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Respiratory System. Purpose : To provide oxygen needed by all the body’s cells and to remove carbon dioxide (toxin) from the body. Processes: a) ventilation : the movement of gases in and out of the body. b) gas exchange : The exchange of oxygen
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Respiratory System • Purpose: To provide oxygen needed by all the body’s cells and to remove carbon dioxide (toxin) from the body. • Processes: a) ventilation: the movement of gases in and out of the body. b) gas exchange: The exchange of oxygen carbon dioxide.
As the branching continues the surface area to volume ratio keeps increasing.
Gas Exchange • Diffusion: is the movement of a substance (i.e. gas) from an area of high concentration to an area of low concentration. • At the alveoli CO2 in the venous blood coming from the heart is in high concentration while O2 is low. The air in the lung is the opposite. (O2 high and CO2 low) • By diffusion the O2 moves into the red blood cells while the CO2 moves into the alveoli. Capillaries and alveoli are only 1 cell layer thick. • The O2 rich blood now flows back to the heart where it can be pumped to the rest of the body. • The reverse process happens in all tissues throughout the body.
We are negative pressure breathers. That means that air moves from an area of high pressure to an area of low pressure passively. If the volume of a container decreases then the air pressure will increase. If the volume increases then the air pressure will decrease. If the diaphragm (muscle) contracts then it goes down. The lungs are stuck to the diaphragm by the pleura so they move down as well. The muscles in the rib cage also contract lifting the rib cage pulling the lungs up and out. The volume of the lungs has just increased so the air pressure is less in the lungs than in the atmosphere. O2 rich air passively flows into the lungs Gas exchange takes place. Breathing Inhalation
Breathing exhalation Now the diaphragm relaxes and moves back up and the rib cage muscles relax and the rib cage falls. The volume of the lungs has now decreased . The air pressure in the lungs is now greater than in the atmosphere. So CO2 rich air will passively flow out of the nostrils or mouth. What happens when we exercise? What happens when we hold our breath? Why do we yawn?
