resp 8 Flashcards
what is the other mechanism besides converted to acid to remove CO2?
-when O2 leaves Hb at the tissues, CO2 binds with free hemoglobin at exposed amino groups (-NH2), forming carbaminohemoglobin
what is the respiratory gas equilibrium between eh venous blood and the cells graph?
-would continue until PCO2 is equilibrated between cell, plasma and RBC
what is the CO2 removal at the lungs?
-plasma CO2 diffuses into alveoli-> RBC CO2 diffuses into plasma
-causes CO2 to unbind from Hb and diffuse out of RBC
-as CO2 levels in RBC drop, the equilibrium of CO2- and HCO3- is disturbed causing the reaction to reverse (Hb releases H+ joins HCO3- to become carbonic acid, CA then converted to H2O and CO2)
-as HCO3- drops, Cl-/HCO3- exchanger reverses
what is the whole graph of O2 pickup to CO2 delivery?
breathing is a rhythmic process that often occurs __________________
SUBCONSCIOUSLY SIMILAR TO THE BEATING OF THE HEART
what is the regulation of ventilation?
-skeletal muscles that control ventilation cannot contract spontaneously
-spontaneously firing networks of neurons in the brainstem
-this network is influenced by sensory and chemoreceptors, as well as by higher brain centers
-neural control of ventilation considered “blackbox” (still don’t understand)
what is the current model for control of respiration?
- respiratory neurons in the medulla control inspiratory and expiratory muscles
- neurons in the pons integrate sensory information and interact with medullary neurons to influence ventilation
- rhythmic pattern of breathing arises from a neural network with spontaneously discharging neurons
- ventilation is continuously modulated by various chemo and mechanoreceptor-linked reflexes and by higher brain centers
neurons in the ____________control breathing
MEDULLA
what is the graph of the neural networks in the brainstem that control ventilation?
what does the NTS do?
nucleus tractus solitaris
-NTS of the medulla contains the dorsal respiratory group of neurons (DRG) that mainly control inspiratory muscles via phrenic nerve and intercostal nerve
-NTS receives input from the peripheral mechano and chemoreceptors
what does the PRG do?
pontine respiratory group
-receives sensory info from DRG
-provides tonic input to DRG to help the medullary networks coordinate a smooth respiratory rhythm
-does not create the rhythm
what are the areas and functions of the VRG (ventral respiratory group)?
-pre-botzinger complex: contain pacemaker neurons that may initiate respiration
-control muscles of active inspiration and expiration, remain quiet otherwise
-outputs that keep upper airways open (tongue, larynx, pharynx). Sometimes outputs slow down too much while asleep: sleep apnea, snoring
what is the graph of neural activity during quiet breathing?
believed to be initiated by a pacemaker
-positive feedback loop recruits more neurons “ramping” recruiting more outputs to inspiratory muscles
what do peripheral chemoreceptors do?
-aortic and carotid bodies sense changes in arterial PO2, PCO2 and pH and adjust ventilation accordingly
what are glomus cells?
it takes a large drop in arterial PO2 to trigger peripheral chemoreceptors
-respond to PO2 in plasma
-can also respond to increases in H+
-respond to increases in CO2
what is the huge graph that we don’t have to know? (glomus response)
what do central chemoreceptors respond to?
-respond to pH changes in the cerebrospinal fluid (CSF) caused by CO2, but not to changes in plasma pH (H+ cannot cross the blood brain barrier well, but CO2 can)
-neurons in these region contain H+ sensitive channels (ASIC) that become activated and transmit AP’s to the respiratory control central
what is the graph of CSF and central chemoreceptors?
what happens when there is decreased arterial O2?
what happens when there is increased arterial H+?
what happens when there is increased arterial CO2?
-most sensitive to changes in CO2
-mediated by both central chemoreceptors (70% primary) and peripheral chemoreceptors (30%)
-very high PCO2 will actually depress ventilation
what are irritant receptors?
respond to inhaled particles or noxious gases
-send input into the CNS, parasympathetic outputs then respond by causing bronchoconstriction
-leads to rapid shallow breathing and turbulent airflow to deposit irritant in mucosa
-reflexes can initiate coughing or sneezing
what are stretch receptors?
in the lung prevent over inflation of the lungs “Hering-Breuer inflation reflex”
what is the summary slide of what control breathing?
how is ventilation influenced by exercise?
what are the graphs of how ventilation is affected during exercise?
-ventilation can increase 20-fold during exercise
