Transcript Nervous Control of Breathing

Nervous Control of
Breathing
Control of Breathing
Respiratory Center
Other aspects
Control of Breathing

Respiratory muscles can be controlled
voluntarily

Normal breathing is rhythmic and
involuntary
Respiratory Center

Control by a group of neurons in the brainstem: the
respiratory center



Neurons in the Medulla control the rhythm of
breathing


Medulla oblongata = “rhythmicity area”
Pons = “pneumotaxic area”
Neurons emit impulses that signal the diaphragm and other
inspiratory muscles to contract. Neurons remain inactive
while expiration occurs passively
Neurons in the Pons transmit impulses to the medulla
continuously and regulate the duration of inspiratory
bursts (control of rate)
Transport of CO2

Blood in capillaries gain CO2 because body tissues contain
high PCO2

The CO2 could be transported
 Dissolved in blood (only~7%)
 As Carbaminohemoglobin (~23%)
 As HCO3- (most important form)
 CO2 + H2O
H2CO3 w/ aid of carbonic anhydrase

Carbonic acid dissociates:
H2CO3
H + HCO3-

Chemoreceptors in the carotid and
aortic bodies detect changes in the
blood pH
Other facts about breathing


Breath test: Respiratory
surfaces are so thin that
certain substances other that
CO2 may diffuse into the
alveolar air and be expelled
during breathing
A person emotionally upset
may hyperventilate (become
dizzy, lose consciousness ,
faint: alkalosis) due to low
CO2 conc, and a rise in
blood pH



CO may combine
w/hemoglobin more
effectively than O2
Ordinary air contain 0.04%
CO2
Air to which additional CO2
is added is used to stimulate
the rate and depth of
breathing. If a person
inhales air containing 4%
CO2 the breathing rate
usually doubles