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Reproduction, Development and Ageing > 1. Reproductive physiology > Flashcards

1. Reproductive physiology Flashcards

1
Q

What are the 2 main functions of the testes?

A
  • Provision of androgens (primarily androgens) to initiate and sustain the male phenotype
  • Production of mature sperm
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2
Q

Are the names of LH and FSH related to their biological action in males?

A

No

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3
Q

Where is sperm stored prior to ejaculation?

A

Epididymis

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4
Q

What happens to sperm at ejaculation?

A
  • Pass through Vas Deferens (contractile)
  • Mixed with fluid from the seminal vesicles
  • Passes into urethra and mixes with secretions from the prostate gland
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5
Q

Where are the Leydig cells and what do they do?

A
  • Outside the seminiferous tubules
  • Primary source of androgens in all male mammals
  • LH acts here
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6
Q

Where are the sertoli cells and what do they do?

A
  • In the seminiferous tubules
  • Support spermatogenesis
  • Driven by FSH and testosterone
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7
Q

What does androgen binding protein (ABP) do?

A

Protein that binds to testosterone, to mediate its effects into the Sertoli cells

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8
Q

Describe the negative feedback to constrain the production of GnRH

A
  • Testosterone from the Leydig cells feeds back to the hypothalamus and pituitary gland (also direct on LH and FSH)
  • Inhibin from the Sertoli cells feeds back to the hypothalamus

Pulsatile manner

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9
Q

What makes up the majority of the tissue of the testes?

A

Seminiferous tubules (where sperm are made)

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10
Q

Which cells does the beginning of the production of all gametes start with?

A

Primordial germ cells

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11
Q

Can men produce sperm after the age of 70?

A

Yes, even though quality and quantity declines

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12
Q

What stimulates some development of ovarian follicles and 17β-oestradiol synthesis?

A

FSH

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13
Q

What stimulates progesterone production?

A

LH

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14
Q

What produces LHRH and what does it do?

A
  • Produced by hypothalamus (pulsatile)
  • Drives the pulsatile release of LH and FSH from the pituitary gland

(like GnRH)

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15
Q

Which cells are responsible for the production of oestrogens?

A

Thecal cells of the developing follicles

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16
Q

Which cells produce oestrogens/progesterone during the second half of the ovarian cycle?

A

Granulosa-luteal cells

17
Q

When does oestradiol change from a negative to a positive feedback effect on the hypothalamus and pituitary?

A
  • 17β-oestradiol rises before mid-cycle
  • This drives a peak of LH (and FSH) in the MID-CYCLE - change to positive feedback
  • LH drives ovulation
18
Q

When does the cycle go back from a positive to negative feedback mechanism?

A

Luteal phase - but progesterone is mainly being produced from the ovary instead of oestrogen

(LH, FSH and oestrogen fall)

19
Q

Why does the hypothalamic-pituitary axis switch off in pregnancy?

A

Continuous rising progesterone levels - negative feedback

20
Q

Would a change in menstrual cycle length be due to the follicular or luteal phase length?

A

Luteal phase, as follicular phase is relatively constant

21
Q

What is the range of the menstrual cycle?

A

21-35 days

can be up to 45 days in younger teenagers

22
Q

What number of eggs will be turned into ova during a normal reproductive lifespan in a female?

A

450

23
Q

What stage of development are eggs at just before puberty, and after?

A

Early stage of meiosis (that has been halted) - prophase I
• then resume at puberty
• go through final stages of folliculogenesis
• the longer they are held, the poorer the organisation of DNA

24
Q

What does the dominant follicle become when it enters the second part of development, and what does this give rise to?

A
  • Antral follicle

* Gives rise to the egg that is released

25
Q

How long does it take for the growth of a follicle?

A

3 months

26
Q

What division is linked to the LH surge?

A

First meiotic division, completed during the formation of the secondary follicle (Graafian follicle)

27
Q

When does meiosis I start in a female?

A

During embryonic development

28
Q

For the follicles that become secondary follicles, what stage do they pause at before fertilisation?

A

Metaphase of meiosis II

29
Q

When does an egg need to be fertilised?

A

Within 24 hours of release

30
Q

What happens when the nucleus of a sperm is released into the cytoplasm of the egg?

A
  • Nucleus expands rapidly in size
  • Converts itself into the male pro-nucleus (haploid)
  • The egg completes meiosis and switches from 2n to n (haploid - 23 chromatids) - female pro-nucleus
  • The pro-nuclei merge to form 2n
  • DNA mixes and is duplicated (4n) - there are enough chromosomes for this
  • Cell divides - first mitotic division
31
Q

Which nerve/system is involved in the stimulation of the penis?

A
  • Tactile - pudendeal nerve - afferent system

* Limbic system from brain (mesolimbic dopaminergic system)

32
Q

What changes occur during an erection?

A
  • Initiated by increased parasympathetic activity to the smooth muscle of the pudendal artery
  • Increased activity of nitric oxide synthase => nitric oxide => increased cGMP
  • Dilatation of arterial smooth muscle
  • Counteracts with sympathetic-maintained myogenic tone
  • Increased blood flow to corpus cavernosum
  • This compresses the dorsal vein, restricting outflow

(similar reason for increased blood flow and growth of clitoris in a female)

33
Q

What tissue protects the urethra during an erection?

A

Surrounding corpus spongiosum

34
Q

What de-activates cGMP during an erection?

A

Phosphodiesterase

35
Q

How does viagra work?

A

Inhibits phosphodiesterase from de-activating cGMP

36
Q

Describe the process from the deposition of sperm to fertilisation

A
  • Deposited near cervix
  • Cervical mucus changes at mid-cycle to permit sperm to enter
  • Passage through the uterus into the fallopian tube and ampulla, moving at 2mm/min
  • Sperm meets the egg - acrosome reaction allowing penetration of Zona Pellucida and Coronal cells
37
Q

How many chromosomes in sperm and oocyte (before fusion)?

A

Sperm - 23

Oocyte - 46 (then 23 after sperm fuses as it can carry on from metaphase II)

Reproduction, Development and Ageing (7 decks)

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