Breathing and Exchange of Gases PDF

**CHAPTER 14** **BREATHING AND EXCHANGE OF GASES** - - - **How do we breathe? The respiratory organs and the mechanism of breathing:** **RESPIRATORY ORGANS** Mechanisms of breathing animals depends on their habitats and levels of organisation. - - - - - - **Human Respirato...

**CHAPTER 14** **BREATHING AND EXCHANGE OF GASES** - - - **How do we breathe? The respiratory organs and the mechanism of breathing:** **RESPIRATORY ORGANS** Mechanisms of breathing animals depends on their habitats and levels of organisation. - - - - - - **Human Respiratory System**  - - - - - - - - - - - - - - - - - - - - - - **MECHANISM OF BREATHING OR PULMONARY VENTILATION** - - - - - - 1. 2. 1. 2. - - - **Respiratory Volumes (RV) and Capacities (RC)** **Respiratory Volumes (RV)** **Tidal Volume (TV):** Volume of air inspired or expired [during a normal respiration]. It is approx. 500 mL/ breath i.e., a healthy man can inspire or expire [approx 6000 to 8000 mL] of air per minute. 12-15 breaths/ mint × 500 ml = 6000 ml- 8000 ml. **Inspiratory Reserve Volume (IRV):** Additional volume of air, [that can be inspired by a forcible inspiration]. This averages [2500 mL to 3000 mL]. **Expiratory Reserve Volume (ERV):** Additional volume of air, [that can be expired by a forcible expiration]. This averages [1000 mL to 1100 mL]. **Residual Volume (RV):** Volume of air [that remain in the lungs even after a forcible expiration]. This averages [1100 mL to 1200 mL.] **Respiratory Capacities (RC);** By adding up a few respiratory volumes described above, various pulmonary capacities, can be derived. Respiratory Capacities (RC) are used in clinical diagnosis. **Inspiratory Capacity (IC):** Complete volume of air that can be inspired after a normal expiration. Inspiratory Capacity (IC) is tidal volume (TV) and inspiratory reserve volume (IRV). IC= TV+IRV. **Expiratory Capacity (EC):** Complete volume of air that can be expired after a normal inspiration. This includes tidal volume (TV) and expiratory reserve volume (ERV). EC= TV+ERV **Functional Residual Capacity (FRC):** Volume of air that remains in the lungs after a normal expiration. FRC= ERV+RV. **Vital Capacity (VC):** The maximum volume of air that can be breathe into the lungs, after a forced expiration, or the maximum volume of air that can be breathe out after a forced inspiration. VC= ERV+TV+IRV **Total Lung Capacity (TLC):** Total volume of air that can be hold in the lungs at the end of a forced inspiration. TLC= RV+ERV+TV+IRV OR TCL= RV + VC **EXCHANGE OF GASES** - a. b. - c. d. - - e. f. -  - - - -  1. 2. 3. **TRANSPORT OF GASES** - - - **Transport of Oxygen** **Haemoglobin:** It is a red coloured pigment which contains iron, and present in the RBCs. - - - - - - - - - - - **Transport of Carbon dioxide CO2** **In the form of carbamino-haemoglobin:** - - - - **In the form of bicarbonate:** 70 per cent of CO2 is transported as bicarbonate through RBCs. **Enzyme for CO2 transportation:** - - - - **In the form of dissolved state:** About 7 per cent of CO2 is transported in a dissolved state through plasma. **REGULATION OF RESPIRATION** - - - - - - - **DISORDERS OF RESPIRATORY SYSTEM** **Asthma** It is a difficulty in breathing causing wheezing due to inflammation of bronchi and bronchioles. **Emphysema** It is a chronic disorder in which alveolar walls are damaged due to which respiratory surface is decreased. One of the major causes of this is cigarette smoking. **Occupational Respiratory Disorders:** In certain industries, especially those involving grinding or stone-breaking, so much dust is produced that the defense mechanism of the body cannot fully cope with the situation. Long exposure can give rise to inflammation leading to fibrosis (proliferation of fibrous tissues) and thus causing serious lung damage. Workers in such industries should wear protective masks.