reproduction

Question 1

what are the key reproductive hormones

Answer 1

• GnRH
• LH
• FSH
• oestrogen
• progesterone
• testosterone

Question 2

what does FSH cause to happen

Answer 2

• causes testes to produce sperm
• causes growth of ovarian follicles
• causes ovary to secrete oestrogen

Question 3

what does LH do

Answer 3

• causes testes to secrete testosterone
• causes ovulation
• causes progesterone production by the corpus luteum

Question 4

what is GnRH responsible for the release of

Answer 4

release of FSH and LH from anterior pituitary

Question 5

how is GnRH secreted

Answer 5

In males GnRH is secreted in pulses at a constant frequency whereas in females the frequency of the pulses varies during the menstrual cycle

Question 6

what do high frequency GnRH pulses stimulate

Answer 6

LH pulses

Question 7

what do low frequency pulses stimulate

Answer 7

FSH release

Question 8

what hormone reduced frequency of GnRH pulses

Answer 8

increase in progesterone concentrations

Question 9

how long is the follicular phase of the menstrual cycle

Answer 9

typically 14 days +/- 7

Question 10

what happens after FSH stimulates growth of ovarian follicles

Answer 10

• Rising oestrogen levels in turn exert negative feedback regulation (level of hypothalamus and pituitary) to lower FSH levels (temporarily)
• Once oestrogen reaches a certain concentration it exerts positive feedback regulation resulting in an increase in FSH levels and the LH ‘surge’

Question 11

what does the LH surge lead to

Answer 11

• LH surge eventually leads to ovulation and regulates the formation of the corpus luteum and progesterone production and secretion
• Increasing progesterone decrease LH secretion by influencing GnRH pulsatility

Question 12

what does a follicle consist of

Answer 12

an oocyte surrounded by follicular cells

Question 13

what happens in the ovary and endometrium during the 28 days

Answer 13

• growth entails an increase in the number of follicular cells and accumulation of follicular fluid
• both resulting in an increase in the diameter and overall size of follicle
• endometrium thickens under the influence of oestrogen
• becomes a secretory tissue under the influence of progesterone

Question 14

what happens in folliculogenesis

Answer 14

• once a follicle reaches a certain size it becomes gonadotrophic dependent
• only one follicle is secreted

Question 15

why does only one follicle get released

Answer 15

because with rising oestrogen levels, FSH levels initially decrease so only one follicle able to cope with this fall in FSH

Question 16

how is the corpus luteum made

Answer 16

• Occurs under the influence of LH
• Granulosa and theca cells transform to luteal cells
• Increase in progesterone production
• LH stimulates angiogenesis (ensures efficient delivery of cholesterol (substrate for progesterone synthesis))
• LH stimulates enzymes involved in conversion of cholesterol to progesterone

Question 17

what are the functions of oestrogen

Answer 17

• increase in thickness of the vaginal wall
• regulate LH surge
• reduce vaginal pH through an increase in lactic acid production
• decrease viscosity of cervical mucous to facilitate sperm penetration

Question 18

how does progesterone maintain pregnancy

Answer 18

• maintains thickness of endometrium
• responsible for infertile mucus
• relaxes the myometrium

Question 19

how does sperm transport through the cervix

Answer 19

sperm enter the cervical canal rapidly where they encounter cervical mucus

Question 20

what is the sperms ability to penetrate the mucus regulated by

Answer 20

• Thickness of the mucus- Hydration of cervical mucus under hormonal control
• Motility of the sperm- Only progressively motile sperm are able to pass through. Poorly motile cells get stuck
• Interaction with reactive oxygen species (produced by leukocytes that have infiltrated the cervical mucus)
• Interaction with mucins (see De Jonge diagram)

Question 21

features of spermatogenesis

Answer 21

• Occurs within the testes
• Under endocrine control (LH, FSH and testosterone)
• Entire spermatogenic process takes 70 days
• Estimates suggest that humans produce as many as 1,000 sperms for every heartbeat
• Begins at puberty for and occurs for 60 years or more
• Sperm need to be motile to successfully traverse the female reproductive tract

Question 22

what are the two compartments of the testicles

Answer 22

• extratubular compartment

- intratubular compartement

Question 23

what is most of the testosterone released taken up by

Answer 23

sertoli cells

Question 24

what does testosterone do in spermatogenesis

Answer 24

• maintains integrity of blood-testes barrier

- release of mature spermatozoa from sertoli cells by influencing peritubular myoid cells

Question 25

when does estradiol peak in the menstrual cycle

Answer 25

before ovulation

Question 26

when does progesterone peak in the menstrual cycle

Answer 26

following ovulation

Question 27

where is estrogen secreted from

Answer 27

the ovaries and adrenal cortex | -the placenta in pregnancy

Question 28

what secretes progesterone

Answer 28

the corpus luteum | -placenta during pregnancy

Question 29

what does progesterone inhibit the secretion of

Answer 29

LH

Question 30

what is spinnbarkeit

Answer 30

The formation of a thread by mucus from the cervix uteri when spread onto a glass slide and drawn out by a cover glass

Question 31

what is basal body temperature

Answer 31

Body temperature in the morning before moving about or eating after at least 6 hours of sleep