Lecture 31 Reproductive Flashcards Preview

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Flashcards in Lecture 31 Reproductive Deck (37)
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1

Organs

gonads = testes + ovaries
ducts
accessory glands
external genitalia

2

Meiosis

46 chromosomes (2n, diploid) → 23 chromosomes (n, haploid)

3

46 Chromosomes
when does DNA replicate

22 homologous pairs of autosomes + 1 pair of sex chromosomes (XX = female, XY = male)
DNA replicates prior to meiosis; each chromosome is duplicated, consists of 2 sister chromatids

4

Meiosis I

homologous pairs separate, 2n (duplicated) → n(duplicated)

5

Meiosis II

sister chromatids separate, n (duplicated) → n (single chromosomes)

6

male

1 primary spermatocyte (2n) → → 4 sperm cells (n)

7

female

1 primary oocyte (2n) → 1 egg cell (n) … → 1 fertilized egg + polar bodies

8

Spermatogenesis

occurs in seminiferous tubules of testes
spermatogonia → primary spermatocyte → secondary spermatocytes → spermatids → sperm

9

Sertoli cells

support developing spermatocytes + endocrine function

10

blood testis barrier

tight junctions between Sertoli cells form barrier to immune system

11

hormonal control
general pattern

hypothalamus: GnRH → anterior pituitary: FSH & LH → gonads: steroid sex hormones + others

12

FSH

stimulates gamete production in male and female

13

LH

stimulates secretion of sex hormones by gonads and stimulates ovulation in females

14

Steroid sex hormones

♂: testosterone, DHT; ♀: estrogen [estradiol], progesterone
- stimulate gamete production, overall reproductive function, development
of reproductive organs and secondary sexual characteristics

15

Negative feedback

Negative feedback control regulates hormone levels in males and partly in females

16

Positive feedback

Positive feedback control triggers ovulation in females

17

Hormonal Control of Spermatogenesis

Sertoli cells
Leydig (interstitial) cells
Negative feedback control

18

Sertoli cells

respond to FSH, support developing spermatocytes
- androgen binding protein (ABP) binds and concentrates testosterone

19

Leydig (interstitial) cells

produce testosterone in response to LH
- testosterone binds to ABP in Sertoli cells → promotes spermatogenesis

20

Negative feedback control
(Spermatogenesis)

inhibin - secreted by Sertoli cells, inhibits FSH secretion
testosterone inhibits GnRH and LH secretion

21

Oogenesis

occurs in ovarian follicles in ovaries
follicular cells (granulosa cells and theca cells) surround a developing egg cell (oocyte)

22

Follicle

primary follicle → secondary follicle → mature follicle → (Ovulation) corpus luteum

23

Egg

oogonia → primary oocyte → (meiosis 1) secondary oocyte (egg) → (requires fertilization, meiosis 11)

24

Ovarian Cycle

follicular phase (day 0-14)
ovulation (day 14)
luteal phase (day 14-28)

25

follicular phase

growth and maturation of follicle, oocyte goes through meiosis I

26

ovulation

egg bursts through wall of ovary, swept into uterine tube

27

luteal phase

corpus luteum forms from remaining follicle cells;
- corpus luteum continues to secrete estrogen and progesterone;
degenerates at the end of the cycle unless fertilization occurs

28

Uterine Cycle

menses (0)
proliferative phase (14)
secretory phase (28)

29

menses

- uterine lining (endometrium) is sloughed off and discharged

30

proliferative phase

endometrium regrows, becomes thicker and vascularized