Lecture 5.1: Chemical Control of Ventilation

Question 1

What is Eupnoea?

Answer 1

Normal Breathing

Question 2

What are the 2 significant groups of medullary neurons?

Answer 2

• Dorsal Respiratory Group (DRG) • Ventral Respiratory Group (VRG)

Question 3

What is the role of the Dorsal Respiratory Group (DRG)?

Answer 3

• It receives input from peripheral
chemoreceptors
• And other types of receptors via the
vagus and glossopharyngeal
nerves
• These impulses generate
inspiratory movements and are
responsible for the basic rhythm of
breathing

Question 4

What is the role of the Ventral Respiratory Group (VRG)?

Answer 4

• The VRG contains both inspiratory
and expiratory neurons
• The ventral respiratory group of
neurons are active in forceful
breathing and inactive during quiet,
restful respirations
• The VRG sends inhibitory impulses
to the apneustic center
• Many expiratory neurons don’t fire
during eupnoea, those that do don’t
initiate contraction of expiratory
muscles
• Botzinger complex may inhibit some
neurons in DRG
• Pre-Botzinger complex may be the
pacemakers

Question 5

What is the Apneustic Center?

Answer 5

The apneustic center sends signals for inspiration for long and deep breaths

Question 6

Where is the Ventral Respiratory Group (VRG) located?

Answer 6

• The VRG is located in the ventrolateral
region of the medulla
• Retrofacial nucleus, the nucleus
ambiguus, the nucleus para-
ambigualis, and the nucleus
retroambigualis
• Inspiratory and expiratory neurons

Question 7

Where is the Dorsal Respiratory Group (DRG) located?

Answer 7

• The dorsal respiratory group is located
in the distal portion of the medulla
• Located nucleus tractus solitaries
• Many projections to VRG (but receives
few in return)

Question 8

What is the Pneumotaxic Center?

Answer 8

• The pneumotaxic center controls
both the rate and the pattern of
breathing
• The pneumotaxic center is
considered an antagonist to the
apneustic center, (which produces
abnormal breathing during
inhalation) cyclically inhibiting
inhalation

Question 9

What receptors sense O2?

Answer 9

• Peripheral chemoreceptors
• Those in the carotid body more important than aortic
body