Functions of lungs other then respiration
Animals are exposed to pollutants like dusts, ammonia, pungent gases carbon monoxide, products of plant and animal origin, parasites, bacteria, viruses, spores, endotoxins, diesel fumes, ozonized oxides of nitrogen.
During transport the animals and animals reared under intensive housing are exposed to stressor promoting agents like pneumonia/pleuritis. Non-infectious stress for prolonged time leads to chronic airway diseases. These treats are handled by variety of defense mechanism of the lung.
Non-specific immunity/Innate immunity
Protects against harmful inhaled substances. This includes mucociliary system; cough reflex, phagocytic activity of the alveoli.
Toll-like receptors
Proteins on the surface of the cell membrane that can recognize the molecules which are common to many bacteria/fungi. On stimulation of these receptors initiates the activities of proinflamatory cytokinins.
Specific defense against specific agents (Bacteria/virus)
It takes several days for the activation of the process of immune memory to protect future attack of the same organism.
Fluid exchange
Continuous exchange of water and solutes between the alveolar epithelium and interstitial cells through interstitial septum. Hydrostatic and oncotic pressures also favors fluid exchange
Alveolar epithelium is impermeable to certain substances, hence prevents the leak of fluid into the alveoli. The fluid between pleura has less protein, lubricates the pleura
Fluid from the interstitium as well as pleural fluids are cleared by lymphatic system and by pumping of the lung during respiration.
Metabolic functions of the lung
Endothelial surface is good enough to clear the blood of substances produced in other part of body. More over pulmonary capillary blood receives total cardiac output which favours cleansing.
Endothelial surface is studded with clveolae which houses many enzymes involved in metabolism of vasoactive substances. Monoamino oxidases neutralizes serotonin and norepinephrine.
Angiotensin converting enzymes metabolizes bradykinin and convert angiotensin I to II Neutralizing enzymes of PGE2, F2 and leukotrienes are present. Toxic exogenous substances are also neutralized in lungs.
Other Functions of lungs also-
- Sneezing
- Phonation
- Cooling of blood going to the brain
- Olfaction
- Panting in dogs
- Purring in cats