4A: Gas Exchange

Question 1

Where is the neural respiratory center, and describe its effect on HR?

Answer 1

Medulla - rate is slow and irregular, TV is low

Question 2

What area mediates neural respiratory control?

Answer 2

To areas in the pons - make it even and rhythmical

Question 3

What is the first site of chemical mediation?

Answer 3

Through the BBB where H+ indirectly signals CO2 levels

Question 4

What is the primary driver to breath?

Answer 4

Increase in CO2 in the cells

Question 5

What is the function of chemoreceptors in relation to chemical mediation?

Answer 5

Secondary drive to breathe

Question 6

Where are chemoreceptors found?

Answer 6

Carotid and aortic bodies

Question 7

What are chemoreceptors sensitive to?

Answer 7

Hypoxemia - low oxygen levels

Question 8

What is the effect when chemoreceptors are stilumated?

Answer 8

Increase respiration

Question 9

What is the role of the spinal cord in relation to neural input from activity?

Answer 9

Receives info regarding motion and activity, stimulates the medulla to increase RR

Question 10

What does the spinal cord receive info from?

Answer 10

Skeletal muscle receptors, stretch, tension, and metabolic changes

Question 11

What stimulates J-receptors?

Answer 11

Hyperinflation of the lungs

Question 12

What happens when J-receptors are stimulated?

Answer 12

Bronchoconstriction and increased mucous

Question 13

What is the general function of the J-receptors?

Answer 13

Play a role in protecting the lungs during times of threat from chemicals, thermal agents, and other environmental stressors

Question 14

What is the action of J-receptors?

Answer 14

Reduce tidal volume and constrict the bronchial airways, to cause increased mucous production, and coughing

Question 15

What is V/Q influenced by?

Answer 15

Gravity and positioning

Question 16

Are ventilation and perfusion equally distributed in lungs?

Answer 16

No - when upright, lung and perfusion increase from apex to base

Question 17

Does ventilation or perfusion have a greater differential from the apex to base of the lung?

Answer 17

Perfusion increases 3x faster from apex to base than ventilation

Question 18

What is the major contributor to ventilation difference?

Answer 18

Higher RV in uppermost alveoli creates dead space compared to dependent lung

Question 19

What is perfusion?

Answer 19

Gravity affects the lungs and how blood is distributed

Question 20

What is the greatest influence to perfusion?

Answer 20

Low pulmonary pressures and distensibility properties of capillaries

Question 21

What lung area does the majority of gas exchange occur and why?

Answer 21

In the base due to higher perfusion

Question 22

In a variety of positions, what area of the lungs will get the greatest perfusion?

Answer 22

The most dependent tissue (gravity dependent)

Question 23

Describe ventilation in sidelying

Answer 23

Most dependent hemi-diaphragm has the greatest excursion and results in greater ventilation

Question 24

Describe elasticity of the lungs

Answer 24

The ability for it to retract and recoil

Question 25

What is compliance?

Answer 25

A measure of distensibility or stiffness - measure of how much lung tissue will expand