Physiology of Pregnancy & lactation Flashcards
Fertilisation
- describe what happens on day 1
- Day 3-5
- Days 5-8
- fertilisation occurs at the ampulla of the fallopian tube
- transport of blastocyst into the uterus
-Blastocyst attaches to the lining of the uterus
the inner cells develop into an embryo
outer cells burrow into the uterine wall and become placenta
Describe early human development in vitro days 1-6
early day 1- zygote late day 1- 2 cell stage early day 2- 4 cell stage Late day 3- 16 cell stage Day 4- Morula Day 5- blastocyst Day 6- hatching
Blastocyst implantation
-what happens?
- free floating blastocyst adheres to the endometrial lining, cords of trophoblastic cells begin to penetrate the endometrium
- Advancing cords of trophoblastic cells tunnel deeper into endometrium, carving out a hole for the blastocyst
boundaries between cells in the advancing trophoblastic tissue disintegrate - When the implantation is finished the blastocyst is completely buried in the endometrium
blastocyst becomes buried in endometrium
Placenta
- derived from what tissue?
- main type of cells, what they differentiate into and their function?
- how are placental villi formed?
- how does exchange of material occur?
- when does the placenta become functional?
- name the main hormones involved here?
-derived from both trophoblast & decidual tissue
-Trophoblast cells (chorion) differentiate to multinucleate cells (syncytiotrophoblasts)
these invade the decidua nd break down capillaries to form cavities filled with maternal blood
-Developing embryo sends capillaries into the syncytiotrophoblast projections
-each villus contains foetal capillaries separated from maternal blood by a thin layer of tissue
there is a two way exchange of respiratory gases, nutrients, metabolites etc, largely down diffusion gradient
- week 5
- HCG signals the corpus lute to continue secreting progesterone (stimulates decimal cells to concentrate glycogen, proteins and lipids)
name the space that exists between mother’s blood and embryo’s blood
the embryos blood in the villi is separated from the mothers blood in the intervillous space by a thin membrane
O2 transport
-how does the placenta carry out a respiratory function? i.e. how is gas exchanged?
- exchange between the maternal blood and the umbilical blood
- oxygen diffuses from the maternal into the foetal circulation system as the maternal partial pressure of O2 is greater than that of the foetus
- carbon dioxide follows a reversed gradient
- fetal, oxygenated blood returns to the foetus via the umbilical vein while maternal O2 poor blood flows back into the uterine artery
name the 3 factors that facilitate the transport of Oxygen around the foetus
Fetal Hb
has increased ability to carry O2
Higher level of Hb
higher concentrations in the fetal blood
Bohr effect
foetal Hb can carry more O2 in a low pCO2 than in a high pCO2
how do the following substances move across the placenta?
- water
- elecrolytes
- Glucose
- fatty acids
- waste products
- give examples of drugs that can cross
- diffuses into placenta along osmotic gradient
- follow water (iron and Ca only go from mother to child)
- simplified transport
- free diffusion
- based on Conc gradient
- known as teratogenic drugs
e. g.Thalidomide, Carbamazepine, Coumarins, Tetracycline, Alcohol, nicotine, heroin, cocaine, caffeine
describe the pattern of change and their action in the following hormones during pregnancy:
- HCG
- HC somatomammotropin
- Progesterone
- Estrogens
- what does Estriol level indicate
-this increases until 10 wks of gestation then rapidly decreases until around 15 wks after which point it levels off
it prevents involution of the corpus luteum and effects the testes of the male fetus
-increases slowly from wk 5
GH like effects: protein tissue formation & decreases insulin sensitivity in the mother
also involved in breast development
-increases from around week 6, triggers development of decidual cells, decreases uterine contractility and prepares for lactation
-increase from around wk 5
cause enlargement of the uterus and breast development, relaxation of ligaments
-vitality of the foetus
name the hormones produced by the placenta and the detrimental effect they ca have on the mother
CRH > ACTH > increased aldosterone & cortisol > hypertension & gestational DM
HCG & HC thyrotropin > hyperthyroidism
Inc Ca demands > Hyperparathyroidism
Cardiovascular changes
- describe the changes in CO and why they occur
- Changes in HR?
- Changes in BP?
-increase in CO to 30-50% above normal till 24 wks
Due to demands of uteroplacental circulation/inc metabolism/skin thermoregulation/renal circulation
Decrease in CO in last 8 wks as uterus compresses vena cava
- increases up to 90/min to increase CO
- drops during 2nd trimester (uteroplacental circulation expands & peripheral resistance decreases)
Hematologic changes
- plasma volume?
- RBC?
- Hb?
- iron requirement?
- increases with CO
- erythropoesis increases by 25%
- Hb is decreased by dilution (inc blood viscosity)
- increases significantly so iron supplements needed
Respiratory Changes
- Why do these occur?
- what 3 factors contribute to the lowered CO2
-progesterone increases and uterus enlarges
-Progesterone signals brain to lower CO2 levels
O2 consumption increases to meet metabolic need
Growing uterus
Urinary system changes
- what happens to GFR and renal plasma flow?
- what affects renal function in pregnancy?
-increases from 30-50%, inc urine
-positional changes
upright (reduces)
supine (^)
lateral (^^)
what is pre-eclampsia?
- presentation features?
- risk factors?
- what is Eclampsia?
- Eclampsia causes what?
- eclampsia treatment?
pregnancy induced hypertension + proteinuria
-increasing BP since week 20
oedema formation in hands & feet
reduced GFR & renal blood flow
-pre existing hypertension diabetes autoimmune disease renal disease fam hx pre-eclampsia obesity multiple gestations PREV PRE-ECLAMPSIA
-extreme pre-eclampsia
-vascular spasms
extreme hypertension
chronic seizure
coma
-vasodilators & c-section
