Chap 4

Question 1

Describe the period of the zygote

Answer 1

1. Ovulation occurs: an egg is dropped from the fallopian tube (it takes only 24hours for implementation to occur)
2. Fertilization: a sperm cell reaches the egg to create a zygote
3. Egg cell division
4. Implantation: the zygote attaches to the uterus

Question 2

Describe the period of the embryo

Answer 2

The 3 layers of the internal organs develop:

• the ectoderm is the skin, hair and nervous system
• The mesoderm: the muscles, bones and circulatory system
• the endoderm: The digestive system and lungs

Question 3

Describe the period of the fetus

Answer 3

At 12 weeks, the fetus develops sex organs. The fetus begins undergo rapid growth and brain function alongside other bodily systems begin to work. At 22-28 weeks, this is considered the age of viability

Question 4

What are the 2 principles of growth?

Answer 4

1. Cepholocaudal (top down): The head develops before the rest of the body
2. Proximodistal (inwards out): The arms and legs develop before the hands, feet, fingers and toes

Question 5

What are 3 major risk factors on prenatal development ?

Answer 5

1. Nutrition
2. Stress
3. Mothers age

Question 6

What is the importance folic acid in prenatal development?

Answer 6

A woman who is pregnant must consume enough folic acid for the proper development of the fetus’ nervous system . If there is not enough folic acid, the fetus is at risk for spina bifida

Question 7

What is the optimal age for conception?

Answer 7

A study from Denmark suggest between 25-34 years old

Question 8

What are teratogens? Give an example

Answer 8

Teratogens are any agents or factors that cause malformations to the embryo
For example, drugs, alcohol, diseases like AIDS and environmental toxins

Question 9

What are the main factors to consider in terms of the effects of teratogens ?

Answer 9

1. A person’s genotype may buffer the effects slightly
2. Time of exposure will effect the fetus differently
3. Different teratogens cause different effects
4. Effects may not be present until later in life

Question 10

What are the 3 main stages of labour and delivery?

Answer 10

1. The cervix begins to dilate from contractions where it will dilate up to 8cm
2. At full dilation the baby descends down the birth canal, the baby’s head will crown and will emerge from the body
3. The placenta must be expelled from the body as well