Human Reproduction (Part 6 - Embryo and Birth)

Question 1

Germ layer

Answer 1

Layer of cells in an embryo that gives rise to specific tissues

Question 2

types of germ layers

Answer 2

Ectoderm - Skin
Endoderm - Lining of gut
Mesoderm - Blood

Question 3

Embryo development (First 8 weeks)

Answer 3

Nervous system forms
Heart and circulatory system forms
Digestive, reproductive and excretory systems form
Skeleton forms…made of cartilage

Question 4

Embryo development (Next 4 weeks)

Answer 4

Bone begins to replace cartilage

Nervous co-ordibation begins

Question 5

Embryo development (12th week on)

Answer 5

Increase in size

Question 6

Birth

Answer 6

38 weeks

• Placenta stops producing progesterone
• Pituitary gland starts producing the hormone oxytocin
• Initiates birth (Parturition)

Question 7

Birth (Stage 1)

Answer 7

Dilation (6-18 hours)

• Oxytocin causes contractions
• Cervix dilates
• Amniotic fluid released

Question 8

Birth (Stage 2)

Answer 8

Emergence (30 - 60 mins)

• Contractions - push baby out
• Umbilical cord is cut and clamped

Question 9

Birth (stage 3)

Answer 9

Placental - Afterbirth (5-10 mins)

Further contractions expel placenta and other structures like the amnion

Question 10

Lactation

Answer 10

Production of milk by the mammary glands

• Drop in progesterone after birth causes pituitary gland to to start producing hormone prolactin
• colostrum is produced for 2/3 days before milk

Question 11

Biological benefits of breast feeding

Answer 11

Milk contains right nutrients in the exact right amount
antibodies provides short term immunity
Reduce the risk of breast cancer
Helps the mother to recover after pregnancy
Helps ‘bonding’

Question 12

Infertility

Answer 12

Inability to produce offspring
Cause:Low sperm count due to 
- drugs
- underproduction of testosterone
Treatment: In vitro fertilisation
Females
Cause: Failure to ovulate due to 
- underproduction of sex hormones
Treatment:In vitro fertilisation

Question 13

In vitro fertilisation

Answer 13

Removing eggs from the ovary and fertilising with sperm outside the body

• Female treated with hormones
• Eggs collected
• Fertilised with sperm
• Eggs that are developed into embryos are introduced to the uterus