human reproduction
Cards (27)
- when embryo reaches uterus - forms a placenta
- placenta is an exchange organ - allows foetus to connect to mothers blood supply
- umbilical cord allows the exchange of vital nutriets: oxygen, glucose, amino acids, antibiotics
- placenta adaptations:
- villi = increase surface area
- good blood supply = maintain concentration gradient
- thin membranes = short diffusion pathway
- amniotic fluid cushions baby from shocks
- foetal heart: has two adaptations for more effective blood flow:
- connection between the atria
- connection between aorta and pulmonary artery
- oxygen enters blood via umbilical cord = not all blood needed to go to lungs
- fertilisation occurs when sperm meets egg cell
- oestrogen produced in ovaries
- testosterone produced in testes
- menstrual cycle: the cycle of an ovum maturing and being released
- menstrual cycle is across 28 days
- day 0-5: a period happens and uterus lining is lost
- day 6 - 13: uterus lining builds up again
- day 14: ovulation occurs and an ovum is released
- day 15 - 28: the uterus lining is maintained
- ovary makes oestrogen and progesteronepituitary gland makes FSH and LH
- FSH from pituitary gland matures an ovum and stimulates oestrogen
- oestrogen thickens uterus lining - inhibits FSH and stimulates LH
- LH causes ovulation and stimulates progesterone
- progesterone maintains uterus lining - inhibits LH and FSH
- reproduction = the production of new members of a species, replacing those who die of old age, disease and competition
- sexual reproduction involves two parents who have sex organs that produce sex cells that fuse in fertillisation
- asexual reproduction involves one parent and no fusion of sex cells
- zygote has 46 chromosomes - 23 from sperm 23 from ovum
- XY - sex chromosomes
- sperm structure:
- nucleus of a sperm has 23 chromosomes
- a chromosone has digestive enzymes in
- mitochondria produce ATP for the flagellum to use for swimming
- large amount of sperm released = high failure ratevery small - light to swim