Control of Respiration Flashcards
What are the components of neural control of respiration?
generation of respiration rhythm
regulation of rate/depth of breathing
modification of respiratory movements
What os the pre-Botzinger complex?
importation for generation of respiration rhythm
similar to SA node - “primes” pump
- can be modified by [gas] in blood
contains pacemaker cells that initiate spontaneous breathing
assigns rhythmic pattern of breathing
Describe the dorsal respiratory group. What kind of neurons? What stimulated it? What do they stimulate?
inspiratory neurons ONLY
expiration occurs when neuronal firing ceases
stimulated by:
CSF chemoreceptors - how much CO2 from arteries
carotid/aortic chemo and baroreceptors from vagus and glossopharyngeal nerves
bpneustic center - pons
stimulates: diaphragm and external intercostal muscles
Describe the ventral respiratory group. What kind of neurons? What do they stimulate?
inspiratory and expiratory neurons - motor control for inspiration/expiration during exercise
- increases force of inspiratory, forced exhalation
expiratory neurons stimulate internal intercostal and anterior abdominal muscles
inspiratory neurons activate accessory inspiratory muscles
What is the ramp affect and which respiratory group is responsible for them?
ramp effect - after pre-Botzinger effect, increased firing frequency increase the depth of inspiration
- once firing stops, passive exhalation occurs
Describe the pontine respiratory group (pneumotaxic center). What is its function? What does it receive input from, and what effect does it have on the apneustic center?
regulates the quantity of air inhaled with each inspiration
receives excitatory input from limbic, cerebral cortex, and ANS
- when activated, inhibits apneustic center
- in turn, this inhibits the inspiration neurons of dorsal respiratory group and decreases time of inspiration
quick, shallow breaths when activated
without pontine respiratory group - prolonged inspiration and short expiratory gasps
Describe the pons or apneustic center. What is its function? What does it receive input from? What does it affect?
fine tuning over medullary centers - stimulate inhalation
pneumotaxic center has inhibitory effect
has excitatory effect on dorsal respiratory group
- prolongs deep inhalations
- prevents cessation of breathing
How do the central chemoreceptors in the 4th ventricle know the [H+] in arterial blood?
H+ cannot cross BBB, but CO2 can
- CO2 crosses BBB into cerebrospinal fluid
- combines with H2O via Carbonic anhydrase to make H2CO3
H2CO3 dissociates into H+ and HCO3-
- central chemoreceptors in 4th ventricle bind to H+ and stimulates respiratory control centers to increase ventilation
Where are the peripheral chemoreceptors and what are they sensitive to?
locations:
aortic arch - vagus nerve
fork of common carotid artery - glossopharyngeal
glomus cells - receptors for H+ and O2 cause K channels to close
- located in carotid body
- constantly hyper polarized, when H+/O2 enter, cell depolarizes and Va channels open, vesicles with dopamine open
- signals to medullary centers to increase ventilation
sensitive to: arterial pH, PO2, PCO2 (low sensitivity)
What are the Hering Breur and irritant reflexes?
Hering Breur - stretch receptors present in visceral pleura and bronchi/bronchioles
- inhibitory impulses are sent to medullary respiratory centers
Irritant - reflex construction of bronchioles
reflex stimulus of cough or sneeze
Describe how PCO2, arterial pH, and PO2 affect rate and depth of breathing
PCO2 - higher PCO2 in arterial blood causes pH to fall
- lower pH increases rate and depth of breath
- most powerful respiratory stimulant
Arterial pH - H+ ions in venous blood do not shift easily into CSF
- H+ ions increase due to CO2 retention and metabolic disorders
PO2 - low O2 tension augments effect of CO2 in carotid sinus
- when PO2 drops below 60 mmHg, it becomes the major stimulus to respiration via peripheral chemoreceptors
