Female reproduction Flashcards

1
Q

What are the components of the HPG axis?

A

Hypothalamus
Anterior pituitary gland
Gonads (Ovaries or testes)

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2
Q

What hormones are produced by the ovaries?

A

Oestrogen
Progesterone

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3
Q

What are the 3 main forms of oestrogen?

A

Oestrone - Menopause
Oestrodiol - Reproductive
Oestriol - Pregnancy

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4
Q

What affect does oestrogen and progesterone have on the hypothalamus and anterior pituitary?

A

They can both stimulate or inhibit hormone production from them, forming the axis

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5
Q

How is GnRH released from the hypothalamus in females?

A

From neurones in a pulsatile manner

The frequency of pulses then corresponds to the hormones produced by the pituitary

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6
Q

How does GnRH pulse frequency affect pituitary secretion?

A

Increased frequency ⇒ Increased LH levels
Decreased frequency ⇒ Increased FSH

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7
Q

How does oestrogen increase GnRH pulsatility?

A

Oestrogen increases pulsatility,

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8
Q

How does progesterone affect GnRH pulsatility?

A

Progesterone decreases pulsatility

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9
Q

How do oestrogen and progesterone affect GnRH pulsatility, when GnRH neurones do not contain their receptors?

A

They interact with receptor on kisspeptin hormones, which then go on the activate the neurones

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10
Q

How long is the average menstrual cycle?

A

28 days

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11
Q

What are the 2 main phases of the menstrual cycle?

A
  • Follicular (Proliferative) Phase
  • Luteal (Secretory) phase
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12
Q

Which of the 2 menstrual stages is most variable in length?

A

Follicular, lasting 14 days, but varying by around 7 days either side

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13
Q

Describe the changes in hormones during the follicular phase of the menstrual cycle

A
  1. GnRH stimulates LH and FSH release
  2. Follicular phase causes increase of FSH
  3. FSH stimulates oestrogen release from ovarian follicles
  4. Oestrogen causes decrease of FSH
  5. Oestrogen also stimulates LH surge
  6. LH surge leads to ovulation
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14
Q

On what day of the menstrual cycle is ovulation?

A

14 days

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15
Q

Describe the changes in hormones during the luteal phase of the menstrual cycle

A
  1. LH surge also leads to corpus luteum formation
  2. This produces progesterone
  3. Progesterone decreases LH
  4. Lack of pregnancy causes cessation of progesterone release from corpus luteum, causing period
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16
Q

How long does bleeding usually last in the menstrual cycle?

A

<7 days

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17
Q

What are the functions of oestrogen in the menstrual cycle?

A
  • Increase the thickness of the endometrium
  • Regulating LH surge
  • Reducing vaginal pH through increase in lactic acid production
  • Decreasing viscosity of cervical mucus to facilitate sperm penetration
18
Q

What is the corpus luteum?

A

The corpus luteum is the cholesterol filled remnant of the ovarian follicle responsible for progesterone release, used in pregnancy

19
Q

What are the functions of progesterone in the menstrual cycle?

A
  • Maintaining endometrial thickness
  • Maintaining infertile thick mucus (Prevent sperm transport and prevents infection)
  • Relaxing the myometrium
  • Increasing basal body temperature
20
Q

What causes bleeding in the menstrual cycle?

A

Depleting levels of progesterone then cause shedding of the uterine lining and unfertilised egg, leading to a ‘period’, which causes bleeding lasting <7days

21
Q

What is caused by removal of progesterone in pregnancy?

A

Termination of the pregnancy

22
Q

What makes up an overian follicle?

A

Oocyte (Egg)
Follicular cells
Antrum containing follicular fluid

23
Q

What are the 2 types of follicular cells?

A
  • Granulosa cells
  • Theca cells
24
Q

What is the function of the follicle?

A

Allow for oocyte maturation and play a role in oestrogen production

25
Q

How do follicular cells allow for production of oestrogen?

A

LH binds to receptors on theca cells and stimulates the conversion of cholesterol to androgen

This androgen is shuttled to the granulosa cells, where FSH binding and aromatase allow for the conversion of androgen into oestrogen

26
Q

How many primordial follicles are found in each developing ovary?

A

7 million

27
Q

How many primordial follicles are found in each ovary at birth?

A

2 million

28
Q

How many primordial follicles are found in each ovary at puberty?

A

0.5 million

29
Q

Describe the selection process of a follicle for ovulation

A

Early stages of growth occur independently of gonadotrophins, however, once a follicle reaches a certain size, they become dependant on FSH to grow

During each cycle around 7 follicles are picked up as they are at the right size during the FSH peak

Only 1 (Dominant follicle) will be selected for ovulation, totally dependant on FSH levels

30
Q

What occurs when a follicle grows, but not in line with FSH spike?

A

Atresia, meaning it cannot grow further

31
Q

Describe the formation of the corpus luteum

A

Granulosa and theca cells transform to form luteal cells
LH stimulates angiogenesis, allowing for cholesterol delivery to the corpus luteum
Cholesterol is then stored for conversion to progesterone

32
Q

Describe the histology of the cervix

A

Stroma (In the wall) is made up of collagen matrix and fibroblasts
Epithelium is made up of columnar epithelium

33
Q

What is the function of the stroma of the cervix?

A

Regulates rigidity of the cervical wall

34
Q

What is the function of the epithelium of the cervix?

A

Mucus secretion

35
Q

Describe the course of the cervix

A

The cervix contains a series of folds or grooves, some of which are not much wider than the head of the sperm

36
Q

What is thought to be the functions of the grooves and folds of the cervix?

A

Allows for better sperm selection

37
Q

Describe the changes that occur in different regions of the cervix

A

The fluid secretion, immune cells and mucus thickness varies in different regions of the cervix

38
Q

What are some ways of predicting ovulation?

A
  • Ovulation predictor kits
  • Spinnbarkeit
  • Basal body temperature
39
Q

How do ovulation predictor kits work?

A

Detect LH surge which occurs 24-36 hours before ovulation

40
Q

What is spinnbarkeit?

A

Spinnbarkeit is the ability to form a thread by mucus from the cervix uteri when spread onto a glass slide and drawn out

Maximum length usually precedes or coincides with the time of ovulation

41
Q

How does basal body temperature change in menstruation?

A

It shifts up by 0.2-0.4ºC