Cardiac Development Flashcards
What are the four sequential stages of prenatal lung development?
- Embryonic period
- Pseudoglandular period
- Cannicular period
- Terminal sac period
When does the embryonic period occur?
First five weeks after conception
What forms during the embryonic period?
Main and lobar bronchi are formed, with the pulmonary arteries following the airways as they divide
When does the pseudoglandular period occur?
5-16 weeks gestation
What forms during the pseudoglandular period?
Mucous glands form and increase in number; muscle fibres and elastic tissue and early cartilage form to establish a tracheobronchial tree; diaphragm develops
When does the cannicular period occur?
13 - 25 weeks gestation
What occurs during the cannicular period?
Increases in the surface of the respiratory epithelium; formation of alveolar buds, with type I and II pneumocytes
When does the terminal sac period occur?
24 weeks to birth
What occurs during the terminal sac period?
Cilia begin to develop, alveolar buds becomes saccules, cough and gag reflex develops
What are the two phases of the terminal sac period?
- Saccular phase (28-36 weeks)
2. Alveolar phase (36 weeks to 8 years)
What factors influence lung development?
- Hormones
- Growth factors
- Extracellular matrix interactions
- Corticosteroids and thyroid hormones
- Distension of the lung
When does the heart start to beat?
Day 22 - 23
What is septation?
Converting of simple tube into four chambered heart
When does the closure of the ductus ateriosus occur?
Immediately after birth due to a muscular contraction
List common cardiac anomalies
- Patent ductus arteriosus (PDA)
- Coarctation of the aorta
- Atrial septal defect
- Ventricular septal defect (VSD)
- Tetrology of Fallot
What are some significant anatomical differences of babies vs adults in the upper respiratory tract?
- larger head
- larger tongue
- lack of hair leads to increased heat loss
- nose breathers until 3-4 months of age
- smaller nostrils
- crico-thyroid membrane is narrow and vulnerable to open suction and intubation
- larger heart, adenoids and tonsils
What are some significant anatomical differences of babies vs adults in the lower respiratory tract?
- Lungs less compliant (stiffer)
- ## Horizontal ribs
