Pulmonary Lecture 4

Question 1

How does gravity affect Regional Variations in ventilation

Answer 1

The top alveolus will have the weight of the lung pulling it open

The bottom alveolus will be squeezed by the wieght of the lung

V_Bot/V_Top = 2.5

The bottom will have more airflow - Volume doesnt matter but change in volume. Because the bottom alveolus is smaller, there is a greater volume change

Question 2

In this picture will the bottom or top alveolus have more compliance

Answer 2

The bottom alveolus has higher compliance

Question 3

What are the two characteristics of Oxygen in Blood

Answer 3

1. Oxygen is poorly soluble
2. Oxygen binding sites on hemoglobin are mostly saturated

Question 4

How does exercise effect diffusion of Oxygen?

Answer 4

It slows diffusion because blood is flowing more quickly and there is less time for Oxygen to diffuse

Question 5

How does interstitial disease effect diffusion of Oxygen?

Answer 5

It causes a thickening in the diameter thus causing diffusion to dramatically slow

Question 6

How is Carbon Dioxide effected by interstital disease or exercise?

Answer 6

Carbon Dioxide is generally never effected by a diffusion problem because it has a much higher solubility. Sometimes it is slow, but not nny much

Question 7

Define Perfusion

Answer 7

Blood Flow in the lung

Question 8

Define Minute Perfusion

Answer 8

Blood flow in the lung in one minute
Normal = 5L

This also equal Cardiac Output as they are so close together

Question 9

How does Oxygen tension effect Perfusion

Answer 9

Hypoxic Pulmonary Vasoconstriction

It causes areas where oxygen levels are low to constrict.

Mechanism to help divert blood to a part of the lung to have higher gas exchange - adaptive mechanism

Question 10

How does Capillary Recruitment effect Perfusion?

Answer 10

Have a lung where blood vessels are relatively constricted. When exercising, it causes the blood vessels to dilate recruiting capillaries to allow for a higher gas exchange

Question 11

How does Gravity Affect Perfusion?

Answer 11

Introduces Regional Variations

Gravity generates regional variation of blood flow at different parts of the lung. If the person is standing upright the blood will pool at base of lung because of gravity. Causes blood pressure below to increase and dilate them.

Question 12

What is V/Q Mismatch

Answer 12

The ratio of the amount of ventilation that is flowing in and out of the alveolus to the amount of blood flow

V/Q

Question 13

If you occlusion of a bronchiole how is V/Q mismatch effected

Answer 13

It will lower

Question 14

If you have occlusion of an artery how wil V/Q mismatch be affected

Answer 14

It will be higher

Question 15

If there is a region of low V/Q in the lung, how will the lung compensate?

Answer 15

Other regions V/Q will become higher. This is to maintain normal CO2 Levels

Question 16

In an area that has a high V/Q to increase ventilation why will the total oxygen in the blood plateau?

Answer 16

Due to the oxyhemoglobin dissociation. Total blood volume of oxygen can only go so high due to saturation

Question 17

In a situation of V/Q Mismatch where one blood vessel has a higher V/Q and one has a lower how is oxygen affected?

Answer 17

The total oxygen will be lower due to saturation

Question 18

How does V/Q Mismatch affect arterial levels of CO2?

Answer 18

It does not have an effect.

Question 19

How does Gravity effect V/Q mismatch

Answer 19

The mechanism will favor a higher level of ventilation and perfusion at the bottom vs. the top

Question 20

How does gravity effect the pressure of the pressure in alveoli compared to the pressure in arterioles

Answer 20

It causes the pressure in arterioles to be 5-10 Torr lower

Question 21

What does complete occlusion of an arteriole lead to?

Answer 21

Dead space - as the alveoli is no part of the lung that does not engage in gas exchange

Question 22

What does complete occlusion of the bronchiole lead to?

Answer 22

Shunt: A volume of blood that does not engage in gas exchange

Causes: Lung/heart disease

Question 23

How does a shunt limit Oxygen in the blood

Answer 23

If one vessel has a V/Q of 0, no oxygen exchange in occuring. Due to oxygen hemoglobin saturation, other parts arterioles cannot make up for this decrease