Exercise 40 Respiratory Physiology 1

Processes of respiration Pulmonary ventilation External respiration Transport of respiratory gases Internal respiration or cellular respiration 2

Mechanisms of respiration Pulmonary ventilation Inspiration Expiration Respiratory muscles Diaphragm External intercostal Others 3

Mechanisms of respiration Steps of ventilation Contraction of diaphragm and external intercostal muscles Increase of thoracic volume Expansion of the pleural cavities and lungs Decrease of lung pressure below atmospheric pressure 4

Mechanisms of respiration Inspiration Lung pressure becomes equal to atmospheric pressure Air stops to flow inside Relaxation of respiratory muscles Recoiling of the lung tissue 5

Mechanisms of respiration Decrease of intrathoracic and intrapulmonary volumes Increase of pulmonary pressure Expiration 6

Mechanisms of respiration Pneumothorax it is the entry of air into the pleural cavity It breaks the fluid bond between the visceral and parietal pleura It will cause the lung to collapse – atelectasis 7

Respiratory volumes and capacities Spirometry Tidal volume (TV) It is the amount of air inspired or expired with each breath under resting conditions 500 ml 8

Respiratory volumes and capacities Inspiratory reserve volume (IRV) It is the amount of air that can be forcefully inspired after a normal tidal inspiration 3100 ml 9

Respiratory volumes and capacities Expiratory reserve volume (ERV) It is the amount of air that can be forcefully expired after a normal tidal expiration 1200 ml It is reduced in conditions in which the elasticity of the lungs is decreased 10

Respiratory volumes and capacities Vital capacity (VC) It id the maximum amount of air that can be expired after a maximal inspiration 4800 ml VC = TV + IRV + ERV 11

Respiratory volumes and capacities Residual volume (RV) It is the amount of air that remains in the lung after a ERV 1200 ml 12

Respiratory volumes and capacities Functional residual capacity (FRC) It is the amount of air that remains in the lung after a quiet respiratory cycle 2400 ml FRC = ERV+RV 13

Respiratory volumes and capacities Total lung capacity (TLC) It is the total volume of the lungs 6000 ml TLC = VC+RV 14

Respiratory volumes and capacities 15

Respiratory volumes and capacities Nonrecording spirometer Handheld dry spirometer Measures only expired air Wet spirometer Measures only expired air Recording spirometer Measures inspired and expired air 16

Pulmonary disorders Obstructive Bronchitis Asthma Restrictive Tuberculosis Poliomyelitis 17

Respiratory volumes and capacities Forced vital capacity (FVC) It is the amount of air expired after a deep inspiration and a forced and quick expiration Reduced in restrictive pulmonary diseases 18

Respiratory volumes and capacities Forced expiratory volume measurement (FEV1%) It is the percentage of vital capacity that is exhaled during specific intervals of time It is reduced in obstructive diseases 19

Respiratory rate and depth Factors that changes the RR Exercise Coughing Waking Talking Laughing, etc 20

Respiratory sounds Bronchial sounds Heard below the larynx Vesicular sounds Air filling the alveolar sacs Heard over the chest Crepitation (crackles) Wheezing – a whistling sound 21

Role of respiratory system in acid-base balance of blood Blood pH Carbonic acid-bicarbonate buffer The main body buffer 22

Acid-base imbalance Alkalosis Blood pH above 7.45 Respiratory or metabolic Acidosis Blood pH bellow 7.35 Respiratory or metabolic 23