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

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.

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.

Gestation Week 1 Fertilization Implantation Embryonic Growth Foetal Birth

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

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

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

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

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

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

Gestation Fertilization Implantation Embryonic Growth Foetal Growth Birth

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.

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.

Gestation Fertilization Implantation Embryonic Growth Foetal Growth Birth

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.

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

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

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).

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

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

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

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

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

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

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!

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.

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.