6.7 - The mechanism of breathing Flashcards
1
Q
How is the diffusion of gases maintained across the alveolar epithelium
A
- ventilation, done by:
1) Inspiration (inhalation)
2) Expiration (exhalation)
2
Q
What is inspiration
A
- when the air pressure of the atmosphere is greater than the air pressure inside the lungs
- Causing air to be forced into the lungs
3
Q
What is expiration
A
- when the air pressure in the lungs is greater than that of the atmosphere
- Causing air to be be forced out of the lungs
4
Q
How are the pressure changes within the lungs brought about
A
- movement of 3 sets of muscles
1. the diaphragm (sheet of muscle that separates the thorax from the abdomen
2. The intercostal muscles (which lie between the ribs) There are 2 types:
3. Internal intercostal muscles (whose contraction leads to expiration) and external intercostal muscles (whose contraction leads to inspiration)
5
Q
Is breathing an active process
A
- yes
- Uses energy
6
Q
Describe how inspiration occurs
A
- Ex intercostal muscles = contract, int intercostal muscles = relax
- The ribs are pulled upwards and outwards, increasing volume of the thorax
- The diaphragm muscles contract, causing it to flatten in shape —> further increases volume in thorax
- The increased volume of thorax = reduction of pressure in the lungs
- Atmospheric pressure = greater than pulmonary pressure, and so air is forced into the lungs
7
Q
Is breathing out an active process
A
- no
- Doesn’t require much energy
8
Q
Describe how expiration occurs
A
- int intercostal muscles = contract, ex intercostal muscles = relax
- The ribs move downwards and inwards, decreasing volume of thorax
- The diaphragm muscles relax, contents of abdomen (that were pushed down during inspiration) push up at diaphragm goes into a dome shape —> further decreases volume in the thorax
- The decreased volume of the thorax increases the pressure in the lungs
- The pulmonary pressure = greater than the atmospheric pressure, and so air is forced out the lungs
9
Q
A
10
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A
11
Q
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