Chapter 22: Pressure, Resistance and Airflow

unit for pressure is...

cmH2O

during inspiration

the lungs follow the thoracic cage expansion because of intrapleural pressure

intrapleural pressure

the slightly negative pressure that exists between the two pleural layers causing the lungs and chest wall to pull in opposite directions

how do the visceral and parietal pleura stay together

cohesion of water

during inhalation visceral pleura stretches the alveoli and they increase in volume this causes...

intrapulmonary pressure to drop below atmospheric pressure and air flows into lungs

a force that expands lungs

warming of inhaled air on a cooled day (charles law)

expiration

intrapulmonary pressure rises and air flows down its pressure gradient out of the lungs

pneumothorax

presence of air in the pleural cavity when the thoracic wall is punctured and air comes in through the wound causing lung to collapse

atelectasis

collapse of part or all of a lung

two factors that influence airway resistance

bronchiole diameter and pulmonary compliance

diameter of the bronchioles

bronchodilation and bronchoconstriction

bronchodilation

epinephrine and sympathetic stimulation to increase airflow

bronchoconstriction

histamine, cold air, parasympathetic nerves to decrease air flow

pulmonary compliance

the ease with which the lungs can expand

compliance is limited by...

the surface tension of water film inside alveoli, surfactant effects this

infant respiratory distress syndrome

premature babies lacking surfactant are treated with artificial surfactant until they can make their own

what air is availabe for gas exchange

only air that enters alveoli

anatomical dead space

air in conducting zone that does not participate in gas exchange

physiological dead space (total)

sum of anatomical dead space and any pathological dead space

alveolar ventilation rate

amount of air ventilating alveoli per minute

function of AVR

very relevant to the bodys ability to get oxygen to the tissues and dispose of carbon dioxide