Part VII Flashcards
What is the goal of regulation of ventilation?
to keep arterial levels of CO2 and O2 constant
The nervous system adjust the level of what to match perfusion of lungs?
respiratory rate and tital volume (ventilation)
match ventilation w/ pulmonary blood flow
match ventalation with what?
overal metabolic demand
Where is the dorsal repsiraotyr group located?
primarily in the nucleus tractus solitarius in the medulla
Ther termination of what cranial nerves is also in the medulla?
CN IX and X
What does the dorsal respiratory group receive input from?
peripheral chemoreceptros, baroreceptors and receptors in the lung
What neurons are rhythmically self-excitatory?
dorsal respiratory group
What muscles does the dorsal respiratory group excite?
muscles of inspiration
What sets the basic drive of ventilation?
dorsal respiratory group
What happens when the pneumotaxic center is inhibited?
it increases the duration of inspiration and increases tital volume
Where is the pneumotaxic center located?
nucleus parabrachialis of upper pons
How can the pneumotaxic center inhibit the duration of inspiration?
by turning off dorsal respiratory group ramp signal after the start of inspiration
Where are the ventral respiratory groups of neurons located?
bilaterally in the ventral aspect of medulla oblongata
What can the ventral respiratory group of neurons excite?
both inspiratory and expiratory respiratory muscles during increased ventilatory drive
What is the function of the apneustic center?
functions to prevent inhibition of dorsal respiratory group under some circumstances
Where is the apneustic center located?
lower pons
Herring Breuer Inflation reflex.
stretch receptors located in the wall of the airways
When are Herring stretch receptors stimulated?
when stretched @ tital volumes greater than 500mL
Irritant receptors
among airway epithelium
What do irritant receptors do?
stimulates sneezing and coughing and possibly airway consriction
J receptors
alveoli next to pulmonary capillaries
When are J receptors stimulated?
stimulated when pulmonary caps are engorged (pulmonary edema)
Why is pulmonary edema bad?
because it makes it so theres not enough oxygen because blood isn’t pumped through fast enough and can create a feeling of dyspnea
What are the physiologic consequences of hyperventilation?
decreased stroke volume and decreased coronary blood flow, repolarization of the heart is impaired, oxy-hemoglobin affinity increased, cerebral blood flow decreased, skeletal muscle spams and tetany, serum potassium decreased
What is the common thread in most of the physiologic consequences of hyperventilation?
hypocapnic alkalosis
How does brain edema effect ventilation?
depresses or inactivates the respiratory centers
How do you treat brain edema?
intravenous hypertonic solution
What is the most prevalent cause of respiratory depression?
anesthesia/narcotics
How does exercise stimulate ventilation?
the increased corticospinal traffic which will collaterally stimulate respiratory centers in the brain stem
What comes from active muscle spindles and joint proprioceptors?
reflex neural signals
What stimulates local chemoreceptors when it comes to exercise?
fluctuations in O2 and CO2
What is the most important adjustment in life?
breathing
How is the first breath stimulated?
cooling of the skin, slightly asphyxiated state (increased CO2)
How much negative pressure do babies have to get through in order to open alveoli for the first breath?
40-60cm H2O
How much negative pleural pressure is needed for every other breath? (minus the first one)
2.5cm H2O
What are the circulatory changes at birth?
placenta disconnects, TPR increases, pulmonic resistance decreases (elimination of hypoxia), closure of the foramen ovale (atrium), closure of the ductus arteriosis (great vessels), closure of ductus venosus (bypass liver)
What are chemosensitive areas of the respiratory center stimulated by?
hydrogen ions and carbon dioxide
What is the primary stimulus of chemosensitive areas of the respiratory center?
hydrogen ions
Can hydrogen ions cross the BBB?
no
Can carbon dioxide cross the BBB?
yes
Why is there a faster increase in ventilation when there is a rise of CO2 in the CSF?
because there aren’t buffers to prevent CO2 from coming in like there is in plasma
chemosensitive areas of the respiratory center are unresponsive to what?
oxygen, it just depresses normal activity
How much CO2 increases ventilation?
70-80%
