Physiology of Placenta and Physiology Flashcards
Fertilization: what key events occur on each of the following days:
- day 3
- day 4
- day 5
- day 6
- day 7
3: two cell stage, cell division occurs.
4: the solid mass of blastomere cells called the MORULA arrives in the uterine cavity
5: Blastocyst = outer layer & inner layer.
OUTER LAYER = trophoblast = placenta and fetal membranes
INNER LAYER = cell mass to become embryo and fluid.
6-7: implantation occurs; trophoblast invades endometrium.
Decidua: what is this?
Nitabuchs layer: what is the function of this?
uterine lining during pregnancy. the thick layer of modified mucous membrane that lines the uterus during pregnancy and is shed with the afterbirth.
Nitabuchs layer: allows for the sheering of the placenta off at birth.
Functions of Placenta
- prevents rejection of fetal allograft
- enables resp gas exchange
- transports nutrients
- eliminates fetal waste products
- secretes peptide and steroid hormones.
- glycogen synthesis
- cholesterol synthesis
- removal of lactate
- protein metabolism
- Immunoglobulin G
What are the placental peptide hormones and what is their function?
Human chorionic gonadotropin (hCG): maintains corpus luteum production of progesterone until placenta takes over at 6-8wks.
human placental lactogen (hPL): antagonizes maternal secretion of insuline to increase fetal glucose supply
placental corticotropin-releaseing hormone (CRH): stimulates fetal ACTH resulting in fetal adrenal making DHEA-S as a precursor to placental estrogen.
What are the placental steroid hormones and their function?
Progesterone: maintains a non-contractile uterus
Estrogens: stimulated by placental hCG
Maternal Physiology:
- effects of estrogen
- effects of progesterone
Estrogen:
- enlargement of uterus
- breast enlargement & growth of ductal structure
- enlargement of external genitalia
- relaxation of pelvic ligaments
Progesterone:
- inhibits myometrial contractions*
- may be involved with immune tolerance of fetus
- influences breast for lactation
- develops thick mucus plug of cervix
- allow for sufficient stretching of cervix, vagina, and vulva during delivery.
Changes during pregnancy
- ophthalmic
- dental
- GI
Ophthalmic:
- cornea thickens
- decreased intraocular pressure
- w/ toxemia of pregnancy, choroidal vascular insufficiency causes secondary retinal detachments.
Dental:
- gingivitis
- epulis (hypertrophy of gums)
GI:
-relaxation of esophageal sphincter leading to increased incidence of GERD d/t progesterone.
- decreased peptic ulcer dz d/t increased mucus an decreased gastric secretion
- gallbladder emptied incompletely in response to meals during pregnancy..risk of gallstones.
- delayed gastric emptying, slowed small bowel transit and decreased large bowel peristalsis–constipation, fecal impaction
- N/V (4-16wks)
- hyperemesis gravidarum caused from rapidly rising serum levels of hCG and estrogen. (persistent and severe N/V leading to weight loss, dehydration and electrolyte imbalances)
Changes during pregnancy:
-renal and urinary
- progesterone relaxes the bladder wall and reduces ureteral tone and peristalsis
- physiologic hydroureter of pregnancy (can hold 200-300ml urine)
- hydronephrosis (R MC than L)
- changes predispose pregnant women to UTIs and pyelonephritis. Asymptomatic bacteruria
- enlarged uterus displaces and flattens bladder decreasing capacity; associated with incontinence.
- increased frequency and nocturia.
- renal blood flow and glomerular filatration increase 40-50%
- creatinine, BUN, and uric acid drop.
Changes during pregnancy:
- respiratory
- CV
Resp:
- hyperventilation causing resp alkalosis
- compensated by renal excretion of bicarb.
- increased nasopharyngeal blood flow (epistaxis, congestion, polyp specific to prego)
- residual lung capacity decreases by 20% d/t enlarging uterus.
- tidal volume increases
- oxygen consumption increase 20%
CV:
- extracellular volume increase (total body water increases 6-8L; 2/3 of this is extravascular)
- total blood volume increases
- plasma volume increases
- red cell volume barely increases.
- stroke volume increases 10-30%
- heart rate increases 12-18beats/min
- cardiac output increase 40%
- SBP(4-6mmhg) and DBP(8-15mmhg) decrease!!
- muscle mass of heart increases*
- heart shifted to the left
- wide split S1 and S2
What is supine hypotensive syndrome?
compression of venous blood flow by baby. This can cause varicosities in the pregnant female, dramatically lower BP, nauseated, feel light headed and pass out.
What is physiologic anemia of pregnancy?
Anemia is defined as what hgb? hct?
a decrease in hemoglobin concentration d/t plasma volume increasing greater than the red call mass.
Anemia is defined as Hg less than 11 (10.5 in 2nd tri) or HCT less than 33%
Iron requirements in pregnancy:
- average iron stores in normal women?
- iron requirements during pregnancy?
- is the amount of iron absorbed from the diet plus stored iron sufficient enough to meet the requirements of pregnancy?
Avg iron stores: 254mg
iron requirement during pregnancy: 1040mg
No.
Women of reproductive age should take how much folic acid?
Describe coagulaion changes in pregnancy
women should take 4-8mg/day of folic acid.
Coagulation:
- increase of procoagulant fibrinogen and clotting factors II, VII, X, IX, XII, and XIII
- decrease in protein S level leads to inhibition of fibrinolysis.
- Hypercoagulable state*
Changes in pregnancy:
-musculoskeletal
Musculoskeletal:
- 25-35lb weight gain
- joint laxity of lumbar spine
- lordosis and forward flexion of neck
- stretching of abd muscles
- SI joints and pubic symphysis widen and have increased mobility
- pelvis tilted more anteriorly
- carpel tunnel
- sciatic nerve pain
Hypothalamic hormones in pregnancy
Anterior Pituitary Hormones during pregnancy
Intermediate lobe of the pituitary hormones during pregnancy
Posterior pituitary hormones in pregnancy
GnRH: increase (also from placenta)
CRH (corticotropin releasing hormone): (also released from placenta)
*placental CRH drives the maternal and fetal pituitary
Anterior Pituitary hormones:
- decline in gonadotropins d/t high estradiol and progesterone levels
- GH declines (replaced by placental derived GH)
- TSH increased
- Prolactin increased
- increased ACTH
Intermediate:
-MSH is increased leading to linea nigra and melasma
Posterior
- ADH: less sensitive to the action of ADH b/c of inactivating enzyme from placenta for ADH
- Oxytocin: increased, involved in labor and milk let down.
