Lecture 8: Resistance to Airflow

resistance to airflow have the same principles as

blood flow

F=

change in pressure/resistance

what produces airflow

pressure gradient

two factors influence airway resistance

1. bronchiole diameter
2. pulmonary compliance

bronchodilation

-increase in diameter
-epinephrine and sympathetic stimulation
-increase airflow

bronchoconstriction

-decrease in diameter
-histamine, parasympathetic nerves, cold air, chemical irritants
-decrease airflow
-suffocation can occur from extreme bronchoconstriction

pulmonary compliance

ease with which the lungs can expand
change in lung volume relative to a given pressure change

compliance is reduced by

degenerative lung diseases
the lungs are stiffened by scar tissue

determinants of lung compliance

elasticity
surface tension

effect of H ions

pulmonary ventilation is adjustd to maintain pH of brain

acidosis

excessive acidity of body fluids

normal pH

7.35-7.45

alkalosis

pH above 7.45

PCO2 usually ranges from

37mmHg-43mmHg in arterial blood

hypocapnia

condition of deficient carbon dioxide (in the blood)

hypercapnia

excessive carbon dioxide in the blood

what if ventilation cannot match the rate of CO2 production?

pH imbalances
respiratory acidosis
respiratory alkalosis

ketoacidosis

excessive production of ketones, making the blood acid

is the effect of CO2 direct or indirect?

indirect

effect of respiration and exercise

-brain sends signals to respiratory centers to anticipate increased need = increase ventilation
-feed forward
-keeps gases at normal levels