RESPIRATORY SYSTEMCONTINUED

What is the stimulus for breathing?

• In an experiment, it was observed that the breathing rate decreases when the subject is breathing 100% oxygen, but increases when the subject is breathing a mixture of 92% oxygen and 8% carbon dioxide.

What is the stimulus for breathing?

• The higher the concentration of carbon dioxide, the higher the breathing rate.

• Hence, the stimulus for breathing is a high concentration of carbon dioxide in the blood or in the alveolar air, not a lack of oxygen.

EFFECTS OF TOBACCO SMOKE ON HUMAN HEALTH

Chemicals in Tobacco Smoke

Properties of the Chemicals

Effects on the Body

Nicotine • Addictive drug• Causes the

release of the hormone adrenaline

• Makes blood clot easily

• Increase in heartbeat & blood pressure

• Increased risk of blood clots in blood vessels

Chemicals in Tobacco Smoke

Properties of the Chemicals

Effects on the Body

Carbon Monoxide • Combines with hemoglobin to form carboxyhemoglobin – reduces oxygen transport efficiency of red blood cells

• Death if concentrations in the air are increased by 1%

Chemicals in Tobacco Smoke

Properties of the Chemicals

Effects on the Body

Carbon Monoxide • Increases the rate of fatty deposits on the inner arterial wall

• Damages the lining of blood vessels

• Increased risk of atherosclerosis

• Increased risk of blood clotting in the arteries

Chemicals in Tobacco Smoke

Properties of the Chemicals

Effects on the Body

Tar • Contains cancer-causing (carcinogenic) chemicals which induce uncontrolled cell division of the epithelium

• Blockage in the air sacs & reduction in gas exchange efficiency

Chemicals in Tobacco Smoke

Properties of the Chemicals

Effects on the Body

Tar • Paralyzes cilia lining the air passages

• Dust particles trapped in the mucus lining the airways cannot be removed

Chemicals in Tobacco Smoke

Properties of the Chemicals

Effects on the Body

Irritants (e.g. hydrogen cyanide, formaldehyde)

• Paralyzes cilia lining the air passages

• Increased risk of chronic bronchitis & emphysema

CHRONIC BRONCHITIS

• Chronic inflammation of the bronchial tubes

• Symptoms include:

- the epithelium lining the airways becomes inflamed

- excessive mucus is secreted by the epithelium

CHRONIC BRONCHITIS

- The cilia on the epithelium are paralyzed. Mucus & dust particles cannot be removed.

- The airways become blocked, making breathing difficult

- The person has to cough persistently to clear his airways in order to breathe.

EMPHYSEMA

• a type of chronic obstructive pulmonary disease (COPD) involving damage to the air sacs (alveoli) in the lungs

EMPHYSEMA• Symptoms include:

- Violent coughing breaks the partition walls between the air sacs.

- The surface area for gaseous exchange decreases.

- The lungs becomes inflated with air.

- The lungs lose their elasticity.

- Breathing becomes difficult. The person wheezes and suffers severe breathlessness.

LUNG CANCER

• Lung cancer is the uncontrolled growth of abnormal cells that start off in one or both lungs; usually in the cells that line the air passages.

• The abnormal cells do not develop into healthy lung tissue, they divide rapidly and form tumors.

Number of cigarettes smoked per day

Risk of lung cancer compared with a

non-smoker

10 10 times greater

20 20 times greater

30 30 times greater

LUNG CANCER• Symptoms include:

- may have no symptoms but tumor can be seen in a chest X-ray- cough

- shortness of breath- wheezing- chest pain