Non respiratory functions of lung ( The Guyton and Hall physiology)

Non respiratory functions of lung ( The Guyton and Hall physiology)

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  NON RESPIRATORY FUNCTIONSOF LUNGS/RESPIRATORY SYSTEM Source: The Guyton and Hall physiology Maryam Fida(o-1827)
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  NON-RESPIRATORY FUNCTIONS OF RESPIRATORYTRACT  Besides primary function of gaseous exchange, the respiratory tract is involved in several non respiratory functions of the body
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  1. OLFACTION Olfactory receptorspresent in the mucous membrane of nostril are responsible for olfactory sensation. 2. VOCALIZATION Larynx alone plays major role in the process of vocalization. Therefore, it is called sound box. 3. PREVENTION OF DUST PARTICLES Particles, which escape the protective mechanisms in nose and alveoli are thrown out by cough reflex and sneezing reflex.
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  4. DEFENSE MECHANISM Lungsplay important role in the immunological defense system of the body. Defense functions of the lungs are performed by their own defenses and by the presence of various types of cells in mucous membrane lining the alveoli of lungs. These cells are leukocytes, macrophages, mast cells, natural killer cells dendritic cells.
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  5. MAINTENANCE OFWATER BALANCE Respiratory tract plays a role in water loss mechanism. During expiration, water evaporates through the expired air and some amount of body water is lost by this process. 6. REGULATION OF BODY TEMPERATURE During expiration, along with water, heat is also lost from the body. Thus, respiratory tract plays a role in heat loss mechanism.
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  7. REGULATION OFACID-BASE BALANCE Lungs play a role in maintenance of acid-base balance of the body by regulating the carbon dioxide content in blood. 8. ANTICOAGULANT FUNCTION Mast cells in lungs secrete heparin. Heparin is an anticoagulant and it prevents the intravascular clotting. 9. SECRETION OF ANGIOTENSINCONVERTING ENZYME Endothelial cells of the pulmonary capillaries secrete The angiotensin converting enzyme (ACE). It converts the angiotensin I into active angiotensin II, which plays an important role in the regulation of ECF volume and blood pressure.
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  10. SYNTHESIS OFHORMONAL SUBSTANCES  Lung tissues are also known to synthesize the hormonal substances, prostaglandins, acetylcholine and serotonin, which have many physiological actions in the body including regulation of blood pressure