Human Phys 6.4

Question 1

What are the sites with the greatest resistance?

Answer 1

Medium sized bronchi

Question 2

Why do smaller airways have reduced airway resistance?

Answer 2

Because of their parallel arrangement

Question 3

What does parasympathetic stimulation of muscarinic receptors cause?

Answer 3

Bronchoconstriction

Question 4

What does sympathetic stimulation of beta 2 receptors cause?

Answer 4

Bronchodilation

Question 5

What does histamine have?

Answer 5

Potent Bronchoconstriction

Question 6

What does a decrease in lung volume lead to?

Answer 6

Increased airway resistance

Question 7

Interdependence of alveoli

Answer 7

If alveoli open, adjacent ones will too (vice versa if they close)

Question 8

What is compensatory bronchoconstriction?

Answer 8

In poorly perfused alveoli, the high CO2 and pH causes bronchoconstriction of nearby airways to redirect airflow from areas of dead space to well perfused areas

Question 9

What is the breathing cycle at rest?

Answer 9

No air is moving out (P of arteriole is 0)

Pleural pressure is -5

Volume=FRC

Question 10

What is the breathing cycle during inspiration?

Answer 10

Diaphragm contracts causing pleural pressure or -6.5 and -8 at the end of inspiration

Air flows into the lungs until pressure of arteriole is 0

Volume= volume of trachea

Question 11

What is the breathing cycle of expiration?

Answer 11

Normally a passive process

Pressure of arteriole is 1 as air flows out

All pressures and volumes return to their resting values at rest

Question 12

What may forced expiration cause in emphysema?

Answer 12

Collapse of airways

Question 13

Why does forced expiration in emphysema cause collapse of airways?

Answer 13

Due to an increase in lung compliance due to loss of elastic fibers

Question 14

What do patients with emphysema due to prevent collapse of lungs?

Answer 14

Expire slowly with pursed lips to raise airway pressure and prevent collapse

Question 15

What happens as air moves out of the lungs?

Answer 15

Driving pressure for expiratory gas flow decreases

Question 16

What is the point at which pressure inside the airways is equal with surrounding pressure?

Answer 16

Point between the alveoli and mouth called equal point pressure

Question 17

What occurs in the absence of disease?

Answer 17

Dynamic airway compression in airways that contain cartilage, to resist collapse

Question 18

What causes a premature airway closure?

Answer 18

Flow limitation due to increased airway resistance (mucus, edema, bronchoconstriction)

Flow limitation due to decreased elastic recoil (emphysema)

Question 19

Why is ventilation in the alveoli not uniform?

Answer 19

Because of airway resistance and compliance and is described by the time constant

Question 20

What do alveolar with long time constants do?

Answer 20

Fill and empty slowly

Question 21

What does an alveolar unit with increased airway resistance or increased compliance take?

Answer 21

Longer to fill and longer to empty

Question 22

What is normal inspiratory time?

Answer 22

2 seconds inspiratory and 3 seconds expiratory (used to reach volume equilibrium)

Question 23

What does COPD cause?

Answer 23

Long time constants (breath at a low respiratory rate)

Question 24

Hyperinflation

Answer 24

Lung volumes increase further and the lung becomes less compliant increasing the work of breathing