Physiology of pregnancy Flashcards
Describe the duration of human pregnancy?
280 days (40 weeks) from last menstrual period
266 days (38 weeks) from fertilisation
How is foetal age estimated?
Length and US measurements of foetus
Describe the physical signs of pregnancy?
Cessation of mestruation
Morning sickness
Increased frequency of urination
Increased breast size
Fatigue
Darkening of areolae
How is pregnancy determined biochemically?
Human chorionic gonadotropin in blood and urine
Where does hCG arise from?
Produced by trophoblast
Why are physiological adaptations required in pregnancy?
Maintain uteroplacental perfusion
Maintain foetal demands
What are the functions of the umbilical veins and arteries?
Umbilical vein carries well-oxygenated blood to the embryo
Umbilical arteries return embryoinic blood to placenta
How does material from the mother reach the embryo/foetus?
Placenta
Some material via diffusion, other materials must be transported
Which organs does the placenta substitute for in utero?
Lungs
Kidneys
GIT
Describe the endocrine function of the placenta?
hCG: rescues corpus luteum
Human placental lactogen: breast development, maternal metabolic effects
Oestrogen and progesterone: pregnancy maintenance and breast development
Describe the difference between monozygotic and dizygotic multiple pregnancies?
Monozygotic: single fertilised ovum, genetically identical
Dizygotic: 2 oocytes ovulated and fertilised by 2 separate sperm, not genetically identical
Describe the changes to the cervix prior to parturition?
Softening
Describe the changes that occur to the reproductive system during labor?
Rhythmic uterine contractions
Cervical dilation
How are the uterine contractions maintained during labor?
Positive feedback
What occurs during parturition after the baby is delivered?
Placental release and expulsion
Descirbe the regulators of parturition?
Trigger for labor unknown
Stretch of cervix stimulus
Oxytocin
Positive feedback
Describe the mammary gland development in puberty, pregnancy and late pregnancy?
Puberty: oestrogen stimulates growth of ducts and fat deposition
Pregnancy: oestrogen, GH and cortisol stimulate further gland development
Late pregnancy: progesterone stimulates conversion of ducts to secretory epithelium
Describe lactation before birth?
Prolactin-inhibiting hormone blocks prolactin
High sex steroid levels supres milk production
Describe lactation after birth?
High prolactin and low oestrogen > lactation
Describe the effect of suckling?
Inhibits prolactin inhibiting hormone > prolactin > milk production
Oxytocin > milk ejection
Inhbits GnRH and ovarian cycle
Why does suckling inhibit GnRH and the ovarian cycle?
Want all of the energy going into breastfeeding, not carrying another child
Describe the hormonal control of milk secretion and release?
