Obs notes Flashcards
(688 cards)
What do primordial follicles contain?
The primary oocyte
What are oocytes?
Germ cells that undergo meiosis to become the mature ovuum ready for fertilisation
What produces b-hCG?
synciotrophoblast
Around what day does implantation occur?
8-10
What week does the fetal heart form and begin to beat?
Around 6 weeks
What week have all major organs began to develop?
8 weeks
What later of the fertilised egg implants into the uterus (and which part?)
The synciotrophoblast implants into the endometrium via finger like projections (chorionic villi)
What are the 5 functions of the placenta?
Respiration, nutrition, excretion, endocrine, immunity
What is the placenta’s role in respiration?
Source of oxygen for the fetus. Fetal haemoglobin has a high affinity for O2, so draws O2 away from the mother across the placental membrane
When do hCG levels plateau?
Around 10 weeks gestation
What is the job of hCG?
Maintains the corpus luteum until the placenta can take over the production of oestrogen and progesterone
What hormones does the placenta produce?
Oestrogen and progesterone
What is the function of the oestrogen being produced by the placenta?
- softens tissues and makes them more flexible
- allows the muscles and ligaments of the uterus and pelvis to expand
- helps cervix become soft and ready for birth
- enlarges and prepares breasts
What is the primary role of progesterone in pregnancy?
To maintain the pregnancy
By what week does the placenta take over progesterone production
Around 5 weeks
How does progesterone maintain the pregnancy?
- relaxation of the uterine muscles (prevents contractions and labour)
- maintains endometrium
What effects does the rise in progesterone have on other parts of the body than the uterus?
- relaxes the lower oesophageal sphincter and causes heartburn
- relaxes the bowel (constipation)
- blood vessels (hypotension, headaches, skin flushing)
- raises body temp by ~1 degree celsius
How does gas exchange occur in terms of the umbilical vessels?
x2 umbilical arteries leave the fetus (deoxygenated), and x1 umbilical vein comes back in (oxygenated). Exchange occurs across the placenta, specifically lacunae
What cardiovascular changes occur in pregnancy?
- increased blood volume
- increased plasma volume
- increased cardiac output (increased stroke volume + heart rate)
- decreased peripheral vascular resistance
- decreased blood pressure in early/middle pregnancy
- varicose veins
- peripheral vasodilation
How does cardiac output, HR and stroke volume change in pregnancy?
Increases
Why might there be ankle oedema and varicose veins in pregnancy?
Enlarged uterus may interfere with venous return
How do tidal volume and respiratory rate change in pregnancy?
Increase
What hormone causes increased tidal volume?
Progesterone
Why might their be some dyspnoea in pregnancy?
Pulmonary ventilation increased by 40%, but oxygen requirements only rise by 20%. Therefore, over breathing can lead to a fall in pCO2 and give a sense of dyspnoea. Can be worsened by elevated diaphragm