Physiology Pregnancy Flashcards
During what days of fertilisation does the blastocyst move to uterus?
day 3-5
During what days of fertilisation does the blastocyst attach to the lining of the uterus?
Days 5-8
What do the inner and outer cells of the blastocyst become?
Inner cells become embryo and outer cells burrow into uterine wall to become placenta
How does the blastocyst implant into the uterine wall?
Cords of trophoblastic cells begin to penetrate the endometrium, advancing cords then tunnel deeper into endometrium to carve out hole for blastocyst & boundaries between trophoblastic cells disintegrate and decidua forms
What tissues is the placenta derived from?
Trophoblast and decidual tissue
How does the corpus luteum help with implantation?
Makes more progesterone than oestrogen to make low oestrogen:progesterone ratio which is necessary for implantation
At what day does trophoblast start producing HCG?
Day 8
Around what week (and what trimester) does HCG peak?
Week 9 so in trimester 1
When does corpus luteum shrivel up and stop producing hormones?
Week 13 - end of first trimester
What type of cells of the placenta take over hormone production after corpus luteum, and what do they produce?
Syncytiotrophoblast cells and they produce progesterone, estriol, little bit HCG, and Human Placental Lactogen (hPL)
How does the body compensate for uterus pressing on diaphragm during pregnancy?
Progesterone relaxes ligaments of the thorax to increase transverse and anterioposterior diameter of ribcage
hPL is produced from about week 5. What is the function of hPL AKA human chorionic somatomammotropin? (3)
To counteract the effects of maternal insulin to leave enough glucose in blood for baby,
has growth hormone-like effects so promotes protein tissue formation,
is involved in breast development
At what week gestation does uterus reach umbilicus?
20 weeks
At what week gestation does uterus reach xiphoid process?
36 weeks
What is the fundal height and what does it measure?
Distance from pubic symphsis to top of uterus, measures size of baby so checks size with gestational age
Why does BP slightly fall during pregnancy?
Progesterone causes vessels to dilate
Pregnancy is a high volume state. By how much does blood volume increase during pregnancy and what component increases most?
between 30-50%, plasma increases a lot (50%) while rbc’s increase less (25%) so physiological anaemia of pregnancy
Why does heart rate increase by about 20 BPM in pregnancy?
To pump the high volume of blood around
Why can pregnancy cause varicose veins?
Uterus presses on pelvic veins so blood can back up, causing varicose veins and swelling in lower legs and ankles
How can pregnancy cause hypotension when lying down?
Uterus can press on inferior vena cava and so less blood can get to RA
Why does eGFR and urinary output increase in pregnancy? By how much does it increase and when does this peak?
Due to increased CO and increased bloodflow to kidneys and pressure on bladder from uterus. By 30-50% and peaks 2nd trimester
What is physiologic hydronephrosis and physiologic hydroureter?
Physiological response of kidneys and ureters to increased volume, calyces, renal pelvises and ureteres increase in size to compensate
What is pica?
Craving for non-food items e.g. ice
What causes GI symptoms (gastric reflux and heart burn, constipation and bloating) in pregnancy?
Hormonal changes cause relaxation of lower oesophageal sphincter and cause smooth muscle relaxation of intestines and decreased peristalsis
Why are pregnant women more prone to upper UTIs?
Due to progesterone causing hypomotility of ureters and increased capacity to store urine leading to renal stasis
Increased tidal and minute respiratory volumes in pregnancy lead to decreased CO2 and a mild respiratory alkalosis. What does this mild alkalosis enhance?
Enhances gas exchange with placenta
What causes nasal stuffiness, sinus congestion and nosebleeds during pregnancy?
Oestrogen causes increased vascularisation and capillary engorgement of upper resp tract
What causes the waddling gait of pregnancy?
Progesterone and relaxin from the placenta loosen the SI joint and symphysis pubis
What causes breasts to grow (ductile system and development of lobule-alveolar system) in pregnancy and feelings of breast tingling, fullness and tenderness?
Oestrogen - ductile system, progesterone - development of lobule-alveolar system. Increased blood flow can cause those symptoms.
What does each placental villus contain and what is its function?
Each villus contains fetal capillaries separated from maternal blood by a thin layer of tissue. The function is 2 way exchange of gases, nutrients and metabolites down diffusion gradient
By what week of pregnancy is placenta and fetal heart functional?
Week 5