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Control of ventilation
Terms in this set (32)
what does the medulla oblongata do?
maintains involuntary & volunatry rhythm of breathing
sends neural impulses down Rt & Lt phrenic nerve to diaphram and sends neural impulses down cervical, thoracic and lumbar motor nerves to stimulate external intercostal muscles
medulla contains what 2 groups?
dorsal respiratory group & ventral respiratory group
what do the 2 respiratory groups do?
receive impulses, evaluate & prioritize these signs and sends out impulses to muscles of ventilation
what are afferent signals?
sensory-- transmission of nerve impulses to CNS
what are efferent signals?
motor- transmission of nerve impulses away from the CNS
information on dorsal respiratory group:
located dorsally in posterior of medulla, consists of inspiratory neurons,sends neural impulses every few seconds to muscles of inspiration, responsible for rhymthn of breathing,
-sends impulses of 12-15breaths/min & lasts for 1-2 secs then relaxes
information on ventral respiratory group:
network neurons through brainstem, spinal cord, pons, and medulla
contains both inspiratory and expiratory neurons, active during heavy excercise or stress
-sends impulses to muscles of exhalation and accessory muscles of inspiration
pontine respiratory center contains what?
apneustic center & pneumotaxic center
what is the apneustic center?
located in lower potion of pons, sends impulses to stimulate inspiratory neurons of DRG and VRG
-if restrained breath hold occurs= apneustic breathing
-is inhibited by pneumotaxic center
what is the pneumotaxic center?
located in upper potion of pons, sends impulses to inspiratory center to shorten inspiratory phase, strong signals decrease IT and increase RR
-weak signals increase IT & decrease RR
what are conditions that depress the respiratory center?
-reduced blood flow through medulla: excess pressure from cerebral edema & intracerebral abnormality
-drugs: suppression of central nervous system
what does the monitoring system do:
sends impulses to DRG & VRG w/ information
two major systems: central chemoreceptors & peripheral chemoreceptors
central chemoreceptors do what?
regulate ventilation through the INDIRECT effects of CO2 on the pH of the CSF
-monitors H ion concentration of CSF
what happens when CO2 increases and cross over the BBB?
increase H ions go into CSF causing central chemoreceptors to send signal to respiratory center to increase ventilation to decrease CO2.
peripheral chemoreceptors do what?
located on upper part of internal and external carotid arteries & on the aortic notch
-react to oxygen levels in the blood ex: PaO2= 60 is SaO2= 90
what happens when PaO2 levels in the blood are too low?
afferent (sensory) signals are sent to resp center in medullar from carotid bodies (peripheral chemoreceptors)(nerve IX), or from aortic bodies (nerve X)
-this sends efferent (motor) signals to resp muscles to increase ventilation
-carotic bodies play role in response than aortic bodies
what chemoreceptors are sensitive to PO2 of blood?
what are conditions where PO2 is normal but O2 content of blood is very low?
chronic anemia & carbon monoxide poisoning
what are other factors that will stimulate the monitoring system?
peripheral can be stimulated by decreased pH
-PCO2 level not responsible for arterial H ion level change, increased lactic acid & increaesd ketones
those other factors do what?
stimulate hyperventilation to decrease CO2 through peripheral chemorecptors
what are responses to the peripheral chemoreceptors stimulate?
peripheral vasoconstriciton, increase PVR, systemic arterial hypertension, tachycardia, increase in left ventricular performance
what are the reflexes that influence ventilation?
hering-breuer reflex (inflation reflex), deflation reflex, irritant reflex, juxtapulmonary-capillary receptors, peripheral proprioceptor reflexes, hypothalamic controls, cortical controls, aortic & carotid body sinus baroreceptors
what is the Hering-Breuer reflex?
generated by stretch receptors, become excited when lungs over inflate, sends signals to medulla to cease inspiration, protective mechanism especially in newborns.
what is the deflation reflux?
mechanism for this reflex unknown, premise that RR increase when lungs are deflated
what is the irritant reflux?
stimulated when lungs are exposed to noxious gas or accumulated mucus
-cause RR to increase, cough, sneeze or bronchoconstriction
what is the juxtapulmonary- capillary receptors?
receptors located near alveolar caps, react to chemicals and mechanical stimulation to trigger rapid, shallow breathing pattern
what is the peripheral proprioceptor reflexes?
located in muscles, joints, tendons and pain receptors of muscles and skin
-send impulses to medulla which sends out inspiratory signals
what is the hypothalamic controls?
sympathetic center in hypothalamus activated by strong emotions
what are cortical controls?
activation of conscious voluntary control of ventilation
what is aortic & carotid body sinus baroreceptors?
initiate refluxes to increase or decrease RR.
what is involved in normal neuromuscular function of breathing?
chemoreceptors (central & peripheral), respiratory centers (apneustic & pneumotaxic), peripheral nerves, respiratory muscles (diaphram, external intercostal, scalene, sternocleidomastoid)
what are a few neuromuscular disorders?
CNS (central sleep apnea, sedative overdose), Neuronal Pathway (spinal cord injury, multiple sclerosis, ALS), Neuromusclar junction (myasthenia gravis), Muscular Function (muscula dystrophy)
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