3. Physiology
        3.13. Respiratory
            3.13.4. Regulation of respiration
3.13.4.1. Receptor

Receptors

  1. Central chemoreceptors
  2. Peripherial chemoreceptors
  3. Lung receptors
  4. Other receptors

1. Central chemoreceptors

Detects only changes in PaCO2.
--> Thus responsible for hypercapnic drive

NB:

Location

Effect of PaCO2 on central chemoreceptors

Changes in PaCO2
--> Changes in PCO2 in CSF

Since there are less protein and haemoglobin in CSF (i.e. less buffer)
--> changes in PCO2 in CSF leads to great changes in pH

When PaCO2 increase
--> Cerebral vessels dilate
--> Faster diffusion of CO2
--> Faster changes in pH in CSF

Prolonged change in PaCO2

When changes are prolonged

--> HCO3 moves across the blood-brain barrier to buffer the pH change in CSF (unknown if transport is active or passive)

--> CSF pH change is buffered BEFORE renal compensation of blood pH changes

--> Respiratory change is reduced

Summary - central chemoreceptor

2. Peripheral chemoreceptors

Rapid response

Location

  1. Carotid bodies (important)
    @ Common carotid bifurcation
    * Innervated by carotid sinus nerve, then glossopharyngeal
    * Connect to medulla [WG22:p674]
  2. Aoric bodies
    @ Above and below aortic arch
    * Innervated by vagus nerve [WG22:p674]

Carotid bodies

Contains glomus cells (type I and type II)

 

Factors stimulating peripheral chemoreceptors

Responds to:

Additional effects of peripheral chemoreceptors

In addition to increased ventilation, peripheral chemoreceptor stimulation also causes

Others

Summary - peripheral chemoreceptors

Stimulated by:

3. Lung receptors

Pulmonary stretch receptor

(slow adapting)

1.  Hering-Breuer reflex
--> Distension of lung
--> Stimulation
--> Increase in expiration time and decrease in RR
--> Acts primarily to limit or prevent hyperinflation, and are less important for controlling respiratory rate.

2. Deflation reflex
--> deflation of lung
--> tends to initiate inspiratory effort

@@Please WG22:p678-679 for more info

Irritant receptors

Irritation (noxious gas, cigarette, dusts, cold air)
--> bronchocontriction and hypercapnoea

Others

4. Other receptors

Arterial baroreceptors

Pain and temperature

Joint/muscle receptor

Other notes

About
Created20050220
Updated20050220
Reviewed20050303
Printed1.0


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