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Biology A Level Unit 4 > Sexual Reproduction - Humans > Flashcards

Sexual Reproduction - Humans Flashcards

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1
Q

testes function

A

contain seminiferous tubules for sperm production

testerone production

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2
Q

scrotum function

A

holds testes outside body for temp regulation

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3
Q

penis function

A

removes waste

delivers sperm in reproduction

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4
Q

urethra function

A

passage of urine/semen through penis

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5
Q

vas deferens function

A

muscular tube transport sperm from epididymis to top of urethra

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6
Q

seminal vesicles function

A

secrete mucus into vas deferens - 70% of semens liquid content

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7
Q

prostate gland function

A

30% of semens liquid content

alkaline to maintain sperm mobility, provide nutrients, neutralise acidity of urine/vaginal tract

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8
Q

epididymis function

A

sperm complete development

stores sperm until ejaculation

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9
Q

ovary function

A

egg production

oestrogen + progesterone production

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10
Q

uterus function

A

embryo/foetal development

3 layers = perimetrium (thin, around outside), myometrium (muscle), endometrium (inner mucous membrane)

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11
Q

endometrium function

A

varying thickness

highly vascularised - supplies foetus

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12
Q

oviduct (Fallopian tubes) function

A

carrues egg from ovary to uterus by muscular contractions and cilia
site of fertilisation

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13
Q

cervix function

A

ring of muscle that supporta embryo/foetus

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14
Q

vagina function

A

muscular Ru where penis is placed during intercourse

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15
Q

where does spermatogenesis take place

A

seminiferous tubules (testes)

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16
Q

spermatogenesis

A 
germinal epithelial tissue (lines seminiferous tubules) (2n)
mitosis
spermatogonium (2n) (+1 stays as germinal epithelial cell)
mitosis
primary spermatocytes (2n)
meiosis 1
secondary spermatocytes (n)
meiosis 2
spermatids (n)
spermatozoan
17
Q

what protects sperm

A

cells of Sertoli

18
Q

where does oogenesis take place

A

ovary

19
Q

oogenesis

A

germinal epithelial tissue (2n) (also divides to form primary follicles that surround primary oocytes)
mitosis
oogonia (2n)
growth
primary oocytes (2n)
meiosis 1 (ends at prophase 1) to produce first polar body (n) + secondary oocyte (n)
ovulation - primary follicles develop into secondary then Graafian follicles which migrate to ovary, burst and release secondary oocyte
meiosis 2 (ends at metaphase 2)
secondary oocyte moves along fallopian tubes…

20
Q

oogenesis if no intercourse/sperm

A

secondary oocyte passes along fallopian tubes, reaches uterus, lost in menstruation

21
Q

oogenesis if intercourse takes place

A

sperm + secondary oocyte in fallopian tubes, sperm ‘capacitated’ bursts in contact with corona radiata enters secondary oo cute triggering meiosis 2
meiosis 2 completes making ovum + second polar body
Graafian follicle becomes corpus luteum - produces hormones

22
Q

sexual intercourse

A

penis erect, enters vagina, sperm ejaculated through cervix into uterus

23
Q

fertilisation

A

capacitation - cholesterol + glycoproteins removed from acrosome on sperm head making membrane permeable to calcium ions
acrosome reaction - acrosome releases proteases digesting corona radiata, acrosome membrane ruptures releasing acrosin hydrolysing zona pellucida around secondary oocyte
sperm + secondary oo cute cytoplasm fuse - ovum
cortical reaction - calcium ions into cytoplasm, cortical granules fuse with cell membrane releasing enzymes by exocytosis, zona pellucida forms fertilisation membrane, prevent polyspermy
meiosis 2 completes, ovum nucleus divides an expels second polar body
mitosis combine genetic material produces 2 cells (embryo)

24
Q

implantation

A

embryo down oviduct, divides my mitosis many times (cleavage)
ball of cells hollow - blastocysts (with trophoblast cells) divide making inner cell mass on one side
blastocyst moves from oviduct to uterus
endometrium thickens, increased blood supply for embryo
trophoblastic villi penetrate endometrium increasing surface area for nutrient absorption
blastocyst into endometrium = implantation

25
Q

menstrual cycle

day 0

A

endometrium break down, gonadotrophic releasing hormone secreted by hypothalamus stimulates anterior pituitary gland to secrete FSH + LH
FSH stimulates primary follicles in ovary, 1 matures forms theca + secretes fluid into antrum = Graafian follicle
FSH thecal cells make oestrogen (+feedback)
lots of LH, Graafian follicle to ovary surface releasing secondary oocyte +feedback effect on FSH
Graafian follicle into corpus luteum, secretes oestrogen + progesterone inhibit FSH + LH

26
Q

menstrual cycle

day 6-7

A

oestrogen levels rise - endometrium rebuilds, FSH inhibited (-feedback), stimulates LH (+feedback)

27
Q

menstrual cycle

day 12

A

progesterone increase - maintains endometrium so if secondary oocyte is fertilised there’ll be suitable tissue for embryo to implant
no implantation - fall in FSH + LH causes progesterone decrease, endometrium sheds

28
Q

menstrual cycle

day 14

A

LH peak causes ovulation

Graafian follicle becomes corpus luteum, secretes I estrogen + progesterone

29
Q

menstrual cycle

day 21

A

oestrogen + progesterone levels drop

oestrogen falls, FSH not inhibited, increases, next follicle develops

30
Q

menstrual cycle

day 28

A

progesterone levels not high enough to maintain endometrium - menstruate
FSH levels rise - cycle restarts

31
Q

if fertilisation occurs…

A

progesterone + oestrogen levels remain high

embryo produces HCG, maintains corpus luteum for progesterone + oestrogen

32
Q

hormones + birth

A

more oestrogen than progesterone in last 3 months of pregnancy, oxytocin + prolactin no longer inhibited
posterior pituitary gland secretes oxytocin causing myometrium to contract, +feedback more oxytocin, myometrium contracts top down to push foetus through cervix
anterior pituitary gland secretes prolactin stimulates glandular tissue in mammary glands to synthesise, milk released when oxytocin causes muscles around milk ducts to contract

33
Q

placenta function

A

connects embryo and foetus to uterus wall
produces hormones in pregnancy
exchange between mother + foetus blood (nutrients, waste, gases)
stops blood mixing (different pressures)
passive immunity to foetus
protects mothers immune system

34
Q

placental hormones

A

embryo secretes HCG after fertilisation made by chorion (inner layers of placenta) after implantation, maintains corpus luteum (secretes progesterone maintains endometrium)
corpus luteum secretes oestrogen + progesterone, placenta increases, FSH, LH, prolactin, oxytocin inhibited by progesterone, oestrogen stimulates uterus growth accommodating foetus + mammary gland growth

Biology A Level Unit 4 (6 decks)

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