2.2 Movement and exchange of gases in the human body

2.2 MOVEMENT AND EXCHANGE OF
GASES IN THE HUMAN BODY

NAMA : LIM ZHEN XUN
KELAS : 33
GURU : NOR’AIN BINTI RAZAK

MOVEMENT AND EXCHANGE OF OXYGEN AND CARBON
DIOXIDE IN THE HUMAN BODY

• Observe the movement and exchange of oxygen and carbon dioxide in the alveolus and blood
capillaries as shown image below.

Image Movement and exchange of oxygen and
carbon dioxide in the human body

1) The air inhaled into the alveolus has a 2) In red blood cells, there is a dark red-coloured
higher concentration of oxygen compared compound known as haemoglobin. Haemoglobin will
to the concentration of oxygen in the combine with oxygen to form oxyhaemoglobin which is
blood. Therefore, oxygen will diffuse an unstable compound and bright red in colour.
through the wall of the alveolus into the
wall of the capillaries and into the blood. Haomoglobin + oxygen ——— oxyhaemoglobin

4) When the blood reaches the area around the body 3) Blood with oxyhaemoglobin is transported
cells that has a low concentration of oxygen, the from the lungs to the heart and pumped to
oxyhaemoglobin being an unstable compound will the other parts of the body
decompose to release oxygen molecules and change
back into haemoglobin

Oxyhaemoglobin -> haemoglobin + oxygen

5) In the body cells, the diffused oxygen oxidises 6)Carbon dioxide released by the cells
glucose molecules into carbon dioxide, water and diffuses into the blood capillaries and is
energy through the process of cellular respiration as transported to the alveolus to be removed
summarized in the following chemical equation. during exhalation

Glucose + oxygen -> carbon dioxide + water + enegry

IMPORTANCE OF THE ADAPTIONS OF THE
ALVEOLAR STRUCTURE

• The adaptations of the alveolar structure increase the efficiency and maximise the
exchange of gases in the human body.

Adaptation of the alveolar structure

• Thickness of the walls of alveolus and blood capillaries

-The alveolus and blood capillaries have thin walls which are made up of only one layer of cells. This structure facilitates and increases the

rate of diffusion of gases across the walls of the alveolus and blood capillaries.

• Moist wall of alveolus

-The moist wall of alveolus allows respiratory gases to dissolve and diffuse into the blood capillaries.

• Surface area of alveolus

-The lungs contain millions of alveolus which provide a large surface area for the exchange of gases.

• Network of capillaries covering the alveolus

-The alveolus is covered by a compact network of capillaries which increases the rate of gaseous exchange between the alveolus and the
blood capillaries.

SCIENCE INFO

• Other than the alveolus structure, another factor that can increase the exchange of gases in
the human body is the difference in concentration of gases in the alveoli and blood
capillaries. The greater the difference in concentration of a gas in the alveoli and blood
capillaries, the higher the rate of diffusion of the gas between the alveoli and the blood
capillaries.