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Birth and development. Beginning of life cycle. Fertilization- Only one sperm fertilizes the egg. In the first week the egg undergoes many cell divisions and travels to the uterus. Zygote- United sperm and egg
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Beginning of life cycle • Fertilization- Only one sperm fertilizes the egg. In the first week the egg undergoes many cell divisions and travels to the uterus. • Zygote- United sperm and egg • Cell division- From the two cell stage till about nine weeks the growing structure is called an embryo.
The Blastocyst- 5 days after fertilization the embryo reaches the uterus where it floats free for a few days. At this time made up of 50-100 cells. The structure is now called a blastocyst and is a sphere of cells surrounding a hallow center. • Implantation- The blastocyst begins to attach itself to the wall of the uterus.
Development in the uterus • Amniotic Sac- Surrounds the embryo and is filled with amniotic fluid. • Placenta- Attachment holding the embryo to the wall of the uterus. Oxygen, nutrients and blood pass through to the embryo through the placenta. Harmful things can pass too..Like? • Umbilical cord- 25 days after fertilization this rope like cord develops between the embryo and placenta.
Development • During the first 2 months of development major body systems and organs start to form. • By the end of 8 weeks the embryo is about an inch long and has recognizable external features(eyes, nose, limbs ect) • The thrid month until birth the developing human is called a fetus.
Fetus • During this time the fetus kicks and moves which shows muscle development. • As the nervous system develops, the fetus becomes sensitive to light, sounds, and alternates periods of activity with periods of sleep • 7-9 months the fetus grows in proportion to the size of the head. At 9 months the fetus is born.
Stages • Zygote- Sperm fertilizes egg • Embryo- From 2 cell stage until 9 weeks • Fetus- Three months until birth
The Birth Process • Labor: 2-24 hrs or longer. Strong contractions of the muscles of the uterus cause the cervix to dilate. • Each contraction lasts approximately 30-90 seconds. At first they may be minutes apart but are usually only a few seconds apart at the end of the birth process. • Amniotic sac breaks and cervix becomes softer and wider.
Delivery of the baby: Takes 30 mins- over 2 hrs. • Contractions of the uterus continue and the baby is pushed out, usually head first, through the cervix and vagina. • Doctor will then clamp and cut the umbilical cord, which has no nerve endings. • Nose and mouth are suctioned • Eye drops added to prevent infection • An injection of vitamin K to prevent excess bleeding from umbilical cord • Heel is pricked to check blood for protein levels
Delivery of after birth: Contractions of the uterus push out the placenta. • This stage takes typically 15-30 mins
Postpartum Period • This is the 6 week period of adjustment for the parents and new born. • Circulatory system and heart under go changes that send more blood to the lungs, because the baby now gets its oxygen there. • Nervous system reacts to sensations. • The new born is learning to build a close bond with its mother and father and is learning to get what it needs for survival.
Mother: Changing hormone levels tell the body to produce milk and cause the uterus to gradually shrink to normal size. • Mother may feel overwhelmed or very sad. • If this depression lasts longer or causes the mother to withdraw from the baby or people, she should seek prompt medical help. • This means she could have postpartum depression.
Complications • Cesarean Section- A surgical method of birth. Done when a mothers hips are too narrow or illness or other conditions are present. • Stillbirth- Occurs when the fetus dies and is expelled from the body after the twentieth week of pregnancy.
Premature birth- Delivery before 37 weeks. The baby is not fully developed and complications can arise. • Low birth weight- Some are premature while others just have not grown enough before birth. Can reduce the chance of this happening by practicing healthy habits during pregnancy.
Multiple Births • Identical twins- Develops from a single fertilized egg. Embryo divides into two separate embryos. • Fraternal Twins- Two eggs are fertilized by two sperm. Can be different sex.