C o n t r o l o f t h e r a t e a n d d e p t h o f b r e a t h i n g b y t h e r e s p i r a t o r y c e n t e r •
F ig u r e 1 3 . 7
The respiratory center consists of four groups of neurons in
the medulla oblongata and pons.
The pneumotaxic area turns
off the inspiratory area to
shorten inhalations and
increase breathing rate.
The apneustic area activates
the inspiratory area to prolong
inhalation for a long, deep
inhalation.
->
■ >
The inspiratory area
establishes the basic
rhythm of breathing by
turning on and off.
INSPIRATORY AREA
ACTIVE
INACTIVE
Sagittal
plane
The expiratory
area becomes
active during
forceful exhalation.
INSPIRATORY AREA
ACTIVE
Activates
y
—►
EXPIRATORY AREA
2
seconds
Diaphragm and external
intercostals contract
I 3 seconds
I
Diaphragm and external
intercostals relax,
followed by elastic
recoil of lungs
I
Diaphragm,
sternocleidomastoid,
and scalene muscles
contract
I
Internal intercostal
and abdominal
muscles contract
Normal quiet inhalation
Normal quiet exhalation
Forceful inhalation
Forceful exhalation
over the breathing process if the cerebrum attempts to
do anything that becomes potentially life-threatening. As
soon as the buildup of CO2
and H+ in your blood and ce-
rebrospinal fluid (CSF) gets to a certain point, the brain-
stem sends a powerful stimulus to breathe.
When you laugh or cry, your respiration is also sig-
nificantly different from normal, quiet breathing. Nerve
impulses from the hypothalamus and limbic system stim-
ulate the respiratory center, allowing emotional stimuli
such as laughing or crying to alter respirations.
The Brain Controls Breathing 387
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