Lecture 7Physiology of Respiratory System

By Dr: Nassar Ayoub (Sohage Univers.)

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