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Year 2 Clinical > Physiology and Pharmacology: Reproduction/sex steroid axis > Flashcards

Physiology and Pharmacology: Reproduction/sex steroid axis Flashcards

1
Q

Development of the egg?

A

……….

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2
Q

……….

A

……….

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3
Q

Methods of assisted conception?

A

IVF (in vitro fertilisation)

Intrauterine insemination

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4
Q

Time period for oogenesis?

A

Takes many years to complete

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5
Q

Process of oogenesis?

A
  1. Begins in utero, where there is mitotic division of oogonia (diploid cell)
  2. Commencement of 1st meiotic division forms the primary oocyte
  3. There is arrest in prophase
  4. It is then suspended for many years; following puberty, it begins again, prior to ovulation
  5. The entire process is completed at fertilisation
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6
Q

What are polar bodies?

A

1st polar body is 1 of 2 products in the first stage of meiosis; both are relatively small and contain little cytoplasm

Presence of 2 polar bodies signifies sperm entry and completion of the 2nd meiotic division

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7
Q

No. of eggs at different times in the human biological clock?

A

Very high no. of germ cells mid-trimester; at birth, this drops to below half

Even less by the time puberty begins and even fewer are ovulated (300-400)

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8
Q

……….

A

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9
Q

………..

A

………..

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10
Q

Time period of the menstrual cycle?

A

Lasts for an average of 28 days

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11
Q

2 phases of the menstrual cycle?

A

Follicular phase - 1st half of the cycle that allows:
• Maturation of the egg so that it is ready for ovulation at mid-cycle

Ovulation signals end of the follicular phase

Luteal phase - 2nd half of the cycle that allows:
• Development of corpus luteum
• Induction of preparation of reproductive tract for pregnancy (if fertilisation occurs)

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12
Q

What is the primary follicle?

A

Before birth, primary oocyte is surrounded by a single layer of granulosa cells; each of these primary follicles can produce a single ovum

Until puberty, all primary follicles degenerate to scar tissue (atresia) before ovulation

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13
Q

Development of the secondary follicle?

A

After puberty, secondary follicles develop cyclically

Oocyte grows and the follicle expands and become differentiated; after puberty, 300-400 are ovulated and rest undergo atresia

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14
Q

What occurs in the luteal phase?

A

Follicular cells left behind after ovulation undergo luteinisation (transformation to the corpus luteum)

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15
Q

Function of the corpus luteum in the luteal phase?

A

Secretes progesterone and oestrogen

Oestrogen secreted in the follicular phase and progesterone in the luteal phase are essential for:
• Preparation of uterine lining for implantation

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16
Q

What happens to the corpus luteum after ovulation?

A

Grows for 8-9 days

If no fertilisation has occurred, it survives no longer than 14 days after ovulation; the corpus albicans forms (a white body of fibrous tissue) and progesterone and oestrogen production decresease

If fertilisation has occurred, corpus luteum persists and produces increasing progesterone and oestrogen until after pregnancy

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17
Q

What does degeneration of the corpus luteum signal?

A

Start of a new follicular phase

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18
Q

Production and release of GnRH?

A

AKA Gonadotrophin-releasing hormone

Synthesised by hypothalamic neurons and is released in a pulsatile manner

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19
Q

Function of GnRH?

A

Stimulates synthesis and release of hormones from the anterior pituitary:
• FSH (low frequency pulses)
• LH (high frequency pulses)

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20
Q

Functions of FSH?

A

Stimulates follicular development and thickens the endometrium

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21
Q

Functiosn of LH?

A

LH peak stimulates ovulation

Stimulates corpus luteum development

Thickens endometrium

22
Q

Secretion of oestrogen?

A

Primarily by the ovaries

Also be adrenal cortex and, in pregnancy, by the placenta

23
Q

Functions of oestrogen?

A
  1. Thickens endometrium
  2. Responsible for fertile cervical mucous
  3. Maturation of ovarian follicles
  4. Mildly accelerates sodium and water reabsorption by kidney tubules; this increases water content of the uterus
  5. Responsible for development of secondary sexual characteristics
  6. High oestrogen conc:
    • Inhibits secretion of FSH and prolactin
    • Stimulates secretion of LH
  7. Low oestrogen conc. after pregnancy:
    • Stimulates secretion of prolactin
24
Q

Consistency of fertile cervical mucous?

A

Clear, stringy, stretchable and slippery

Has fern patterns when dry

25
Q

Production of progesterone?

A

Secreted by the corpus luteum; also, by the placenta during pregnancy

26
Q

Functions of progesterone?

A
  1. Inhibits LH secretion
  2. Has a thermogenic effects (increases basal body temp)
  3. Relaxes smooth muscles
  4. Responsible for inferile mucous
  5. Maintains thickness of endometrium
  6. Maintains pregnancy
27
Q

Consistency of infertile cervical mucous?

A

Opaque, sticky, thick, non-stretchable mucous

No fern patter when dry

28
Q

Effects of different hormones in the follicular phase?

A
  1. FSH stimulates follicular development
  2. Dominant follicle develops and produces increasing follicular fluid (contains oestrogen)
  3. Oestrogen stimulates endometrial thickening
  4. Increased serum oestrogen:
    • Suppresses FSH secretion
    • Favours LH secretion
  5. LH stimulates ovulation and initiates corpus luteum development
29
Q

What happens during the luteal phase?

A

Cavity of the ruptured follicle replaced with the corpus luteum, which secretes progesterone and oestrogen

Progesterone stimulates secretory changes in endometrium to prepare for implantation; also, maintains endometrium during early phase of pregnancy

30
Q

What happens during the menstrual phase?

A

Corpus luteum degenerates

Progesterone and oestrogen production by the corpus luteum ceases, so endometrium degenerates and menstruation occurs

31
Q

What stimulates production of FSH and a new cycle?

A

Drop in blood levels of oestrogen and progesterone

32
Q

What happens during the LH surge?

A

Oocyte resumes meiosis; secondary oocyte + polar bodies (degenerates)

Stops at metaphase II (only complete if fertilisation has occurred)

Cytoplasmic maturation occurs

LH receptors are stimulates to synthesise progesterone

33
Q

When does ovulation occur?

A

36.5 hours after the LH surge

34
Q

What happens after the ovulation?

A

Collapsed follicle forms corpus luteum

35
Q

How is ovulation detected?

A

Detect the LH surge (blood tesT)

Basal body temperature rises during ovulation (track over 6 months)

Test urine with LH detection kits

36
Q

Gross appearance of corpus luteum?

A

Lutein is a carotenoid pigment that makes it orange/yellow

37
Q

What day of the cycle would progesterone be measured to assess if ovulation has occurred?

A

Day 21

38
Q

Functions of the male genital tract?

A

Acts as a route for sperm

Production of testosterone

39
Q

Route of sperm?

A
  1. Testes
  2. Epididymis
  3. Vas deferens
  4. Ejaculatory duct
  5. Urethra
40
Q

Describe spermatogenesis

A

Occurs within the seminiferous tubules of the testes; germ cell mitosis is reactivated at puberty and is constant

41
Q

Control of testes?

A

LH - acts on Leydig cells to regulate testosterone secretion

FSH - acts on Sertoli cells to enhance spermatogenesis (essential for spermatic re-modelling)

Both of these hormone are released due to the action of GnRH

42
Q

Functions of Leydig and Sertoli cells?

A

Leydig - secrete testosterone

Sertoli (in seminiferous tubules) - secrete androgen binding globulin (ABG) and inhibin; also, support germ cells in development

43
Q

Functions of dihydrotestosterone?

A
  • Enlargement of male sex organs
  • Secondary sexual characteristics
  • Anabolism
44
Q

Describe feedback effects of testosterone

A

Feedback to anterior pituitary:
• Reduces sensitivity of LH-secreting cells to GnRH; LH is inhibited more than FSH

Feedback to hypothalamus:
• Suppression of GnRH bursts

45
Q

Describe feedback of inhibin

A

Feedback to anterior pituitary:

• Suppress FSH-secreting cells production of FSH

46
Q

Effects of testosterone on different body systems?

A

Skin:
• Produces facial and body hair
• Supports collagen production

Male sex organs:
• Produces sperm
• Prostate growth
• Erectile dysfunction

Brain:
• Responsible for sex drive
• Produces feelings
• Aids memory

Bone marrow:
• Produces RBCs

Bone:
• Maintains bone density

47
Q

Stages of germ cell development?

A
  1. Spermatogonia
  2. Primary spermatocytes
  3. Secondary spermatocytes
  4. Spermatids (Early to elongated)
  5. Testicular spermatozoa
48
Q

Special structures developed by the mature sperm cell?

A

Golgi (acrosome)

Cilium (tail)

Cytoplasm is reduced, as several spermatids link via cytoplasmic bridges

49
Q

Factors that have adverse effects on human spermatogenesis?

A

Heat (Taxi Driver’s syndrome - sitting increases temp by 2 degrees within 2 hours)

Alcohol

Smoking

Chemo/radiotherap

Vasectomy (minor effect based on time)

50
Q

If sperm cannot be collected from ejaculate, what should be done?

A

Surgical sperm aspiration (indicated for azoospermia)

51
Q

What does a high FSH level signify?

A

…………..

52
Q

Key differences between oogenesis and spermatogenesis?

A

Oogenesis only leads to production one final ovum

Production of an ovum occurs only once a month

Also, in oogenesis, polar bodies are formed and these eventually disintegrate

Year 2 Clinical (119 decks)

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