6.4 Gas Exchange--Respiratory system

A respiratory system´s function is to allow gas exchange. The space between the alveoli and the capillaries, the anatomy or structure of the exchange system, and the precise physiological uses of the exchanged gases vary depending on the organism. In humans and other mammals, for example, the anatomical features of the respiratory system include airways, lungs, and the respiratory muscles. Molecules of oxygen and carbon dioxide are passively exchanged, by diffusion, between the gaseous external environment and the blood. This exchange process occurs in the alveolar region of the lungs.

6.4.1 Ventilation--gas exchange -- cellular respiration

breathing animation- http://health.howstuffworks.com/adam-200020.htm

	Ventilation- physical exchange of gases Inspiration (inhalation)- breathing in by contracting the diaphragm, expanding the lungs and letting air move in. Exhalation- breathing out by relaxing the diaphragm, compressing the lungs and forcing air out.
	Gas Exchange- two different exchanges systems 1. occurs between capillaries and alveoli of the lungs 2. occurs between capillaries and cell membranes within specific tissues
	Cellular Respiration

Gas Exchange animation: http://www.bmu.unimelb.edu.au/examples/gasxlung/

Oxygen binding animation: http://media.pearsoncmg.com/bc/bc_marieb_ehap_8/activities/chapter13/Act13B.html

6.4.2 - Ventilation system - need

6.4.3 - Alveoli

An alveolus is an anatomical structure that has the form of a hollow cavity. Found in the lung, the pulmonary alveoli are spherical outcroppings of the respiratory bronchioles and are the primary sites of gas exchange with the blood. Alveoli are particular to mammalian lungs. Different structures are involved in gas exchange in other vertebrates

6.4.4 - Ventilation system

6.4.5- Ventilation mechanism

• During inspiration (inhaling),
  • The external intercostal muscles contract, lifting the ribs up and out.
  • The diaphragm contracts, drawing it down .
• During expiration (exhaling), these processes are reversed and the natural elasticity of the lungs returns them to their normal volume. At rest, we breath 15-18 times a minute exchanging about 500 ml of air.
• In more vigorous expiration,
  • The internal intercostal muscles draw the ribs down and inward
  • The wall of the abdomen contracts pushing the stomach and liver upward.
  Under these conditions, an average adult male can flush his lungs with about 4 liters of air at each breath. This is called the vital capacity. Even with maximum expiration, about 1200 ml of residual air remain.

Ventilation animation: http://msjensen.cehd.umn.edu/1135/Links/animations/Flash/0034-swf_alveolar_press.swf