Flashcards in 3) Placental Metabolism Deck (145)
When does the fastest growth of the placenta occur? Why?
- During the first half of pregnancy
- To prepare for the fetal growth spurt during the second half of pregnancy
What is the placenta?
The interface between the microcirculatory systems of the mother and fetus
What are functions of the placenta?
- Exchange of nutrients, respiratory gases, and metabolic waste
- Protection of the fetus from xenobiotics
- Acting as a source of hormones
When is there mixing of the maternal and fetal blood?
- There is NEVER any direct mixing of the maternal and fetal blood
- The placenta is composed of a maternal and fetal portion
Where does the majority of amniotic fluid come from?
The maternal blood via diffusion from the intervillus spaces of the placenta
What are functions of amniotic fluid?
- Acts as a shock absorber
- Prevents desiccation of the fetus
- Provides room for fetal movements
- Assists in body temperature regulation
The ________ plate forms the fetal surface of the placenta.
______________ are cells from the placenta that connect the mother and fetus.
What components form the large area for exchange of fetal and maternal material?
- Cytotrophoblastic shell
- Anchoring villi
Where does the exchange between maternal and fetal material occur?
Within the intervillus spaces, as maternal blood flows around the villi
What is the major functioning unit of the placenta?
What placental defects do IUGR infants display?
They have microscopically less branching of the villi
What is the function of the villi within the placenta?
Enhances the surface area, allowing for greater exchange of gases and nutrients
The placenta uses 50% of _______ and 65% of _______ from the maternal blood supply.
What substances does the placenta synthesize for fetal use?
What substances cannot cross the placental membrane?
Compounds possessing a large molecular weight
What substances are transported across the placental membrane via passive diffusion?
- Oxygen and carbon dioxide
- Fatty acids
- Fat-soluble vitamins
How does fetal hemoglobin differ from regular hemoglobin?
Fetal hemoglobin has a greater binding capacity for oxygen
How are fatty acids transported through the placental membrane?
- Passive diffusion
- Carrier-mediated transport for long-chain FAs (enhancement of PUFA transport)
- The fetus depends on a supply of EFAs
Of the substances that are transported via passive diffusion, there is a poor transfer of which one?
How are sugars transported through the placental membrane?
Carrier-mediated facilitated diffusion
What is the importance of glucose transporters within the placenta?
- Glycation is a mechanism of teratogenesis
- Glucose transporters are used to protect the fetus from high glucose levels
If a mother experiences hyperglycemia, is a fetus exposed to a hyperglycemic environment as well? Why or why not?
- No, the fetus experiences a lower glucose level
- Because of the use of glucose transporters
What substances require energy-dependent active transporters to cross the placental membrane?
- Amino acids
- Certain cations
- Water-soluble vitamins
What do iron and folate require to cross the placental membrane?
What do water and solutes use to cross the placental membrane?
The fetal size is proportional to the _______ size.
How may maternal malnutrition, such as iron deficiency, affect placental size and fetal growth retardation?
- Reduced blood volume expansion
- Decreases cardiac output and placental blood flow
- Decrease in placental size, reduced nutrient transfer, and subsequent fetal growth retardation
What conditions may decrease uterine blood flow and affect placental transport?
- Renal disease
- Placental infarction