9. Changes at birth II Flashcards
(14 cards)
What radical changes occur in the circulatory system at birth?
Pressure changes: placenta provides low resistance before birth; lungs have high resistance. After birth, placenta is lost; lungs dilate and become low resistance.
This transition is crucial for adapting to breathing air and circulating blood effectively.
What must the left ventricle do after birth?
Increase its force.
This adaptation is necessary to accommodate the changes in blood flow and pressure.
What are the two phases of heart growth after birth?
Hyperplasia (cell number increase) and hypertrophy (cell size increase).
These processes help the heart adapt to its new functional demands.
What triggers the transition from hyperplasia to hypertrophy in heart muscle cells?
Thyroid hormones (T3/T4) increase dramatically at birth.
These hormones play a significant role in heart development.
What impact does premature birth have on heart cells?
May result in fewer heart cells for life, requiring compensatory changes.
This can affect cardiovascular health later in life.
What are the phases of lung development?
- Embryonic (18-19 days)
- Pseudoglandular (up to ~16 weeks)
- Canalicular (~24 weeks)
- Saccular (producing alveolar sacs)
- Alveolar (36-38 weeks to ~7 years)
Each phase is critical for proper lung function and structure.
What correlates with survival at premature birth?
Surfactant production (starting ~23-24 weeks).
Surfactant is essential for reducing surface tension in the lungs.
At what age is full lung maturity reached?
About age 7.
Lung function continues to develop well after birth.
What cells produce surfactant?
Type II alveolar cells.
These cells are crucial for maintaining alveolar stability.
What is the composition of surfactant?
- 92% lipids (mainly dipalmitoylphosphatidylcholine)
- Proteins
The lipid component is vital for its function in reducing surface tension.
How much does surfactant reduce surface tension in alveoli?
By 5-10 fold.
This reduction is essential for preventing alveolar collapse.
What are the key surfactant proteins and their functions?
- Proteins B and C stabilize surfactant sheets
- Proteins A and D have immune functions.
These proteins play critical roles in maintaining lung health and function.
What regulates surfactant production?
- Glucocorticoids
- Thyroid hormones
- Physical stress
These factors ensure adequate surfactant levels at birth.
What is the significance of the coordinated changes in the circulatory and pulmonary systems at birth?
Critical for successful transition from fetal to neonatal life.
These changes allow the newborn to adapt to life outside the womb.
