Applied Physiology: Control of Breathing

Question 1

Control of Ventilation

Answer 1

Has three major components and several minor

Major:
1) Brain
2) Chemoreceptors (Central & Peripheral)
3) Lung receptors

Question 2

The Brain

Answer 2

Brainstem
3 nuclei centers
medullary, apneustic& pneumotaxic

Cortex
Can dominate them all, to a degree

Question 3

Medullary Nuclei

Answer 3

Pre-BotzingerComplex-responsible for the generation of the rhythm

Dorsal Respiratory Group-We are #1!! Think inspiration (Most fundamental role)

Ventral Respiratory Group-Think primarily expiration

Question 4

Dorsal Respiratory Group

Answer 4

Receives signals from peripheral chemoreceptors, baroreceptors and lung receptors

Gives a signal to the diaphragm over about 2 seconds that gradually ramps up, then ceases for about three seconds
This leads to natural rate of breathing 60 secs / 5 secs = 12 breaths

Question 5

Ventral Respiratory Group

Answer 5

Remain mostly Inactive during normal respiration

When increased respiration is needed, signals spill over from the dorsal side and expiration becomes active

Question 6

Pneumotaxic Center

Answer 6

In the upper Pons

Switches off the inspiratory ramp

Indirectly effects the respiratory rate

Question 7

ApneusticCenter

Answer 7

Stimulates the inspiratory area

Prolongs the inspiratory ramp

Question 8

The CORTEX

Answer 8

Can over ride the brainstem to a certain extent

You can hyperventilate yourself, but not to death

Question 9

Central Chemoreceptors

Answer 9

Again, The Brain……

The most important for respiration are in the medulla

They respond to changes in CO2 and H+ concentration

How does that work? (LOOK THIS UP!!!)

Do they respond to changes in O2?

Question 10

Peripheral Chemoreceptors

Answer 10

Aortic Arch and Carotid Bodies… mostly respond to decreased PO2 however response to decreased PO2 magnified by hypercarbia

Carotid Bodies: Two types of cells. Type 1 & Type 2In addition to PO2, responds to low pH

Question 11

Lung Receptors

Answer 11

Pulmonary stretch receptors-Hering-Breuer Reflexes

Irritant receptors-lay between airway epithelial cells

J receptors-nonmyelinatedC fibres… juxtacapillary… can cause rapid shallow breathing, OR apnea

(NOT REALLY COVERED IN THE TEST)

Question 12

Response to CO2

Answer 12

Under most circumstances, is the major stimulus to ventilation

Primarily which chemoreceptors? Central chemoreceptors

Question 13

Altered

Answer 13

Metabolic Acidosis = breath faster
Narcotics = slow it down

Question 14

Response to O2

Answer 14

Which receptors? Peripheral Chemoreceptors

Generally not active until PO2 around 50

Question 15

Response to pH

Answer 15

Peripheral chemoreceptors primarily

Can affect central chemoreceptors if huge decrease as BBB becomes permeable to H+