Tracthe: Control of Ventillation

Question 1

What are the major sensors controlling respiration?

Answer 1

Central controller

Peripheral sensors (chemoreceptors)

Efferent mechanisms (nerves and muscles)

Question 2

Where is the central controller located?

Answer 2

Brainstem (Pons and medulla)

Question 3

What is unique about the cells of the central controller?

Answer 3

UNSTABLE resting membrane potentials (pacemaker activity)

Question 4

How can the cortex increase or decrease breathing?

Answer 4

OVERRIDES the brainstem

Question 5

What affect do panic attacks have on Pco2

Answer 5

HALVE it

Question 6

How much does alveolar ventilation need to be increased to half PCO2?

Answer 6

Double

Question 7

What are the most important sensors in day to day regulation of ventilation?

Answer 7

Central chemoreceptors

Question 8

What do the central chemoreceptors do?

Answer 8

Respond to pH

Question 9

What and where are the peripheral chemoreceptors located?

Answer 9

Carotid bodies in the Aortic arch

Question 10

What do the peripheral chemoreceptors respond to?

Answer 10

PCO2 and PO2

AND

pH

Question 11

What are the lung receptors?

Answer 11

Stretch receptors
irritant receptors
J receptors
Bronchial C fibers

Question 12

What stimulates the central pH receptors?

Answer 12

increase in H

Question 13

What affect does alkalosis have on respiration?

Answer 13

SUPPRESSES it

Question 14

What surrounds the central pH receptors?

Answer 14

Cerebrospinal fluid

Question 15

How does H stimulate the central pH receptor?

Answer 15

H can’t cross the BBB>
CO2 diffuses across and is converted to CA by carbonic anhydrase>
plasma CO2 determines CSF pH

Question 16

What is normal CSF pH?

Answer 16

7.32

Question 17

How does the CSF compensate for an aberrant CSF acidosis?

Answer 17

HCO3 retention

Question 18

HCO3 retention by the CSF is observed in pts w/ what condition?

Answer 18

Pts with EMPHYSEMA have LOW PO2 and HIGH PCO2 and low respiration rates b/c of the compensation

Question 19

What are the two types of peripheral chemoreceptors?

Answer 19

Aortic arch

Carotid bodies

Question 20

What peripheral chemoreceptors are particularly good at detecting hypoxia?

Answer 20

Carotid bodies

Question 21

When do the peripheral chemoreceptors respond to hypoxia? What happens to the firing rate?

Answer 21

100 mmHG

Increases as PO2 decreaes

Question 22

Which peripheral chemoreceptors respond to a decrease in pH?

Answer 22

Carotid bodies

Question 23

Which peripheral chemoreceptors respond to hypercapnia?

Answer 23

Carotid AND aortic but they’re not as important as the CENTRAL CHEMORECEPTORS

Question 24

What is the stimulus for increased breathing in exercise?

Answer 24

movement of limbs>
joint/muscle receptors>
increases RR

Question 25

How does an increase in PCO2 affect ventilation?

Answer 25

Each 1 mmHg increase> | 2-3 L increase in ventilation

Question 26

When do most individuals respond to hypoxia?

Answer 26

If CO2 is held constant> | not until PO2 drops BELOW 50 mmHg

Question 27

What are exceptions to the normal response to hypoxia?

Answer 27

High altitude Chronic obstructive lung disease (adapts to changes in pH caused by CO2 retention)

Question 28

How does low pH affect ventilation?

Answer 28

Stimulates it--often seen in metabolic acidosis (diabetic ketoacidosis)

Question 29

How does exercise typically affect PCO2 and PO2?

Answer 29

FALL in PCO2 | RISE in PO2

Question 30

How does exercise affect pH?

Answer 30

Stable until intense levels

Question 31

What is the chief baseline control of respiration?

Answer 31

Brainstem (pacemakers)

Question 32

What are the chief inputs that control respiration?

Answer 32

pH in CSF PCO2, PO2 and pH in the periphery

Question 33

How do medullary pH sensors monitor arterial PCO2?

Answer 33

by its influence on CSF acidity

Question 34

What do carotid and aortic bodies sense?

Answer 34

PCO2 | arterial pH

Question 35

What do ONLY carotid bodies sense?

Answer 35

O2

Question 36

What causes an increase in breathing?

Answer 36

HIGH PCO2 LOW PO2 pH

Question 37

What is most relevent for day to day control of ventilation?

Answer 37

CO2

Question 38

WHat is most relavent for altitude adaptations and chronic lung disease?

Answer 38

PO2