1. Hypoxia Oxygen Supply to tissues is not sufficient

2. 1.Hypoxic Hypoxia Oxygenation in the lungs is not proper e.g. High altitude, obstructive and restrictive lung diseases or Pulmonary ventilation is not proper as in depression of respiratory centers 2.Anemic Hypoxia O2 carriage is improper e.g. Decreased Hb, impure Hb etc. 3.Stagnant Hypoxia Poor blood flow e.g. Heart failure, circulatory shock 4.Histotoxic Hypoxia Tissues are unable to utilize o 2 e.g. cyanide poisoning which inhibits cytochrome oxidase

3. Asphyxia  Gaseous exchange is badly affected. There is both hypoxemia and Hypercapnia i.e. O2 level is decreased and CO2 level is increased.  Hanging, drowning, strangulation etc.  Unconsciousness, heart dilates, Ventricular fibrillation etc.  Death occurs within 2 – 3 minutes

4. Non respiratory functions of the lungs  Act as reservoirs of blood  Helps in return of blood to heart  Secrete surfactant  Synthesizes prostaglandins, histamine, heparin  Partially inactivates serotonin, bradykinin, noradrenalin  Angiotensin converting enzyme is present on surface of pulmonary capillary endothelial cells  Lymphocytes, plasma cells and macrophages  Pulmonary venules can trap particles so prevent entry into systemic vessels  Mucous secretion contains IgA, lysozymes  Secretes ADH and ACTH in tuberculosis, lung abcess

5. Caisson’s Disease or Dysbarism or Decompression Sickness or Bends  2.5 – 3 ml of N 2 is dissolved in 100 ml of blood In deep sea divers, more nitrogen is dissolved in  lipids of body e.g. Brain, subcutaneous tissue, adrenal cortex etc.  When come out at land, nitrogen bubbles in blood, lungs, coronary arteries, bones etc.  Severe pain i.e. Bends  Treatment is gradual decompression or in special chambers