2.2 MOVEMENT & EXCHANGE OF GASES IN THE HUMAN BODY
1. Alveolus
2. Blood
3. Oxygen
transport to
whole body
4. Cell
5. Respiration in
cell
6. CO2 Transport
to alveolus
Oxygen is diffuse through the wall of the alveolus into the
walls of the capillaries and into the blood. (Because the air
inhaled into the alveolus has a higher concentration of
oxygen compared to the concentration of oxygen in the
blood)
Haemoglobin + oxygen → oxyhaemoglobin
Haemoglobin will combine with oxygen to form
oxyhaemoglobin.
Haemoglobin → dark red-coloured compound in red blood
cells.
Oxyhaemoglobin → unstable compound and bright red in
colour
Blood with oxyhaemoglobin is transported (lungs →heart
→other parts of the body)
When the blood reaches the area around the body cells that
has a low concentration of oxygen, oxyhaemoglobin will
decompose to release oxygen molecules.
Oxyhaemoglobin → haemoglobin + oxygen
In the body cells, the process of cellular respiration occurs.
Glucose + oxygen → carbon dioxide + water + energy
Carbon dioxide diffuses into the blood capillaries and is
transported to the alveolus to be removed during exhalation.
Importance of the Adaptations of the Alveolar Structure
To increases the rate of gaseous exchange between the alveolus and the blood capillaries.
1.
2.
3.
4.
Thin walls of alveolus and blood capillaries (made up of only one layer of cells).
Moist wall of alveolus (allows respiratory gases to dissolve and diffuse into the blood capillaries).
Larger surface area of alveolus (for the exchange of gases).
Compact network of capillaries covering the alveolus.
1.
The figure below shows the exchange of gases in the alveoli.
(a) Study the figure and answer the following questions.
(i) Name structure X and Y in the space provided. [2M]
(ii) Name process R and S in the space provided. [2M]
(iii) Name gas P and Q in the space provided. [2M]
(b) The figure below shows the structure of an alveolus and blood capillaries.
Explain how oxygen is transported to the body cells starting from the alveoli. [3M]
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(c) The figure below shows the structure of an alveolus.
(i) Name the process involved in the gaseous exchange between the alveolus and blood capillaries. [1M]
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(ii) Explain how this process occurs. [2M]
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2.
(a) Explain the importance of gaseous exchange in human. [2M]
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(b) The following are two equations which involve in the formation and decomposition of oxyhaemoglobin.
Equation 1: Oxygen + Haemoglobin → Oxyhaemoglobin
Equation 2: Oxyhaemoglobin → Oxygen + Haemoglobin
(i) The process in Equation 1 is disrupted due to the defect of red blood cells. State the effect. [1M]
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(ii) Where does the Equation 2 occur? [1M]
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(iii) What happen to the oxygen in the product of Equation 2? [1M]
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(c) Complete the following statements using the words below. [4M]
capillary
moist
large
thin
(i) Alveolus has _____________________ surface area due to its small size.
(ii) The alveolar surface is kept ____________________ as it is covered by the liquid.
(iii) Alveolus has a _________________ wall where the thickness is only one layer of cells.
(iv) Each alveolus is surrounded by a dense network of___________________.
1.
a.
b. Inhaled air enters the alveoli and diffuses into the blood capillaries. Oxygen combines with
haemoglobin to form oxyhaemoglobin. Oxyhaemoglobin is transported to body cells and
decomposed to release oxygen. Oxygen then diffuses into the body cells.
c. (i) Diffusion
(ii) Concentration of oxygen in the alveoli is higher and causes oxygen to diffuse from the lungs into
the alveoli. Concentration of carbon dioxide is higher in the blood capillaries and causes carbon
dioxide to diffuse from the blood capillary into the alveoli.
2.
a. To supply oxygen for cellular respiration and remove carbon dioxide from the body.
b. (i) Less oxygen transported to body cells
(ii) In body cells
(iii) Oxygen diffuses into the body cells and used in cell respiration.
c. (i) Large
(ii) Moist
(iii) Thin
(iv) Capillary