science Flashcards
(31 cards)
what does the placenta do?
exchanges nutrients and waste from the mother to the foetus
what is the placenta?
A disc shaped filtration system
What connects the placenta to the foetus?
The umbilical cord
How does the placenta give the foetus nutrients?
It implants into the uterus wall and food and oxygen from the mothers blood passes through the placenta and then to the foetus
What is the egg called in the first 8 weeks (not including the first 2)?
embryo and its still developing specialised cells
What does the embryo float in?
amniotic fluid
what is the fluid protecting the baby enclosed by?
amnion (membrane)
What does the amniotic fluid do?
It protects the foetus by acting as a shock absorber and also maintains a constant temperature
Does the mothers blood mix with the embryos blood? why?
No becuase the mother could be a different blood type and immune system will attck it or if the foetus is a boy the female hormones will damage the foetus and maternal BP is too high.
How does an embryo get rid of its waste?
Carbon dioxide and other waste substances pass through the placenta from the embryo to the mothers blood(difusion). (then the blood will undergo normal filtration and cellular respiration)
What can the placenta also do?
stop harmful substances passing through the embryo
what is gestation period?
A period which offspring develop in the uterus
What does the amount of weeks pregnant refer to?
refers to the time since the first day of a woman’s last period
What are the stages of pregnancy called?
1st, 2nd and 3rd trimester
what are the 3 stages of birth?
labour, delivery and afterbirth (Placental delivery)
What is labour?
Dilation of the cervix to 10cm (ten hours)
Mucus plug comes away with a little blood.
Uterus contracts & cervix dilates.
Amnion usually breaks =breaking of waters.
Baby will have normally turned so that its head is
facing down.
What is delivery?
Birth of the baby via the vagina (expulsion)
Contractions are strong & close together
Baby’s head is pushed face-down out the birth canal = delivery
What is afterbirth?
Placental delivery
Half an hour after birth, further contractions expel the placenta
and amniotic sac
How does the placenta form?
The embyryo develops finger-like projections which implant into the uterus wall and this enlarges and forms the placenta.
what is copulation
sexual reproduction
What is ejaculation
seamen squeezes out of the penis and serval hundred million sperm deposits near the cervix
What do the sperm do from the cervix
they swim into the uterus
Do all the sperm make it to the egg?
No only a few hundred survive and most die and only along the way
What do sperm do when they encounter an egg?
they swarm over it’s surface
