Physiology of Pregnancy and the Fetus Flashcards
What are the main functions of the placenta? (4)
- supply nutrients to fetus
- supply O2, exchange CO2
- regulate fluid volume, dispose of waste
- is an endocrine gland synthesizing steroids and proteins
What are 3 major features of the placental interface?
- chorionic villi
- intervillous space
- decidua basalis
What does maternal blood flow to placenta look like? Source, movement, and exit.
- Arterial blood flow comes from spiral arteries
- goes into intervillous space which slows its blood flow and gives enough time for nutrient exchange
- drains through venous orifices and enters placental veins
What does fetal blood flow look like? Flow, oxygenated vs deoxygenated, etc.
Umbilical arteries carrying deoxygenated blood branch and penetrate chorionic plate, form chorionic villi network
- O2/nutrients return to fetus through umbilical vein
How does oxygen and CO2 get exchanged between mother and fetus?
- Fetal hemoglobin has higher affinity for oxygen than maternal hemoglobin, accepts it more readily
- fetal hemoglobin has lower affinity for CO2 than maternal hemoglobin, gives it up more readily, also there’s a concentration gradient
What are the methods of solute transfer? (4) What substances use these methods?
- passive exchange = non-protein nitrogenous waste, lipid soluble hormones
- facilitated diffusion = glucose
- primary and secondary active transport = amino acids, vitamins, minerals
- receptor-mediated endocytosis = large molecules (LDL, hormones, Abs)
What are the endocrine functions of the placenta? (2)
- manufacturing hormones, amines, polypeptides, proteins
- paracrine regulation of hormones
What are the general endocrine functions of placental hormones in pregnancy? (5)
- maintain pregnant state of the uterus
- stimulating lobuloalveolar growth and function of maternal breasts
- adapt aspects of maternal metabolism and physiology to support a growing fetus
- regulate aspects of fetal development
- regulate timing and progression of parturition
What do the levels of hCG do during pregnancy? What is the function of hCG? What symptoms might it be responsible for? What does it stimulate in the fetus?
- Levels double daily up to 10 weeks, peaks at ~100mIU/ml
- it stimulates LH receptors in corpus luteum, rescuing the CL
- morning sickness!!
- stimulates fetal Leydig cells to produce testosterone
What is human placental lactogen also known as?
human chorionic somatomammotropin
What is the function of HPL? (3)
- it coordinates fuel economy of fetoplacental unit
- has antagonistic effect to maternal insulin, mebbe causing gestational diabetes
- promotes development of mammary glands during pregnancy
What is the function of progesterone during pregnancy? (4)
- required for implantation and early maintenance of pregnancy
- reduces uterine motility
- inhibits propagation of uterine contractions
- inhibits mammary growth and differentiation
What is the function of estrogen during pregnancy? (3)
- increases uteroplacental blood flow
- induces prostaglandins and oxytocin receptors necessary for parturition
- increases growth and development of mammary glands
What can the placenta not produce? Why?
- cholesterol
- b/c it lacks 17 alpha hydroxylase and 17, 20 desmolase needed for estrone and estradiol
- lacks 16, alpha-hydroxylase for estriol
What is the pathophysiology of preeclampsia? (when it occurs, characteristics, symptoms)
- Occurs after 20 weeks of pregnancy
- characterized by high blood pressure, signs of damage to other organs (often kidneys)
- can have protein in urine and generalized edema
