Respiratory physiology

(Representation of Human Respiratory Tract.)



Respiratory physiology is the branch of human physiology focusing upon respiration.

Volumes

• lung volumes
  
• vital capacity
• functional residual capacity
• dead space
• spirometry
• body plethysmography
• peak flow meter

Mechanics

(Front view of thorax.)

Breathing in, or inhaling, is usually an active movement. The contraction of the diaphragm muscles cause a pressure variation, which is equal to the pressures caused by elastic, resistive and inertial components of the respiratory system.

Where P_el equals the product of elastance E (inverse of compliance) and volume of the system V, Pre equals the product of flow resistance R and time derivate of volume V (which is equivalent to the flow), Pin equals the product of inertance I and second time derivate of V. R and I are sometimes referred to as Rohrer's constants.

• Anatomy: pleural cavity, thoracic diaphragm, Intercostales externi muscles, Intercostales interni muscles
• inhalation and exhalation
• lung, pulmonary alveolus
• With insufficient pulmonary surfactant, the pulmonary alveoli collapse, causing atelectasis (in infants, infant respiratory distress syndrome)
• the law of Laplace,
• compliance (physiology) - decreased with fibrosis, increased with emphysema
• Poiseuille's law
• asthma and COPD
• hysteresivity

Circulation, ventilation, and perfusion

(Pulmonary circulation)

• pulmonary circulation
  
• positive pressure ventilation
• hypoxic vasoconstriction
• ventilation (physiology), perfusion, ventilation/perfusion ratio (V/Q), and ventilation/perfusion scan
• shunts: right-to-left (tetralogy of fallot), left-to-right (patent ductus arteriosus)
• respiratory rate and respirometer

Gas exchange/transport (primarily oxygen and carbon dioxide)

(Oxygen-hemoglobin dissociation curve)

• gas exchange
  
• Dalton's law
• hemoglobin
• oxygen-hemoglobin dissociation curve, Bohr effect, Haldane effect
• carbonic anhydrase
• oxyhemoglobin
• respiratory quotient
• arterial blood gas

Control and response

(Pons)

• control of respiration
  
• reticular formation
• pons (apneuistic and pneumotaxic)
• chemoreceptors (medulla, carotid body, aortic body)
• Hering-Breuer reflex
  
• involuntary control of respiration
• exercise
• hyperoxia
• hypoxemia (hypoxic hypoxia)

Disorders

• altitude sickness
  
• asthma
• carbon monoxide poisoning
• chronic obstructive pulmonary disease
• emphysema
• infant respiratory distress syndrome
• pulmonary edema