22 Questions
What is the typical duration of the third stage of labour?
15-20 minutes
What is the function of oxytocin in the birth process?
Promotes contraction of the uterine wall
What happens to the umbilical cord after birth?
It is tied and cut, and the part connected to the baby will shrivel up and become the belly button
What is the primary function of the placenta during pregnancy?
To provide oxygen and nutrients to the baby
What is the primary reason for a Caesarean section?
To reduce the risk of maternal and/or foetal distress
What is the role of oestrogen in the development of mammary glands?
It stimulates the growth and development of milk glands and milk ducts
What is the main function of the umbilical vein?
Carries oxygenated blood and nutrients from the mother to the foetus
What happens to the placenta at the end of pregnancy?
It becomes less efficient, leading to the need for birth to occur
What is the primary function of the placenta in regards to the foetus?
To provide the foetus with oxygen and nutrients
What is the process by which the foetus, surrounding membrane, and placenta are expelled from the mother's body?
Parturition
What is the purpose of the amniotic fluid surrounding the foetus?
To cushion and protect the foetus from external injury or impact
What is the function of the umbilical arteries?
Carry waste products from the foetus to the mother's bloodstream
What is the function of the yolk sac?
Forms the umbilical cord
During what stage of pregnancy does the majority of differentiation occur?
Embryonic period
What is the function of the trophoblast?
Relates to feeding and develops into the placenta
What is the purpose of the placenta?
Supplies the fetus with oxygen and nutrients
During what stage of pregnancy does the fetus receive antibodies from the mother?
Foetal period
What is the function of the amnion?
Is a membrane that fills with fluid
During what stage of pregnancy does the heart begin to beat?
Embryonic period
What is the purpose of the umbilical cord?
All of the above
What is the function of the villi in the placenta?
Grows into the endometrium to form the placenta
During what stage of pregnancy does the fetus turn, with its head pointing towards the cervix?
Foetal period
Study Notes
Labour and Birth
- 2-3 weeks prior to birth, the foetus moves into position, with the head pointing down towards the cervix
- High levels of oestrogen in the mother's body cause the pituitary gland to secrete oxytocin, promoting uterine contractions
- Stage 1 of labour: dilation of the cervix; myometrium starts contracting, becoming more frequent and intense, causing the cervix to dilate up to 10cm
- At 10cm, the amniotic fluid is released, and the cervix is fully dilated
- Stage 2: delivery of the baby; powerful contractions of the uterus and abdominal muscles push the baby out through the vagina, usually head first
- Stage 3: expulsion of the placenta, which usually occurs within 20 minutes after birth and lasts for around 15 minutes
Birth Options
- Vaginal birth: natural or assisted with medication
- Caesarean section: surgical delivery, usually performed if there are complications and the mother and/or foetus are at risk
Mammary Glands
- Produce milk; contain milk-secreting glands
- Lactation: milk production stimulated by oestrogen and progesterone, which develop milk glands and ducts
- Oxytocin promotes milk letdown
Placenta
- Develops from chorion and villi that penetrate the endometrium
- Villi provide a large surface area for exchange of substances with maternal blood supply
- Functions:
- Oxygen and dissolved nutrients pass from mother to foetal blood
- Waste products pass from foetus to mother for excretion
- Maternal antibodies pass to foetus, providing passive immunity
- Acts as a barrier, preventing harmful substances from entering the foetus
- Produces progesterone and oestrogen, maintaining uterine changes during pregnancy
- Later in pregnancy, secretes relaxin, which relaxes joints and ligaments for delivery
Amnion and Amniotic Fluid
- Amnion: membrane surrounding the embryo and foetus
- Amniotic fluid: surrounds the foetus, protecting it from external injury and providing a medium for breathing and swallowing movements
- Functions:
- Supports foetal development
- Cushions and protects the foetus
- Holds urine released by the foetus
- Regulates temperature and prevents dehydration
Umbilical Cord
- Flexible cord connecting the foetus to the placenta
- Contains two umbilical arteries and one umbilical vein
- Umbilical arteries: carry waste from the foetus to the mother's bloodstream
- Umbilical vein: carries oxygenated blood and nutrients from the mother to the foetus
Human Reproduction: Pregnancy and Birth
Copulation and Fertilization
- Copulation: sexual intercourse, transferring sperm into the vagina
- Fertilization: fusion of the sperm nucleus with the egg nucleus, forming a diploid zygote
Gestation (Pregnancy)
- Time between conception and birth (280 days or 40 weeks)
- Embryo and foetus develop in the uterus
Early Development (0-2 months)
- Fertilization: fusion of sperm and egg nuclei
- Blastocyst formation: morula develops into a hollow fluid-filled ball of cells
- Implantation: blastocyst sinks into the endometrium
Early Development (3rd-8th week)
- Formation of embryo and amnion
- Yolk sac forms part of the umbilical cord
- Trophoblast develops into the chorion, forming villi that penetrate the endometrium to form the placenta
- Embryo develops into three layers: ectoderm, endoderm, and mesoderm
Later Development (Foetal period)
- From week 9 to birth, the foetus grows rapidly
- Bones ossify, subcutaneous tissue forms, and antibodies enter the foetus via the placenta
- Foetus turns, with the head pointing towards the cervix
Learn about the structure and functions of the placenta, including the role of villi, capillary networks, and maternal blood supply in facilitating the exchange of substances between the mother and fetus. Understand the importance of the placenta in providing oxygen and essential nutrients to the fetus.
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