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gasous exchange - Coggle Diagram

- - - - Patent airway
      - Functional respiratory muscles
      - Adequate lung compliance
      - Intact neurological control
      - Normal pressure gradients
      - Physiological Laws
        
        Boyle’s Law
        
        Pressure inversely proportional to volume
        
        Inspiration:
        
        ↑ thoracic volume
        
        ↓ intrapulmonary pressure
        
        air enters lungs
        
        Expiration:
        
        ↓ thoracic volume
        
        ↑ intrapulmonary pressure
        
        air exits lungs
        
        Clinical Examples
        
        Asthma
        
        Bronchoconstriction
        
        Increased airway resistance
        
        Reduced ventilation
        
        COPD
        
        Air trapping
        
        Hypoventilation
        
        Pneumothorax
        
        Lung collapse
        
        Impaired ventilation
        
        Assessment Findings
        
        Tachypnoea
        
        Bradypnoea
        
        Dyspnoea
        
        Accessory muscle use
        
        Reduced chest expansion
        
        Wheeze
        
        Reduced SpO₂
        
        Abnormal ABGs
- - - - Small decrease in airway radius greatly increases resistance
    - - Impaired lung expansion changes pressure gradients and airflow
- - - - Airway obstruction
      - Sedation/opioids
      - Neuromuscular weakness
      - COPD
    - - ↑ PaCO₂
      - Respiratory acidosis
      - Hypoxaemia
  - - - Anxiety
      - Pain
      - Hypoxaemia
      - Metabolic acidosis
      - ↓ PaCO₂
        Respiratory alkalosis
- - - - Alveoli → pulmonary capillary blood
      - Oxygen Transport
        
        Mostly transported bound to haemoglobin
        
        Small amount dissolved in plasma
    - - Pulmonary capillary blood → alveoli
      - Carbon Dioxide Transport
        
        Dissolved in plasma
        
        Bound to haemoglobin
        
        Mostly transported as bicarbonate (HCO₃⁻)
    - - Fick’s Law
        
        Gas diffusion depends on:
        
        Surface area
        
        Membrane thickness
        
        Pressure gradient
      - Dalton’s Law
        
        Gases move according to partial pressure gradients
      - Henry’s Law
        
        Amount of gas dissolved in blood proportional to pressure
    - - Pulmonary oedema
        
        Fluid impairs oxygen diffusion
      - Anaemia
        
        Reduced oxygen carrying capacity
      - Shock
        
        Reduced tissue perfusion
        
        Tissue hypoxia
      - COPD
        
        CO₂ retention
        
        Respiratory acidosis
    - - Hypoxaemia
      - Cyanosis
      - Dyspnoea
      - Tachypnoea
      - Reduced SpO₂
      - Elevated PaCO₂
      - Elevated lactate in tissue hypoxia
- - - - Pulmonary oedema→ crackles→ hypoxaemia→ increased work of breathing
    - - Collapsed alveoli→ reduced lung expansion→ decreased ventilation
    - - Increased surface tension
      - Alveoli collapse more easily
      - Increased work of breathing
      - Clinical Example
        
        ARDS→ stiff lungs→ severe hypoxaemia
    - - Laplace’s Law
        
        Increased surface tension increases alveolar collapse risk
      - Boyle’s Law
        
        Reduced lung expansion alters pressure changes and ventilation
      - Fick’s Law
        
        Thickened membrane impairs diffusion
    - - Tachypnoea
      - Dyspnoea
      - Crackles
      - Reduced SpO₂
      - Hypoxaemia
      - Increased work of breathing
      - Reduced lung compliance
    - - Impaired alveolar function→ reduced ventilation→ impaired diffusion→ hypoxaemia and respiratory distress
- - - - Fick’s Law
        
        Reduced surface area or increased membrane thickness impairs gas exchange
      - Dalton’s Law
        
        Altered pressure gradients reduce oxygen diffusion
- - - - Pulmonary Circulation
        
        Right ventricle pumps deoxygenated blood into pulmonary arteries
        
        Pulmonary arteries carry blood to lungs
        
        Pulmonary capillaries surround alveoli
        
        Gas exchange occurs at alveolar-capillary membrane
        
        Oxygenated blood returns to left atrium via pulmonary veins
        
        Function of Pulmonary Circulation
        
        Delivers blood for gas exchange
        
        Removes carbon dioxide
        
        Supplies oxygen to blood
    - - Bronchial Circulation
        
        Arises from aorta
        
        Supplies oxygenated blood to lung tissues
        
        Nourishes:
        
        Bronchi
        
        Connective tissue
        
        Pleura
        
        Large blood vessels
        
        Pulmonary Capillaries
        
        Thin-walled vessels surrounding alveoli
        
        Site of oxygen and carbon dioxide diffusion
        
        Physiological Laws
        
        Fick’s Law
        
        Gas exchange depends on:
        
        Surface area
        
        Membrane thickness
        
        Pressure gradient
        
        Dalton’s Law
        
        Oxygen and carbon dioxide move according to partial pressure gradients
        
        Clinical Examples
        
        Pulmonary embolism
        
        Blocked pulmonary artery
        
        Reduced perfusion
        
        Hypoxaemia
        
        Pulmonary hypertension
        
        Increased pulmonary vascular resistance
        
        Heart failure
        
        Pulmonary congestion
        
        Impaired gas exchange
        
        Assessment Findings
        
        Hypoxaemia
        
        Tachypnoea
        
        Dyspnoea
        
        Cyanosis
        
        Reduced PaO₂
        
        Increased work of breathing