Part 1_Pregnancy physiology Flashcards
Explain the hormonal regulation of ovarian activity
- GnRH is released in a pulse frequency
- It stimulates FSH and LH release
- FSH: stimulates folicular development
- LH: Stimulates oestrogen production by folicle
- Oestrogen (low) has an inhibitory effect on LH
- After 10 day: there is a switchover effect of oestrogen
- At high levels it has a stimulatory effect
- At day 14 there is an LH surge
- LH surge leads to ovulation
What are the functions of Oestrogen
- Exerts -ve feedback on anterior pituitary gland
- Stimulates endometrial growth
- Stimulates secretion by glands in endometrium
- Promotes female sex characteristics
- Affects CNS - female sex drive
- Stimulates bone and muscle growth
Explain the following phases:
- Menstrual
- Proliferative
- Secretory
Menstrual:
- Functional zone of endometrium disintegrates leading to menstruation
Proliferative:
- There is regeneration of functional zone of endometrium due to rising estrogen
Secretory:
- Glands enlarge and secretes fluids, mucus etc
What is the definition of sperm capacitation
Physiological changes undergone by the sperm in the female reproductive tract to enable fertilisation of oocyte
Explain what is meant by the following:
- Acrosomal activation
- Oocyte activation
- Cortical reaction
Acrosomal reaction:
- Enzymes released by sperm digest corona radiata and zona pellucida
Oocyte activation:
- Sperm entry causes calcium release into the oocyte resulting in Meiosis 2 resumption
Cortical reaction:
- Hardening of zona pellucida and deactivation of sperm receptors
What is amphimixis
Fusion of pronucleus. Cell becomes a zygote
What happens in each trimester of pregnancy
1st trimester: Pre-embryonic to early fetal development - rudiments of major systems appear
2nd trimester: Development of organ systems, body shape and proportions change
3rd trimester: Rapid growth of the foetus, most organs functional
Explain the 4 general processes in the first trimester
- Cleavage: Sequence of divisions immediately after fertilisation
- Implantation: Starts with blastocyst attachment to the endometrium
- Placentation: Starts with blood vessel formation around the periphery of the blastocyst the the development of the placenta
- Embryogenesis: Formation of a viable embryo
List the functions of the placenta
Endocrine function
Metabolic function
Gas and nutrient exchange function
List the endocrine functions of the placenta
- Human chorionic gonadotropin (hCG) - formation an d maintenance of corpus luteum gravitates
- Human placental lactose (hPL): Foetal growth and development, Increased maternal insulin production and tolerance, Breast development
- Corticotropin releasing hormone (CRH): Foetal lung maturation, Surfactant production
- Progesterone: Maintains pregnancy, Expression of uterine oxytocin receptors, Physiological adaptations in the mother
- Oestrogen: Uterine growth, development of breast tissue
How does progesterone maintain pregnancy
- Zygote transport
- Endometrial transformation
- Closure of cervix
- Immunosuppression
- Inhibition of contractions
What are the metabolic functions of the placenta
Glycogen synthesis
Cholesterol synthesis
Protein synthesis
What are the exchange functions of the placenta
- Gas exchange: O2, CO2
- Nutrient & Electrolyte transfer: Glucose, Amino acids, Peptides, Hormones, Vitamins
- Antibody transfer: IgG
- Other: Drugs, Infection
What are the cardiovascular adaptations during pregnancy
- Peripheral vascular resistance decreases
- Blood volume increases
- Blood pressure fluctuates
- Heart rate increases
Oedema especially lower limbs, Displaced apex beat, Systolic murmur
What are the Respiratory changes during pregnancy
Increased O2 consumption
Increased CO2 production
Pregnancy dyspnoea
Decreased maternal pCO2
