respiration

• respiration is the overall process by which oxygen is taken from air and transported to body cells for the metabolic process; while carbon dioxide and water, generated by these cells, are returned to the environment
• four processes of respiration:

  1. ventilation or breathing
  2. external respiration
  3. transport of respiratory gases
  4. internal respiration
• ventilation is the largely involuntary movement of air into and out of the lungs, in response to changes in gases levels in the blood, and nervous stimulation of the diaphragm and intercostal muscles
• inspiration and expiration occurs during ventilation
• inspiration is the movement of air into the lungs
• expiration is the movement of air out of the lungs
• external respiration is the exchange of oxygen and carbon dioxide between the alveoli and the blood in the pulmonary capillaries
• transport of respiratory gases occurs through the body by blood in the cardiovascular system
• internal respiration is the exchange of oxygen and carbon dioxide between tissue cells and the blood in systemic capillaries