The Structure and Function of the respiratory tract

Mechanics of Breathing

Gas exchange at the alveoli

•The partial pressure of a gas is a measure of the concentration of a gas in a mixture of gases

•The partial pressure (measured in mmHg or kPa) is the pressure that a particular gas exerts in a gas mixture.

•The pressure is caused by the impact of moving molecules against a surface.

•Gases which are dissolved in body fluids or tissues also have partial pressures. The dissolved gases move around and impact against surfaces exerting pressure in the same way a gas exerts its own partial pressure in a gas phase.

•Atmospheric pressure at sea level is approximately 760 mmHg

•Oxygen constitues 21 % of the atmospere, so its partial pressure is 21 % of 760 = 159 mmHg. Nitrogen constitutes 78 %, so its partial pressure is 78 % of 760 = 593 mmHg. Carbon dioxide constitutes only 0.04 %, so its partial pressure is 0.04 % of 760 = 0.3 mmHg.

Partial Pressures of Gases

Partial Pressures of Gases

Lungs in relation to heart

Respiratory System Disorders - BronchitisRespiratory System Disorders - Bronchitis

• Bronchitis is an inflammation of the air passages in the lungs.

•The condition occurs over a long period and recurs over several years.

•Symptoms include excessive bronchial mucus with a cough producing sputum.

•Cigarette smoking (active and passive exposure) is the chief cause of this disease, with air pollution, infection, familial factors, and allergies making the condition worse

www.nlm.nih.gov/.../ency/fullsize/19357.jpg400 x 320 - 25k

Normal versus inflamed bronchioleNormal versus inflamed bronchiole

Bronchial AsthmaBronchial Asthma

• Like bronchitis, asthma involves the inflammation of the bronchi and bronchioles

•Unlike bronchitis, it is usually triggered by an allergic reaction

•The allergen causes excess mucus to be produced by the goblet cells

•The smooth muscles surrounding the bronchi and bronchioles go into spasms causing the air passages to narrow and making it difficult to breathe

http://www.medbroadcast.com/channel_humanatlas_info_details.asp?video_id=205&channel_id=1006&relation_id=49286

3 changes that occur in people with asthma

1)

2)

3)

Normal versus Asthmatic airwayNormal versus Asthmatic airway

What types of medications are used in asthma inhalers?

•Medications used in asthma inhalers are anti-inflammatory (steroids such as prednisone)

•bronchodilators (beta-2 agonist medications), or both (a combination inhaler).

Human Atlas Videos - Lung Health - Medbroadcast

Asthma inhalersAsthma inhalers

•Carbon monoxide is a small gas molecule which has an unusual affinity for the hemoglobin or the molecule on our red blood cells which carries oxygen.

•In fact, carbon monoxide molecule is 200 times more likely to bind with hemoglobin than the oxygen molecule.

•As carbon monoxide is inhaled, it displaces the oxygen molecules which are vital for all tissues in the human body.

Carbon Monoxide PoisoningCarbon Monoxide Poisoning

•Carbon monoxide is a colourless, odourless gas produced by cars, barbecues, gas stoves and furnaces

Carbon monoxide binding to hemoglobinCarbon monoxide binding to hemoglobin

Source:http://services.epnet.com/getimage.aspx?imageiid=4865

•Cigarette smoking causes 87 percent of lung cancer deaths (1).

• Lung cancer is the leading cause of cancer death in both men and women (3).

•Smoking is also responsible for most cancers of the larynx, oral cavity and pharynx, esophagus, and bladder. In addition, it is a cause of kidney and pancreatic cancer.

Ries LAG, Eisner MP, Kosary CL, et al. (eds). SEER Cancer Statistics Review, 1975–2001, National Cancer Institute. Bethesda, MD, 2004

Smoking and lung cancerSmoking and lung cancer

•Cigarette smoking causes 87 percent of lung cancer deaths (1).

• Lung cancer is the leading cause of cancer death in both men and women (3).

•Smoking is also responsible for most cancers of the larynx, oral cavity and pharynx, esophagus, and bladder. In addition, it is a cause of kidney and pancreatic cancer.

Ries LAG, Eisner MP, Kosary CL, et al. (eds). SEER Cancer Statistics Review, 1975–2001, National Cancer Institute. Bethesda, MD, 2004

Smoking and lung cancerSmoking and lung cancer