10. Changes at birth III

Question 1

What does the ductus arteriosus become after birth?

Answer 1

The ductus arteriosus becomes fibrotic and changes to ligamentum arteriosum

The ductus arteriosus connects the pulmonary artery to the aorta.

Question 2

How is the ductus arteriosus related to surgical intervention?

Answer 2

It can occasionally act as a ligature affecting the trachea and esophagus

This may require surgical intervention.

Question 3

Which muscle types retain stem cells after birth?

Answer 3

Skeletal and smooth muscle retain stem cells

Cardiac muscle cells cannot increase in number.

Question 4

What is the role of satellite cells in muscle regeneration?

Answer 4

Skeletal muscle uses satellite cells for regeneration

Cardiac muscle does not have this capability.

Question 5

What happens to the lungs at birth?

Answer 5

Lungs transition from a secretory to absorptive system

Before birth, lungs are filled with fluid secreted by lung epithelium.

Question 6

What causes fluid absorption in the lungs at birth?

Answer 6

Changes in ion channels cause sodium absorption to replace chloride secretion

Hormonal drivers include glucocorticoids, thyroid hormones, and adrenaline.

Question 7

What maintains the new absorption pattern in the lungs after birth?

Answer 7

Oxygen exposure maintains the new absorption pattern

This is critical for lung function after birth.

Question 8

How does blood flow change in the pulmonary system after birth?

Answer 8

Blood flow increases from ~20% to 50% of cardiac output

This is accompanied by a decrease in pulmonary arterial pressure.

Question 9

What mechanisms contribute to reduced vascular resistance in the lungs after birth?

Answer 9

Massive vasodilation and reduced vascular resistance

Mechanisms include nitric oxide production and prostaglandin A1.

Question 10

What are potential complications of pulmonary changes in newborns?

Answer 10

Persistent pulmonary hypertension and alveolar hyaline disease

Alveolar hyaline disease is common in premature births due to surfactant deficiency.

Question 11

What changes occur in hemoglobin after birth?

Answer 11

Fetal hemoglobin transitions to adult hemoglobin

Fetal hemoglobin has a higher oxygen affinity at low oxygen partial pressures.

Question 12

What adaptation allows fetal hemoglobin to facilitate oxygen transfer across the placenta?

Answer 12

2,3-BPG regulator binds poorly to fetal hemoglobin due to serine instead of histidine

This is crucial for oxygen transfer in low oxygen environments.

Question 13

What is the percentage decrease of fetal hemoglobin by 12 months after birth?

Answer 13

Fetal hemoglobin decreases from 85% at birth to ~1% by 12 months

Maintaining some fetal hemoglobin can be beneficial in conditions like sickle cell anemia.