Question

1) Describe the structure of the respiratory membrane.

2) During contraction of the diaphragm:

a. in what direction does the diaphragm move?

b. what does this movement do to the volume of the lungs?

3) Put the following respiratory events in the correct order:

a. air moves, b. alveolar volume changes, c. pleural pressure changes, d. alveolar pressure changes.

4) Describe what would happen to a lung if the pleural cavity pressure became equal to atmospheric pressure.

5) State what would happen to each of the following as a result of lung fibrosis (increase, decrease, or no change):

a. lung compliance

b. alveolar surface tension

c. airway resistance

d. tidal volume

6) State what happens to the following as altitude increases (increase, decrease, or no change):

a. atmospheric pressure

b. % of air made of oxygen

c. partial pressure of oxygen

7) When oxygen is in a state of partial pressure equilibrium between the alveoli and pulmonary capillaries, state: (lower than, higher than, or equal to)

a. how alveolar and capillary PO2 compare.

b. how the alveolar and capillary concentrations of O2 compare.

Answer 1

1) Respiratory membrane

The exchange of O2 and CO2 between blood in alveolar capillaries and alveolar space occur across respiratory membrane. It composed of alveolar wall and capillary wall.

Respiratory membrane consists of four layers

• a alveolar wall consists of type I and Type II alveolar cells
• An epithelial basement membrane underlying to the alveolar wall
• A capillary basement membrane of the alveolar capillaries which is fused with epithelial basement membrane
• A capillary endothelium of alveolar capillary

2) Diaphragm is a dome- shaped skeletal muscle which divides thoracic cavity from abdominal cavity. It is an important muscle involved during respiration

a. During inhalation diaphragm contract- Contraction of diaphragm cause diaphragm to descend (move down and lowering its dome shape result in flate shape)

b. Contraction of diaphragm flatten the diaphragm and vertical diameter of thoracic cavity increases that result in increase of lung volume

3) c. pleural pressure changes, b. alveolar volume changes,  d. alveolar pressure changes, and a. air moves

4) Pressure exerted by atmospheric gases are called called atmospheric pressure (760mmHg) and pressure present at the intrapleural space (space between visceral and parietal pleura) is called intrapleural pressure. Normally intrapleural pressure is always negative than atmospheric pressure ( that is during inhalation intrapleural pressure is 754mmHg and 756mmHg during exhalation)

When intrapleural pressure become equals to atmospheric pressure (means increased intrapleural pressure), it compress the lung, prevent the recoiling of the lung thereby lung Collapse occur