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RESPIRATIONScience Form 3 Chapter 1

Last update: 10/8/2010

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B. Breathing Mechanism

Nose Trachea Bronchi Bronchioles Alveoli

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2. In passing through the nose, the air is:

a) Filtered by the fine hairsb) Warmed by the body temperaturec) Moistened by mucus

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3. Please draw the schematic diagram for inhalation and exhalation

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Model to show the Action of the Diaphragm

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What does the parts of model represents?

i. Plastic Y tube: trachea and bronchiii. Bell jar: thoracic cavityiii. Thin rubber sheet: diaphragmiv. Balloons: lungs

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Transportation of oxygen

1. Diffusion: the movement of gas molecules from higher concentration to lower concentration

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2. During inhalation, fresh air is taken into the alveoli

• There is more oxygen in this fresh air than in the blood capillaries

• As a result, oxygen from the alveoli diffuses into the blood capillaries surrounding the alveoli

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2. During inhalation, fresh air is taken into the alveoli

• The oxygen combines with the haemoglobin the red blood cells, producing oxyhaemoglobin

• Blood containing oxyhaemoglobin is called oxygenated blood, which is bright red colour

Haemoglobin + oxygen oxyhaemoglobin

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3. During inhalation, at the same time,

The higher concentration of carbon dioxide in the blood capillaries causes carbon dioxide to diffuse from the blood capillaries into the alveoli. This carbon dioxide is expelled from the alveoli during inhalation

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4. The alveoli are suitable for diffusion of gas because of the following reasons

a. The alveoli have very thin and moist wallsb. The alveoli are present in large numbers in the

lungsc. The alveoli are richly supplied with blood

capillariesd. There is always a difference in the concentration of

gases (oxygen & carbon dioxide) btw the alveoli and the blood capillaries.

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5. The heart pumps the oxygenated blood out to the body cells which require oxygen

• By the time the oxygenated blood reaches the target body cells, the blood is carried in one-celled thick blood capillaries

• There is less oxygen in the body cells than in the blood of the blood capillaries.

• There is more carbon dioxide in the body cells than in the blood of the blood capillaries

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5. The heart pumps the oxygenated blood out to the body cells which require oxygen

• As a result, oxygen from the oxyhaemoglobin diffuses out of the blood capillaries into the body cell. The oxyhaemoglobin becomes haemoglobin again the blood

Oxyhaemoglobin oxygen + haemoglobin

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6. At the same time, carbon dioxide in the body cells diffuses into the blood capillaries

a) The body cells receives oxygen and release carbon dioxide

b) The blood capillaries release oxygen and receive carbon dioxide

c) The blood capillaries now carry deoxygenated blood which is dark/dull red in colour

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7. The deoxygenated blood is finally carried back to the heart and then to the blood capillaries surrounding the alveoli in the lungs.

8. The deoxygenated blood releases carbon dioxide to the alveoli and absorbs oxygen, forming oxygenated blood again

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E. Cell Respiration

1. The process in which food is oxidised in the cells to get energy is called cell respiration / tissue respiration / internal respiration.

2. Cell respiration takes place in all living cells, i.e. in both plants cells and animal cells.

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E. Cell Respiration

3. Cell respiration can be represented in an equation:

Glucose + oxygen energy + carbon dioxide + water

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E. Cell Respiration4. The raw materials for cell respiration are

glucose and oxygen5. The waste products for cell respiration are

carbon dioxide and water6. Cell respiration which uses oxygen is classified

as aerobic respiration7. Some organism such as yeast and some

bacteria do not use oxygen for respiration. They carry out anaerobic respiration

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F. Harmful substances to the respiratory system

1. Sulphur dioxide2. Carbon monoxide3. Carbon dioxide4. Dust5. Smog

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G. Harmful chemicals in cigarettes

1. Nicotine2. Tar3. Carbon monoxide4. Carcinogen5. Other irritants in

cigarette smoke

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H. Diseases of respiratory system

1. Asthma2. Smoker’s cough3. Bronchitis4. Lung cancer5. Emphysema6. Heart disease7. Infant death