Physiological Changes During Pregnancy Flashcards
Explain the sperm journey to the ovum
- 300 to 400 million sperms are introduced to the vagina,
- About 2 million reach the cervix, only motile sperms can pass through this barrier,
- Uterine contractions due to high estrogen, oxytocin (orgasm) and prostaglandins,
- Sperms undergo capacitation,
- About 200 sperms reach the secondary oocyte in the uterine tube
What are the two things that happen to the sperms during capacitation?
Cell membrane becomes weaker due to cholesterol removal, less seminal fluid,
Increase of cell membrane permeability to Ca2+
What facilitates the acrosome reaction?
The increased cell membrane permeability to Ca2+
What helps the transport of the cumulus-oocyte complex (pre-zygote)?
- Progesterone: stimulates fluid secretion from oviduct epithelium,
- Estrogen: stimulates cilia to beat towards the uterine cavity, contraction of the oviduct.
Which part of the fallopian tube helps capture the cumulus-oocyte complex?
The fimbriated end
What triggers the acrosome reaction?
Sperm binding to the ZP3 receptors
What is the zone pellucida made of?
4 glycoproteins: ZP1, ZP2, ZP3, ZP4.
Which glycoproteins does the sperm cell have receptors for?
ZP2 and ZP3
Explain the process of fertilisation?
PH-20 breaks down the hyaluronic acid,
Sperm has receptors to ZP3, so it binds to ZP3,
Acrosome reaction occurs,
Loss of ZP3 receptors, Secondary binding to ZP2.
What happens during the acrosome reaction?
Sperm head continents are released, PLCζ converts PIP2 to DAG & IP3.
What is the function of IP3?
IP3 sends a message to increase intracellular calcium, which causes exocytosis of small granules (cortical) and meiosis II.
What is the function of cortical granules?
They cause cortical reaction and remove/digest ZP2 so no polyspermy.
What is the rapid mitotic division of the zygote called?
Cleavage
Where are the inner mass cells in relation to the endometrium during implantation?
They are facing the endometrium
What is the endometrium known as after implantation?
Decidua
What passes using passive diffusion through the placenta?
Water, electrolytes, free fatty acids, steroids, fat soluble vitamins, alcohol, oxygen and CO2
What passes using facilitated diffusion through the placenta?
Glucose
What passes using active transport through the placenta?
Amino acids, water soluble vitamins, calcium, iron, iodine
What passes using endocytosis through the placenta?
Phospholipids, globulins, lipoproteins
Which haemoglobin has higher affinity?
The fetal because there is a high RBC count in the fetus.
What is the Bohr effect?
CO2 diffuses from fetal blood to maternal because there is low PCO2 in fetal blood.
Why does BMR increase during pregnancy?
Due to thyroxine, cortisol and androgens increase
What is the primary energy source for the mother during pregnancy?
Fatty acids, achieves that by adapting a catabolic state, so maternal insulin resistance increases.
What happens to the mean atrial pressure during pregnancy?
It decreases towards mid-pregnancy and increases to equilibrium towards the end.
What affects Mean Arterial
Pressure?
There is an increase in cardiac output but a decrease in total peripheral resistance
What causes the decrease in total peripheral resistance?
Progesterone relaxes smooth muscles.
What causes increase in cardiac output?
Increase in heart rate and stroke volume
What happens to the minute ventilation during pregnancy? Why?
Increases 40 to 50%
Increase in respiratory rate and tidal volume due to progesterone
What happens to GFR during pregnancy? Why?
Increases 40 to 50% due to renal vasodilation (relaxin and nitric oxide)
What happens to Na+, Cl- and H2O reabsorption? Why?
50% increase due to aldosterone and oestrogen
What happens to urine formation during pregnancy?
Increase due to H2O intake increase
What are some skin changes pregnant women endure?
Chloasma, caused by an increase in melanin-stimulating hormone,
Linda nigra, due to increase in melanin stimulating hormone,
Striae gravidarum: stretch marks due to damage of elastic fibers in the dermis,
Acne,
Hair growth, cortisol and androgens
