Session 2

Question 1

What is the HPG axis?

Answer 1

Hypothalamus-pituitary-gonad axis

Question 2

Which hypothalamic releasing hormone is associated with the HPG axis?

Answer 2

GnRH

Question 3

What is the name of the depression in the sphenoid bone in which the pituitary gland is located?

Answer 3

Sella turcica

Question 4

What other name can be given to the pituitary gland?

Answer 4

Hypophysis

Question 5

What other names can be given to the anterior pituitary gland?

Answer 5

Pars distalis

Adrenohypophysis

Question 6

What other name can be given to the posterior pituitary gland?

Answer 6

Pars nervosa

Question 7

What are the six peptide hormones produced by the anterior pituitary gland?

Answer 7

Prolactin
Growth hormone (GH)
Thyroid-stimulating hormone (TSH)
Adrenocorticotropic hormone (ACTH)
Follicle-stimulating hormone (FSH)
Luteinizing hormone (LH)

Question 8

Which two hormones are secreted by the anterior pituitary in response to GnRH?

Answer 8

LH

FSH

Question 9

Describe the release of of GnRH from the hypothalamus.

Answer 9

Pulsatile (every 1-3 hours)

Travels to the pituitary via the hypophysial portal system

Question 10

What is the name given to the cells of the anterior pituitary that secrete FSH and LH?

Answer 10

Gonadotrophs

Question 11

Which cells of the testis secrete testosterone?

Answer 11

Leydig cells

Question 12

Which hormone stimulates Leydig cells?

Answer 12

LH

Question 13

Which hormone stimulates Sertoli cells of the seminiferous tubules?

Answer 13

FSH

Question 14

What two functions are provided by Sertoli cells?

Answer 14

Increased spermatogenesis

Inhibin secretion

Question 15

In the male, what feedback effect will testosterone have on the HPG axis?

Answer 15

Negative feedback on the hypothalamus and anterior pituitary gland

Question 16

Which hormone of the anterior pituitary stimulates theca cells of the ovary and what do they secrete?

Answer 16

LH

Progestins (and androgens)

Question 17

Which hormones stimulate the granulosa cells of the ovary and what do they secrete?

Answer 17

LH and FSH
Oestrogens
Progestins
Inhibin

Question 18

In what conditions will oestrogen promote negative feedback on the hypothalamus?

Answer 18

Moderate concentration of oestrogen

Question 19

In what conditions will oestrogen promote positive feedback on the hypothalamus?

Answer 19

High concentrations of oestrogen AND an absence of progesterone (this causes the LH ‘surge’)
Progesterone increases the inhibitory effects of moderate oestrogen and prevents positive feedback of high oestrogen

Question 20

Predominantly, the secretion of which hormone is inhibited by inhibin?

Answer 20

FSH (Inhibin has a small inhibitory effect on LH)

Question 21

In the female, by what mechanisms can oestrogen have both a positive and negative feedback effect on the HPG axis?

Answer 21

Moderate concentrations of oestrogen will cause negative feedback on the HPG axis.
High concentrations of oestrogen, in the absence of progesterone, will cause positive feedback on the HPG.

Question 22

Which two events does the the menstrual cycle refer to?

Answer 22

Uterine cycle

Ovarian cycle

Question 23

In the early stage of the menstrual cycle, steroid and inhibin levels are low. The levels of which hormone subsequently rise?

Answer 23

FSH

Question 24

What is the effect of rising levels of FSH?

Answer 24

Follicular development continues
The follicle is now capable of secreting oestrogen
Inhibin levels rise

Question 25

When oestrogen is being secreted by the follicle, what feedback effect is seen on the hypothalamus and anterior pituitary?

Answer 25

Positive feedback

Question 26

What effect is seen as a response to the positive feedback caused by high concentrations of oestrogen?

Answer 26

Increase in LH

Question 27

What causes the LH surge and what does this trigger?

Answer 27

Rapid rise in circulating oestrodial and inhibin | Ovulation

Question 28

What are the effects of LH after ovulation?

Answer 28

Luteinisation of the follicle (formation of the corpus luteum)

Question 29

What is secreted in large quantities by the corpus luteum?

Answer 29

Progesterone (negative feedback on LH secretion) Oestrogen Inhibin

Question 30

After how long will the corpus luteum spontaneously regress in the absence of a further rise in LH?

Answer 30

14 days (after this point a dramatic fall in gonadal hormones will occur, relieving negative feedback and restarting the cycle)

Question 31

What is secreted by a conceptus that will support the corpus luteum after 14 days?

Answer 31

Human chorionic gonadotropin (HCG is an LH analogue produced by the syncytiotropoblast in the second week of development)

Question 32

The corpus luteum, supported by placental hCG, produces steroid hormones to support the pregnancy. eventually, what will take over the production of steroid hormones?

Answer 32

Placenta

Question 33

What are the names given to the two phases of the ovarian cycle?

Answer 33

``` Follicular phase (more variable in length) Luteal phase (14 days) ``` Ovulation occurs between the two phases

Question 34

What are the names given to the three phases of the endometrial cycle?

Answer 34

Menses Proliferative phase Secretory phase

Question 35

What are the physical effects of oestrogen during the follicular phase of the ovarian cycle?

Answer 35

``` Fallopian tube function Thickening of endometrium Growth & motility of myometrium Thin alkaline cervical mucus Vaginal changes Changes in skin, hair, metabolism ```

Question 36

What are the physical effects of progesterone during the luteal phase of the ovarian cycle?

Answer 36

Further thickening of endometrium into secretory form Thickening of myometrium, but reduction of motility Thick, acid cervical mucus Changes in mammary tissue Increased body temperature Metabolic changes Electrolyte changes