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83 Cards in this Set
- Front
- Back
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corona radiata
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attached granulosa cells around the ovum when ovulation occurs
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what are the cilia of the fibriated ends of each fallopian tube activated by
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estrogen
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Based on conception studies, what percent of ova enter fallopian tubes
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as many as 98%
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What is the transportation of sperm aided by
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contractions of uterus stimulated by prostaglandins in male seminal fluid
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how many sperm generally make it to the ampulla
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a few thousand out of the almost half million deposited
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what occurs to sperm when entering ovum
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head swells to form pronucleus
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Why does it take 3-5 days for fertilized ovum to enter uterus
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fallopian tubes are lined with rugged, crytoid surface that impedes passage and isthmus remains spastically contracted for 3 days after ovulation until progesterone from corpus luteum causes relaxation
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The action of what cells of the blastocyst cause implantation
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trophoblast cells over the surface of the blastocyst
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How do trophoblast cells cause implantation
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they secrete proteolytic enzymes that digest and liquify adjacent cells of uterine endometrium
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when does the placenta begin to supply nutrition
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after the 16th day beyond fertilization (~1 week after implantation)
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how long does the embryo receive nutrition from the trophoblast
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some up through 8 weeks
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relationship of embryo villi and maternal blood pools
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villi grow into maternal blood pools and become surrounded by sinuses containing maternal blood
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number of unbilical vessels
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2 umbilical arteries and 1 umbilical vein
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SA of villi in mature placenta
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few square meter, many times less than pulmoary membrane in lungs
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permeability of placental membrane
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low permeability in early months due to thick placental membrane
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end of pregenancy maternal and fetal PO2
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maternal 50 mmHg and fetal 30 mmHg
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how is 30 mmHg O2 sufficient to supply fetus
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1) hemoglobin type 2) hemoglobin concentration 50% greater than mother 3) Bohr effect (can carry more O2 at low PCO2 than high)
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Why is maternal-featl circulation considered to have a "double" bohr effect
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operates in one direction in maternal blood and the other in fetal blood essentially doubling the effect
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What causes the Bohr effect
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Fetal blood 'gives' maternal circulation CO2 causing fetal blood to be slightly alkaline and maternal slightly acidic, changing binding of O2
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diffusing capacity of entire placenta at term
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1.2 mL O2/min/mmHg; compares with the lungs of newborn
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what allows adequate CO2 diffusion from fetus to mother
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Pco2 of fetus is 2-3 mmHg higher than maternal blood; CO2 is extremely soluble in placental membrane and diffuses 20 times as rapidly as O2
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what substances diffuse easily into fetal blood
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ketone bodies, K+, Na+, Cl-, glucose (facilitated diffustion), and fatty acids
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what diffuses easily into maternal blood
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nonprotein nitrogens like urea, uric acid (easily diffuses, concentration ~maternal concentration), creatinine (slow/difficult diffusion, concentration much greater than maternal)
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what hormones does the placenta form in large quantities
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HCG, estrogens, progesterone, human chorioic somatomammotropin
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HCG info
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secreted by syncytial trophoblast cells; glycoprotein with MW 39,000; structure similar to LH
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HCG fxn
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prevent involution of corpus luteum and cause greater secretion of its sex hormones (progestone and estrogen)
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what occurs if corpus luteum is removed before 7 weeks and possibly up to 12th week
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spontaneous abortion
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what occurs to corpus luteum after 13th to 17th week and why
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slowly involutes since placenta is mature enough to provide necessary hormones
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what does HCG do to male testis
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interstitial cell stimulating, produce testosterone until after birth; causes testis to descend into scrotum
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what are estrogen and progesterone secreted by in the placenta
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sycytial trophoblast cells
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what are estrogens in placenta made from
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androgenic steroid compounds like dehydroepiandrosterone and 16-hydroxydehydroepiandrosterone, which are formed in the maternal adrenal glands and fetal adrenal glands
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what do the trophoblast cells convert the androgenic steroid compounds into
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estrdiol, estrone, and estriol
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what do extreme quantities of estrogen cause in pregnancy
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1) enlargement of uterus 2) enlargement of breasts and growth of ductal structure 3) enlargement of mothers external genitalia 4) relax pelvic ligaments 5) may affect growth/cell reproduction of fetus
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special effects of progesterone in pregnancy
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1) decidual cell development 2) decreases contractility of uterus 3) increases secretions of fallopian tubes and uterus before implantation 4) may affect cell cleaveage in early embryo dvlp 5) helps estrogen prepare breasts
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human chorionic somatomammotropin info
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protein MW 38,000; secreted by placenta beginning week 5; unknown fxn; secretion exceeds all other hormones; similar structure to GHs
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potential fxns of human chorionic somatomammotropin
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lactation/breast dvlp in lower animals, weak GH, decreased insulin sensitivity and glucose utilization in mother, promotes release of free fatty acids in mother
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pituitary secretion in pregnancy
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enlarges 50% and increases corticotropin, thyrotropin, and prolactin production; FSH and LH supressed
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Corticosteroid secretion in pregnancy
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glucocorticoids moderately increased; 2 fold increase in aldosterone
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what can increased aldosterone and actions of estrogens cause
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reabsorption of excess Na+ which can lead to pregnancy-induced hypertension
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thyrois gland secretion in pregnancy
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enlarges up to 50%, increases thyroxine producation caused partly by HCG and human chorionic thyrotropin
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parathyroid gland secretion in pregnancy
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enlarge especially if calcium deficient, even greater during lactation
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relaxin by ovaries and placenta
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increased by HCG; polypeptide MW 9000; relaxation of ligaments (weak), may soften cervix
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uterus growth
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from 50 g to 1100 g
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average weight gain break down
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24 lbs total: 7 lbs fetus, 4 lbs amniotic fluid, placenta, and fetal membranes, 2 lbs breasts, 2 lbs uterus, 6 lbs extra body fluids (blood, ECF), 3 lbs fat accumulation
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basal metabolic rate increase during pregnancy
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about 15% during later half
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Iron in later pregnancy
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600 mg needed in mother, 375 mg needed in fetus; normal storage is btwn 100-700
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why is vitamen K inportant shortly before birth
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ensure baby has sufficient clotting factors
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blood flow end of pregnancy in placenta
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625 mL each minute
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Mothers CO end of pregnancy
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30-40% above normal by 27th week, falls to just above normal 8 weeks before end
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safety factor of bleeding during birth
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extra 1-2 L, usually inly loose 1/4 L
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oxygen requirement before birth
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20% above normal
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progesterone effect on respiration
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increases respiration center sesitivity to CO2, causing increased resp.
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urine formation
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reabsorptive capacity for Na+, Cl-, and water increased up to 50%; glomerular filtration rate increases up to 50% which increases water and electrolyte secretion in to urine
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amniotic fluid replacement
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about every 3 hours; electrolytes (Na+ and K+) replaced every 15 hours
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incidence of preclampsia
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~5%; rise of arterial BP to hypertensive levels and preotein leakage into urine
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what effects can preclampsia have
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arterial spasm due to vascular endothelium impairment - occurs in kidneys, brain, and liver
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suspected causes of preclampsia
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1) excessive placental/adrenal hormones 2) autoimmunity/allergy 3)insufficient blood supply to placenta
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Two major changes that lead to parturition
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1) progressive hormonal changes 2) prgressive mechanical changes
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hormonal changes that lead to parturition
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decreased progesterone along with increased estrogen
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how do estrogens affect parturition
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increase number of gap jxns btwn adjacent uterine smooth muscle cells
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oxytocin
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secreted by neurohypophysis and causes uterine contraction
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how oxytocin causes effects
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1) uterine SM increases oxytocin receptors 2) oxytocin secretion increased at labor 3) labor prolonged without 4) stretching of cervix causes release
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fetal hormones in uterine contraction
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oxytocin, cortisol from adrenals, prostaglandins from fetal membranes
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average of twin birth compared to singleton
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about 19 days earlier
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direction of uteran contration
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top of uterine fundus and spread downward over body of uterus
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force of strong uterine contractions
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25 lbs downward
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fetus position in delivery
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95% head first
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3 satges of parturition
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1) to full dilation 2) delivery of baby 3) separation and delivery of placenta (10-45 mins after baby delivery)
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how does uterus contrations stop bleeding
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smooth muscle fibers in figures of eight around blood vessels; vasocontrictor prostaglandins cause additional blood vessel spasm
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early labor pains are likely caused by
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hypoxia of uterine muscle; not felt when hypogastic nerves sectioned (carry visceral sensory info from uterus)
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2nd stage labor pain
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cervical stretcing, perineal stretching, stretching/tearing of vaginal canal; pain conducted by somatic nerves
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how long does it take for uterus to return to normal size after parturition
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half weight after 1 week and if nursing may be normal size by 4 weeks
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lactation effect on post-deliery uterus size
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suppression of pituitary gonadotropin and ovarian hormone secretion druing first few months of lactation
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lochia
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uteran discharge after parturition continution for about 10 days; bloody first, then serous
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hormones important for ductal system
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estrogens, GH, prolactin, adrenal glucocorticoids, and insulin; play roles in protein metabolism
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final dvlp of breasts into milk secreting organs requires…
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progesterone
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specific effect of estogen and progesterone on breasts
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encourage dvlp, but inhibit milk secretion
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colostrum composition
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proteins, but NO/little fat
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secretion of milk requires background secretioon of…
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GH, cortisol, PTH, insulin; provide aas, fatty acids, glucose, and Ca+
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prolactin level after parturition
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normal except for about 1 hour following nursing where it increases 10-20 fold
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hypothalmus control over anterior pituitary hormones
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stimulates all, but inhibits prolactin
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hypothesized prolactin inhibitory hormone
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dopamine (a catecholamine)
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milk let-down
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oxytocin
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