Respiratory physiology

Gaseous exchange in the lung.

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

Topics include:

Volumes

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

Mechanism

Front view of thorax.

Inhalation (breathing in) 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. In contrast, expiration (breathing out) is usually a passive process.

$\begin{align} P &= P_{el} + P_{re} + P_{in} \\ P &= EV + R\dot{V} + I\ddot{V} \end{align}$

Where P_el equals the product of elastance E (inverse of compliance) and volume of the system V, P_re equals the product of flow resistance R and time derivate of volume V (which is equivalent to the flow), P_in 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

See also

• Breath sounds
• Pulmonology
• Respiratory system
• Wikipedia:MeSH G09#MeSH G09.772 --- respiratory physiology
• Respiratory monitoring

Additional images

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External links

• Overview at Johns Hopkins University

• Clinical Sciences - Respiratory An iPhone app covering detailed respiratory physiology and anatomy