birth and lactation Flashcards
what do estrogen and progesterone do during pregnancy?
the
progesterone and estrogen
produced by the placenta
maintain the endometrium
(uterine lining), suppress the
menstrual cycle and promote the
growth of breast tissue.
what causes labor?
the
levels of progesterone and
estrogen produced by the
placenta begin to fall and this
signals the onset of the uterine
contractions known as labor.
what happens during labor?
progesterone and estrogen drop= uterine contractions
this also causes the uterus lining to secrete group of hormones= Prostaglandins–> initiate uterine contractions and at the same time stretch receptors in the cervix stimulate–> hypothalamus –> signal pituitary gland–> secrete oxytocin
what is oxytocin and its effects?
a hormone that continues the stimulation of muscle in uterus to contract.
what is oxytocin controlled by?
controlled by positive feedback– small uterine contraction triggers the release of more oxytocin= next contraction bigger and stronger contraction etc..
stages of birth– dilation stage
lasts about 2-20 hours.
uterine contractions and
oxytocin cause the cervix to
dilate
amnion breaks and fluid is
released
expulsion stage
lasts about 0.5-2 hours
contractions become so forceful that the
baby is pushed through the cervix into
birth canal
the head of the baby rotates making it
easier to pass through the birth canal
placental stage
the placenta and umbilical cord are
expelled from the uterus
usually happens between 10-15 minutes
after the baby is born
what happens after birth
blood level of hormone prolactin from anterior pituitary increase
what does prolactin do?
stimulate the mild production by mammary glands
what happens when the baby suckles
prolactin secretion is maintained and ocytocin is released from posterieor pituitary.
