472 3- role of placenta

by term, the fetus is 5-6 times heavier than placenta

4 types of functio of placenta

metabolic, endocrine, immunologic, transport

placenta is also a radiator with 85% of feetal heat production transmitted to the mother via placenta

placenta function-metabolic

placenta has high metabolic rate

rates of oxygen consumption and glucose utilization by the placenta approximates those of the brain

placenta is also an active synthesizer of glycogen,FA, cholesterol, and enzymes

placenta function-endocrine

four main hormones- hcg, hpl, progesterone and estrogen

neuro-hormones

growth factors- IGF1 and IGF2. these growth factors regulate cell growth and differentiation. IGF 1 acts by enhacning aa and glucose uptake and precenting protein breakdown

placental growth hormone stimulates maternal gluconeogenesis and lipolysis in the second half od pregnancy to increase nutrient availability to fetus

placenta functions- immunologic

placenta functions to protext fetus from pathogens and prevention of rejection by mother

maternal antibodies of the IgG pass easily

most bacteria are to big to cross placenta but viruses may. cytomegalovirus (CMV) is benign to motheres but fetus can be severely affected with a weakened immune system

some bacteria like listeria can cross

placental barreir

maternal fetal circulations are separated by key layers of tissue reffered to as the placental membrane/barrier

MVM (microvillous membrane) faces maternal blood\

BM (basal membrane) faces fetal capilary

in the human placetna there are two cell layers between the maternal blood in the intervillous space and in the fetal circulation: the syncytiotrophoblast transporting epithelium and the fetal capillary endothelium

whats ST in placental barrier

syncytiotrophoblast is a multinucleate mass of cytoplasm that is not separated into cells, polarized, epithelial cell layer separating the maternal blood from fetal cappliary

• at term, the ST cell layer is only 10 microns, to allow for rapid transfer of small hydrophohbic molecules and gases

placental barrier at term

• functional unit of the huma placenta is the trophoblast villous tree (VT), containing fetal blood vessels and covered by the syncytiotrophoblast (ST)

• the syncytiotrophoblast is directly exposed to maternal blood entering the intervillous space (IVS) from the spiral arteries (SA)

• at term the st and fetal capillary endothelial cells are the only largely continuous cell layers betwen maternal and fetal blood

• The ST represents the primary barrier for movement of most solutes from the maternal to the fetal circulatoins

limiting steps for net flux from maternal to fetal circulations

transfer across the two polarized plasma membrane of the ST, the MVM facing toward maternal blood in the Intervillous space and the BM facing the fetal capillaries

compounds like water, o2, co2, FAs, fs vitamins transport across the placanta via

simple diffusion

glucose from mother to fetus, lactate from fetus to mother tranasports via

facilitated diffusion (transport via protein carriers from hgiehr to lower conc)

aas, potassium, ws vitamins,calsium, iron, iodone transported via

active transport (energy dependent carrier. move substanances against conc gradietn)

IgG, or IgE (low amounts), phospholipids, lipoproteins, and some antibodies cross via

endocytosis

the only immunoglobulin to significantly cross placenta

igG

treponema pallidum

a causative organism of syphilis which is of particular concern during pregnancy cuz of its risk of transplacental infection to the fetus

how does pplacenta function as a nutrient sensor

the placenta can adjust how much nutrient it transports to the fetus depending on how much nutrition and oxygen are available from the mother.

fir ex. With intrauterine growth restriction (IUGR) the placenta may register a lack of normal increase in placental blood flow or maternal malnutrition and as a consequence some key placental transporters are down-regulated in order to decrease fetal growth.

Similarly, hyperglycemia early in pregnancy (which is common even in the well-regulated IDDM patient) may convey a “good nutrition” signal to the placenta resulting in up-regulation of glucose and amino acid transporters.

mTOR signalling system

mTOR is a serine/threonine kinase and repressents an importnat nutrietn sensing oathway in mammals by controlling cell growth thru regulation of translation and transcription in response to nutrietn availability

• in particular, branched chian aas, (leucine) atp status tend to act more strongly on mTOR

mTOR stands for mechanistic target of rapamycin. It's a protein that helps cells decide when to grow and make more proteins.

• 🍗 Amino acids (especially leucine) signal that building materials are available.

• 🍚 Energy and insulin signal that fuel is available.

• ✅ When mTOR is activated, cells increase protein synthesis and growth.

• ⬇ When mTOR activity decreases, cells generally reduce growth and protein synthesis.

In pregnancy/nutrition: mTOR helps regulate placental growth and nutrient transport to the fetus.

amniotic fluid made up of

98% water, with some electrolytes, creatinine, urea, bile pigments, renin, glucose, hormones, fetal cells

why amniotic fluid important? what kind of antibacterial factors does it have

• provides spcae for symmetric fetal growth, maintains constant temp and pressure, protects and cushions fetus, and allows free movement of fetus.

• has antibacterial factors such as transferrin (binds iron needed by some bacteria and fungi for growth), FAs. immunoglobulins and lysozyme help to protect fetus from infection

fetal swallowing and fetal membrane transfer back to maternal circulation constitue the major route of clearance. fetal swallowing is crucial for

development of fetal digestive system (baby can swallow its urine

placentophagy whats true? wjats not

post partum women consume placents cuz prevention of PPD, pain relief, uterine contraction, resumption of normal estrogen cyclke and milk production

True: placenta contains hgih levels of prostaglandins which could stimulate involutin of uterus

false: benefits.

given documented high levles of some compounds/ substances and unproven benefits placenta consumption discouraged