Physiology of Pregnancy Flashcards
Where does fusion of sperm and oocyte occur?
ampulla of fallopian tube
Summarise the key steps in fertilization
- Sex
- Sperm acrosomal release
Sperm and oocyte adhesion and entry - Membrane fusion (cortical reaction)
- Meiosis 2
- Syngamy and mitosis
Describe the key events in embryonic development for the following timelines:
@ day 6-7
@ Week 3
@ Week 3-8
@ Week 4
@ Week 23
Day 6/7 - Implantation of blastocyte into endometrium
Week 3 - Gastrulation - Formation of trilaminar disc ( Endoderm, Mesoderm, Ectoderm
Week 3-8 - Beginning of development of organ systems
Week 4 - Neurulation ( formation of neural tube from extoderm)
Week 23 - Threshold of viability
What are the functions of the placenta
1 - EXCHANGE
Gas Exchange (HbF readily accepts O2 gradient)
Nutrition Exchange (glucose, Fatty acids, amino acids)
2-ENDOCRINE
hCG human chorionic gondotrophin
hPL human placental lactogen
Progesterone
Oestrogen
What are the functions of the placenta?
Resp - Gas exchange
Nutrition - Glucose, Fatty acids, AA
Renal - Excretes and purify blood
Immunity - IgG can cross placenta
Hormonal - hCG, Oest, Prog, hPL
What are the functions of placental hCG?
Produced by trophoblast cells
Maintains corpus luteum to allow for sufficient progesterone production until the placenta takes over.
What is corpus luteum and its function
Formation
The corpus luteum is a temporary organ that forms after ovulation when the ovarian follicle ruptures and fills with blood.
The corpus luteum produces hormones that prepare the uterus for pregnancy, including progesterone, inhibin A, and estradiol.
what are the functions of placental hPL
hPL human placental lactogen
Increase maternal free fatty acid and insulin levels as well as inducing maternal insulin resistance
What are the functions of placental oestrogen
Stimulates myometrial growth (myometrium is the muscular middle layer of the uterus that’s responsible for uterine contractions)
oxytocin receptor synthesis
and pregnancy related breast changes
What are the functions of placental progesterone
Inhibits uterine contractility
thickens endometrium (tissue lining utereus / womb)
What Maternal changes occur during pregnancy with regards to CVS
TPR Reduction (Total peripheral resistance)
Increased cardiac output
What Maternal changes occur during pregnancy with regards to heamtology
Clotting factors increase
WBC Increase
RBC Mass increase (due to hPL & erythropoietin)
Decrease in platelets
= Physiological anaemia due to increased plasma volume
What Maternal changes occur during pregnancy with regards to Renal
Increased eGFR = Lower Serum urea and creatinine
Increased sodium resporbtion
What Maternal changes occur during pregnancy with regards to Resp
Medulla sensitised to PaCO2 = Increased minute ventilation
this is to help a steeper foetal maternal concentration
What Maternal changes occur during pregnancy with regards to Immunology
General maternal immunosupression
+ Trophoblast(only one in contact with maternal circulation directly) is immunologically innert
What Maternal changes occur during pregnancy with regards to gyne
Uterus hypertrophy (40-100g ->800-1kg)
Uterine arteries hypertrophy and dilation = increases uterine blood flow)
cervix and vagina become more vascularised, more water and glycosaminoglycans and lose collagen = MORE STRECTHY
Cervical mucus thicken - operculum (mucus plug)
What Maternal changes occur during pregnancy with regards to breasts
Ductal proliferation (in response to high oestrogen levels)
Alveoli growth (Due to progesterone and prolactin)
After pregancy
Prolactin induces milk production. This was inhibited during pregnancy by oestrogen and progesterone
What Maternal changes occur during pregnancy with regards to GID
Progesterone is a smooth muscle relaxant
thus
Gastroemptying is slowed = gastric reflux and constipation
What Maternal changes occur during pregnancy with regards to Skin
Increased pigmentation of face / areola / abdo (linea nigra)
strech marks
What Maternal changes occur during pregnancy with regards to Endocrine
Oestorgen and progesterone rise during pregnancy
Corticotropin releasing hormone also rises third terms-
Summarise the maternal changes in pregnancy
CV - Low BP
Haem- Anemia // Hypercoagulability
GI - Dysmotility // GORD // Constipation
Immunity- Reduced immune response
Endo - Poor Glycemic control: Increased Hypos // DM
GU - Increased Renal Excretion // uti %
Hormones - Increased Oest/prog/prl/BhCG/ALP/prl
