KS3 Biology. 8B Respiration. Contents. 8B Respiration. Releasing energy. The circulation system. The breathing system. Anaerobic respiration. Summary activities. How is digested food used by the body?.
The body needs a constant supply of energy which comes from digested food.
Glucose from digested carbohydrate is an important substance that contains stored chemical energy .
When glucose reacts with oxygena lot of energy is released.
In the body’s cells, glucose and oxygen react to release
energy . Some of this is released as heat and the rest is used by the cells.
The release of energy from glucose is called…
waste product exhaled
waste product exhaled
from the digestive system
from the breathing system
Respirationis the process that the body uses to release energy from digested food (glucose):
This type of respiration is called aerobicrespiration because energy is released with oxygen.
How do the glucose and oxygen needed for aerobic respiration get to the all the body’s cells?
Burning is the reaction between a fuel and oxygen.
This reaction is calledcombustion:
When something burns, heat and light energy are
released and carbon dioxide and water are also produced, so combustion is similar to respiration.
However, combustion is different because it is not a controlled reaction. Respiration is a controlled reaction which slowly releases energy from food in the body’s cells and the cells do not catch fire!
The dissolved food and oxygen needed for respiration are carried around the body by the circulation system.
The circulation system includes the blood, blood vessels, the heart and the lungs.
Which part of the circulation system actually carries dissolved food and oxygen to the body’s cells?
The blood carries oxygen and dissolved food to all the body’s cells so that respiration can take place.
The heart is made of very special muscle called cardiac muscle.
This is because it has to keep beating for the whole of a person’s life!
If you tried to do the same action repeatedly (like the heart does), your muscles would get tired and after a while stop working.
For example, if you keep clenching and unclenching your hand, it will get tired and may even start to get cramp.
Why is it important for respiration that the heart keeps beating?
What happens to the pulse rate whilst someone is running?
The body needs to release more energy:
muscle cells quickly;
What happens to the pulse rate whilst someone is sleeping?
The body needs to release less energy:
The breathing system is used by the body to get the oxygen needed for respiration.
It is also use to get rid of the waste product of respiration, the gas carbon dioxide.
Breathing in and breathing out are separate processes in the body:
Breathing in is also known as inhalation. When you inhale you breathe in air, including oxygen, into your lungs.
Breathing out is also known as exhalation. When you exhale you breathe out the contents of our lungs and getting rid of the waste gas carbon dioxide.
In the lungs, oxygen travels to thousands of tiny air sacs called alveoli. These are covered with tiny blood vessels.
The alveoli give the lungs a huge surface area which is equal
in size to the area of a tennis court!
Gas exchange takes place in the alveoli–oxygen is transferred into the blood and carbon dioxide moves out of the blood.
Each alveolus has a thin wall so that gas exchange between
the lungs and the blood can take place quickly.
carbon dioxide (0.04%)
carbon dioxide (4%)
What are the differences between inhaled and exhaled air?
How could you test for the differences between inhaled and exhaled air?
When the body is able to supply the cells with the oxygen and glucose that they need, it carries out aerobic respiration.
When the body cannot supply the cells with the oxygen needed to break down glucose, then it has to carry out anaerobic respiration. Energy is released without oxygen:
When anaerobic respiration takes place, the lactic acid produced soaks the muscle cells and prevents muscles from doing their job. This causes fatigue and sometimes cramp.
After activity that has lead to anaerobic respiration, the person involved pants and breathes heavily.
This happens because they need lots of oxygen to get rid of lactic acid that has built up in their body.