Reproductive Physiology

Question 1

Describe oogenesis

Answer 1

Oogonia undergoes mitosis to produce primary oocyte during gestation

Primary oocyte begins first meiosis but is frozen in prophase

Dominant primary oocyte finishes first meiosis and becomes secondary oocyte and releases first polar body

Secondary oocyte is fertilised by sperm and undergoes second meiosis to become ovum and release second polar body

Question 2

What is the role of GnRH?

Answer 2

Stimulate LH and FSH secretion from anterior pituitary

Question 3

What is the role of FSH?

Answer 3

Stimulate follicular recruitment and development

Question 4

What is the role of LH?

Answer 4

Maintain dominant follicle, induce follicular maturation and ovulation

Question 5

What is the role of oestrogen?

Answer 5

Supports female secondary sexual characteristics and reproductive organs

Negative feedback control of LH and GnRH, except for late follicular phase as has positive control of LH surge

Stimulates proliferative endometrium

Makes you feel great as you are fertile

Question 6

What is the role of progestogen?

Answer 6

Maintenance of secretory endometrium, negative feedback control of HPO

Makes you feel low, bloated spotty as body thinks its pregnant and is preparing for that

Question 7

What are the phases of the menstrual cycle?

Answer 7

Follicular phase, first 2 weeks

Ovulation, separates both phases

Luteal phase. last 2 weeks

Question 8

Describe the follicular phase of menstruation

Answer 8

FSH makes follicles grow and produce oestrogen from granulose cells

One follicle, with the most FSH receptors and therefore hormone, becomes the dominant follicle and secretes oestrogen for the rest of the follicular phase

Oestrogen then reaches threshold and induces a positive feedback signal, causing a surge in luteinising hormone, triggering the primary oocyte to become the secondary oocyte

Follicle ruptures and releases secondary oocyte for the menstrual cycle, awaiting fertilisation

Question 9

Describe the lutal phase of menstruation

Answer 9

Once the oocyte is released, the follicle remains becomes the corpsus luteum, made of theca cells and granulosa cells

Granulose cells secrete inhibin, which decrease FSH and therefore estrogen and therefore LH

Theca cells release progesterone and becomes dominant hormone

If secondary oocyte is fertilised, progesterone continues to be made

If not, the corpus luteum stops making hormones and breaks down, becoming the corpus albicans and subsequently results in necrosis of the endometrium/vaginal bleeding

Question 10

Describe ovulation

Answer 10

Follicle ruptures and releases oocyte