2.3 - sexual reproduction in humans Flashcards

1
Q

list parts of female reproductive system + explain function

A

ovaries - produce egg cells in follicles
fallopian tubes - transports egg cell from ovary to uterus
uterus - where embryo develops
cervix - separates uterus from vagina, protects fetus
vagina - leads from cervix to outside of body

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2
Q

list parts of male reproductive system + explain function

A

testes - production of sperm cells + testosterone
vas deferens - carry sperm from testes to urethra
prostate gland - secretes alkaline fluid to counteract vaginal acidity
urethra - allows excretion of urine + semen from body
seminal vesicle - secretes fluid (proteins + fructose) to nourish sperm
penis - penetrates vagina, releases sperm
epididymis - stores sperm
scrotum - holds + maintains optimum temperature for testes

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3
Q

how does human body produce gametes

A

via gametogenesis

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4
Q

name 2 types of gametogenesis

A
  • spermatogenesis
  • oogenesis
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5
Q

what is spermatogenesis

A

gametogenesis in males resulting in production of spermatozoa

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6
Q

where does spermatogenesis take place

A

seminiferous tubules

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7
Q

outline stages of spermatogenesis

A

primordial germ cells → spermatogonia → primary spermatocytes → secondary spermatocytes → spermatic → 4 spermatozoa

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8
Q

what’s the germinal epithelium

A

surface layer of cells surrounding ovaries in females + testicles in males that’s involved in gametogenesis

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9
Q

how do primary spermatocytes form

A
  • primordial germ cells divide by mitosis, forming spermatogonia
  • growth period of spermatogonia w/out further division forms primary spermatocytes
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10
Q

how are spermatids formed

A
  • primary spermatocytes divide in meiosis I to form haploid secondary spermatocytes
  • secondary spermatocytes divide in meiosis II to form 4 haploid spermatids
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11
Q

how do spermatozoa form

A

spermatids differentiate to gain flagellum, acrosome, + many mitochondria

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12
Q

the 3 types of cells within testes

A
  • spermatogonia
  • sertoli cells
  • interstitial cells (cells of leydig)
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13
Q

what are leydig cells

A
  • cells located adjacent to seminiferous tubules in testes that secrete testosterone
  • also called interstitial cells of leydig
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14
Q

what are sertoli cells

A

cells located within seminiferous tubules in testes that provide nourishment + protection to cells produced in spermatogenesis

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15
Q

describe structure of mature sperm cell

A

acrosome - contains digestive enzymes which break down zona pellucida of egg
flagellum - propulsion
mitochondria - energy

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16
Q

what’s oogenesis

A

gametogenesis in females that results in production of secondary oocytes

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17
Q

where does oogenesis take place

A

ovaries

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18
Q

outline stages of oogenesis

A

primordial germ cell → oogonia → primary oocyte → secondary oocyte + polar body → ootid + polar bodies → ovum

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19
Q

how do primary oocytes form

A
  • primordial germ line cells in ovaries (+ oviduct) divide by mitosis, forming oogonia
  • growth period of oogonia w/out further division forms primary oocytes
  • meiosis begins but pauses in prophase I until puberty
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20
Q

what happens during first meiotic division of oogenesis

A
  • primary oocytes divide in meiosis I to form secondary oocyte
  • polar body buds off + sticks to oocyte
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21
Q

what’s a polar body

A

haploid cell produced during meiosis in females that doesn’t have ability to be fertilised

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22
Q

when is second meiotic division of oogenesis completed

A

meiosis II initiated but pauses in metaphase II unless fertilisation takes place

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23
Q

what happens during second meiotic division

A

secondary oocyte develops into fertilised ovum + second polar body

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24
Q

describe structure of secondary oocyte

A

corona radiata - outer layer of follicle cells
zona pellucida - coating above cytoplasm that prevents polyspermy + hardens when cortical granules release chemicals
haploid nucleus - fertilisation restores diploid chromosome number

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25
Q

outline stages in development of follicle

A

primary follicle → secondary follicle → graafian follicle → ovulation → corpus luteum

26
Q

what’s a primary follicle

A

immature ovarian follicle surrounded by two layers of follicular cells

27
Q

what’s a secondary follicle

A

larger follicle that’s developed from primary follicle

28
Q

define graafian follicle

A

mature fluid filled follicle in ovary within which egg cell develops

29
Q

what’s a corpus luteum

A

mass of cells that forms from graafian follicle after ovulation
serves as temporary endocrine structure during pregnancy, secreting progesterone

30
Q

what’s sexual intercourse

A

entry of male reproductive organ + deposition of sperm into female reproductive tract

31
Q

explain what happens in fertilisation

A
  1. spermatozoa move into fallopian tubes
  2. acrosome binds to zona pellucida + releases hydrolase enzymes that digest zona pellucida
  3. membranes of sperm + secondary oocyte fuse, allowing sperm nucleus to enter oocyte
  4. nuclei fuse, forming diploid zygote
  5. cortical reaction causes zona pellucida to harden, preventing polyspermy
32
Q

outline stages of early embryo development

A

zygote → blastocyst → implantation

33
Q

how does a blastocyst form

A

several mitotic division of zygote (cleavage) produce ball of cells, the blastocyst

34
Q

define implantation

A

early stage of pregnancy in which blastocyst adheres + sinks into endometrium

35
Q

what is placenta

A

temporary organ attached to lining of uterus during pregnancy

36
Q

name the hormones involved in menstrual cycle

A
  • follicle stimulating hormone (FSH)
  • luteinising hormone (LH)
  • oestrogen
  • progesterone
37
Q

where is FSH secreted from

A

anterior pituitary gland

38
Q

what’s the function of FSH in menstrual cycle

A

binds to follicle cells, stimulating them to mature + secrete oestrogen

39
Q

where is LH secreted from

A

anterior pituitary galnd

40
Q

what’s the function of LH in menstrual cycle

A

initiates ovulation + stimulates development of graafian follicle into corpus luteum

41
Q

what’s the function of oestrogen in menstrual cycle

A

inhibits production of FSH + causes surge in LH production

42
Q

what structure secretes progesterone in menstrual cycle

A

corpus luteum

43
Q

what’s the function of progesterone in the menstrual cycle

A

causes development of endometrium + inhibits production of FSH + LH

44
Q

what happens if implantation doesn’t occur during menstrual cycle

A
  • corpus luteum degenerates due to decreasing FSH + LH levels
  • progesterone levels decrease
  • endometrium breaks down
45
Q

what is HCG

A
  • human chorionic gonadotropin
  • hormone secreted by developing embryo that maintains corpus luteum during early pregnancy
46
Q

describe role of placenta in pregnancy

A
  • exchange of gases + nutrients
  • barrier between fetal + maternal blood
  • secretes progesterone + oestrogen
  • protects mothers immune system
  • protection from difference between maternal + foetal blood pressure
47
Q

what’s the role of progesterone during pregnancy

A

suppresses contractions of uterine wall

48
Q

what’s the role of oestrogen during pregnancy

A

stimulates uterine growth + development of mammary glands

49
Q

how do levels of progesterone + oestrogen change prior to birth

A
  • oestrogen levels increase
  • progesterone levels decrease
50
Q

why do progesterone levels decrease jut before birth

A

allows uterine wall to contract

51
Q

where is oxytocin secreted from

A

posterior pituitary gland

52
Q

describe the role of oxytocin

A

triggers contraction of uterus wall

53
Q

what type of feedback is secretion of oxytocin an example of

A

positive feedback

54
Q

what type of feedback is secretion of oxytocin an example of

A

postive feedback

55
Q

where is prolactin secreted from

A

anterior pituitary gland

56
Q

describe the role of prolactin

A

stimulates lactation during + after birth

57
Q

what is amniotic fluid

A

liquid surrounding embryo in amniotic sac

58
Q

describe role of amniotic fluid during fetal development

A

protects foetus + acts as a shock absorber

59
Q

describe how placenta is adapted for exchange of substances between maternal + fetal blood

A
  • counter current blood flow
  • chorionic villi provide large SA for exchange of products
  • fetal capillaries lie close to surface, giving short diffusion distance
  • abundance of maternal blood vessels
60
Q

what are intervillous sapces

A

spaces between chorionic villi that contain maternal blood

61
Q

describe role of umbilical artery

A

carries deoxygenated blood from fetus to placeta

62
Q

describe role of umbilical vein

A

carries oxygenated blood from placenta to fetus