Regulation of Breathing

Question 1

Involuntary Aspect of Breathing

Answer 1

• it is controlled by the medulla oblongata (lower part of the brain) - the sensory neuroma in this region control motor neurons for respiration in the spinal cord
• breathing can be controlled consciously to an extent, but it cannot be fully suppressed (you can hold your breath but not forever)
• the need to remove CO2 and supply O2 to our cells is too powerful

Question 2

CO2 as a Stimuli for Breathing

Answer 2

• it takes a small increase in CO2 to affect breathing rate

* very sensitive to CO2 changes

Question 3

H+ as a Stimulus

Answer 3

• if the pH is too low/acidic, the brain will trigger more frequent breathing to eliminate more CO2

Question 4

How do the Sensors Work?

Answer 4

• when CO2 enters the blood, bicarbonate (H2CO3) dissociates and released hydrogen ions
• this changes the acidity of the blood
• the sensory receptors actually sense the pH of the blood
• if the pH is too low, the brain will trigger more frequent breathing to eliminate CO2

Question 5

Main Stimuli that Cause Breathing

Answer 5

• CO2 and H+

* CO2 and H+ (blood acidity) are the primary stimuli that cause us to breathe

Question 6

O2 as Stimuli for Breathing

Answer 6

• it takes a large decrease in O2 to affect breathing rate

* NOT SENSITIVE to O2 changes

Question 7

Sensory Receptors

Answer 7

• Two sensory neurons detect these changes in CO2 and H+ levels
• First set is located in carotid arteries
- in the neck, which carry blood to the brain
• second set is located near the aorta
- carries blood to the rest of the body