what originates in the medulla oblongata of the brainstem
rhythmic neural impulses responsible for ventilation
what does DRG stand for
dorsal respiratory group
what does the DRG mainly contain
inspiratory neurons
what does VRG stand for
ventral respiratory groups
what does VRG mainly contain
intermingled inspiratory and expiratory neurons
what provides the main stimulus for inspiration
DRG
what are the 2 main nerves sending impulses for respiration
vagus and glossopharyngeal nerves
where do the vagus and glossopharyngeal nerves transmit the sensory impulse to and from
to the DRG from the lungs, airways, peripheral chemoreceptors, and joint proprioceptors
where are vrg neurons located
bilaterally in the medulla in 2 separate nuclei
what does the vrg neurons contain
both inspiratory and expiratory neurons
where can inspiratory vrg neurons send motor impulses through what nerve
vagus nerve
what does sending inspiratory vrg neurons send motor impulses through the vagus nerve
laryngeal and pharyngeal muscles, abducting the vocal cords, and increasing the diameter of the glottis
where else does vrg inspiratory neurons transmit impulses
diaphragm and external intercostal muscles
where do expiratory vrg send impulses
internal intercostal and abdominal expiratory muscles
what complexes are thought to be responsible for RHYTHMIC breathing
botzinger complex and pre-botzinger complex
what is the inspiratory ramp signal
the signal firing rate increases gradually after expiration ceases, creating a smoothly increasing ramp signal
what does the ramp signal lead to
progressively stronger contraction of inspiratory muscles, smoothly and gradually filling the lungs instead of an abrupt insp gasp
what part of the brain promotes rhythmic breathing
the pons
what are the 2 groups of neurons in the pons
apneustic center
pneumotaxic center
what does the apneusis consist of
prolonged insp gasp interrupted by occasional expirations
what holds the apneusis center in “check”
vagal and pneumotaxic center impulses
what are the pneumotaxic centers
bilateral groups of neurons in the upper pons
what do the pneumotaxic centers control
the off-switch point of the drg inspiratory ramp signal and control the length of inspiration
what do strong pneumotaxic signals cause
shorten the insp time and increase the RR rate
what do weak pneumotaxic signals cause
prolonged insp time and large tidal volumes
what is the primary function of the pneumotaxic center
limit inspiration and hold apneustic center impulses in check
where is the herring-breuer inflation reflex generated
stretch receptors located in the smooth muscle of large and small airways
why are the herring-breur receptors called slowly adapting
bc their activity continues as long as the stimulus persists
what happens when the herring-breur receptors are stretched
they send inhibitory impulses through the vagus nerve to the DRG neurons which stops further inspiration
when is the herring-breuer reflex activated
large tidal volumes b/w 800-1000ml
when is the herring-breuer reflex most important
regulating the respiratory rate and depth during moderate to strenuous exercise
what does a sudden collapse of the lung stimulate
strong inspiratory efforts and increases the respiratory rate
what is the pathway and reflex that effect hyperpnea
vagus nerve (pathway) and herring-breuer reflex
what reflex is responsible for the hyperpnea for pneumothorax
deflation reflex
what does head’s reflex do
maintains large tidal volumes during exercise and may be involved in periodic deep sighs during quiet breathing
what do periodic sighs help prevent
alveolar collapse or atelectasis
what reflex may be involved in stimulating the first breaths of a new born infant
heads reflex
where are the rapidly adapting irritant receptors
epithelium of the larger conducting airways
what sensory nerve fibers do the irritant receptors use
vagal sensory nerve fibers
what happens when the irritant receptors are stimulated
they cause bronchoconstriciton, coughing, sneezing, tachypnea, and narrowing of the glottis
what does a vagovagal reflex cause
laryngospasm, bronchospasm, coughing, and slowing of the heartbeat
what types of things can cause a vagovagal reflex response
endotracheal intubation, airway suctioning, and bronchoscopy
what are j-receptors
c-fibers in the lung parenchyma near pulmonary capillaries
how are j-receptors stimulated
alveolar inflammatory processes (pneumonia) pulmonary vascular congestion (chf), and edema
what does j-receptor stimulation cause
rapid shallow breathing, dyspnea, and expiratory narrowing of the glottis
where are proprioceptors located
muscles, tendons, and joints
what happens when the proprioceptors or positional sensors fire off
they send impulses to the medullary centers which increases inspiratory activity and hyperpnea
what do propriocepters initiate and maintain
increased ventilation during exercise
what are muscle spindles
stretch sensing elements located on muscle fibers
what stimulates chemoreceptors
increase in blood H+ concentrations NOT co2
where do chemoreceptors transmit their impulses
to the medulla
what do the chemoreceptors cause
increase in ventilation
how does H+ rise in the cerebrospinal fluid
from the reaction b/w dissolved co2 and h2o
where are chemoreceptors located
carotid arteries and medulla
what are the common carotid arteries and the aortic arch indirectly sensitive to
hypoxemia and co2