L25: Regulation of Respiration Flashcards
purpose of medullary respiratory centers in brainstem
initiate breathing
located in reticular formation of medulla
broken into a dorsal and ventral group
location and purpose of dorsal respiratory group
in nucleus of the tractus solitarius — aka dorsal part of medulla
sets basic rhythm of respiration
the nucleus of tractus solitarius is the termination of ?
vagal and glossopharyngeal nerves
the dorsal respiratory group receives info from ?
peripheral chemoreceptors
baroreceptors
some receptors in lungs
which respiratory groups is mainly associated w/ inspiration and establishes the ramp signal
dorsal respiratory group
location of VRG
in ventrolateral medulla
rostral part of VRG
the botzinger complex
the intermediate portion of the VRG is associated w/ ?
dilation of upper airway during inspiration
neurons of caudal region of VRG, synapse w/ ?
motor neurons to muscles of forced expiration
mainly internal intercostals
neurons of VRG are totally inactive during?
normal quiet respiration
do not participate in basic rhythm oscillation that controls respiration
location of pontine respiratory group
2 centers in 2 areas w/in the pons
apneustic center = inferior pons
Pneumotaxic center = superior pons
what are the 2 components of the pontine respiratory group
apneustic center
Pneumotaxic center
apneustic center
function to limit lung expansion
loss of function = prolonged inspiratory gasps
apneusis
prolonged inspiratory gasps
Pneumotaxic center
primary function = control switch-off point of inspiratory ramp
controls rate of depth of breathing
the Pneumotaxic center transmits signals to inspiratory center ?
dorsal respiratory group
strong vs weak PRG signals
strong = 30-40 breaths/min
weak = 3-5 breaths/min
pre-botzinger complex
small area of botzinger complex
generates timing of respiratory rhythm
generates pattern
decides length of inspiration/expiration
botzinger complex
anterior part of VRG
may be associated w/ coordinating VRG output
which respiratory group establishes the ramp signal?
dorsal respiratory group
ramp signal
nervous signals transmitted to the inspiratory muscles - mainly diaphragm
ramp signal volume
begins weakly
increase steadily for 2 sec
cease abruptly for 3 sec
rate of increase is rapid during heavy respiration
why does the ramp signal cease abruptly?
to allow for elastic recoil of lungs and chest wall
aka expiration
what is the usual method for controlling the rate of respiration?
control limiting point is at which ramp signal suddenly ceases
what is the function of the hering-breuer inflation reflex ?
a proactive mechanism to prevent excess inflation of the lungs
where does the hering-breuer inflation reflex begin?
stretch receptors in muscular portions of walls of bronchi/bronchioles
signals sent to DRG
causing inspiratory ramp ceased
define apneusis
failure to turn off inspiration
resulting in long inspiratory gasps
loss of function of which respiratory centers leads to apneusis?
apneustic center of the pontine respiratory group that limits lung expansion
define hypercapnia
increase in CO2 levels
define hypoxia
decrease in O2 levels
decreased activity in chemoreceptors is counterproductive why?
it would result in a decrease in gas exchange
when do chemoreceptors increase their activity?
increase their rate of activity when toxic conditions occur
hypercapnia/hypoxia
chemoreceptors are exposed to ______ blood not ______.
arterial not venous
what ions are mainly responsible for regulating ventilation at sea level
pCO2 and H+ ions
pO2 between 60 - 80 mmhg
location of central and peripheral chemoreceptors
central – ventral surface of medulla
peri – in aortic arch – carotid body receptors
central chemoreceptors are indirectly sensitive to ____ levels in blood based upon ___.
CO2 levels
pH
central chemoreceptor hypersensitivity to CO2 levels lasts for hours but declines with ?
renal adjustments to plasma pH
kidneys increase blood bicarbonate levels
central chemoreceptors are especially sensitive to ?
[H+]
H+ does not easily cross blood brain barrier
but CO2 does
peripheral chemoreceptors are sensitive to ?
concentrations of o2, co2, H+
describe type I glomus cells
Chemosensors located close to fenestrated capillaries
function of type I glomus cells in high pO2
K+ efflux when pO2 is high
cells are hyperpolarized
function of type I glomus cells in low pO2
K channels close
cells depolarize
Ca channels open
NTs released
type II Sustentacular cells
play a support role similar to glial cells
location and function of slow-adapting pulmonary stretch receptors
w/in airways of the lungs
sensitive to stretch of airways
important in controlling respiration in infants and adults during exercise
signals from slow-adapting pulmonary stretch receptors
signals travel in vagus n to medulla
effects:
terminate inspiration
prolong expiration
pulmonary stretch receptors are ?
mechanoreceptors
location and function of rapidly-adapting pulmonary stretch receptors
w/in airways of lungs
sensitive to irritation, foreign bodies and stretch
effects of rapidly-adapting pulmonary stretch receptors
signals travel in vagus n to brain
signals elicit cough
these receptor signals override normal respiratory control mechanisms
J receptors location and function
sensory endings in alveolar wall in juxtaposition to pulmonary capillaries - c fibers
sensitive to pulmonary edema
J receptors effects
signals travel to brain via vagus n
signals elicit coup and tachypnea
this reflex can override normal breathing mechanisms
describe the Cheyne-Stokes breathing pattern
cycles of hyperpnea and apnea, repeat
each cycle is 30s to 2 min long
define hyperpnea
increasingly deeper and rapid breathing
followed by a gradual decrease
define apnea
follows hyperpnea resulting in a temporary stop
periodic breathing
Cheyne-stokes breathing is called this when the apnea segment is replaced w/ hypopnea
define hypopnea
abnormally small breaths
these breaths are too small to ventilate the lungs
define central sleep apnea syndrome
when periodic breathing occurs during sleep
caused by damage to central respiratory centers
abnormalities of respiratory neuromuscular apparatus
what conditions lead to Cheyne-Stokes breathing?
a long delay in transport of blood from lungs to brain
such occurs during cardiac failure
or increased negative feedback that occurs in brain damage
