Transcript Chemical Control of Respiration

Chemical Control
of Respiration
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Chemical Control of Respiration
 Central Chemoreceptors----- on ventral surface of medulla, close to
neurons involved in respiratory control
 Peripheral Chemoreceptors----- Aortic(along the arch of aorta) and
carotid bodies( in the bifurcation of common carotid artery)
Location of the peripheral
Chemoreceptors
Peripheral Chemoreceptors
Situated in aortic and carotid bodies
Respond to



Decreases in arterial PO2
Increases in arterial PCO2
Decreases in arterial pH
Effect of threateningly low arterial Po2 on ventilation
Arterial Po2 < 60 mm Hg
Emergency
Life-Saving
mechanism
Peripheral
Chemoreceptors
Medullary
Respiratory
Center
Ventilation
Arterial Po2
Central
Chemoreceptors
Effect of Increased arterial Pco2 on ventilation
Arterial Pco2
Brain ECF
Pco2
H2O
(When
arterial
CO2 +
Pco2
>70 – 80
mm Hg)
Brain ECF
H2CO3
H+
HCO3
Brain ECF
H
Weakly+
Peripheral
Chemoreceptors
Chemoreceptors
Medullary
Respiratory
Center
Ventilation
Arterial PCO2
Central
Effect of increased arterial non- carbonic-acidgenerated hydrogen ion on ventilation
Acidosis
Arterial non-CO2-H
Relieves
Cannot penetrate
Blood-brain barrier
Peripheral
Chemoreceptors
Center
Medullary
Respiratory
Ventilation
Arterial Pco2
Arterial Co2 - H
Central
Chemoreceptors
Influence of Chemical Factors on Respiration
Chemical Factor
Central
Effect on the peripheral
Chemoreceptors
Effect on the
Chemoreceptors
Po2 in the arterial
Stimulates only when the arterial
blood
Po2 has fallen to the point of being
life-threatening (<60 mm Hg); an
emergency mechanism
Central Chemoreceptors
and the respiratory
center itself when
<60mm Hg
Pco2 in the Arterial
Blood ( H+ in the
control of
Brain ECF )
Weakly stimulates
Strongly stimulates; is
the dominant
depresses the
H+ in the Arterial
cannot
blood
Directly
ventilation (Level> 70-80
mm Hg directly depress
the respiratory center
and central
Chemoreceptors)
Stimulates; important in acid-base
balance
Does not affect;
penetrate the
blood -brain barrier
Other factors that effect respiration
 Voluntary control of Respiration.
 Effect of irritant Receptors in the Airways
 Function of Lung “J Receptors”
 Effect of Brain Edema
 Anesthesia
 Influence of emotions
 Pain
 Swallowing
 Joint and muscle receptors
 Lung stretch receptors--- Hering- Breuer reflex
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