GCSE PE. YR10.
1.
UNIT C2.
THE RESPIRATORY SYSTEM.
STRUCTURES OF THE RESPIRATORY SYSTEM.
You need to know the location and brief function of the following.
Location on diagram.
FUNCTIONS:
Nasal Passages: Has various important jobs for inhaled air:
1. Filters air with hairs and mucus.
2. Warms air with blood vessels close to nose lining.
3. Moistens air with water vapour.
All of these are vital for when the air gets to the alveoli.
Larynx:
Voice box. Makes sounds for speaking.
Trachea:
Windpipe. Flexible tube held open by rings of cartilage. Helps filter inhaled air with
microscopic hairs.
Bronchi:
The trachea branches into 2 bronchi in the lungs. Each is a bronchus. Also helps filter
air.
Bronchioles:
The bronchi branch into smaller tubes called bronchioles.
Alveoli:
The bronchioles end in tiny air sacs called alveoli. They have a massive surface area
and would cover 55square metres if they were flattened out. The walls need to be
very clean and moist. They are so thin that air can pass through them to allow
gaseous exchange.
2.
THE MECHANISM OF BREATHING.
During inspiration the
muscles contract and pull the
upwards and outwards. At the same time the
contracts changing from a
dome shape to a flatter shape. These movements cause the
in the
to decrease as the volume increases. This results in air being sucked into the lungs.
During expiration all of these muscles
causing air to be
.
The thorax is lined with a
which joins it to the lungs. When we breathe in
this causes the lungs to be pulled out. It also lubricates the outside of the lungs.
3.
GASEOUS EXCHANGE.
Gaseous exchange takes place in the alveoli. The walls of the alveoli are very thin and moist which
helps the gases pass through. They are covered with capillaries, which transport blood. This blood
carries carbon dioxide from body cells to the alveoli where it is passed through and breathed out.
Oxygen is breathed in and passed through the alveoli and capillary walls and carried to the body cells.
4.
INHALED Vs EXHALED AIR COMPOSIITON.
Gas
Oxygen
Carbon Dioxide
Nitrogen
Water Vapour
% of inhaled air.
20%
0.4%
79%
A Little
% of exhaled air.
16%
4%
79%
A lot
Why is the amount of nitrogen the same in inhaled and exhaled air?
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5.
LUNG VOLUMES & MEASUREMENTS.
Give definitions for the following:
RESPIRATORY RATE: How many times we breath per minute.
At rest: 12 per min (approx)
Exercise: 30 per min
TIDAL VOLUME:
amount of air you breath in or out in one breath.
At rest: 0.5 litres
Exercise: 2.5 litres
MINUTE VOLUME:
amount of air you breath in one minute. = respiratory rate x tidal volume.
At rest: 6 litres per min
Exercise: 75 litres per min
VITAL CAPACITY:
The maximum amount of air that can be forcibly exhaled after inhaling as
deeply as possible.
Average: 4.5 litres.
RESIDUAL VOLUME: The amount of air left in your lungs after exhaling as hard as you can.
You can never completely empty your lungs, as they would then collapse.
Average: 1.5 litres.
6.
CELL RESPIRATION (ENERGY FOR EXERCISE).
When we exercise our muscles need energy in order to contract. This is created by two types of cell
respiration. Both require GLUCOSE which is obtained from breaking down carbohydrates. One uses
oxygen, the other does not.
1.
Aerobic Respiration.
Production of energy with oxygen is called aerobic respiration. The following equation describes this
process:
GLUCOSE + OXYGEN
ENERGY
+ CARBON DIOXIDE + WATER
Some of this energy allows the muscle to move, a lot is converted into heat which is why we get hot
during exercise. If we are doing prolonged steady paced exercise e.g. jogging, cycling; we will use
aerobic respiration. Aerobic respiration produces a lot of energy but produces it slowly. Sometimes we
need a lot of energy very fast and so this is not quick enough.
2.
Anaerobic Respiration.
Production of energy without oxygen. If we need energy very quickly for a quick burst e.g. sprint, shot
putt; we do not need to use oxygen. The following equation describes anaerobic respiration:
GLUCOSE
ENERGY
+ LACTIC ACID
2
This gives off far less energy than aerobic respiration. It produces it much quicker. Lactic Acid is
produced as a bi-product of anaerobic respiration. It is a mild poison and causes pain in your muscles
and eventually you have to stop. It normally starts to hurt after a minute.
Oxygen debt.
After strenuous exercise using anaerobic respiration there is lots of lactic acid left in our muscles. The
amount of oxygen required to get rid of this lactic acid is called OXYGEN DEBT. Most is turned into
carbon dioxide and water. Some is changed back into glucose.
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