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(4) Reproductive System - Sessions > (2.1) The Hormonal Control of the Reproductive System > Flashcards

(2.1) The Hormonal Control of the Reproductive System Flashcards

1
Q

Where is the Gonadotrophin Releasing Hormone (GnRH) produced? What is its action?

A
  • Exon of Hypothalamus
  • Stimulates Gonadotophs of the Anterior Pituitary Gland to release Luteinising Hormone (LH) and Follicle Stimulating Hormone (FSH)
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2
Q

Where is Luteinising Hormone (LH) produced? What type of chemical is it and what is its action in male and in female before and after ovulation?

A
  • Gonadotrophin of Anterior Pituitary Gland
  • Glycoproteins
  • Stimulates Leydig cells (male) to produce Testosterone
  • Stimulates Thecal cells (female) to produce Androgen
  • Stimulates Corpus Luteum (female) to produce Progesterone
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3
Q

Where is Follicle Stimulating Hormone (FSH) produced? What type of chemical is it and what is its action in male and female?

A
  • Gonadotrophin of Anterior Pituitary Gland
  • Glycoproteins
  • Stimulates Sertoli cells (male) to perform Spermatogenesis
  • Stimulates Granulosa cells (female) to convert Androgen to Oestrogen
  • Stimulate Sertoli & Granulosa cells to produce Inhibin
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4
Q

Where is Inhibin produced in both sexes? What is its action?

A
  • Sertoli cells of the Semiferous Tubules in male
  • Granulosa cells in female developing FOLLICLE
  • Inhibits FSH production from Anterior Pituitary Gland alone
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5
Q

What type of chemical is Prolactin and what is its action?

A
  • Polypeptide
  • Enhances effects of LH e.g. stimulates Corpus Luteum to produce more Oestrogen & Progesterone
  • Milk production
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6
Q

Where is Testosterone produced in both sexes? What is its action?

A
  • Leydig cells in male
  • Granulosa cells in female
  • Inhibits production of GnRH from Hypothalamus and productions of LH and FSH from Anterior Pituitary Gland
  • Male characteristics & Anabolic effects & Emotional changes
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7
Q

How is Oestrogen produced and how is its concentration controlled BEFORE ovulation? What is its action on the developing follicle?

A
  • Granulosa cells convert Androgen from Thecal cells into Oestrogen
  • [Intermediate] gives positive feedback to Hypothalamus and Anterior Pituitary Gland
  • Adds LH receptors on to Granulosa cells -> LH surge -> Ovulation
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8
Q

How do Releasing Hormones get from the Hypothalamus to the Anterior Pituitary Gland?

A

Hypophyseal Portal Circulation

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9
Q

What two hormones are released from Corticotrophs?

A

ACTH

MSH

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10
Q

What type of cell releases Growth Hormone? What type of chemical is it and what is its action?

A
  • Somatotrophs of Anterior PItuitary Gland
  • Polypeptides
  • Promotes growth, lipid & carbohydrate metabolism
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11
Q

How is the concentration of Oestrogen controlled before ovulation? What physical changes does it make on the reproductive tract?

A
  • [Intermediate] Oestrogen +ve feedbacks on Hypothalamus and Anterior Pituitary Glands
  • Fallopian Tube: + secretion, cilia, motility
  • Uterine Myometrium: + thickness, motility
  • Cervical Mucus: thins & alkaline (sperm likes)
  • Vaginal Epithelium: + mitotic activity
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12
Q

Suggest two places that Progesterone is released from.

A
  • Corpus Luteum of the follicle

- Plancenta

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13
Q

Other than Inhibin, which other molecule enhances the effect of LH?

A

Prolactin

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14
Q

Why do you get a “surge” of LH, but not FSH?

A

As the follicle becomes more developed:

  • More GnRH is released to stimulate Gonadotrophs
  • More Inhibin is released from Granulosa cells
  • Inhibin only inhibits positive feedback from FSH on to GnRH
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15
Q

Describe the Luteal phase of development.

A
  • The remnant of follicle -> Corpus Luteum

- Corpus Luteum produce Progesterone (Thecal cells) and Oestrogen (Granulosa cells)

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16
Q

Suggest the non-reversible effects of Testosterone.

A
  • Deepens voice, + vocal cords
  • Facial & body hair
    • Stature
    • muscles & bones
17
Q

Suggest the reversible effects of Testosterone.

A
  • Maintenance of the male internal genitalia (Prostate, Seminal Vesicles, Vas deferens, Epididymis)
  • Anabolic effects
  • Aggressiveness, sexual activity
18
Q

At what point in the day are the Testosterone levels the highest?

A

Early morning

19
Q

How do you know which day Ovulation occurs, knowing the date of mensural bleed starts?

A

Counts 14 days backward, because Corpus Luteum has a time span of 14 days e.g. Luteal phase

20
Q

Describe the changes in Gonadotrophin and Steroid levels in the first 12-14 days of the menstrual cycle (the Follicular/Proliferative phase)

A
  • LH & FSH start high due to the small amount of Inhibin & Oestrogen
  • Oestrogen slowly rising, Progesterone still low
  • As follicle grows, Granulosa cells produce more Oestrogen, stimulating GnRH
  • Granulosa cells produce more Inhibin, reducing amount of FSH
  • GnRH acts to produce more LH
  • As Oestrogen reaches its highest level, GnRH and LH surges occur
  • Oestrogen [high] cause -ve feedback, level decreases largely
21
Q

Describe the changes in Gonadotrophin and Steroid levels in the remaining 14 days of the menstrual cycle (the Luteal phase), assuming NO pregnancy takes place.

A
  • The Corpus Luteum is formed and begins to increase levels of Progesterone and Oestrogen
  • Progesterone -> -ve feedback on the release of GnRH, LH and FSH
  • Without pregnancy, Corpus Luteum regresses -> Corpus Albican -> Steroid levels fall -> removing -ve feedback
  • Myometerium regresses and menstruates away
22
Q

Describe the changes in Gonadotrophin and Steroid levels in the remaining 14 days of the menstrual cycle (the Luteal phase), assuming pregnancy TAKES place.

A
  • The Corpus Luteum is formed and begins to increase levels of Progesterone and Oestrogen
  • Progesterone -> -ve feedback on the release of GnRH, LH and FSH
  • Pregnancy, Placenta develops and secretes Human Chorionic Gonadotrophin
  • hCG prevents regression of the Corpus Luteum -> continuous secretions of steroids
23
Q

Why does LH only stimulate follicles that are partly grown and those in pre-antral phase?

A

The young follicles don’t yet have a Theca for the LH to bind to, so FSH needs to bind to the Granulosa to result in the follicle growing enough to have a Theca.

24
Q

What is the significance of the growing follicle releasing increasing amounts of Inhibin as it grows?

A

Inhibin -> inhibits FSH -> prevents further development of new follicles

25
Q

During the Follicular phase, what changes are there to the Uterus?

A

Increased Oestrogen -> thickens Endometrium & increased motility of Myometrium also Endometrial glands secrete alkaline and watery secretions to conduct sperms

26
Q

Suggest some wider (not the reproductive tract) effects of the Follicular Phase on the body.

A
  • Mild Anabolic activity
  • Depresses appetite
  • CVS effects
  • Maintenance of bone structure
27
Q

During the Luteal phase, what changes are there to the Uterus?

A

Increased Progesterone -> reduces Oestrogen -> develops Spiral arteries -> Endometrium & Myometrium thicken & reduced Myometrial motility

28
Q

During the Luteal phase, what changes are there to the Cervical Mucus?

A

Increased Progesterone -> reduces Oestrogen -> thickens & acidic -> reduce Sperm transport

29
Q

Suggest some wider (not the reproductive tract) effects of the Luteal Phase on the body.

A

Increased Progesterone -> reduces Oestrogen:

  • Mild catabolic activity
  • Increased body temperature
  • Increased Na+ and H2) excretion
30
Q

Describe the changes that occur to the reproductive tract when there is a sudden drop in Progesterone and Oestrogen.

A
  • Myometrium regresses & Endometrium also thins -> Menses

- Constricted Spiral arteries reduce bleeding

31
Q

What keeps the existence of a Corpus Luteum?

A

Human Chorionic Gonadotrophin produces by Syncytiotrophoblast of Placenta

32
Q

Why are the changes in LH and FSH secretion at the Menopause different?

A
  • Inhibin is only released if follicle/gametes develops -> BEFORE menopause -> inhibits FSH alone without affecting LH
  • AFTER menopause -> no follicles/gametes -> no Inhibin
  • AFTER menopause -> Oestrogen is always low -> +ve feedback on both FSH & LH
    Therefore after menopause, the increase in [FSH] > [LH]

(4) Reproductive System - Sessions (16 decks)

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