Physiology 3.3

Question 1

Describe the process of gas exchange in a normal lung.

Answer 1

In a normal lung, ventilation takes place, leading to a normal partial pressure of oxygen inside the alveoli. Deoxygenated blood from the pulmonary artery undergoes gas exchange, loading oxygen into the blood, resulting in richly oxygenated blood leaving the lung.

Question 2

What impact does emphysema have on gas exchange in the lungs?

Answer 2

Emphysema leads to a reduction in surface area available for gas exchange, impacting diffusion and resulting in less oxygen entering the blood. This leads to lower partial pressure of oxygen in the pulmonary vein and subsequently in systemic arterial blood.

Question 3

How does fibrosis affect gas exchange in the lungs?

Answer 3

Fibrosis results in the thickening of the alveolar membrane, slowing down gas exchange. It also decreases lung compliance, impacting alveolar ventilation and leading to a lower partial pressure of oxygen in the blood leaving the lungs.

Question 4

Define the impact of reduced surface area on gas exchange in emphysema.

Answer 4

Reduced surface area in emphysema leads to less gas exchange taking place, resulting in a lower partial pressure of oxygen in the blood leaving the lung.

Question 5

Do conditions like emphysema and fibrosis affect the partial pressure of oxygen in the pulmonary vein and systemic arterial blood?

Answer 5

Yes, both emphysema and fibrosis lead to a lower partial pressure of oxygen in the pulmonary vein and subsequently in systemic arterial blood.

Question 6

Describe the impact of fibrous tissue on the alveolar membrane in fibrosis.

Answer 6

Fibrous tissue laid down in fibrosis increases the thickness of the alveolar membrane, slowing down gas exchange and impeding diffusion.

Question 7

How does fibrosis affect lung compliance and alveolar ventilation?

Answer 7

Fibrosis decreases lung compliance, making it difficult to expand the lungs during inspiration, which impacts alveolar ventilation and leads to a lower partial pressure of oxygen inside the alveoli.

Question 8

Define the impact of thickened alveolar membrane on gas exchange in fibrosis.

Answer 8

Thickened alveolar membrane in fibrosis slows down gas exchange, as it increases the thickness of the tissue across which the gas has to diffuse.

Question 9

Describe the impact of pulmonary edema on the distance across which gas has to diffuse.

Answer 9

Pulmonary edema increases the distance across which gas has to diffuse by causing fluid to sit between the alveoli and the capillaries, pushing them apart.

Question 10

Define pulmonary hypertension and its role in causing pulmonary edema.

Answer 10

Pulmonary hypertension is an increase in blood pressure in the pulmonary capillaries, which forces plasma out of the capillaries and into the interstitial space, leading to pulmonary edema.

Question 11

How does pulmonary edema affect the partial pressure of oxygen in the pulmonary vein and systemic arterial blood?

Answer 11

Pulmonary edema leads to a reduction in the partial pressure of oxygen in the pulmonary vein and systemic arterial blood due to the increased diffusion distance and the presence of water, in which oxygen does not dissolve well.

Question 12

Describe the impact of pulmonary edema on the diffusion of carbon dioxide.

Answer 12

Pulmonary edema often results in a normal partial pressure of carbon dioxide, as carbon dioxide is much more soluble in water than oxygen, allowing it to continue to diffuse despite the increased diffusion distance.

Question 13

Do fibrosis and emphysema have a similar impact on the diffusion of oxygen as pulmonary edema?

Answer 13

No, fibrosis and emphysema impact the diffusion of oxygen, but with pulmonary edema, the main target is the effect on the diffusion of oxygen, with a much smaller impact on the diffusion of carbon dioxide.

Question 14

Describe the difference in impact on diffusion between asthma and pulmonary edema.

Answer 14

Asthma does not directly impact diffusion, whereas pulmonary edema significantly affects the diffusion of oxygen, with a smaller impact on the diffusion of carbon dioxide.

Question 15

Describe the impact of asthma on the partial pressure of oxygen in systemic arterial blood.

Answer 15

Asthma leads to a low partial pressure of oxygen in systemic arterial blood due to reduced ventilation, causing a decrease in oxygen entering the alveoli.

Question 16

Define the primary issue in asthma and its effect on ventilation and diffusion.

Answer 16

Asthma primarily affects ventilation by causing inappropriate constriction of bronchiole smooth muscle or inflammation, leading to a reduction in oxygen entering the alveoli and difficulty in getting carbon dioxide out.

Question 17

How does fibrosis impact ventilation and diffusion in the lungs?

Answer 17

Fibrosis results in a reduction in ventilation due to resistance to lung expansion during inspiration and impedes diffusion due to the thickened fibrous tissue, causing a decrease in oxygen entering the blood.

Question 18

Describe the difference in the impact on ventilation between emphysema and fibrosis.

Answer 18

Emphysema primarily affects exhalation due to reasons to be discussed, while fibrosis mainly affects inspiration, making it difficult due to the resistance from fibrous tissue.

Question 19

Do asthma, emphysema, and fibrosis all have issues with diffusion in the lungs?

Answer 19

Asthma primarily affects ventilation, emphysema may have some impact on diffusion, and fibrosis impedes diffusion due to the thickened fibrous tissue.

Question 20

Define the role of fibrous tissue in fibrosis and its impact on lung function.

Answer 20

Fibrous tissue in fibrosis resists lung expansion during inspiration, leading to a reduction in ventilation, and also impedes diffusion due to the thickened membrane, causing difficulty for gases to diffuse through.

Question 21

Describe the appearance of fibrotic tissue on an X-ray.

Answer 21

Fibrotic appears radiopaque on an X-ray, making visible as dense, white areas.

Question 22

What impact does fibrotic tissue have on breathing?

Answer 22

Fibrotic tissue resists lung expansion during inspiration, making it difficult for the patient to breathe.

Question 23

Define pulmonary edema.

Answer 23

Pulmonary edema is the accumulation of fluid in the airspaces and tissues of the lungs, leading to difficulty in oxygen diffusion.

Question 24

How does pulmonary edema affect gas exchange in the alveoli?

Answer 24

Pulmonary edema increases the distance across which gas in the alveoli has to diffuse to reach the blood vessels, impacting oxygen diffusion due to poor solubility in water.

Question 25

Describe the structural changes in an emphysemic lung compared to a normal lung.

Answer 25

In emphysema, there is a breakdown of the alveolar membrane, loss of elastic tissues, and the formation of large, non-functional air sacs, leading to a significant loss of surface area available for gas exchange.

Question 26

What is the main cause of emphysema?

Answer 26

Smoking is the main cause of emphysema, as constituents in cigarette smoke activate an enzyme called elastase, leading to the breakdown of elastic fibers and alveolar walls.

Question 27

Describe the importance of having highly compliant and elastic lungs.

Answer 27

Highly compliant lungs make it easier to inflate the lungs, while highly elastic lungs aid in passive expiration by allowing the elasticity to snap back and push air out.

Question 28

What happens in emphysema in terms of lung elasticity and compliance?

Answer 28

In emphysema, there is a loss of lung elasticity due to breakdown of elastic fibers, leading to increased compliance and making inspiration easier but expiration difficult.

Question 29

How does emphysema affect expiration in comparison to healthy lungs?

Answer 29

In emphysema, expiration becomes incredibly difficult, requiring the use of muscular effort for every breath, unlike healthy lungs where expiration happens passively.

Question 30

Define the impact of fibrosis on lung compliance.

Answer 30

In fibrosis, there is a decrease in lung compliance due to the resistance of fibrous tissue to stretch, making it difficult to expand the thoracic cavity during inspiration.

Question 31

Do smokers with emphysema experience easier or more difficult inspiration compared to healthy individuals?

Answer 31

Smokers with emphysema experience easier inspiration due to increased compliance, but incredibly difficult expiration, requiring muscular effort for every breath.

Question 32

Describe the impact of emphysema on lung surface area and diffusion.

Answer 32

Emphysema results in a loss of lung surface area, which has a major impact on diffusion due to the reduced area available for gas exchange.

Question 33

Describe the impact emphysema on lung compliance and effort of expiration.

Answer 33

Emphysema increases compliance and effort of expiration.

Question 34

Define the impact of fibrosis on lung compliance and effort of inspiration.

Answer 34

Fibrosis decreases compliance and increases effort of inspiration.

Question 35

How does oedema affect gas diffusion in the lungs?

Answer 35

Oedema increases diffusion distance, making it harder for gases, particularly oxygen, to diffuse.

Question 36

Do lung pathologies like emphysema and fibrosis affect the partial pressure of oxygen and carbon dioxide in the blood?

Answer 36

Yes, they would expect to see a decrease in the partial pressure of oxygen and an increase in partial pressure of carbon dioxide.

Question 37

Describe the impact of asthma on ventilation and partial pressure of oxygen and carbon dioxide in the alveoli.

Answer 37

Asthma has a big impact on ventilation, leading to a reduction in the partial pressure of oxygen and an increase in the partial pressure of carbon dioxide in the alveoli.

Question 38

How does asthma disrupt gas diffusion in the lungs?

Answer 38

Asthma disrupts gas diffusion by causing a change in the partial pressure gradients, leading to a change in the partial pressures of gases in the blood.