L35. Maternal Changes, Pregnancy and Birth Flashcards
1
Q
Fertilisation
A
- occurs in the fallipian tube within 12-14 hours after ovulation
- sperm delivered into female reproductive tract during intercourse
- 20-100 million sperm/ ml of ejaculation
- sperm can survive up to 6 days in female reproductive tract
- sperm penetrates corona radiata and zona pellucida around the oocyte
> capacitation
> prevention of polyspermy (only one sperm is allowed to penetrate the egg) - genetic material from sperm cell and oocyte merges into single diploid nucleus
> ZYGOTE= fertilised ovum
2
Q
Sperm fertilization
A
- in order for the sperm to reach the egg, you need thousands of sperm to release an enzyme to create a path through the CORONA RADIATA
- first sperm to penetrate the egg gets fertilised
3
Q
when does fertilisation occur
A
- ovulation typically occurs at day 14
- sperm are viable for up to 6 days in the female reproductive system
- fertilisation is possible if intercourse takes place between day 5-17
4
Q
Placenta
A
- a disc-shaped organ unique to mammals that connects the developing foetus to the uterine wall (via the umbilical cord)
- developed from the same sex cells that form the foetus
- two sides
FUNCTION:
- provides nutrients and O2 to/removes waste from the developing foetus and secretes hormones
5
Q
Hormones of Pregnancy
A
- human chorionic gonadotropin (hCG)
- progesterone
- human placental lactogen (hPL)
- corticotropin releasing hormone (CRH)
- relaxin
- oxytocin
- prolactin
- CORPUS LUTEUM- important source of hormones in the first 7-12 weeks. After this, the placenta takes over as the main source of hormone secretion
6
Q
Human chorionic gonadotropin (hCG)
A
- secreted by the blastocyst and placenta (chorion)
- presence in urine indicates pregnancy (tests)
FUNCTION:
- maintains the corpus luteum (ie. stimulates its growth and keeps it active)
- CORPUS LUTEUM (CL) responsible for estrogen and progesterone secretion
- without hCG, the CL will atrophy and estrogen ans progesterone levels will drop –> contraction of uterus –> endometrium sloughs off
7
Q
Estrogen
A
- by the end of gestation, estrogen levels are > 30 x higher than normal non-pregnant levels
- mostly secreted by the CL initially (for first 12 weeks), then from the placenta
FUNCTION:
- stimulate tissue growth in foetus and mother
- stimulates enlargement of uterus an mother’s external genitalia
- mammary duct development -> increase in breast size
- maintains the uterine lining -> prevents menstruation
- widens pelvis towards the end of gestation
8
Q
Progesterone
A
- large amounts are secreted during pregnancy, initially by the CL, but then mostly by the placenta (6 weeks)
FUNCTION:
- progesterone and estrogen inhibits the ant. pit. gland from secreting FSH and LH -> no follicle development, no ovulation
- maintains pregnancy by relaxing uterus and keeping cervix tightly closed
- prevents menstruation
- promotes mammary gland development
- promotes secretion of a hostile cervical mucous
9
Q
Relative hormone levels
A
- hCG is essential in the first 12 weeks to maintain the CL
- after 12 weeks, the placenta takes over (hCG less important)
10
Q
Oxytocin
A
- produced by hypothalamus
- secreted by posterior pituitary
FUNCTION:
- stimulates uterine contractions during childbirth
- stimulates milk ejection when feeding
11
Q
Prolactin
A
- produced and secreted by the anterior pituitary
FUNCTION:
- stimulates mammary glands to produce milk
12
Q
Maternal adaptation to pregnancy- mother’s circulatory system
A
- increase blood flow to placenta and uterus
- maternal blood volume increases ~45% due to:
> fluid retention
> haemopoiesis (increase blood cell production) - cardiac output increases ~40%
- growing uterus compresses major blood vessels -> interferes with vanous return -> blood pooling in veins -> varicose veins an oedema
13
Q
Maternal adaptation to pregnancy- foetus’ circulatory system
A
- foetal blood has a higher concentration of haemoglobin than maternal blood
> higher affinity for O2 than maternal blood
> favours the transfer of O2 from maternal blood to foetus
14
Q
Maternal adaptation to pregnancy- respiratory system
A
- increase metabolic rate and foetal demands -> 25% increase in O2 consumption
> achieved by increasing the mother’s tidal volume (deep and heavy breathing) - chemoreceptors become more sensitive to CO2
- the growing foetus compresses the lungs, breaths are shallower, compensated by increasing frequency of breath
- breathing becomes more diaphragmatic, less costal
- late in pregnancy, pelvic ligaments relax, foetus drops into pelvic inlet, easing pressure on diaphragm
- airway in bronchial tree dilate, reducing resistance
15
Q
Labour Contractions
A
- every 30 min, then every 1-3 min as labour progresses
- contractions are intermittent
- contractions are strongest in the fundus and body of uterus, weaker in the cervix
POSITIVE FEEDBACK
- stretching of cervix results in reflex contraction of uterus
- stretching of cervix also results in release of oxytocin, which stimulates uterine contraction
- urge to push with abdominal muscles -> increase intra-abdominal pressure
