Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Endocrinology > The Gonads 1 (10) > Flashcards

The Gonads 1 (10) Flashcards

1
Q

How do the gonads (an organ that produces gametes) develop in males and females ?

A

In males they develop as ovaries and in males they develop as the testes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the 2 functions of the gonads

A

Gametogenesis which is the production of gametes for reproduction. In males this is spermatogenesis and in females this is oogenesis. The other function is Steroidogenesis which is the production of steroid hormones. In males this is androgens (and small amounts of oestrogen and progesterone) and in females it is oestrogens and progesterones (and small amounts of androgens).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what are the female germ cells

A

oogonia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what are the male germ cells

A

spermatogonia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Gametogenesis

A

Gametes are derived from germ cells, which multiply and increase in number before birth.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Spermatogenesis

A

Spermatogonia levels remain relatively constant through life (6-7million). These spermatogonia don’t become activated until puberty. Spermatogonia are diploid. Divide at puberty to form primary spermatocytes. Some primary spermatocytes return to quiescent stage so a pool of spermatogonia remain available for subsequent spermatogenic cycles throughout life. Males retain spermatogenic capability thoughtout life, producing 300-600 sperm/gm testis/second.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the steps of the spermatogenesis cycle

A

Germ cells in embryogenesis multiply and differentiate to produce spermatogonia which are diploid. Around puberty - when FSH starts to be released - the spermatogonia divide by mitosis to produce either more spermatogonia or to produce primary spermatocytes. Primary spermatocytes are also diploid.
Primary spermatocytes enter the first meiotic division to give secondary spermatoctyes which are haploid. Secondary spermatocytes enter second meiotic division to give spermatids . Spermatids then mature and differentiate into spermatozoa. Whole cycle takes approximately 65-70 days.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what are the steps of oogenesis

A

Germ cells multiply up to produce diploid oogonia. The oogonia multiply again to produce primary oocytes. Primary oocytes immediately enter their first meiotic division. At prophase, development is halted for 12-50 years so they stay in this stage of development. The oocytes form a layer of cells around them - primordial follicles. This all occurs before birth. Rapid atresia of the oogonia occurs before birth. At puberty, FSH rescues some oocytes and they continue development. The oocytes complete meiotic division by ovulation time, to produce secondary oocyte and polar body. The secondary oocyte enters second meiotic division and does complete that division until fertilisation. If fertilsed, it will produce the ovum and the second polar body.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Ooegenesis

A

Initial total number of oogonia in primordial follicles is approx 6 million; early entry into meiosis halted in prophase. Primordial follicles, arrested in their develipment, enter atresia. By the time of birth the total number of oogonia is approx 2 million and by puberty is is 0.5 million. Only 300-400 reach ovulation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

where does spermatogenesis take place

A

in the seminiferous tubules of the testes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

where do the testes develop

A

in the abdomen but descend into the scrotum just before birth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what happens if the testes do not descend

A

could lead to infertility

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is critical for spermatogenesis

A

that the scrotum is 2-3 degrees cooler than the core temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what lines the seminiferous tubules

A

layers of spermatogonia and layers of sertoli cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what happens to the spermatozoa after they are produced

A

are released into the lumens of the seminiferous tubules, where they migrate to the Rete Testis where they are concentrated and drained by the Vasa efferentia into the epididymis where they are stored

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what happens to the spermatozoa in the epididymis

A

nutrients are secreted for them. they mature here and attain their motility. Then they are propelled via the vas deferens (surrounded by smooth muscle) to the urethra

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is the structure of the seminiferous tubule

A

a lumen surrounded by a layer of elongated Sertoli cells. Above this is a layer of spermatogonia and above that is a layer of connective tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

how are the sertoli cells connected and why is it important

A

at the periphery by tight junctions. this forms a blood testis barrier which keeps large proteins i.e antibodies out - so protects spermatozoa from immune reactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

how do spermatogonia move through the seminiferous tubule

A

Spermatogonia are engulfed into the sertoli cell, where they develop in the cytoplasm into primary and secondary spermatocytes and are released into the lumen of the tubule as spermatozoa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what do the sertoli cells provide

A

provide structural support for spermatogonia and provide metabolic support

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What lies outside the seminiferous tubules

A

Clusters of Leydig cells which are the site of testosterone production

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what are the two types of testicular cells

A

sertoli cells nd leydig cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

why is it important that the leydig cells are nearby to the seminiferous tubules

A

because testosterone is needed for spermatogenesis to take place

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Summarise the sertoli cells

A

They form the seminiferous tubules. synthesise FSH and androgen receptors. In response to FSH produce inhibin. Intimately associated with developing spermatocytes

25
Q

Summarise the leydig cells

A

Lie outside the seminiferous tubules. Synthesise LH receptors. In response to LH are the principal source of testicular androgens (mainly testosterone)

26
Q

what does inhibin do

A

feeds back on the axid and inhibits FSH secretion

27
Q

Describe the structure of the ovarian stroma

A

It consists of primordial follicles undergoing atresia. A graffian follicle (maximum size and is ready for ovulation. Remnants of corpus luteum (after ovulation)

28
Q

What does a graffian follicle consists of

A

contains a maturing oocyte that is surrounded by fluid. 2 layers of cells surround the follicle:
inner granulosa cells and outer thecal cells

29
Q

what steroid hormones do the gonads produce

A

progestogens (C21), androgens (C19) and oestrogens (C18)

30
Q

why do the gonads produce different steroid hormones to the adrenals

A

the enzymes present in the tissue determines the hormones produced

31
Q

what steroid hormones do the adrenals produce

A

mineralcorticoids and glucocorticoids and small amounts of androgens

32
Q

What steroidogenesis reactions only occur in the adrenals

A

progesterone to deoxycorticosterone and eventually to aldosterone. Also 17-hydroxyprogesterone to 11-deoxycortisol and down to cortisol

33
Q

what steroidogenesis reactions only occur in the gonads

A

The testes can convert androsteronedione to testosterone. The ovaries will then aromatise androstenedione and testosterone in to oestrone which can then be converted to 17b-oestradiol

34
Q

How long does the menstrual cycle last

A

28 days approx. (20 to 35 days)

35
Q

when does ovulation occur

A

day 14

36
Q

what does the menstrual cycle consist of

A

The ovarian cycle (ovary) and the endometrial cycle (uterus) which both happen simultaneously

37
Q

what is the ovarian cycle (3 stages)

A

Follicular phase (first half), Ovulation (mid-cycle), Luteal Phase (second half)

38
Q

what is the endometrial cycle (2 phases)

A

proliferative phase and secretory phase

39
Q

what is the endometrium

A

the lining of the uterus and contains a superficial epithelial layer and a deeper stromal layer

40
Q

what causes the proliferative phase in the endometrial cycle

A

the oestrogens produced in the follicular phase. There is an increase in mitosis and an increase in the progesterone and oestrogen receptors. the endometrium thickens and moistens. the endometrial glands get enlarge, coil and increase blood supply

41
Q

How are the follicular phase and proliferative phase connected?

A

The Follicular phase of the ovarian cycle produces oestrogen (17β- OESTRADIOL. This stimulates proliferative phase of endometrial cycle 

42
Q

How are the luteal phase and secretory phase connected?

A

The luteal phase of the ovarian cycle produces progesterone and 17β-estradiol. This stimulates the secretory phase of endometrial cycle

43
Q

what is the effect of progesterone

A

it reduces the proliferation that oestrogen causes by reducing oestrogen receptors. it also causes the endometrium to become secretory. The glands produce glycogen and mucopolysacharides. The glands become engorged with blood

44
Q

What are the first 5 steps of the menstrual cycle

A
  1. Pituitary gland produces FSH so FSH concentration increases.
  2. Many follicles develop in response to FSH (follicle stimulating hormone)
  3. Follicles secrete oestrogen as they develop
  4. Oestrogen has a negative feedback on FSH.
  5. FSH is inhibited and so the follicles stop producing oestrogen and they undergo atresia
45
Q

What are steps 6-10 of the menstrual cycle

A
  1. One follicle will be dominant and continues to produce oestrogen.
  2. The dominant follicle develops further, continuing to produce oestrogen.
  3. Oestrogen levels continue to rise
  4. High levels of oestrogen cause a switch in the pituitary. There is no longer a -ve feedback on FSH/LH, but a + one instead
  5. This causes an LH surge, together with some FSH
46
Q

What are steps 11- 15 of the menstrual cycle

A
  1. LH (luteinising hormone) causes ovulation.
  2. After ovulation, the empty follicle is transformed into corpus luteum which produces large amounts of progesterone
  3. Progesterone levels continue to rise
  4. This causes a -ve feedback on FSH and LH so their levels fall.
  5. Since FSH/LH levels fall, so do progesterone levels
47
Q

What are steps 16- 18 of the menstrual cycle

A
  1. The corpus luteum breaks down (menstruation - the endometrium becomes necrotic and sheds)
  2. The falling levels of progesterone means there is less inhibition of gonadotrophins (FSH/LH)
  3. The pituitary gland produces FSH. The concentration of FSH increases and the cycle restarts
48
Q

why does body temperature increase after ovulation

A

because of progesterone

49
Q

What is the pre antral follicle

A

The follicle containing the oocyte develops over its embryonic life in the absence of gonadotrophins . It is surrounded by layer of cells  

50
Q

what is the early antral follicle

A

FSH allows further development. If FSH levels aren’t high enough to continue development they undergo atresia. The follicle is surrounded by granulosa cells and thecal cells. Antral filled space

51
Q

What is the late antral follicle

A

Same as early antral follicle. Follicle increases in size, therefore more antral filled space surrounding ovum

52
Q

What is the graffian follicle

A

Under the influecne of FSH, the follicles get bigger until they reach their maximum size and it is ready for ovulation. LH surge occurs and causes the follicle to rupture and release an egg.

53
Q

what happens to the graffian follicle after ovulation

A

it is transformed into a corpus luteum which continues to secrete oestrogen and progesterone in the luteal phase of the cycle

54
Q

what does the surge of LH stimulate the egg to do

A

complete` the first meiosis

55
Q

where are the LH receptors in the follicle

A

thecal cells

56
Q

where are the FSH receptors in the follicle

A

granulosa cells

57
Q

what produces androgens in the ovary

A

the thecal cells

58
Q

how do the granulosa cells produce oestradiol

A

androgens stimulate them to convert androgens to oestrogen using aromatase enzymes

59
Q

what does the corpus luteum do after ovulation

A

it produces large amounts of 17b-oestradiol and Progesterone because the cells are still stimulated by LH and FSH

Endocrinology (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions