Unit 7 formative Material- made by Aiza
1. Using the hypothalamus-anterior pituitary gonad axis, describe how endocrine ac-
tivity would respond to a increase in Oestrogen production;
- high levels of oestrogen will stimulate a negetive feedback response
- The hypothalamus will release less GnRh
- So less FSH and LH will be produced
- So less oestrogen will be made
- Unless its in the pre-ovulation phase in whihc high levels of oestrogen has a positive
feedback affect leading to production of LH and more oestrogen.
2. What is the role of the SRY gene on the Y chromosome (2m)
- initiates the differentiation of cells in the genital ridge primordial to become pre-ser-
toli cells and start development of the testes.
3. Describe how endocrine activity is responsible in the development of primary sex-
ual characteristics (4m)
- at the gonadal primordial ridge XY chromosomes will start to express their SRY gene
- This will lead to differentiation of cells and production of pre-sertoli cells
- Pre-sertoli cells cause development of testes,
- Leydig cells in testes start to produce testosterone
- Sertoli cells start to produce MIH
- Testosterone contributes to products of male external genitalia and degeneration of
female external genitalia via Dihydrotestosterone
- Testosterone also causes the mesonephri ducts to form which contribute to male in-
ternal genitalia
- MIH produced by Sertoli cells stops mullerian tubes (female internal genitalia from
forming)
4. Explain how the hypothalamus initiates the onset of puberty in a male using hypo-
thalamus anterior pituitary gonadal axis. (2m)
- Inhibition of GABA stops it inhibition of GnRh neurones in the hypothalamus
- Leads to increase in pulsate secretions of GnRh form the hypothalamus
- This leads to anterior pituitary releasing LH and FSH
- FSH stimulates spermatogenesis in Sertoli cells
- LH stimulates production of testosterone in leydig cells which leads to production of
DHT and secondary sexual characteristic
5. Describe the process of spermatogenesis
-in the periphery of the seminiferous tubules are type A and TypeB spermatogonium
-type A spermatogonium and type B constantly proliferating however type A stay in
the basal compartment of the seminiferous tubules and replenish the supply and type
B migrate to the adluminal compartment of the tubule
- in the adluminal compartment type B spermatogonium become primary spermato-
cytes
- Primary spermatocutes undergo meiosis I to form secondary spermatocytes
- Secondary spermatocytes undergo meiosis II to form spermatids
- Spermatids mature in the epididymis to form spermatozoon A mature sperm.
1. Using the hypothalamus-anterior pituitary gonad axis, describe how endocrine ac-
tivity would respond to a increase in Oestrogen production;
- high levels of oestrogen will stimulate a negetive feedback response
- The hypothalamus will release less GnRh
- So less FSH and LH will be produced
- So less oestrogen will be made
- Unless its in the pre-ovulation phase in whihc high levels of oestrogen has a positive
feedback affect leading to production of LH and more oestrogen.
2. What is the role of the SRY gene on the Y chromosome (2m)
- initiates the differentiation of cells in the genital ridge primordial to become pre-ser-
toli cells and start development of the testes.
3. Describe how endocrine activity is responsible in the development of primary sex-
ual characteristics (4m)
- at the gonadal primordial ridge XY chromosomes will start to express their SRY gene
- This will lead to differentiation of cells and production of pre-sertoli cells
- Pre-sertoli cells cause development of testes,
- Leydig cells in testes start to produce testosterone
- Sertoli cells start to produce MIH
- Testosterone contributes to products of male external genitalia and degeneration of
female external genitalia via Dihydrotestosterone
- Testosterone also causes the mesonephri ducts to form which contribute to male in-
ternal genitalia
- MIH produced by Sertoli cells stops mullerian tubes (female internal genitalia from
forming)
4. Explain how the hypothalamus initiates the onset of puberty in a male using hypo-
thalamus anterior pituitary gonadal axis. (2m)
- Inhibition of GABA stops it inhibition of GnRh neurones in the hypothalamus
- Leads to increase in pulsate secretions of GnRh form the hypothalamus
- This leads to anterior pituitary releasing LH and FSH
- FSH stimulates spermatogenesis in Sertoli cells
- LH stimulates production of testosterone in leydig cells which leads to production of
DHT and secondary sexual characteristic
5. Describe the process of spermatogenesis
-in the periphery of the seminiferous tubules are type A and TypeB spermatogonium
-type A spermatogonium and type B constantly proliferating however type A stay in
the basal compartment of the seminiferous tubules and replenish the supply and type
B migrate to the adluminal compartment of the tubule
- in the adluminal compartment type B spermatogonium become primary spermato-
cytes
- Primary spermatocutes undergo meiosis I to form secondary spermatocytes
- Secondary spermatocytes undergo meiosis II to form spermatids
- Spermatids mature in the epididymis to form spermatozoon A mature sperm.
