?
Regresses (Nothing)
What does Gonad (medulla) form for females?
Regresses (Nothing)
What does Gonad (medulla) form for males?
Testis
What does Wolffian duct form for females?
Regresses (testosterone absent)
What does Wolffian duct form for males?
Forms epididymis, vas deferens, and seminal vesicle (testosterone present).
What does Mullerian duct form for females?
Becomes fallopian tube, uterus, cervix, and upper ½ of vagina (AMH absent)
What does Mullerian duct form for males?
Regress (AMH present)
What is the presence of the Y chromosome associated with?
SRY (sex determining region on Y chromosome) gene
What happens to the cortex and medulla without the SRY gene present?
Cortex turns in ovaries and medulla disappears
What is the SRY gene associated with?
Production and release of testi-determining SRY protein
What does testi-determining SRY protein initiate?
Production of protein that will tun medulla into testis
What is the consequence of medulla turning into testis?
The cortex of medulla disappears
What are the two types of cells in the testis?
Leydig cells and Sertoli cells
What do Sertoli cells secrete?
Anit-mullerian hormone
what is the cause of secretion of Anit-mullerian hormone from Sertoli cells?
Regression of Mullerian duct
What do Leydig cells secrete?
Testosterone
What does secretion of testosterone hormone from Leydig cells control? (2)
Development of wolffian duct into accessory structures
Development of male external genitalia (via DHT)
What is DHT?
Dihydrotestosterone is a male sex hormone. It is formed in the presence of enzyme 5α-reductase.
What is testosterone?
A male sex hormone that is a potent androgen
Where is testosterone synthesized?
Within the Leydig cells of testes (in males) and some from adrenal cortex (in both sexes).
What is testosterone responsible for?
Development and maintenance of male secondary sexual characteristics.
What stimulates enlargement of tastes and male accessary organs?
Testosterone
What does testosterone bind to?
Androgen receptors
Actions of testosterone: Stimulates development of male secondary sex characteristics (5)
- Increased growth of body hair
- Enlargement of the larynx and thickening of the vocal cords
- Thickening of the skin
- Muscle growth, widening of shoulders, narrowing of waist
- Thickening and strengthening of bones
Hormonal Control of Male Reproductive Functions:
Hormones are secreted by:
Hormones are secreted by:
– Hypothalamus
– Anterior pituitary gland
– Testes
Functions
– Development of sperm cells
– Development of secondary sex characteristics
What is the rate at which sperm is produced in males?
At a constant rate with no limit.
