Development Before BirthDevelopment Before Birth

Chapter 13, Lesson 2Chapter 13, Lesson 2

Glencoe TextGlencoe Text

Pages 515-521Pages 515-521

Science Content StandardsScience Content Standards

5e. Students know the function of the 5e. Students know the function of the umbilicus and placenta during pregnancyumbilicus and placenta during pregnancy

Chapter 13, Lesson 2 Main idea:Chapter 13, Lesson 2 Main idea: The normal development of a The normal development of a fetusfetus depends on depends on

the good health of its motherthe good health of its mother Definition - FetusDefinition - Fetus:::: a developing human from a developing human from

usually two months after conception to birth usually two months after conception to birth

Real World Reading Real World Reading ConnectionConnection

Did you know that someone Did you know that someone might have taken your might have taken your picture before you were picture before you were born? A sonogram uses born? A sonogram uses sound waves to produce a sound waves to produce a video image of a fetus. It video image of a fetus. It can help a medical provider can help a medical provider determine if the fetus is determine if the fetus is developing normally and developing normally and whether it is a girl or boy.whether it is a girl or boy.

Fetal DevelopmentFetal Development Sexually produced organisms Sexually produced organisms

began life as a zygote that forms began life as a zygote that forms when a sperm fertilizes and egg when a sperm fertilizes and egg (chapter 3).(chapter 3).

Cell division of a human zygote Cell division of a human zygote

begins about 24 hours after begins about 24 hours after fertilization.fertilization.

Cells continue to divide -after Cells continue to divide -after about 7 days a hollow ball of more about 7 days a hollow ball of more than 100 cells has formed called a than 100 cells has formed called a blastula. blastula.

This ball of cells implants itself This ball of cells implants itself into the endometrium (lining of into the endometrium (lining of uterus).uterus).

After 2 weeks of growth, cells After 2 weeks of growth, cells begin to arrange themselves into begin to arrange themselves into 3 layers. 3 layers.

Different body structures Different body structures eventually form from each eventually form from each layer.layer.

Over 9 months, a human Over 9 months, a human embryo develops into a baby.embryo develops into a baby.

Human sex cells  (not drawn to the same scale)

Growth and Development of Body SystemsGrowth and Development of Body Systems (p. (p. 516)516)

The development of a baby within a The development of a baby within a female’s uterus is called female’s uterus is called pregnancy.pregnancy.

In humans, pregnancy usually lasts In humans, pregnancy usually lasts for about 40 weeks (after the last for about 40 weeks (after the last menstruation cycle).menstruation cycle).

The nine months are divided into 3 The nine months are divided into 3 parts called parts called trimesterstrimesters. .

By the end of the first trimester, an By the end of the first trimester, an embryo has all the structures that embryo has all the structures that will become the major organ systems will become the major organ systems

During the second trimester, an During the second trimester, an embryo is called a embryo is called a fetusfetus which which changes as it continues to develop. changes as it continues to develop. The pregnant female can feel the The pregnant female can feel the fetus' movements. fetus' movements.

During the third trimester, the fetus During the third trimester, the fetus

grows rapidly, nearly tripling in size grows rapidly, nearly tripling in size in preparation for birth. in preparation for birth.

First trimester: 0 - 12 First trimester: 0 - 12 weeks weeks

(0 - 3 and a half (0 - 3 and a half months)months)

Second trimester: 12 - 24 Second trimester: 12 - 24 wks wks

(3 1/2 months to 6 (3 1/2 months to 6 mths)mths)

Third trimester: 24 - 40 Third trimester: 24 - 40 weeks weeks

(7 months to (7 months to delivery)delivery)

Premature BabiesPremature Babies Sometimes, infants are born prematurely, before Sometimes, infants are born prematurely, before

development is complete. development is complete. By definition, premature is any baby born before 37 By definition, premature is any baby born before 37

weeks of gestation. weeks of gestation.

Premature babies can have difficulty surviving Premature babies can have difficulty surviving because some of their organs are not ready to because some of their organs are not ready to function. function.

The lungs are among the last organs to develop fully.The lungs are among the last organs to develop fully.

Premature babies must often be cared for in the Premature babies must often be cared for in the hospital until their lungs fully develop. hospital until their lungs fully develop.

Premature babies usually have low birth weights Premature babies usually have low birth weights which can lead to physical challenges, learning which can lead to physical challenges, learning difficulties, or behavioral problems as they grow older. difficulties, or behavioral problems as they grow older.

Placenta & Umbilical CordPlacenta & Umbilical Cord

Nutrients and oxygen move from the mother’s blood into the placenta, through the umbilical cord, and then to the fetus.

Wastes from the fetus move through the umbilical cord, to the placenta, and then to the mother’s blood.

Placenta & Umbilical CordPlacenta & Umbilical Cord (p. 517) (p. 517) During development, a growing fetus receives oxygen and During development, a growing fetus receives oxygen and

nutrients from its mother. A pregnant women receives carbon nutrients from its mother. A pregnant women receives carbon dioxide and wastes from her fetus.dioxide and wastes from her fetus.

This exchange of materials takes place through a disc shaped This exchange of materials takes place through a disc shaped organ called the organ called the placentaplacenta..

A placenta begins to form when an embryo first implants A placenta begins to form when an embryo first implants itself into the lining of the uterus (Endometrium). The itself into the lining of the uterus (Endometrium). The placenta contains many blood vessels from both the fetus placenta contains many blood vessels from both the fetus and endometrium, but they are not directly connected.and endometrium, but they are not directly connected.

Substances enter and leave the body of a fetus through an Substances enter and leave the body of a fetus through an umbilical cordumbilical cord..

The umbilical cord contains 2 arteries and one vein that The umbilical cord contains 2 arteries and one vein that connect the fetus to the placenta.connect the fetus to the placenta.

When a baby is born, its umbilical cord is cut, but a few When a baby is born, its umbilical cord is cut, but a few inches remain attached to the baby’s body. After a few days, inches remain attached to the baby’s body. After a few days, it dries up and drops off. The place the umbilical cord was it dries up and drops off. The place the umbilical cord was attached to the body is called the navel, or belly button.attached to the body is called the navel, or belly button.

Fetal Health Fetal Health (p. 518)(p. 518) Everything that happens in a women’s body has an Everything that happens in a women’s body has an

effects on her developing fetus.effects on her developing fetus.

Anything that she does that could harm her own Anything that she does that could harm her own health before or during the pregnancy could also health before or during the pregnancy could also harm the fetus.harm the fetus.

It is important that pregnant women take care of It is important that pregnant women take care of

their health before and during their pregnancy their health before and during their pregnancy which is called Prenatal Care (includes advice, which is called Prenatal Care (includes advice, information about nutrition, infections, and information about nutrition, infections, and substances that can harm a baby (some foods, substances that can harm a baby (some foods, liquids, medicines, etc…)liquids, medicines, etc…)

Research shows that a pregnant women who Research shows that a pregnant women who receives prenatal care by a health provider has a receives prenatal care by a health provider has a better chance of delivering a healthy baby.better chance of delivering a healthy baby.

Nutrition Nutrition (p. 518)(p. 518) All the energy and nutrients a fetus All the energy and nutrients a fetus needs for normal development must needs for normal development must come from the mother.come from the mother.

Vitamins, minerals, proteins, fat, Vitamins, minerals, proteins, fat, and carbohydrates pass from mother and carbohydrates pass from mother to fetus through the placenta. Doctors oftento fetus through the placenta. Doctors oftenrecommend vitamin supplements.recommend vitamin supplements.

A pregnant women needs to eat a healthy A pregnant women needs to eat a healthy diet and is usually advised to add about 300 diet and is usually advised to add about 300 more calories a day to her diet. more calories a day to her diet.

The added calories supply the extra energy The added calories supply the extra energy needed for the development of the fetus.needed for the development of the fetus.

A pregnant women should avoid caffeine A pregnant women should avoid caffeine which can increase a women’s blood which can increase a women’s blood pressure and heart rate, which can be pressure and heart rate, which can be stressful to her fetus. stressful to her fetus.

Harmful substances can Harmful substances can reduce the amount of reduce the amount of nutrients to the fetus, nutrients to the fetus, cause premature birth, cause premature birth, birth defects, low birth birth defects, low birth weights, or miscarriage weights, or miscarriage (loss of embryo during the (loss of embryo during the first trimester).first trimester).

Environmental Factors Environmental Factors (p. 519)(p. 519) A pregnant women can encounter A pregnant women can encounter

harmful substances in her harmful substances in her environment that can present health environment that can present health risks for her fetus. risks for her fetus.

A pregnant women is advised to A pregnant women is advised to stay away from:stay away from: Chemicals Chemicals (often found in cleaning (often found in cleaning

supplies)supplies) Pesticides and insect repellentsPesticides and insect repellents Lead Lead (found in electronics, paint, and air (found in electronics, paint, and air

pollution)pollution) Cigarette smoke (even second hand)Cigarette smoke (even second hand) Alcohol (cause FAS) Fetal Alcohol Alcohol (cause FAS) Fetal Alcohol

Syndrome)Syndrome)

Viruses Viruses (p. 520)(p. 520) Viruses can pass from a pregnant women to her Viruses can pass from a pregnant women to her

fetus through the placenta or during childbirth.fetus through the placenta or during childbirth.

Nearly everyone has had an infection caused by a Nearly everyone has had an infection caused by a virus. You’ve probably had colds, flu, or chicken pox. virus. You’ve probably had colds, flu, or chicken pox.

Some viruses do not cause harm to adults, but can Some viruses do not cause harm to adults, but can be very harmful (birth defects or even death) to a be very harmful (birth defects or even death) to a fetus or newborn. fetus or newborn.

Other viral infections include genital herpes and Other viral infections include genital herpes and HIV/AIDS. HIV/AIDS attacks the bodies immune HIV/AIDS. HIV/AIDS attacks the bodies immune system limiting a infected persons ability to fight system limiting a infected persons ability to fight infection. infection.

One out of every 4 pregnant women with HIV One out of every 4 pregnant women with HIV (human immunodeficiency virus) pass the HIV onto (human immunodeficiency virus) pass the HIV onto their fetus. their fetus.