chapter 16 - reproductive cycles / fertilisation Flashcards Preview

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Flashcards in chapter 16 - reproductive cycles / fertilisation Deck (29)
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1
Q

what is the ovarian cycle

A
  • series of events that take place in the ovaries, includes the maturation of the egg which is released into he Fallopian tubes (~28 days)
2
Q

what happens in the ovaries at birth

A
  • women’s ovaries contain ~400,000 immature eggs which are formed before birth
  • primary (dormant) follicle: a single layer of cells surround the immature egg
3
Q

what happens in the ovaries at puberty

A
  • some of the primary follicles develop / enlarge and divide
  • secondary follicle: fluid filled space gradually forces the egg to the edge of the follicle, several secondary follicles commence development (only one completes it)
  • mature (graafian) follicle: as more fluid accumulates, it continues to enlarge and move to the ace of ovary
4
Q

what happens in the ovaries during ovulation

A
  • when a mature follicle bursts it expels the egg, beating cilia (fimbriae) sweep egg into Fallopian tube (only one ovum is usually released)
5
Q

what is the corpus luteum

A
  • ruptured follicle collapses and blood within forms a clot, clot is absorbed by follicle which enlarges and changes colour forming the corpus luteum
  • releases hormones (progesterone) to ensure endometrium develops
6
Q

what happens in the ovaries during fertilisation

A
  • corpus luteum continues to develop (ovarian cycle stops), continues development for 3 months of pregnancy
  • at 3 months placenta is developed and can release its own hormones
7
Q

what happens in the ovaries if no fertilisation occurs

A
  • corpus luteum degenerates after 1 month to produce corpus albicans (eventually disappear)
  • ovarian cycle starts again
8
Q

what is the menstrual cycle

A
  • changes in the uterus (uterine lining endometrium), which are closely associated with stages in the ovarian cycle
9
Q

what happens during menstruation

A
  • days 1-4

- uterine bleeding, accompanied by shredding of the endometrium

10
Q

what happens during pre ovulation

A
  • days 5-12

- endometrial repair begins, development of ovarian follicle, uterine lining gradually thickens

11
Q

what is ovulation ovulation

A
  • days 13-15

- rupture of mature follicle, releasing of egg

12
Q

what happens during secretion

A
  • days 16-20
  • secretion of watery mucous by glands of endometrium, cervix and uterine tubes
  • movement / breakdown of unfertilised egg
  • development of corpus luteum
13
Q

what happens during premenstruation

A
  • days 21-28
  • degeneration of corpus luteum
  • deterioration of endometrium lining
14
Q

what is menarche

A
  • when menstruation first behind in a female (puberty)
15
Q

what is menopause

A
  • when menstruation becomes irregular, then stops (age 45-55)
16
Q

what are the endocrine glands

A
  • secrete hormones into extracellular fluid which surrounds cells -> into capillaries -> blood -> target organ (ovaries / testes)
17
Q

what is the pituitary gland

A
  • endocrine gland under the brain
  • releases follicle stimulating hormone (FSH) lutenising hormone (LH)
  • release prolactin when a woman is pregnant
18
Q

what is FSH

A
  • follicle stimulating hormone

- targets follicles of the ovaries and stimulates development / maturation of the ovarian follicle

19
Q

what is LH

A
  • lutenising hormone

- targets cells of ovaries, promotes maturation of ovarian follicle, ovulation and formation of corpus luteum

20
Q

what is oestrogen

A
  • secreted by developing ovarian follicle and corpus luteum

- acts on pituitary gland to reduce the level of FSH in the blood, develops female reproductive system

21
Q

what is progesterone

A
  • secreted by corpus luteum
  • causes decrease in LH in blood after ovulation
  • maintains endometrium, develops and maintains placenta
  • develops milk secreting glands (pregnant) OR menstruation occurs
22
Q

what is HCG

A
  • human chorionic gonadrophin
  • maintains corpus luteum (while placenta is forming)
  • after 3 months placenta procures its own hormones and the corpus luteum disintegrates
23
Q

what is prolactin

A
  • secreted by pituitary gland

- effects breasts during milk production

24
Q

summarise the ovarian and menstrual cycle

A
  • primary follicle -> FSH promotes maturation -> follicle matures -> secretes oestrogen which decreases FSH levels -> LH acts on follicle -> ovulation occurs -> formation of corpus luteum -> secretes progesterone + oestrogen -> egg enters uterine tube -> fertilisation (implants in uterine wall, HCG produced, development of embryo OR no fertilisation (menstruation, new cycle begins)
25
Q

what is insemination

A
  • ejaculation of sperm into vagina, movement is due to beating of tail and muscular contractions of uterus and fallopian tubes
26
Q

what is sperm mortality

A
  • very high mortality rate
  • required to travel a large distance
  • large numbers of sperm required for fertilisation to occur
27
Q

what is the corona radiata

A
  • layer of follicle cells held by acid surrounding the egg
28
Q

what does the enzyme on the head of sperm do

A
  • breakdown the acid of the corona radiata
  • many sperm are needed to supply enough enzyme
  • once one sperm enters fertilisation membrane forms preventing entry of other sperm
29
Q

what happens after fertilisation

A
  • tail is absorbed, head moves through cytoplasm to form male pronucleus
  • secondary octeocyte completes meiosis II, nucleus of egg develops into a female pronucleus
  • pronucleus’s fuse together to form a nucleus with diploid (2n) chromosomes