Quiz 6 Flashcards
What are the three groups of neurons located in the brainstem?
- Dorsal Respiratory.
- Ventral Respiratory.
- Pneumotaxic center
Which neuron group plays the most fundamental role in control of breathing?
Dorsal Respiratory
Which two nerves deliver sensory information to DRG
The Vagal (X) nerve and Glossopharyngeal (IX)
What is an inspiratory RAMP signal?
Motor signal transmitted from the DRG to the diaphragm is NOT an instantaneous action potential burst. Begins weakly and increases (ramp like) manner for 2 seconds to cause contraction of diaphragm.
What does the pneumotaxic center do for breathing?
Functions to limit inspiration phase of breathing cycle and secondarily to increase rate of breathing.
How does the VRG function differently from DRG?
VRG inactive during normal quiet respiration.
Stimulates abdominal muscles to assist in forced exhalation. Contributes to respiratory drive but NOT rate
What is the Hering-Breuer Reflex ?
Protective feed-back reflex which limits the over inflation of lungs. This reflex also increases the rate of respiration (versus size of breath)
What does excess carbon dioxide do to the respiratory center?
Act directly on respiratory center to increase strength of both inspiratory and expiratory motor signals.
Does oxygen have a direct effect on respiratory centers?
No
Where does oxygen have its effect for respiratory drive?
On peripheral chemoreceptors in carotid and aortic bodies
Which has a greater effect on stimulating chemosenstiive neurons- pH or CO2?
CO2 is believed to cause stimulation of these neurons.
What is the relationship of CO2 between the blood and the brain?
CO2 is highly permeable to blood-brain barrier so blood and brain concentrations are equal
How does chronic increased CO2 concentration differ from acute?
Changes in blood CO2 concentration has potent acute effect on controlling respiration drive but a weak chronic effect after a few days of adaptation
What type of patient might have blunted responses to increased CO2
Chronic Obstructive Pulmonary Disease
Which has a greater effect on alveolar ventilation- PCO2 or pH?
PCO2 changes rapidly change in rate of pulmonary ventilation
Does oxygen have an effect on respiratory center to alter respiratory drive?
No changes in oxygen have virtually no direct effect on respiratory center.
At what PO2 are peripheral chemoreceptors sensing a low oxygen level?
Blood oxygen levels below PO2 of 70mmHg are sensed by peripheral chemoreceptors
Where are the two major peripheral chemoreceptors located?
Carotids and aorta
Which afferent nerve fiber sense back to DRG from the carotid bodies?
CN IX (glossopharyngeal)
Which afferent nerve fiber sense back to DRG from the Aortic body?
CN X (vagus nerve)
What is acclimatization?
When mountain climbers slowly ascend to higher elevation to withstand lower atmospheric oxygen concentrations.
How does low arterial oxygen effect ventilatory drive?
When CO2 and pH remain normal; ventilatory drive y low blood oxygen content is not significant until PO2 falls below 100mmHg.
Ventilation doubles when PaO2 falls below 60mmHg
What causes increase in ventilation during exercise?
Multiple factors:
Muscle/joint movement proprioceptors send.
Hypoxia in muscles elicits afferent nerve signals to excite resp center.
PCO2 and PO2 changes stimulate respiration
What are Lung J Receptors?
Sensory nerve ending in alveolar walls juxtapose the pulmonary capillaries.
They become stimulated when engorged by blood or with pulmonary edema occurring in CHF.
Their excitation may give the feeling of dyspnea
