4A: Gas Exchange Flashcards
Where is the neural respiratory center, and describe its effect on HR?
Medulla - rate is slow and irregular, TV is low
What area mediates neural respiratory control?
To areas in the pons - make it even and rhythmical
What is the first site of chemical mediation?
Through the BBB where H+ indirectly signals CO2 levels
What is the primary driver to breath?
Increase in CO2 in the cells
What is the function of chemoreceptors in relation to chemical mediation?
Secondary drive to breathe
Where are chemoreceptors found?
Carotid and aortic bodies
What are chemoreceptors sensitive to?
Hypoxemia - low oxygen levels
What is the effect when chemoreceptors are stilumated?
Increase respiration
What is the role of the spinal cord in relation to neural input from activity?
Receives info regarding motion and activity, stimulates the medulla to increase RR
What does the spinal cord receive info from?
Skeletal muscle receptors, stretch, tension, and metabolic changes
What stimulates J-receptors?
Hyperinflation of the lungs
What happens when J-receptors are stimulated?
Bronchoconstriction and increased mucous
What is the general function of the J-receptors?
Play a role in protecting the lungs during times of threat from chemicals, thermal agents, and other environmental stressors
What is the action of J-receptors?
Reduce tidal volume and constrict the bronchial airways, to cause increased mucous production, and coughing
What is V/Q influenced by?
Gravity and positioning
Are ventilation and perfusion equally distributed in lungs?
No - when upright, lung and perfusion increase from apex to base
Does ventilation or perfusion have a greater differential from the apex to base of the lung?
Perfusion increases 3x faster from apex to base than ventilation
What is the major contributor to ventilation difference?
Higher RV in uppermost alveoli creates dead space compared to dependent lung
What is perfusion?
Gravity affects the lungs and how blood is distributed
What is the greatest influence to perfusion?
Low pulmonary pressures and distensibility properties of capillaries
What lung area does the majority of gas exchange occur and why?
In the base due to higher perfusion
In a variety of positions, what area of the lungs will get the greatest perfusion?
The most dependent tissue (gravity dependent)
Describe ventilation in sidelying
Most dependent hemi-diaphragm has the greatest excursion and results in greater ventilation
Describe elasticity of the lungs
The ability for it to retract and recoil
What is compliance?
A measure of distensibility or stiffness - measure of how much lung tissue will expand
