Human Reproduction Flashcards
what are the 4 stages of sexual arousal?
excitement
plateau
orgasm
resolution
What happens to males during excitement?
testicular vasocongestion
erection
What happens to females during excitement?
vasodilation of vagina and swelling of labia erection of clitoris lubrication of vagina enlargement of breasts flush to skin
What kind of nervous supply causes the erection?
parasympathetic
What is the plateau phase in men?
increase HR, BP, resps, muscle tension
What is the plateau phase in women?
same as males but also uterus raises, lifts cervix and enlarges upper 1/2 of vagina to make room for ejaculate
What happens during orgasm?
rhythmic contractions of pelvic muscles every 0.8s
increase HR, BP, resp rate muscle tension
ejaculation in men
intense physical pleasure
What are the phases of ejaculation?
emission and explusion
What happens during emission?
sympathetic response causes contraction of the glands in prostate, reproductive ducts and seminal vesicles into the urethra
What happens during expulsion?
motorneurons induce rhythmic contraction of skeletal muscle and force semen out
What is the amount of semen produced per ml?
66million/ml
What is considered to be clinically infertile?
> 20million/ml
Approximately what percentage of sperm reach the ovum and when?
0.001% about 30-60 mins after ejaculation
What is capacitation?
the process sperm must go through in order to be capable of fertilisation
What happens during capacitation?
surface of sperm altered by removal of glycoprotein
tail movements become whip-like
cAMP levels rise to promote acrosomal reaction
What happens upon sperm entry to the ovum?
stimulates Ca release which blocks polyspermy
What happens upon sperm entry to the ovum?
stimulates Ca release which blocks polyspermy
What are the chemicals used by the sperm to penetrate the egg?
Allurin
Fertilin
Acrosomal reaction
What is allurin?
released by mature ovum to guide sperm to the egg using an olfactory receptor
What is fertilin?
protein on sperm that binds to integrin on oocyte
How is the ovum guided to the oviduct?
by fimbriae sweeping it in by smooth muscle contraction and cilia
What is a trophoblast?
the blastocyst that accomplishes implantation and develops into fetal portions of the placenta
What happens upon implantation?
trophoblast cells burrow into the endometrium carving a hole for the blastocyst
What happens when implantation is finished?
the blastocyst is completely buried in the endometrium
How do the trophoblasts burrow into the endometrium?
by releasing proteases
What becomes the foetal placenta?
synctiotrophoblast
What occurs with decidualisation?
increased local vascularisation and nutrient storage for the blastocyst
When is the blastocyst completely buried?
by day 12
How does the embryo get nutrients from the maternal blood supply?
sends capillaries into the synctiotrophoblast to form placental villi
What prevents the mixing of maternal and feotal blood?
the villi and maternal blood are separated by a thin layer of tissue
When are the placenta and foetal heart functional?
by week 5
What hormones maintain during the 1st trimester?
hCG - produced by blastocyst
What is the function of hCG?
maintains corpus luteum and thus progesterone and oestrogen until week 10
What is the function of hCG?
maintains corpus luteum and thus progesterone and oestrogen until week 10
Why does oestrogen not come from the placenta initially?
the placenta does not posses DHEA from the feotal adrenal cortex to convert progesterone to oestrogen at first
What is the role of oestrogen in pregnancy?
stimulates growth of myometrium musculature
stimulate development of mammary gland ducts
What is the role of progesterone in pregnancy?
suppresses contraction of uterine myometrium
promotes formation of mucus plug
stimulate development of mammary milk glands
What are the physical changes the mother undergoes?
enlargement of uterus and placenta enlargement of breasts increase blood vol weight gain increase ventilation increase GFR increased nutritional requirements
Why does the blood vol increase?
oestrogen stimulates angiotensin and renin secretion which results in aldosterone which retains Na and water
What are the endocrine secretions of the placenta?
hCG oestrogen and progesterone hCS PTH-related peptide Relaxin Placental CRH
What is the function of hCS?
decreases maternal blood glucose use, increases plasma FA
prepares breasts for lactation
What is the function of pTH-rp?
mobilises maternal Ca for calcification of foetal bones
What is the function of relaxin?
softens cervix, loosens pelvic connective tissue
What is the function of placental CRH?
stimulates DHEA production by fetal adrenal cortex, important for initiating partuition
What does partuition require?
dilation of cervical canal
contractions of uterine myometrium
What happens in preparation of partuition?
Braxton-hicks
softening of cervix - relaxin and prostaglandins - breaks down cervical collagen fibres
relaxation of pelvic bones - relaxin
foetus drops
What appears to initiate labour?
increased oxytocin receptors triggered by increase estrogen and prostaglandins which increases uterine contraction
What happens in the first stage of labour?
cervix dilates
rupture of amniotic sac
What happens during the second stage of labour?
delivery of baby by uterine and abdominal contractions
What happens during the third stage of labour?
delivery of placenta
What is involution?
shrinkage of uterus to pre-pregnancy size
lochia
What is involution induced by?
fall in oestrogens and progesterone
oxytocine released in response to breast feeding
What do breast ducts terminate in?
lobules made of milk producing glands
What triggers development of the breast?
increased oestrogen (duct) and progesterone (lobule) prolactin - enzymes that produce milk
What does suckling trigger?
neuroendocrine reflex -> prolactin and oxytocin
What are the roles of prolactin and oxytocin in breast feeding?
prolactin - milk production
oxytocin - milk ejection
What is the role of oxytocin in gestation and post-partum?
stimulates contraction of myoepithelial cells
hastens involution
suppresses LH and FSH and thus menstrual cycle
What are the components of breast milk?
water, particles isotonic with plasma, lactose, lipids, vitamins, minerals, immunoprotective agents, other proteins including immunoglobulins
How many calories does breast milk have per L?
600-750kcal
