Lecture 20: Regulation Flashcards
respiratory muscles controlled by
motor neurons
respiratory muscles are sepcial because
they are under automatic AND voluntary controll
automatic resp control depends on neurons in
medulla oblongata
DRG
dorsal resp group
inspiratory neurons
basic rythm of resp
active or not: active to inhale, not to exhale
for normal breathing
just need DRG activated
only active to inhale
VRG
expiratory neurons
ventral resp group
not always active, chilling during resting breathing
VRG and DRG neurons are…
pre motor neurons
synapse on resp neurons
sent out of medulla
rythmic breathing
depends on pacemaker like activity of brainstem
spontaneous depol
pacemaker like cells
are in brainstem
control DRG
alternatively turn inspiratory neurons on and off
deopl, rest, repeat
expiratory neurons at rest…
normally silent
expiratory neurons when breathing increased
activated
VRG used
why is DRG always active
because of rythm gen neruons with pacemaker like activity
pneumotaxic center
to protect you
will inhibit DRG
if breathing too fast to slow you down
apneustic center
promote breathing in
when we need more O2
stims DRG
when you stimulate breathing out forcefully
you’ll also breathing in forcefully
during normal quiet breathing DRG is….
active for 2 seconds
rests for 3 second
receptors involved in breathing
pulmonary stretch receptors
central chemoreceptors
peripheral chemoreceptors
respiratory neurons depend on info from
various specialized receptors
inform neurons about body’s need for ventialtion
Pulmonary stretch receptors in general
alert to how stretch lungs are and how much we are pulling thm
if lungs inflated too high, we can damage tissues
Central chemo-receptors
monitor conc of CO2 ONLY
Peripheral chemo-receptors
monitor conc of O2 (mostly)
also sensitive CO2 and pH
when DRG is active
2 secs
contract diaphragm and external intercostals
inhilation (normal)
when DRG inactive
3 secs
diaphragm and external intercostals relax
elastic recoil of chest wall and lungs
exhilation (normal)
when VRG active
internal intercostals, abdominal muscules contract
forecefull EXHILATION
Forceful breathing
coordination between DRG and VRG
Forceful inhilation
VRG SENDS message to DRG toINHALE harder
internal intecauses diaphragm, sternocleidomastoid, scalenes to contract
pulmonary stretch receptor locations
smooth muscle of
some large conducting airways
bronciloes
bronchi
pulm stretch receptors stimulated when
broncioles inflated/stretch
main stim is rate of change of lung stretch
more stretch=more trigger
pulm stretch receptors innervated by
axons in Vagus nerve (X)
if you try to breath in too fast
body freaks because you change stretch too quickly
central chemo-receptors located
right below ventral surface of medulla
central chemo-receptors respond to
inc H+ ion conc in CSF
inc H+ is result of CO2 that diffuses into CSF from blood and forms of H+ ions
NOT OXYGEN
when conc of H+ goes up
an alarm signal is sent to the central chemo-receptors
peripheral chemo-receptors located
aortic arch
carotid sinus
peripheral chemo-receptors respond to (mainly)
low O2 levels in arterial blood
elevated H+ ion conc
elevation in CO2
peripheral chemo-receptors respond WEAKLY to
elevated H+ ion conc
elevation in CO2
peripheral chemo-receptors innervated by
axons from cranial nerves IX and X (glossopharyngeal and vagus)
peripheral chemo-receptors synapse on
neurons in DRG
pulmonary stretch receptor influences ______ center
pneumotaxic center
pulmonary stretch receptor influence on pneumotaxic center
inhibits DRG
inhibits inhalation
protective function
this means cells switch from inspiration in expiration more quickly
lung inflation stops
deflation strongly encouragedWhen CO2 (central chemoreceptors) receptors are set off..
we breathe in more
trigger inspiration area
response to change in conc of CO2, O2 and pH
negative feedback loop
result of breathing in more because central chemorecptors told us to
increase conc of O2
more air comes in
blow off more CO2
when there central chemoreceptors are set off
too much CO2
negative feeback loop
why peripheral monitor O2 in arterial blood
its on its way to the brain
if peripheral measure high O2
less frequent breathing
if peripheral measure LOW O2
more rapid breathing
irritant receptors
protect lung from changing shape too fast
