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Endocrinology > 10 - The Gonads 1 > Flashcards

10 - The Gonads 1 Flashcards

1
Q

What do the gonads develop as in males?

A

The testes

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2
Q

What do the gonads develop as in females?

A

The ovaries

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3
Q

What genes cause differentiation into testes?

A

Genes on the Y chromosome.

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4
Q

What are the 2 functions of the gonads?

A
  1. Production of gametes for reproduction (gametogenesis)

2. Production of steroid hormones (steroidogenesis)

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5
Q

What gametes are produced in males? What is this process called?

A

Spermatogenesis.

Production of mature spermatozoa.

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6
Q

What gametes are produced in females? What is this process called?

A

Oogenesis.

Production of ripe ova.

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7
Q

What steroid hormones are produced in males?

A

Androgens.

Some oestrogens and progestogens

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8
Q

What steroid hormones are produced in females?

A

Oestrogen and progestogens.

Some androgens

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9
Q

What happens to the amount of oogonia throughout life?

A

Max number at 24 weeks old.
Decrease before birth (atresia)
Even lower by puberty.
Finite number so run out at menopause.

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10
Q

What happens to the amount of spermatogonia throughout life?

A

Peaks before birth.
Remains at same height throughout life.
Dips a bit at old age.

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11
Q

When does spermatogenesis start and what causes this?

A

Starts at puberty.

Caused by GRH and testosterone.

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12
Q

Outline the process of spermatogenesis.

A

Germ cell (2n)

Spermatogonia (2n)
(Mitotic division)

Primary spermatocytes (2n)
(1st meiotic division)
Secondary spermatocytes (n)
(2nd meiotic division)

Spermatids (n)

Spermatozoa (n)

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13
Q

Where does spermatogenesis happen?

A

Seminiferous tubules

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14
Q

Outline the process of oogenesis.

A

Germ cell (2n)

Oogonia (2n)
(Mitotic division)

Primary Oocytes (2n)
(1st meiotic division)

Secondary oocytes (n)
(+ first polar body)
(2nd meiotic division)

Ovum (n)
(+ second polar body)

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15
Q

When does oogenesis pause in females?

A

The prophase of meiosis 1 pauses until puberty.

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16
Q

How many oogonia are there in primordial follicles?

A

6 million.

By birth this reduces to 2 million.

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17
Q

What is atresia?

A

Degeneration of follicles

18
Q

Where are the testes found and what conditions are they kept in?

A

Found in the scrotum.

Kept 2-3 degrees cooler than body temp.

19
Q

What route do the spermatozoa take to get out of the seminiferous tubules?

A 
Go to the end of the tubule.
Collect at rete testis 
Drain into Vasa efferentia
Travel through epididymus via vas deferens (surrounded by smooth muscle)
to urethra
20
Q

Where are sertoli cells found?

A

Lining the lumen off the seminiferous tubule. (They form the tubule)

21
Q

Where are Leydig cells found?

A

Surrounding the outside of the sertoli cells.

22
Q

Where are the spermatogonia found?

A

Outside the sertoli cells.

23
Q

What is the function of the Sertoli cells?

A

Blood-testes barrier.

Make FSH and androgen receptors.
Produce inhibit in response to FSH.
Nourish the germ cells.

24
Q

What is the function of leydig cells?

A

Contain enzymes for steroidogenesis.

Make LH receptors
Make androgens in response to LH.

25
Q

In the ovaries, what is a Graafian follicle?

A

Fluid filled structure where the ovum develops prior to ovulation.

26
Q

What cell types are found in the graafian follicle?

A

Granulosa cells

Thecal cells

27
Q

What is a corpus luteum?

A

A hormone-secreting structure that develops in an ovary after an ovum has been discharged but degenerates after a few days unless pregnancy has begun.

28
Q

What are the gonad hormones derived from?

A

Androstenedione

29
Q

How long does the menstrual cycle last?

A

28 days

30
Q

When does bleeding and ovulation occur?

A

days 1-5 = bleeding

day 14 = ovulation

31
Q

What 2 cycles are in the menstrual cycle?

A

Ovarian cycle (ovary)

Endometrial cycle (uterus)

32
Q

What are the phases of the ovarian cycle?

A

Follicular phase

(ovulation)

Luteal phase

33
Q

What are the phases of the endometrial cycle?

A

Proliferative phase

Secretory phase

34
Q

What hormone comes from the follicular phase and promotes the proliferative phase?

A

Oestrogen (17B-oestradiol)

35
Q

What hormone comes from the luteal phase and promotes the secretory phase?

A

Progesterone and 17B-oestradiol.

36
Q

Describe the hormones throughout the menstrual cycle?

A 
Day 0-5
FSH - high
LH - high
Oestrogen -low
Progesterone - low
Day 5-14
FSH - drops
LH - drops
Oestrogen - rises & peaks
Progesterone - low

Day 14
LH - Massive peak
FSH - small peak

Day 14-28
Progesterone and oestrogen rise.

37
Q

When is basal body temperature highest?

A

After ovulation.

Due to secretion of progesterone.

38
Q

Explain the different follicles during the ovarian cycle.

A

First phase: Pre-Antral follicle.
Gonadotrophin is not required.

If FSH is present: Early antral follicle. (without FSH - atresia)

Growth into late astral follicle.
The best in selected and the others die.

Best = graafian follicle.
=Ovulation
=Graafian follicle become corpus luteum which produced hormones.

39
Q

How are hormones produced in the ovarian cycle?

A 
In Graafian follicle:
LH stimulates steroidogenesis.
Thecal cells make androgens.
Androgens diffuse to granulose cells that contain aromatase.
These synthesis 17B-oestradiol.

In corpus luteum:
Exactly the same but progesterone is also produced.

40
Q

In the endometrial cycle, which hormone has the dominant effect during the proliferative phase and how does this effect the endometrium?

A

Oestrogen.

Causes endometrium to thicken and gland to enlarge.

41
Q

In the endometrial cycle, which hormone has the dominant effect during the secretory phase and how does this effect the endometrium?

A

Progesterone (some oestrogen)

Causes endometrium to become secretory and glands to secrete more.

Endocrinology (18 decks)

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