Exercise 40 Respiratory Physiology 1. Processes of respiration Pulmonary ventilation External...

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 ventilationInspirationExpirationRespiratory muscles

• Diaphragm• External intercostal• Others

3

Mechanisms of respiration

Steps of ventilationContraction of diaphragm and

external intercostal musclesIncrease of thoracic volumeExpansion of the pleural cavities and

lungsDecrease of lung pressure below

atmospheric pressure

4

Mechanisms of respiration

InspirationLung pressure becomes equal to

atmospheric pressureAir stops to flow insideRelaxation of respiratory musclesRecoiling of the lung tissue

5

Mechanisms of respiration

Decrease of intrathoracic and intrapulmonary volumes

Increase of pulmonary pressureExpiration

6

Mechanisms of respiration

Pneumothorax it is the entry of air into the pleural cavityIt breaks the fluid bond between the

visceral and parietal pleuraIt 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 mlIt 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 mlVC = TV + IRV + ERV

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Respiratory volumes and capacities

Residual volume (RV)It is the amount of air that remains in

the lung after a ERV1200 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 mlFRC = ERV+RV

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Respiratory volumes and capacities

Total lung capacity (TLC)It is the total volume of the lungs6000 mlTLC = VC+RV

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Respiratory volumes and capacities

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Respiratory volumes and capacities

Nonrecording spirometerHandheld dry spirometer

• Measures only expired airWet spirometer

• Measures only expired air Recording spirometer

Measures inspired and expired air

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Pulmonary disorders

Obstructive BronchitisAsthma

RestrictiveTuberculosisPoliomyelitis

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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

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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 RRExercise CoughingWakingTalkingLaughing, etc

20

Respiratory sounds

Bronchial soundsHeard below the larynx

Vesicular soundsAir filling the alveolar sacsHeard over the chest

Crepitation (crackles) Wheezing – a whistling sound

21

Role of respiratory system in acid-base balance of blood

Blood pH7.35-7.45Carbonic acid-bicarbonate buffer

• The main body buffer

22

Acid-base imbalance

AlkalosisBlood pH above 7.45Respiratory or metabolic

AcidosisBlood pH bellow 7.35Respiratory or metabolic

23