Respiratory 5

Question 1

What is the bronchial circulation?

Answer 1

Blood supplied via the bronchial arteries arising from systemic circulation to supply oxygenated blood to airway smooth muscle, nerves, lungs and tissues.

Question 2

Describe the flow and pressure of the pulmonary circulation.

Answer 2

• high flow

- low pressure

Question 3

What is systolic pressure?

Answer 3

The maximum arterial pressure during contraction of the left ventricle of the heart.

Question 4

At what rate does blood circulate around both the body and the lungs?

Answer 4

5L/min

Question 5

True or false:

Partial pressure gradients are not the same as concentration gradients.

Answer 5

True

Question 6

What value is the partial pressure of alveolar oxygen in kPa?

Answer 6

13.3 kPa

Question 7

What value is the partial pressure of alveolar carbon dioxide in kPa?

Answer 7

5.3 kPa

Question 8

What value is the partial pressure of arterial oxygen in kPa?

Answer 8

13.3 kPa

Question 9

What value is the partial pressure of arterial carbon dioxide in kPa?

Answer 9

5.3 kPa

Question 10

What value is the partial pressure of venous oxygen in kPa?

Answer 10

5.3 kPa

Question 11

What value is the partial pressure of venous carbon dioxide in kPa?

Answer 11

6.2 kPa

Question 12

True or false:

The diffusion of gases between the alveoli and the blood does not obey the rules for simple diffusion.

Answer 12

False

Question 13

From alveoli to arterial blood, which has the largest partial pressure gradient; oxygen or carbon dioxide?

Answer 13

Oxygen

Question 14

Why is diffusion of oxygen slower than that of carbon dioxide?

Answer 14

Carbon dioxide is more soluble than oxygen.

Question 15

Briefly define emphysema.

Answer 15

Emphysema is the destruction of alveoli, reducing surface area for gas exchange.

Question 16

Briefly define fibrotic lung disease.

Answer 16

• thickened alveolar membrane which slows gas exchange.

- loss of lung compliance may decrease alveolar ventilation

Question 17

Briefly define pulmonary oedema.

Answer 17

• fluid in interstitial space increases diffusion distance

Question 18

Briefly define asthma.

Answer 18

• increased airway resistance decreases airway ventilation

- occurs as bronchioles are constricted

Question 19

Where is the equilibrium point of blood flow and ventilation?

Answer 19

The third rib.

Question 20

Define the term ‘shunt’.

Answer 20

Shunt is the term used to describe the passage of blood through areas of the lung that are poorly ventilated.

Question 21

What happens when ventilation is less than blood flow?

Answer 21

• If ventilation decreases in a group of alveoli, the partial pressures of carbon dioxide increases and oxygen decreases.
• Blood flowing past those alveoli does not get oxygenated.
• This blood then dilutes the oxygenated blood from better ventilated areas.

Question 22

How does the body combat shunting?

Answer 22

• vasoconstriction occurs, allowing less blood to the poor ventilated area and more blood the well ventilated area.
• the build up of carbon dioxide also triggers mild bronchodilation, allowing more oxygen to the poorly ventilated area.

Question 23

What happens when ventilation is greater than blood flow?

Answer 23

This results in alveolar dead space

- through vasodilation and mild bronchial constriction

Question 24

What is alveolar dead space?

Answer 24

• refers to alveoli that are ventilated but not perfused

Question 25

Define ventilation.

Answer 25

Air that reaches the alveoli.

Question 26

Define perfusion.

Answer 26

The blood that reaches the alveoli via the capillaries.

Question 27

Define physiological dead space.

Answer 27

The sum of alveolar dead space and anatomical dead space.