Lecture 25 - Regulation of Respiration

Question 1

What are the different respiratory centers?

L25 S4

Answer 1

• dorsal respiratory group (DRG)
• ventral respiratory group (VRG)
• pontine respiratory group (PRG)
• Botzinger complex (BotC)
• Pre-Botzinger complex

Question 2

What respiratory centers are responsible for normal breathing rhythm and where are they located?

L25 S5

Answer 2

Reticular formation of the medulla:

• dorsal respiratory group (DRG) (tractus solitaries)
• ventral respiratory group (VRG)

Pons:

• apneustic center
• pneumotaxic center/PRG

Question 3

Where is the dorsal respiratory group located and what are its functions?

L25 S9

Answer 3

• located in nucleus of tractus solitarius and dorsal medulla
• sets basic rhythm of respiration
• initiates phrenic nerve activity
• establishes ramp signal which is associated with inspiration
• receives sensory information

Question 4

What is the ramp signal and what is its effect?

L25 S11-12

Answer 4

• stimulates inspiration via the diaphragm
• signal starts weak and then increases
• strong signal results in 30-40 breaths per minute
• weak signal results in 3-5 breaths per minute

Question 5

Where is the pontine respiratory group located and what is its function?

L25 S14-15

Answer 5

• located in the superior pons (penumotaxic center) and inferior pons (apneustic center)
• penumotaxic center controls rate and depth of breathing
• apneustic center limits lung expansion

Question 6

Where is the ventral respiratory group located and what is its function?

L25 S17-18

Answer 6

• located in the ventrolateral medulla
• functions in forced respiration
• inactive during normal respiration

Question 7

What is the Hering-Breuer reflex?

L25 S21

Answer 7

-prevents excess inflation of the lungs using stretch receptors which function to inhibit the ramp signal

Question 8

What types of chemoreceptors are there and what are they sensitive to?

Answer 8

Central:

• located in ventral surface of medulla
• sensitive to CO2 indirectly by pH

Peripheral:

• located in aortic arch and carotid body
• sensitive to oxygen, CO2, and H+

Both increase activity with hypoxia or hypercapnia

Question 9

What is the response pathway of the carotid and aortic chemo receptors?

L25 S30

Answer 9

Carotid body receptors:

• Hering nerves
• CN IX (glossopharyngeal nerve)
• DRG

Aortic bodies:

• CN X (vagus nerve)
• DRG

Question 10

What types of mechanoreceptors are there and what are their functions?

L25 S34

Answer 10

Slow-adapting:

• sensitive to stretch of airways
• function to terminate inspiration and prolong expiration

Rapidly adapting:

• sensitive to irritation, foreign bodies, and stretch
• elicit a cough response

J receptors:

• sensitive to pulmonary edema
• elicit cough and tachypnea

Question 11

What is Cheyenne-Stokes breathing?

L25 S36

Answer 11

• increasingly deep and rapid breathing followed by gradual decrease and a temporary stop
• this pattern repeats and can also be referred to as periodic breathing