Respiratory system
History
First breathing animal lived 380 million years ago
Before the first air breathing animal, all of life evolved in water
The life that lived in the water got the oxygen they needed right from the water, through their membranes
They used simple diffusion "when a material automatically flows from where it is concentrated, to where it is less concentrated, so it balances out"
needed something different because diffusion wasn't very effective in anything larger than a worm.
they moved their respiratory surfaces moved from their outer surfaces to the insides of their bodies.
Gills
simple diffusion doesn't work very effectively because of too many obstacles in the way for the oxygen molecule to get to the cell and gets blocked by the skin, skull, etc.
instead we use bulk flow, moving large numbers of molecules quickly
Your body uses both bulk flow and simple diffusion
Mechanics of breathing
Lungs don't have any contractible tissue to expand
your Diaphragm which is a set of muscles that separates your thorax from your abdomen.
When you breath in your diaphragm contracts, lifting the ribs up and down
Makes the pressure inside the lungs lower than air outside your body, the lungs fill up with outside air. Then the diaphragm relaxes and the pressure inside the lungs becomes higher than the outside air pushing it out.
Diseases
Alveoli at the end of the branches in the lungs
oxygen goes in carbon dioxide comes out
Restrictive: In restrictive diseases you lack oxygen
Obstructive: In Obstructive diseases you can't get air out
Fluid filling up the air sac, making you have less oxygen in your body and more carbon dioxide
Lack of blood getting to where it is supposed to go