Regulation of respiration - chapter 42 guyton

what are the main neurotransmitters?

ACh dopamine

some more recent studies has showed that during hypoxia, what functions as a key excitatory neurotransmitter?

ATP

the afferents of the aortic bodies pass through?

CN X

besides O2, what else can stimulate the chemoreceptors?

CO2 H+

describe the indirect effect of CO2 affecting respiratory center?

CO2 reacts with water of the tissues to form carbonic acid --> dissociates into hydrogen and bicarbonate ions --> hydrogen ions then can stimulate the chemosensitive neurons

since O2 does not have an significant direct effect on the respiratory center, what effect do O2 have then?

O2 acts on peripheral chemoreceptors in carotid and aortic bodies --> send info to respiratory center

what channels do glomulus cells have? describe their action potential

O2-sensitive potassium channels that are inactivated when blood pO2 decreases markedly --> cell depolarizes --> voltage gated calcium channels open -->intracellular calcium ion concentration increases --> neurotransmitter is released that stimulates afferent neurons

location of lung J receptors?

alveolar walls in juxtaposition

what is the Herings nerve?

branch of CN IX that transmits signals from carotid bodies to CN IX

effect on breathing by acclimatization?

breathing becomes deeper - as in mountain climbers

what are glomulus cells?

cells located in the carotid and aortic bodies that function as the chemoreceptors

location and function of dorsal respiratory group?

dorsal portion of medulla - inspiration

where is the basic rhythm of respiration generated mainly?

dorsal respiratory group

what is the division of the respiratory center?

dorsal respiratory group ventral respiratory group pneumotaxic center

location and function of pneumotaxic center?

dorsally in the superior portion of the pons - controls rate and depth of breathing

excitation of the chemosensitive neuron by........ions is likely the primary stimulus

hydrogen ions

why does blood CO2 have a more potent effect in stimulating the chemosensitive neurons than do blood hydrogen ions?

hydrogen ions cannot easily pass thought the blood-brain barrier, but CO2 can pass

what is Cheyne-Stoke breathing?

irregular breathing

what is the difference in CO2 or H+ stimulating the peripheral chemoreceptors compared to stimulus directly in respiratory center?

is less powerful in the peripheral chemoreceptors, but is faster response than in the center

why is morphine not used as a anesthetic anymore?

it greatly depresses respiratory center

what occurs in increased CO2 levels during 1-2 days?

kidneys increse bicarbonate in blood --> binds with hydrogen ions. - bicarbonate can also cross the blood-brain barrier

the respiratory center is composed of several groups of neurons located bilaterally in the?

medulla oblongata and pons of the brainstem

when is the Hering-Breuer mechanisms activated in humans?

not until the tidal volume increases to more than 3x normal(ca 1,5 liters per breath)

the pneumotaxic center, located dorsally in the...?

nucleus parabrachialis of the upper pons

pneumotaxic center functions as a?

on-off switch for inspiration --> controls the filling phase of the lungs, also affects the rate of inspiration

describe the Hering-Breuer inflation reflex

stretch receptors are located in muscular parts of the walls of the bronchi and bronchioles --> these receptors transmit signals via the vagus nn to the dorsal respiratory group of neurons when lungs are overstretched. this is feedback mechanism that terminates insipration - this reflex also increases the rate of respiration

solitary tract nucleus is the sensory termination of both?

vagus & glossopharyngeal nn

location and function of ventral respiratory group?

ventrolateral part of medulla - expiration

do CO2 have much or little effect in stimulating the neurons in the chemosensitive area?

very little effect --> but it has a potent indirect effect

when do peripheral chemoreceptors respond?

when the blood O2 falls below pO2 70mmHg

what is the reason for the acclimatization?

within 2-3 days the respiratory center looses ca 4/5 of its sensitivity to pO2 changes and H+

where are most of the neurons of the dorsal respiratory group located?

within solitary tract nucleus