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Flashcards in Physiology - Lassies Deck (17)
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1
Q

List the major female reproductive hormones?

A

Gonadotrophin releasing hormone (GnRH)

Gonadotrophins - FSH & LH

Steroid hormones - Estrogen, progesterone & Testosterone

2
Q

Trace the Hypothalamo-Pituitary-Ovarian Axis (HPO)

A

Hypothalamus produces GnRH

GnRH act on Pituitary –> FSH & LH

FSH & LH act on ovaries –> Ova & Oestrogen/progesterone

3
Q

Describe the normal feedback effect of the HPO axis?

A

Oestrogen and progesterone normally have a -ve feedback effect on the Hypothalamus & Ant Pit

4
Q

When & how does the feedback effect of the HPO axis change?

A

Roughly day 12-14 of the menstrual cycle.

Oestrogen reaches a peak level that flips it from -ve to +ve feedback resulting in a surge of Gonadotrophins (mainly LH)
–> LH surge leads to Ovulation

5
Q

What do we call the phases of the ovarian cycle?

A

Follicular stage

Luteal phase

The switch happens at ovulation

6
Q

What occurs during the follicular phase of the ovarian cycle?

A

FSH & LH initiate the growth of new follicles

Primary Oocyte –> Developing follicle –> mature graafian follicle

7
Q

What occurs during the Luteal phase of the ovarian cycle?

A

The now empty follicle forms a corpus luteum that then degenerates to scar tissue known as a corpus albicans

FSH & LH fall

8
Q

What are the phases of the menstrual cycle?

A
Menstrual Phase (0-4 days)
Proliferative Phase (4-14 days) - Then ovulation
Secretory Phase (14-26 days)
Premenstrual phase (26-28 days)
9
Q

.What type of hormone are oestrogen and progesterone?

A

Steroid Hormones

10
Q

Describe how the gonadotrophins change over the course of the month?

A

They rise a bit then remain fairly steady throughout Follicular phase then spike at ovulation before falling away again during the luteal phase

11
Q

Describe how ovarian hormones change throughout the month?

A

Oestrogen & PRogesterone start very low.

Oestrogen rises during the follicular phase and peaks at ovulation before falling away again near the end of the luteal phase

Progesterone starts to rise after ovulation, peaking & overtaking oestrogen in the middle of the luteal phase and falling away again before the start of the next follicular phase

12
Q

Describe how the endometrial wall changes throughout the month?

A

Starts thick
Sheds during the menstrual phase (aka 0-4days aka start of follicular phase)

Thickens during the proliferative stage from 4-14 days

After ovulation the secretory phase starts at which point glands develop (14-26 days)

Premenstrual phases features high vascularisation (26-28 days)

13
Q

Describe the process of Oogenesis BEFORE BIRTH

A

Oogonium (Stem cell) undergo mitosis to form Primary Oocytes.

These undergo Meiosis but pause in the prophase

14
Q

Describe the process of Oogenesis after Menarche?

A

Every month 1 Primary Oocyte completes meiosis to form a 2nd* Oocyte & a polar body.

Secondary oocyte is releasd in ovulation

15
Q

Describe the process of Oogenesis after fertilization?

A

The secondary oocyte that was released in ovulation is fertilized with sperm

Only then does it undergo meiosis II to form a mature Ovum & polar body

16
Q

What is the purpose of the menstrual cycle?

A

To prepare the endometrium for pregnancy

Should no fertilization occur the menstrual phase happens, clearing the way for the next cycle

17
Q

How does follicle number decline with age?

A

Roughly 1,000,000 at birth
~half that at 18
~Down to 100,000 by 30

Considered non-fertile by 41 when egg number hits ~10,000

Irregular cycles start from around 45

Menopause occurs at roughly 50

Theses are rough numbers and don’t matter specifically, just important to understand how ovarian reserve changes with age