Cell reproduction and the Continuity of Life: Pregnancy and Labour

Question 1

What is the birthing process called?

Answer 1

Parturition.

Question 2

What are the events associated with parturition refered to as?

Answer 2

Labour, which includes both hormonal and neural components in its onset.

Question 3

What begins the onset and continuation of labour?

Answer 3

Uterine contractions (induced by cervix stretches) result in oxytocin releasing from the posterior pituitary. Positive feedback assists this for as the cervix stretches more and more, more and more oxytocin is released.

Question 4

What are the 3 stages of delivery?

Answer 4

• Dilation stage
• Expulsion stage
• Placental stage

Question 5

What happens in the dilation stage?

Answer 5

Oxytocin and Uterine contractions make the cervix dilate. The amniotic sac breaks and releases fluids through the vagina. Stage lasts 2-20 hours.

Question 6

What happens in the expulsion stage?

Answer 6

Forceful contractions push the baby through the cervix and birth canal. Passing the cervix, the baby’s head rotates so the body may easier pass through the birth canal. Stage lasts 0.5-2 hours.

Question 7

What happens in the placental stage?

Answer 7

10-15 minutes after baby is birthed, the placenta and umbilical cord expel from the uterus. Placenta is now called the afterbirth.

Question 8

What is lactation?

Answer 8

The secretion and formation of breast milk in a mother. Onset by hormones.

Question 9

What hormone is needed for milk production?

Answer 9

Prolactin. Not secreted during pregnancy due to high estrogen and progesterone levels suppressing the anterior pituitary’s release. Only secreted after birth due to hormone levels falling.

Question 10

When does milk production start?

Answer 10

A few days after birth.

Question 11

What is secreted before milk is produced?

Answer 11

Colostrum. Thin yellow fluid akin to milk, but less fatty with more protein. Also contains antibodies from the mother to protect against infections.

Question 12

What happens when infants suck during breast feeding?

Answer 12

Oxytocin release from the posterior pituitary causes contraction of the mammary lobules, which are vital in the release of milk.

Question 13

What changes occur during the first trimester? (Week 1-12)

Answer 13

• All events prior to implantation
• Limbs, eyes, and spine form after 4 weeks
• Bone cells start developing
• Embryo becomes a fetus at 8 weeks
• Organogenesis (formation of body organs)
• Reproductive organs form by 12th week and gender is identifiable

Question 14

What changes occur during the second trimester? (Weeks 13-24)

Answer 14

• Rapid fetus growth
• Nervous function begins
• Mother feels movement
  -Skeleton continues forming
• Most organs are finished forming, still developing
• Heart is audible to stethoscope

Question 15

What changes occur during the third trimester? (Weeks 25-38)

Answer 15

• Major size increase
• Major increase to brain cell and network function
• Layer of fat develops beneath skin
• Immune system develops
• Eyes open
• Fetus now requires many calories
• Testes descend into scrotum
• Digestion and respiratory develop last

Question 16

What are the two types of twins and their differences?

Answer 16

Identical: Single sperm fertilizes single egg which splits in two. Genetically identical. Less likely type.

Fraternal: Two sperm fertilize two eggs separately. Not identical. More likely type.

Question 17

What are teratogens?

Answer 17

Any agent that causes a structural abnormality due to exposure during pregnancy.

Question 18

What are some teratogens?

Answer 18

• Alcohol use (FAS)
• Recreational drugs (Low birth weight, learning issues)
• Smoking cigarettes (Reduced food supply to fetus, low birth weight)
• Viruses (Measles)(Deafness)
• Prescription drugs (Thalidomide)(Missing limbs, other defects)
  -Toxins (Heavy metals, pesticides)(Cancer, genetic defects)
• Certain nutrients ingested in a surplus (Builds tolerance for post birth, becomes deficient)