6: Pregnancy Flashcards
What is implantation? (2 things)
- Interstitial (within internal tissues)
- Uterine epithelium breached → conceptus implants within stroma
What happens to the placental membrane during pregnancy?
Becomes progressively thinner as the needs of the foetus increase
What is the property of placenta?
It is Haemomonochorial: only 1 layer of trophoblast separates maternal blood from foetal capillary wall
What are the aims of implantation (3 things)
- Establish basic unit of exchange
- Anchor placenta
- Establish maternal blood flow within placenta
How does implantation establish a basic unit of exchange?
- Primary Villi = Fingerlike projections of trophoblast
- Secondary Villi = Invasion of mesenchyme into core
- Tertiary Villi = Invasion of mesenchyme core by foetal vessels
How is the placenta anchored?
Through establishment of outermost cytotrophoblast shell
What happens regardless of fertilisation?
Endometrium preparation for implantation
What is the endometrium preparation for implantation signalled by?
Progesterone from ovary
What does the endometrium contain? (2 things)
- Pre-decidual cells
- Elaboration of Spiral artery blood supply
What is decidualisation?
The balancing force acting against the invasive force of the trophoblast at implantation
What do decidual cells do?
Prevent excessive invasion of Trophoblast at implantation
Decidual cells are the British soldiers stopping the Spanish Armada invasion
Why are ectopic pregnancies at the fallopian tube dangerous?
No decidual cells at fallopian tube
So implantation is so invasive → haemorrhage of fallopian tube
What are Spiral Arteries?
Arteries that temporarily supply blood to the endometrium in the luteal phase of menstrual cycle
How do Spiral Arteries meet the foetal demands?
Spiral arteries create low resistance vascular beds → maintains high flow
What are some implantation defects? (3 things)
- Ectopic Pregnancy
- Placenta Praevia
- Incomplete Invasion
Where do ectopic pregnancies usually occur?
Fallopian tube
What is Placenta Praevia?
Implantation in the lower uterine segment
What can Placenta Praevia cause?
Haemorrages
What does Placenta Praevia require?
C-section delivery
What can Incomplete Invasion cause? (2 things)
- Placental Insufficiency
- Pre-eclampsia
What is placental insufficiency and what does it cause?
Insufficient blood flow to the placenta → affects foetus CNS development
What are the risk factors of placental insufficiency? (3 things)
- Smoking
- Diabetes
- Hypertension
What is pre-eclampsia?
High blood pressure @ pregnancy / labour
What is the difference between the placenta in the 1st trimester and at term?
1st Trimester
Thick (4 Layers)
- Capillary Endothelium
- Undifferentiated Mesoderm
- Cytotrophoblast
- Synciotrophoblast
Term
Thin (2 Layers)
- Capillary Endothelium
- Synciotrophoblast
Larger surface area for exchange
What are the layers of the placenta in the 1st trimester?
- Capillary Endothelium
- Undifferentiated Mesoderm
- Cytotrophoblast
- Syncytiotrophoblast
Need CUCS to get pregnant at da beginningg
What are the layers of the placenta at term?
- Capillary Endothelium
- Syncytiotrophoblast
Don’t need CUCS now it’s just its own CS
What does the umbilical cord link?
Placental blood vessels → Developing foetus
What does the umbilial cord contain?
2 Umbilical Arteries
1 Umbilical Vein
What do the umbilical arteries carry?
Deoxygenated blood from foetus → placenta
Opposite to what arteries carry in adults innit
What does the umbilical vein carry?
Oxygenated blood from placenta → foetus
Opposite to what arteries carry in adults innit
What are the functions of the placenta? (3 things)
- Metabolic
- Endocrine
- Transport
What does the placenta synthesise? (Metabolic Function) (3 things)
- Glycogen
- Cholesterol
- Fatty Acids
What is the purpose of the glycogen synthesised by the placenta?
Storage of maternal glucose to be transferred to foetus
What is the purpose of the cholesterol synthesised by the placenta?
Cholesterol is a precursor of Progesterone and Oestrogen
What is the Fatty Acids synthesised in the placenta made from?
The breakdown products of fats in the maternal circulation
What are the types of hormone that the placenta produces? (Endocrine function) (2 types)
- Proteins
- Steroids
What are the protein hormones produced in the placenta? (4 things)
- hCG
- hCS
- hCT
- hCC
GSTC
Where is hCG produced?
Syncytiotrophoblast in placenta
What does hCG support?
The secretory function of the Corpus Luteum
What is hCG used as and why?
Pregnancy tests because its secreted in maternal urine
What do hCS and hPL do?
Increase glucose availability to the foetus by:
Switching mothers from glucose to F.A metabolism
They are CSI and PoLice agents that infiltrate and change the mums metabolism
What are the 3 transport methods across the placenta? (Transport function)
- Simple diffusion
- Facilitaed diffusion
- Active transport
What things use Simple Diffusion across the placenta? (4 things)
- Water
- Electrolytes
- Urea + Uric Acid
- Gases
What uses Facilitated Diffusion across the placenta?
Glucose
What things use Active Transport across the placenta? (3 things)
- A.A
- Iron
- Vitamins
They have specific transporters in the syncytiotrophoblast
How is passive immunity acheived by the foetus?
By Receptor Mediated Endocytosis (RME)
- Receptors are specific for igG (antibodies)
- igG transported from maternal → foetal blood
What are the physiological changes of pregnancy? (6 things)
- Respiratory System
- Immune System
- GI System
- CVS
- Urinary System
- Metabolic changes
RIGCUM
What are the CVS changes of pregnancy?
(3 things: 5 increases, 2 decreases and 1 other change)
Increased:
- Plasma Volume
- CO
- Stroke Volume
- Heart Rate
- Coagulation factors and fibrinogen
Decreased
- Serum album concentration
- Blood pressure in first 2 trimesters
Compression of IVC by uterus
What are the Urinary System changes of pregnancy? (2 things)
Increased:
- GFR
- Increased Renal Plasma Flow
What are the Respiratory System changes of pregnancy?
(4 things: 2 increases, 2 decreases)
Increased:
- Tidal Volume
- pO2
Decreased
- pCO2
- Function Residual Capacity (because diaphragm displaced)
What are the GI System changes of pregnancy? (4 things)
- Nausea and vomiting
- Delayed emptying
- GI reflux
- Appendix moves to RUQ
What are the Metabolic changes of pregnancy? (1 thing)
Increased insulin resistance → body switches to gluconeogenesis and alternative fuels
What are the signs and symptoms of pre-eclampsia? (2 things)
- Increased blood pressure
- Prroteinuria
What is Gestational diabetes?
Insulin resistance in pregnancy
What can gestational diabetes cause? (3 things)
- Macrosomic foetus (big baby)
- Still birth
- Congenital defects
What causes anaemia in pregnancy? (2 things)
- Increase in plasma volume
- Iron deficiency
