Terms you need to know about respiration and oxygenation

Ventilation	The movement of air in and out of the lungs
Perfusion	The movement of blood into and out of the lungs
Pulmonary circuit	The path of blood from the heart to the lungs and back again
Surfactant	The soapy coating that lines the alveoli, making them easier to inflate
Dead space	The parts of the respiratory tract that don’t pass O2 to the blood
Accessory muscles	The muscles besides the diaphragm that are used to inhale and exhale
Pleural cavity	The cavity the lungs are in
Pleurae	The two layers of membrane round the lungs
Parietal pleura	The layer of membrane that is attached to the body wall, lining the pleural cavity
Visceral pleura	The layer of membrane that is attached to the surface of the lungs, covering them
Pleural space	The space between the visceral and parietal pleurae
Pleural fluid	The fluid in the pleural space
Alveolar ventilation	The amount of air entering the alveoli in one minute
Myoglobin	The protein in red muscle that holds stored oxygen. Made of a protein chain wrapped around a heme group. Can hold one oxygen molecule
Hemoglobin	The protein in red blood cells that carries oxygen. Made of four protein chains, each one wrapped around a heme group. Can carry 4 oxygen molecules.
Heme	A ring of atoms around an iron atom. The part of myoglobin or hemoglobin that holds the oxygen.
Alpha and beta chains	The protein chains that make up normal adult hemoglobin
HbA or a2b2 hemoglobin	Adult hemoglobin, made of two alpha and two beta chains
HbF or a2g2 hemoglobin	Fetal hemoglobin, made of two alpha and two gamma chains
Oxygenated hemoglobin	Hemoglobin that is carrying oxygen - red
Deoxygenated hemoglobin	Hemoglobin that is not carrying oxygen - blue
Oxygen saturation	The amount of oxygen the hemoglobin is carrying, divided by the maximum amount it could possibly carry. Given in %.
Oxygen capacity	The amount of oxygen a blood sample could carry, in mL O2/100 mL of blood
Oxygen affinity	How hard the hemoglobin holds on to the oxygen it has picked up.
Oxygen unloading	When hemoglobin drops oxygen off in the tissues that need it.
Oxygen loading	When hemoglobin picks oxygen up in the lungs.