Males Flashcards
What are androgens sythesised from?
Cholesterol
What does the delta 4 pathway do?
Converts progesterone to androgens
What is the functions of the testis?
Sperm production
Steroid hormone production
What is the function of the Epididymis?
Sperm collection and maturation
What is the function of the ductus deferens?
Transport and storage
What is the function of the accessory glands?
Contributions to seminal fluid
What is the function of the urethra?
Transport
Which part of the testes are sperm produced in?
Seminiferous tubules
Which cells are seminiferous tubles surrounded by?
Myoid cells?
What do the spaces between seminiferous tubles contain?
Leydig cells
Where does the biosynthesis of testosterone occur?
In leydig cells
Where does the conversion of testosterone to dihydrotestosterone (DHT) occur and by which enzyme?
Sertoli cell
5a-reductase
What is similar about the receptors for all the major classes of steroid hormone?
Proteins that have two binding sites (one for steroid and one for DNA)
The binding of steroid produces a complex that acts on DNA
Binding of complex to DNA alters genes expressed
=Transcription factors
What are androgens?
Compounds that interact with the androgen receptor
What processes are androgens responsible for?
Development of secondary sex characteristic
Anabolic effecs
Spermatogenesis
Which hormones control male sex steroid production?
Gonadotrophins (LH and FSH)
What controls Gonadotrophin release from the anterior pituitary?
Gonadotrophin Releasing Hormon released from the Hypothalamus
Pulsatile release but constant frequency so no fluctuation in LH and FSH
Which cells have receptors for FSH and LH?
Sertoli - FSHR
Leydig - LH
How do the receptors for sex steroids and gonadotrophins differ?
Gonadotrophins need receptors at the cell surface wheras the steroids have intracellular receptors
What action does LH have on Leydig cells?
Stimulates production of testosterone from cholesterol
Cholesterol transported to Sertoli cell
What action does FSH have on sertoli cells?
Converts T to DHT
ABP binds to T and DHT and concentrates them in the liminal fluid
Stimulated: spermatogenesis, maturation, accessory gland secretions, myoid cell contractile activity
Which hormones exert negative feedback?
Inhibin from sertoli (on AP)
Testosterone for Leydig (on AP and H)
What moves sperm along the seminifeous tubule?
Myoid cell contractility
AR-positive cells so action is androgen dependent
Where is the sperms ability to swim aquired?
Epididymis (DHT-dependent) and further in the female tract
