Respiratory Physiology PDF

Respiratory System  a) Pulmonary ventilation Entrance of atmospheric air into lung External Resp. b) Gas exchange between alveoli & venous Blood in capillaries around alveoli Resp...

Respiratory System  a) Pulmonary ventilation Entrance of atmospheric air into lung External Resp. b) Gas exchange between alveoli & venous Blood in capillaries around alveoli Resp. function Carriage of O2 & CO2 by the blood of Blood to & from the tissue Oxidation of food stuff with Internal Resp. production of Energy for body activity.  The air passage and lung Conducting zone Respiratory zone Nose Respiratory bronchioles Nasopharynx Alveoli Larynx Trachea Main bronchi Bronchioles Terminal bronchioles  The conducting zone: Characters:  The walls the conducting part are thick  do not allow gas exchange. Functions of the conducting part: 1. Air Conducting into the respiratory zone. 2. Air conditioning: To make the temperature of air entering the lung = 37°C. 3. Air moistening: Adding water vapor to the inspired air. 4. Air filtration: The air conducting part filters air from particles and bacteria. 5. Protective reflexes: To remove irritant substances from the airways (sneezing reflex and cough reflex) 6. Non- respiratory functions: include Smell and Phonation. The respiratory zone: Consists of:  Respiratory bronchioles  Alveoli Characters:  The wall is thin  Allow gas exchange.  Respiratory cycle Consists of inspiration (1.3 sec) followed by expiration (1.7 sec) then expiratory pause (0.7 sec)  So, the total duration of respiratory cycle = 3.7 sec.  Respiratory rate is about 16/minute.  In children respiratory rate is about 25/minute. Def It is process of renewal of alveolar air (air in lungs) from atmospheric air  Inspiration Expiration 1) Active process 1) Passive process 2) It is due to contraction of 2) It is due to relaxation of diaphragm which ↑ vertical diaphragm & external diameter of chest 1.5-7 cm & intercostal ms contraction of external intercostal ms which ↑ antero-posterior & transverse diameter of chest.  Inspiration Expiration 3) chest cavity ↑ in all its 3) chest cavity ↓ in all its dimensions dimensions 4) lung volume ↑ 4) lung volume ↓ 5) pressure in alveoli ↓ to –2 5) pressure in alveoli ↑ to + 2 mmHg mmHg 6) air rushes into the lung 6) air rush out of the lung  Surfactant Pressures in Compliance Pulmonary the thoracic Ventilation cavity. Resistance of air passage Each 100 ml arterial blood contains 20 ml O2 present in two forms: O2 Transport 1) O2 in physical 2) O2 in Chemical solution combination O2 It is about It determines O2 that It is more dissolved 0.3 ml O2 / the O2 tension combined than 98% physically 100 ml (PO2) in the with Hb in of the O2. in plasma blood RBCs. blood  Each 100 ml arterial blood contains 48 -52 ml CO2 CO2 Transport 1) CO2 in physical 2) CO2 in Chemical solution combination 5% dissolved Carbamino Bicarbonates physically in plasma compounds and RBCs 6% with Hb and plasma proteins 89% bicarbonates 12  Hypoxia Definition: O2 deficiency at tissue level due to disturbance in the respiratory process. Types of hypoxia: 1) Disturbance in external respiration: Hypoxic hypoxia: as lung diseases. 2) Disturbance in respiratory function of the blood: - Anemic hypoxia: as all types of anemia. - Stagnant hypoxia: as in heart failure. 3) Disturbance in internal respiration: Histotoxic hypoxia: as cyanide poisoning.  Cyanosis It is bluish coloration of the skin and mucus membrane due to increased amount of reduced Hb in the blood.