Physiology Flashcards
Internal Respiration
Intracellular mechanisms which consumes O2 and produces CO2
External Respiration
Events that lead to exchange of O2 and CO2 between external environment and the body. Include: Ventilation, Gas exchange between alveoli and blood, gas transport in the blood & gas exchange at the tissue level.
Ventilation
Mechanical process of moving gas in and out of the lungs.
Gas Exchange between Alveoli and Blood
Exchange of O2 & CO2 between air in alveoli and blood in pulmonary capillaries.
Gas Transport in the Blood
Binding & transport of O2 and CO2 in the blood
Gas Exchange at Tissue Level
Exchange of O2 and CO2 between blood in systemic capillaries and the body cells.
Boyle’s Law
As volume of a gas increases the pressure decreases. .
How is ventilation of the lungs achieved?
By expansion of the thoracic cavity and lungs during inspiration.
Forces holding thoracic wall and lungs in close opposition
Intrapleural fluid cohesiveness & negative intrapleural pressure.
Pressures important in ventilation
Atmospheric, intra-alveolar & intra-pleural pressure.
Inspiration
Inhalation
Expiration
Exhalation
Is inspiration active or passive?
Active
Is expiration active or passive?
Passive
Inspiratory muscles used during normal breathing
Diaphragm & External intercostal muscles.
Movement of Diaphragm in normal inspiration
Contracts, increasing thorax vertically.
Movement of intercostal muscle in normal inspiration
Contracts, lifts ribs and moves out sternum “bucket handle”
What causes lung recoil during expiration
Alveolar Surface Tension & Elastic Connective tissue.
LaPlaces Law
Smaller alveoli have a higher tendency to collapse.
Alveolar Surface Tension
Created by attraction between water molecules at liquid-air surface.
How to reduce surface tension
Pulmonary Surfactant: intersperses water molecules on lungs.
Expiratory muscles used during active expiration
Internal intercostal muscles, abdominal muscles.
