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27 Cards in this Set
- Front
- Back
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where is the respiratory center
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bilaterally in the medulla oblongata and pons of the brain stem
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3 major collections of neurons in the respiratory center
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1) dorsal respiratory group 2) ventral respiratory group 3) pneumotaxic center
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dorsal respiratory group main fxn
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inspiration; most fundamental role
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ventral respiratory group main fxn
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expiration; inactive in normal respiration - mostly used in pulmonary overdrive like exercise
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pneumotaxic center main fxn
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rate and depth of breathing
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where are most of the neurons in the dorsal respiratory group
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nucleus of the tractus solitarius
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what transmits signals to the nucleus solitarius and from where
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sensory termination of vagal and glossopharyngeal nerves from primary chemoreceptors, baroreceptors, and several types of receptors in the lungs
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nervous signal to diaphragm
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begins weakly and increases steadily in a ramp manner for ~2 seconds, then ceases abruptly for next 3 seconds
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where is the pneumotaxic center located
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nucleus parabrachialis of upper pons; control switch-off point of inspiratory ramp
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strong vs weak pneumotaxic signal produces
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short vs prolonged inspiration
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where is the ventral respiratory group located
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nucleus ambiguus rostrally and nucleus retroambiguus caudally
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stretch receptors
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located throughout lungs and send signals via vagi to dorsal respiratory group when overstretched
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Hering-Breuer inflation reflex
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stretch receptors acting much like pneumotaxic center to stop inspiration; protective mechanism
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what does excess CO2 and H+ act on to affect respiration
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mainly act directly on respiratory center causing greatly increased strength of inspiratory and expiratory motor signals
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how does O2 affect respiration
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acts on peripheral chemoreceptors located in carotid and aortic bodies which transmit signals to respiratory center
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what has a potent direct affect on chemosensitive area of respiratory center
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H+ ions, but don't cross blood-brain barrier, so CO2 indirectly affects via buffer system with bicarb
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acute vs chronic CO2 affects on respiration
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potent acute effect, weak chronic effect due to adjustments in buffer system by kidneys
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at what partial P does O2 have an affect on respiration
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mainly below 70 mmHg
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afferent nerve fibers of carotid bodies travel through
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Hering's nerves to glossopharyngeal nerves then to dorsal respiratory center of medulla
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afferent nerve fibers of aortic bodies travel through
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vagi to dorsal respiratory center of medulla
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peripheral vs central stimulation by CO2 and H+
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peripheral occurs as much as 5 times more rapidly and may be important at the onset of exercise
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sensitive cells of carotid bodies
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may be glandular-like glomus cells or nerve endings may be directly sensitive
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acclimatization of mountain climbers
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within 2-3 days respiratory system center loses about 4/5 sensitivty to changes in PC)2 and H+, thus can be much more sensitive to changes in O2
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exercise and respiration stimulation
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may be due to motor impulses to exercising muscles also sending signal to stimulate respiration
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two conditions that can cause Cheyne-Stokes breathing
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1) long delay for blood transport from lungs to brain (severe cardiac failure) 2) increased negative feedback (brain damage)
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basic reason for Cheyne-Stokes breathing
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pCO2 in brain and pulmonary blood are not equal
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sleep apnea symptoms
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daytime drowsiness, increased sympathetic activity, high heart rates, pulmonary and systemic hypertension, greatly elevated risk for heart disease
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