L2 Physiology Mechanism of Breathing (Respiratory System) PDF

Assistant Professor Mohamed Adel 1, Mechanics of breathing Mechanics of breathing Respiration is divided into: I) External respiration External respiration is the intake of O 2 and removal of CO2 from the body. II) Respiratory function of blood a) Carriage of O2. b) Ca...

Assistant Professor Mohamed Adel 1, Mechanics of breathing Mechanics of breathing Respiration is divided into: I) External respiration External respiration is the intake of O 2 and removal of CO2 from the body. II) Respiratory function of blood a) Carriage of O2. b) Carriage of CO2. III) Internal respiration  It is utilization of O2 in oxidation of food stuffs and production of energy. Physiological anatomy of respiratory system Respiratory system consists of: 1) Air passage and lungs. 2) Respiratory muscles. 3) Respiratory centers controlling respiration. Functions of conducting zone 1) Conduction of air to the respiratory zone 2) Air conditioning: Adjusting the temperature of inspired air to be equal to that of body by adding heat to cold air and remove of excess heat from hot air. 3) Filtration Means filtering air from foreign particles. 4) Protective reflexes For removal of foreign bodies and irritant substances from respiratory passages, they include: 1 Assistant Professor Mohamed Adel 1, Mechanics of breathing a) Cough reflex. b) Sneezing reflex. 5) Non respiratory functions a) Smell: by the olfactory epithelium in the nose. b) Phonation: by vibration of vocal present in the larynx. Respiratory zone  The membrane separating blood in pulmonary capillaries and air in alveoli is very thin. So, gas exchange occurs freely and rapidly.  Pulmonary ventilation; Renewal of air in lung alveoli from the atmospheric air by movement of air in (Inspiration) followed by its movement out (Expiration).  This occurs in cycles “Respiratory cycles”.. 2 Assistant Professor Mohamed Adel 1, Mechanics of breathing  Respiratory cycle = 1.3+1.7+0.7 = 3.7 sec.  Respiratory rate (Number of respiratory cycles/min.) = 60/3.7 = about 16 cycles / minute.  In children the rate is about: 25 /minute. 3 Assistant Professor Mohamed Adel 1, Mechanics of breathing 4 Assistant Professor Mohamed Adel 1, Mechanics of breathing Forced breathing Forced inspiration  This is similar to normal inspiration (Diaphragm and external intercostal) but requires effort from the inspiratory accessory muscles. Forced expiration  Unlike normal expiration, this is an active process.  It involves contraction of the abdominal muscles which forces the diaphragm upwards reducing the volume of the thoracic cavity.  It, also, requires contraction of the internal intercostal muscles. 5