1. Gestation and Birth Viv Rolfe 23.08.01
Need to look at the physiology of puberty
The physical and hormonal changes that occur.
There are various stages within childhood - the baby grows into a toddler, then becomes a school-child until entering adolescence.
So what is puberty and when does it happen?
Viv Rolfe
Puberty.ppt

2. Lecture Outline
To investigate the major events of gestation and parturition.
What is implantation?
3 stages of gestation (germinal, embryogenic and foetal phases).
Structure and function of the placenta and umbilical cord.
3 stages of parturition.

3. Gestation and Partition (Pregnancy and birth)
(280 days/9 months)
Development of the zygote / embryo / foetus
in the female reproductive tract, and delivery from the female.

4. Gestation Week 1 Fertilization Implantation Embryonic Growth Foetal
Birth

5. Implantation Fertilization
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

6. Cellular Changes
The ZYGOTE rapidly divides into a mass of cells called the MORULA.
The cells DIFFERENTIATE (change type) forming the BLASTOCYST:
Trophoblast – large fluid-filled sphere (foetal placenta)
Inner cell mass (embryo)
Blastocyst
cavity

7. Implantation
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

8. Implantation
6-8 days after fertilization the blastocyst implants into the uterine wall.
The endometrial glands start to enlarge and becomes more vascularised.

9. What is the word for the implantation and development of the embryo outside of the uterine cavity?
Ectopic pregnancy.

10. Inutero-development Body Stalk (Umbilical cord)
Chorionic villi (Placenta)
Ectoderm
Mesoderm
Endoderm
(GERM LAYERS)
Yolk sac
Early source of nutrients

11. Gestation Fertilization Implantation Embryonic Growth Foetal Growth
Birth

12. Embryonic Period Weeks 1-8.
A time of rapid cell differentiation and growth.
All the body tissues and organs develop from the PRIMARY GERM LAYERS.
The placenta also begins to develop.

13. Germ layers Ectoderm Endoderm Mesoderm Nervous system
Epidermis of the skin
Eye, ear
Endoderm
Mucosal surfaces
Glands
Mesoderm
Skeletal, smooth and cardiac muscle.
Cartilage, bone, blood, lymphoid tissue.

14. Gestation Fertilization Implantation Embryonic Growth Foetal Growth
Birth

15. Foetal Period Weeks 12-38. The embryo is referred to as a FOETUS.
It has a human appearance.
It now rapidly grows (from a few cm to up to 50 cm), occupying all of the abdominal space.

16. Placenta
and umbilical
cord are fully developed
(2-3 months)

17. Placenta
Forms a barrier between mother and embryo to deliver NUTRIENTS and OXYGEN.
Removes WASTE from embryonic blood.
Becomes an endocrine organ by producing HORMONES (oestrogen, progesterone) to control pregnancy

18. Summary of the Stages of Pregnancy
1st trimester (first 3 months)
Embryonic period - development of body organs
Baby’s heart starts beating about 4 weeks.
2nd trimester (months 4-6)
Foetal period – rapid growth and much activity.
3rd trimester – (months 7-9).

19. Effects on the mother Enlargements of the uterus
Gastrointestinal symptoms
Morning sickness is due to elevated progesterone
Heartburn due to organ crowding by the fetus
Constipation is caused by declining motility
Urinary System
Kidneys have additional burden and produce more urine
The uterus compresses the bladder

20. Effects on the mother Cardiovascular system Body water levels rise
Blood volume increases by 25 to 40 percent
Blood pressure and pulse increase
Varicose veins are common

21. Gestation/pregnancy (280 days/9 months) Fertilization Implantation
Embryonic
Growth
Foetal
Growth
Birth

22. Birth - parturition
Labour – the series of events that expel the infant from the uterus
Initiation of labor
Estrogen levels rise
Prostaglandin starts uterine contractions

23. Labour Dilation Expulsion Placental stage Cervix becomes dilated
Uterine contractions begin and increase
The amnion ruptures
Expulsion
Infant passes through the cervix and vagina
Normal delivery is head first
Placental stage
Delivery of the placenta

25. Effects of birth on the foetus
The baby undergoes amazing physiological changes at birth.
What happens?

26. Oxygen and nutrients no longer supplied by the mother.
Carbon dioxide and other wastes aren't eliminated by her.
Loss of protection from the uterus.
Temperature drop.
Exposed to microbes!

27. Rapid Changes in the Lungs
Change from being fluid filled and collapsed in the uterus, to filled with air.
Blood CO2 is high at birth stimulating the respiratory centre in the brain.
The baby draws its first breath.

28. Rapid Changes in the Heart
Closure of the foramen ovale in the heart (which doesn’t close in “hole in the heart baby’s”).
This diverts de-oxygenated blood to the LUNGS and not to the PLACENTA.
The umbilical artery and vein close down.
There is rapid red and white blood cell production at birth.