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BMSC > Reproductive Physiology > Flashcards

Reproductive Physiology Flashcards

1
Q

What are the major male accessory sex glands?

A

Seminal vesicles
Prostate Gland
Bulbourethral Gland

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2
Q

What are the three different sex levels?

A

Genetic
Gonadal
Phenotypic

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3
Q

When does gonadal specificity occur in the fetus?

A

Around the seventh week

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4
Q

Describe what happens in male fetus during sex differentiation.

A

The gonadal ridge of a genetic male begins to differentiate into the testes under the influence of SRY. SRY codes for testis determining factor

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5
Q

What gene is responsible for sex differentiation?

A

SRY

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6
Q

Describe what happens in female fetus during sex differentiation.

A

The lack of SRY gene means that there is no production of TDF and by defualt ovaries start to develop by the ninth week.

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7
Q

What is the difference between genetic, gonadal and phenotypic sex?

A

Genetic - sex chromosomes (Presence of absence of a Y chromosome)
Gonadal - whether ovaries or testis develop
Phenotypic - The apparant anatomical sex of an individual.

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8
Q

Describe the embryonic tissue that later develops into the external genitalia? Describe each part and what is later develops into in the male and female

A

In both sexes the undifferentiated external genitalia consists of:

  • Genital tubercle (develops into erotic tissue ie the glans penis in the male and the clitoris in the female)
  • Paired urethral folds (Penis, labia minora) surrounding a urethral groove
  • Genital (Labioscrotal) swellings (Scrotum and prepuce, Labia majora)
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9
Q

Describe the embryological development of the internal genitalia

A

Two primitive duct systems, the Wollfian ducts and Mullerian ducts develop in all embryos. In males the reproductive tracts develop from the wollfian ducts and the mullerian ducts degenerate and the opposite occurs in the female

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10
Q

What two hormones cause development of the fetus into a male and where are these produced?

A

Testosterone (produced by leydig cells)

Anti mullerian hormone (produced by sertoli cells)

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11
Q

What hormone induces descent of the testis?

A

Testosterone

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12
Q

What is the precursor molecule for sex steroids?

A

Cholesterol

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13
Q

How does the testosterone hormone work to exert its effects?

A

Binds with androgen receptors in the cytoplasm of targets cells.
The androgen - receptor complex then moves to within the nucleus and binds with the androgen response element on DNA where it causes the synthesis of new proteins to induce thee required cellular response.

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14
Q

Describe the role of testosterone before and shortly after birth?

A

Before birth secretion by the leydig cells of the fetal testis masculinizes the reproductive tract and external genitalia as well as promoting descent of the testes. After birth testosterone secretion ceases and the testes and remainder of the reproductive system remain small and non functional until puberty

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15
Q

What is the reason for the lowering androgen levels and reduction in sperm production seen in men in their 60s and beyond?

A

Degenerative changes in the small testicular blood vessels.

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16
Q

What enzyme converts testosterone to oestrogen?

A

Aromatase

17
Q

Why is important that developing sperm are held together by cytoplasmic bridges?

A

The X chromosome (not the Y) code for genes that are essential for sperm maturation. The connections allow the developing sperm to exchange cytoplasm and since half of the sperm only have Y chromosomes it is important that they can share cytoplasm with those with an X chromosome to allow complete development.

18
Q

What are adjacent sertoli cells joined by?

A

Tight junctions

19
Q

What is spermiation?

A

The release of a mature spermatozoa from the sertoli cell. This requires the breakdown of the tight and gap junctions between the sertoli cells and spermatazoa.

20
Q

Describe how sertoli cells nourish the developing sperm?

A

Developing sperm cells do not have access to blood borne nutrients so the sertoli cells have to provide nourishment for them.
They take up glucose via the GLUT 1 symporter, metabolize the glucose to lactate and then transfer the lactate to the sperm cells which can use it as an energy source.

21
Q

What is the phagocytic role of sertoli cells?

A

They engulf the cytoplasm extruded from the spermatids during their remodelling and they destroy defective germ cells

22
Q

Describe the production and function of androgen binding protein

A

Produced by the sertoli cells
Binds androgens to maintain a high level of testosterone within the seminiferous tubules. Testosterone is 100 times more concentrated in the tubules than in the blood

23
Q

Why is androgen binding protein necessary?

A

It means testosterone is kept within the lumen as otherwise, being a lipid soluable molecule, it would likely diffuse out and into the blood.

24
Q

What stimulates the production of androgen binding protein?

A

Testosterone

25
Q

Where are the receptors for testosterone and FSH on the sertoli cells?

A

Testosterone - Intracellular

FSH - On the membrane surface

26
Q

What is inhibin? What cells secret inhibin?

A

Sertoli cells. Acts in a negative feedback loop to regulate FSH secretion.

27
Q

What are Kiss 1 neurones?

A

Neurones found in the arcuate nucleus of the hypothalamus that release kiss peptins which are peptide neurotransmitters that stimulate GnRH secretion. Testosterone exerts in negative feedback effect on the kiss1 neurone, not directly on the GnRh neurones. GnRH neurones do not have testosterone receptors where as kiss1 neurones do. By directly inhibiting kiss1 neurones testosterone indirectly inhibits GnRH secreting neurones by blocking kiss1 neurones excitatory action on GnRh secreting neurones. Kisspeptin signalling in vital in initiating puberty and maintaining reproductive function.

28
Q

What do the seminal vesicles do?

A
  1. Supply fructose which is the main energy source for ejaculated sperm.
  2. Secrete prostoglandins which induce contractions in the male and female reproductive tract thereby helping sperm reach the female oviduct.
  3. Provide around 60% of the ejaculate volume
  4. Secrete fibrinogen, a precursor of fibrin, which performed the meshwork of a clot.
29
Q

What does the prostate gland do?

A
  1. Secretes an alkaline fluid that neutralizes the acidic vaginal secretions (helpful as sperm are more viable in an alkaline environment)
  2. Provides clotting enzymes
  3. Releases PSA. The prostatic clotting enzymes act on fibrinogen to form fibrin which clots the semen and thus helps to keep the ejaculated sperm in the female after ejaculation and removal of the penis. Shorty after PSA acts as a fibrin degrading enzyme and allows sperm to mobilise again once inside the tract,
30
Q

What are the three physiologically important oestrogens?What is the principla ovarian oestrogen?

A

Estradiol
Estrone
Estriol
(Estradiol is the principal ovarian oestrogen)

31
Q

During a typical natural cycle how many follicles are initially recruited?

A

15 - 20

32
Q

How many days into development is a dominant follicle observed?

A

Around 14 days

BMSC (17 decks)

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