Endocrine Signalling 4

Question 1

Where are sperm produced

Answer 1

Seminiferous tubules then drained into epididymis for 15 days

Question 2

What 3 glands make seminal fluid

Answer 2

Seminal vesicles, prostate and bulbourethral gland

All androgen dependent

Question 3

What do leydig cells produce

Answer 3

Testosterone

Question 4

What do seritoli cells do

Answer 4

facilitate the progression of germ cells to spermatozoa via direct contact and by controlling the environment within the seminiferous tubules - gives nutrients and take away waste products.

Produces inhibin B

Question 5

What are the stages of spermatogenesis

Answer 5

Spermatogonia —> daughter cell becomes primary spermatocyte –> secondaey spermatocyte –> spermatids (75 days) –> spermatozoa in seminiferous tubule –> spermatozoa in epidiymis (15 days)

Question 6

What happens in spermiogenesis

Answer 6

Get tail, mitochondria mid piece, dense DNA material

Question 7

What is capacitation

Answer 7

The process of allowing sperm to move during ejaculation

Question 8

What is the feedback control in men

Answer 8

GnRH pulse –> LH pulse to leydig cells –> testosterone pulse –> seritoli cells, secondary characteristics, androgen-binding protein

Question 9

What is the role of androgen binding protein

Answer 9

Binds to testosterone to keep it in the testes as it is steroid hormone it is hydrophobic so can leave cell at any point

Question 10

Give some features of negative feedback in men

Answer 10

Inhibin on FSH
Testosterone on LH and GnRH

Question 11

What secondary roles do testosterone have

Answer 11

Male pattern baldness
CNS - aggression
Enlarged penis
Enlarged testes
Enlarged muscles
Enlarged prostate
Deeper voice
Facial hair

Question 12

What is inhibin B a marker of

Answer 12

Seritoli cell function (as secreted by it)

1 seritoli cell to 40 spermatogeneic cells

Question 13

How many days between the first day of menstrual bleeding and LH surge

Answer 13

14 days (follicular phase)

Question 14

What happens after the LH surge

Answer 14

Oocyte ovulated from the dominant follicle

Question 15

What happens after oocyte ovulation

Answer 15

14 days of corpus luteum (luteal phase)

Question 16

What occurs after the luteal phase

Answer 16

Secretory phase - mature endometrium is maintained by corpus luteum during luteal phase but it sheds at this point due to no HbGC hormone

Question 17

What does inhibin B do in women

Answer 17

Inhibits FSH via negative feedback at AP

Question 18

What does the inhibin B negative feedback do to these follicles

Answer 18

The handful of mature poteintial follicles start competing for the finite supply of inhibin B leaving one follicle alive which is ovulated

Question 19

What triggers the LH surge

Answer 19

Oestrogen produced by the ovulated follicle

Question 20

What does the corpus luteum produce

Answer 20

Oestrogen - drive and support endometrium
Progesterone - drive and support endometrium
Inhibin A - negative feedback

Question 21

What is a key physiological change in the luteal phase

Answer 21

Spike in body temperature

Question 22

What does LH do

Answer 22

Maintains the dominant follicle

Question 23

What does FSH do

Answer 23

Stimulates follicular recruitment and development

Question 24

What does oestradiol do

Answer 24

Supports secondary sexual characteristics
Negative feedback of FSH and LH

Question 25

Where is inhibin B made

Answer 25

Granulosa cells

Question 26

Where is inhibin A made

Answer 26

Corpus luteum

Question 27

What is the role of inhibin B

Answer 27

Negative control of FSH

Question 28

What is the role of inhibin A

Answer 28

Negative control of hypo-pituitary axis

Question 29

What is the role of progesterone

Answer 29

Released by corpus luteum to maintain the endometrium

Question 30

How do ovaries make oestrodiol

Answer 30

2 cell types and 2 gonadotrophins needed -
Theca cells (LH receptors found on them and when bound, uses cholesterol to make androsteindione

Androsteindione is then released by the tehca cell and given to the granulosa cell where aromatase makes esterone –> estradiol which is released to have its effects. (dependent on FSH binding)

Question 31

As a follicle grows, what does it become more dependent of

Answer 31

FSH

Once reaches 2mm –> in competition with other follicles for ovulation (14 days)

Question 32

What stops the LH surge

Answer 32

1 - Refractory period for GNRH receptors in anterior pituitary
2 - dominant follicle to corpus luteum which oestrogen, inhibin A and progesterone production occur which causes just big GnRH impulses

Question 33

How does menstruation cause a rise in FSH again

Answer 33

Loss of corpus luteum results in loss of oestrogen, inhibin A and progesterone production so negative feedback is lost increasing the GnRH and FSH release

Question 34

Give some targets for oestrogen

Answer 34

Blood clotting
Bone turnover
Breast development
Fat distribution

Question 35

What regulates androgen binding protein

WIDER READING - Hansson 1976

Answer 35

FSH but produced by seminiferous tubules of the testis

Question 36

What clears androgen binding protein

Wider reading - Ma 2015

Answer 36

Testosterone (aka negative feedback)

Question 37

When would inhibin A and B sometimes be raised

Wider reading - Lappohn et al 1989

Answer 37

Ovarian tumours - granulosa cell tumour.