Physiology of Respiratory
System
Respiration
• Pulmonary ventilation
– Breathing- air movement in and out of body
• External respiration
– Oxygen loading and Carbon dioxide loading
• Respiratory gas transport
– Gases transported via bloodstream
• Internal respiration
– Exchange between capillaries and tissue cells
Breathing
• Inspiration
– Diaphragm flattens creates a vacuum pulling air
into the lungs
• Expiration
– Muscles relax and push air out of the lungs
Respiratory Volumes and
Capacities
• Tidal Volume (TV)- volume of air moved
into and out of the lungs each breath
• Inspiratory reserve volume (IRV)- amount
of air you can forcibly be taken in
• Expiratory reserve volume (ERV)- amount
of air that can be forcibly expelled
Respiratory Volumes and
Capacities
• Residual Volume- air that cannot be
expelled from the lungs
• Vital capacity (VC)- total amount of
exchangeable air TV + IRV + ERV
• Dead Space volume- the amount of air that
doesn’t make it to the lungs in a breath
External Respiration
• Gas exchange at the lungs
• Oxygen into blood and CO2 removed from
blood
Gas Transport in the Blood
• Oxygen forms oxyhemoglobin with
hemoglobin molecules
• CO2 in transported via
bicarbonate in plasma
Internal Respiration
• Exchange of gases between blood and tissue
cells
• Oxygen unloaded and CO2 loaded
Hypoxia
• Inadequate supply of oxygen to the body
tissues
• Causes skin to become cyanotic
Carbon Monoxide Poisoning
• CO binds to the binding site that oxygen
binds to on hemoglobin preventing gas
transport of oxygen
Respiratory Terms
• Eupnea- normal respiratory rate
• Hyperpnea- increased respiratory rate
(exercising)
• Apnea- stopped breathing
• Dyspnea- difficult breathing
Hyperventilation
• Body’s reaction to increased levels of
carbon dioxide or acids in blood
Smoker’s Lungs Versus Healthy
Lungs