Regulation of Respiratory System I/II

Question 1

Where is a cycle of inspiration and expiration automatically generated?

Answer 1

In the CNS central pattern generator (CPG)

Question 2

What drives the CPG?

Answer 2

Chemoreceptors (both central and peripheral) sensing PO2, PCO2 and pH

Question 3

What does the CPG regulate specifically?

Answer 3

Respiratory muscles, most importantly the diaphragm

Question 4

What is eupnea?

Answer 4

Quiet, normal, easy breathing

Question 5

What does negative feedback on the CPG come from?

Answer 5

An increase in alveolar ventilation

Question 6

How is the CPG affected b higher center respiratory motor activity?

Answer 6

They send inputs to the CPG during intense exercise

Question 7

Where is the central pattern generator located?

Answer 7

Ventrolateral medulla oblongata

Question 8

What does the pons do in respiration?

Answer 8

It only modulates respiratory output but is not necessary for respiratory output itself

Question 9

What is the dorsal respiratory group (DRG)?

Answer 9

Has sensory input and contains primarily inspiratory neurons

Question 10

Where are the DRG found?

Answer 10

Nucleus of solitary tract in the medulla

Question 11

What is the ventral respiratory group (VRG)?

Answer 11

Primarily motor and contains both inspiratory and expiratory neurons

Question 12

What is the CPG composed of?

Answer 12

DRG and VRG

Question 13

What center can terminate inspiration?

Answer 13

Pontine apneustic center

Question 14

What modulates the apneustic center and fine tunes respiration?

Answer 14

Pneumotaxic center

Question 15

What do peripheral chemoreceptors respond to?

Answer 15

Primarily sensitive to decreasing PO2 less so to increase in PCO2 and decreased pH

Question 16

What are central chemoreceptors sensitive to?

Answer 16

Increase in arterial PCO2 (H+)

Question 17

What generates the respiratory rhythm?

Answer 17

Pacemaker neurons or synaptic interactions within the CPG

Question 18

What is the chemosensor in the carotids and aortic bodies?

Answer 18

Glomus cell

Question 19

What does acidosis cause in the carotid chemosensors?

Answer 19

Makes it more sensitive to arterial PCO2

Question 20

What occurs when PaCO2 goes from 40 to 45 mmHg?

Answer 20

Ventilation will double

Question 21

How does the central chemoreceptor respond to CO2 and H+?

Answer 21

CO2 can cross BBB but H+ cannot therefore the brain responds to local acidosis

Question 22

What stimulates ventilation more hypoxia or respiratory acidosis?

Answer 22

Respiratory acidosis

Question 23

What do juxtacapillary (J receptors) do?

Answer 23

Sense mechanical or chemical irritants and elicit rapid and shallow breathing, bronchoconstriction and mucous secretion as a defense mechanism

Question 24

What do the slowly-adapting pulmonary stretch mechanoreceptors (PSR) do?

Answer 24

Detect lung volume and inhibit the medullary output to phrenic motor neurons producing Hering-Breuer Reflex

Question 25

What does the Hering-Breuer reflex do?

Answer 25

Stops over-inflation of the lungs