Respiratory Physiology

Question 1

What are the features of type 1 pneumocytes?

Answer 1

Very thin squamous cells which cover around 97% of the alveolar surface

Question 2

What are the features of type 2 pneuocytes?

Answer 2

Cuboidal cells

Secrete surfactant

Start to develop around 24 weeks gestation, however adequate surfactant production does not take place until around 35 weeks so premature babies are prone to respiratory distress syndrome

Can differentiate into Type 1 pneumocytes during lung damage

Question 3

What is the function of clubb cells?

Answer 3

Club cells (previously termed Clara cells) are non-ciliated dome-shaped cells found in the bronchioles. They have a varied role including protecting against the deleterious effects of inhaled toxins and the secretion of glycosaminoglycans and lysozymes.

Question 4

What is the function and structure of pulmonary surfactant?

Answer 4

phospholipids, carbohydrates and proteins released by type 2 pneumocytes. The main functioning component is dipalmitoyl phosphatidylcholine (DPPC) which reduces alveolar surface tension.

reduces the muscular force needed to expand the lungs (i.e. decreases the work of breathing)
lowers the elastic recoil at low lung volumes and thus helps to prevent the alveoli from collapsing at the end of each expiration

Question 5

What centre control respiration?

Answer 5

Control of respiration:
- central regulatory centres
- central and peripheral chemoreceptors
- pulmonary receptors

Question 6

What is the physiological response in hypoxia?

Answer 6

fall in the partial pressure of oxygen in the blood leads to vasoconstriction of the pulmonary arteries. This allows blood to be diverted to better aerated areas of the lung and improves the efficiency of gaseous exchange

Question 7

What is the definition of lung compliance?

Answer 7

Lung compliance is defined as change in lung volume per unit change in airway pressure

Question 8

What are causes of increased lung compliance?

Answer 8

Causes of increased compliance
age
emphysema - this is due to loss alveolar walls and associated elastic tissue

Question 9

What are causes of decreased lung compliance?

Answer 9

Causes of decreased compliance
pulmonary oedema
pulmonary fibrosis
pneumonectomy
kyphosis

Question 10

What is the hering bruer reflex?

Answer 10

stretch receptors, lung distension causes slowing of respiratory rate (Hering-Bruer reflex)