Sexual Reproduction - Humans Flashcards
testes function
contain seminiferous tubules for sperm production
testerone production
scrotum function
holds testes outside body for temp regulation
penis function
removes waste
delivers sperm in reproduction
urethra function
passage of urine/semen through penis
vas deferens function
muscular tube transport sperm from epididymis to top of urethra
seminal vesicles function
secrete mucus into vas deferens - 70% of semens liquid content
prostate gland function
30% of semens liquid content
alkaline to maintain sperm mobility, provide nutrients, neutralise acidity of urine/vaginal tract
epididymis function
sperm complete development
stores sperm until ejaculation
ovary function
egg production
oestrogen + progesterone production
uterus function
embryo/foetal development
3 layers = perimetrium (thin, around outside), myometrium (muscle), endometrium (inner mucous membrane)
endometrium function
varying thickness
highly vascularised - supplies foetus
oviduct (Fallopian tubes) function
carrues egg from ovary to uterus by muscular contractions and cilia
site of fertilisation
cervix function
ring of muscle that supporta embryo/foetus
vagina function
muscular Ru where penis is placed during intercourse
where does spermatogenesis take place
seminiferous tubules (testes)
spermatogenesis
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
what protects sperm
cells of Sertoli
where does oogenesis take place
ovary
oogenesis
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…
oogenesis if no intercourse/sperm
secondary oocyte passes along fallopian tubes, reaches uterus, lost in menstruation
oogenesis if intercourse takes place
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
sexual intercourse
penis erect, enters vagina, sperm ejaculated through cervix into uterus
fertilisation
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)
implantation
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
menstrual cycle
day 0
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
menstrual cycle
day 6-7
oestrogen levels rise - endometrium rebuilds, FSH inhibited (-feedback), stimulates LH (+feedback)
menstrual cycle
day 12
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
menstrual cycle
day 14
LH peak causes ovulation
Graafian follicle becomes corpus luteum, secretes I estrogen + progesterone
menstrual cycle
day 21
oestrogen + progesterone levels drop
oestrogen falls, FSH not inhibited, increases, next follicle develops
menstrual cycle
day 28
progesterone levels not high enough to maintain endometrium - menstruate
FSH levels rise - cycle restarts
if fertilisation occurs…
progesterone + oestrogen levels remain high
embryo produces HCG, maintains corpus luteum for progesterone + oestrogen
hormones + birth
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
placenta function
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
placental hormones
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
