Summary Blood And Breathing

Page 69.

Releasing energy

We need energy to keep alive.
For energy we need Glucose (sugar) + Oxygen à carbon dioxide + water + energy

Glucose is sugar, we need it to make energy, you find it in your food.

We call this process respiration. because we need oxygen for it to happen, it is called aerobic respiration. All living things carry out respiration. Even plants.

Page 70

Using energy

Your body needs energy for many different things. Energy is used up:

- Working yours muscles
- Transporting chemicals
- Absorbing food
- Sending messages along nerves
- Building cells for growth
- Keeping your body temperature constant.

Respiration takes place in all our cells all the time.

Our cells contain tiny structures called mitochondria. This is where energy is released from glucose.

Muscle cells use up lots of energy. They have lots of mitochondria.

We did a experiment with seeds, boiled and living seeds. We saw that the living seeds produced more heat than the boiled seeds. This is the reason:

- The boiled seeds are dead, so they don’t respire, so they don’t produce heat.
- The living seeds respire, because they are living, so they produce heat.

Page 71.

Carbon dioxide is a waste gas made in respiration. It can become toxic if it builds up in our cells. This is called lactic acid.

We also did a experiment with that lime water thingy. It show us that there is water vapour in carbon dioxide, because it gets cloudy.

Page 72.

Below you can see a table with what you breath in and what you breath out.

Gas Inspired air (breathing in) Expired air (breathing out)
Oxygen 21 % 16 %
Carbon Dioxide 0.04 % 4 %
Nitrogen 78 % 78 %

We breath less oxygen out than in, because our body need to make energy, and you need oxygen to make energy. We breath more carbon dioxide out than in, because our body makes carbon dioxide, and we don’t need it. We don’t produce or need any nitrogen, so we breath the same amount in as out.

Page 73


· Your breathing system
you breath in air to get oxygen, and you breath out the get rid of the carbon dioxide. This is called a gas exchange. It takes place in our lungs.

Lungs are inside your chest or thorax. They are surrounded and protected by your ribs. One lung is as big as a rugby ball.

The muscles below your lungs are called diaphragm. It separates your thorax from your abdomen.
To breath you need your ribs and diaphragm.

Air enters trough your nose and mouth and then down trough your windpipe or trachea.
Cold, dry and dirty air might damage your lungs so it is first:
- warmed up
- moistened
- filtered and cleaned
the cells in your nose and trachea makes slimy mucus. Dust and germs get trapped in the slime. The cells have tiny hair or cilia on them. These beat to carry the mucus up to your nose and throat.
The air which enters your nose is cleaner.

· Two-way trip to your lungs
Before air enters your trachea it enters your larynx. It’s a knob in your neck and you can feel it on the outside, sometimes it’s called the Adam’s apple.
The larynx contains vocal cords, when air blows over these you make sound.

when you swallow, a flap of skin called the epiglottis drops over the opening to your larynx. that’s why food can’t go down your windpipe.

your windpipe doesn’t collapse because the windpipe is kept open by rings of cartilage, they are C-shaped.

your lungs are spongy , they are surrounded by the pleural membrane. this makes a slippery fluid.

· Breathing in
· Your intercostal muscles contract.
they raise your ribs upwards and outwards.

· The muscle in your diaphragm contracts.
your diaphragm flattens.

· These increase the volume of your thorax.
The pressure inside your thorax decreases.

· Air is sucked into your lungs.
· Breathing out
· Your intercostals muscles relax.
This lowers your ribs downwards and inwards.

· The muscle in your diaphragm relaxes.
Your diaphragm bulges upwards.

· These decrease the volume of your thorax
The pressure inside your thorax increases.

· Air is forced out of your lungs

· Deeper into your lungs
windpipe à bronchus à bronchioles à alveoli (air sacs)

Each air sac is surrounded by a network of blood capillaries. The air sacs have thin walls, and they are moist.

· Swopping gasses
oxygen dissolves in the water lining each air sac. it diffuses through the air sac wall and the capillary wall into the blood.

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An adult can take in about 5 litres of air in their deepest breath. At rest, about half a litre of air is breathed in and out. During exercise, an extra 2 litres of air can be taken in.

We did also a experiment with lung capacity. It showed us that men have a larger lung capacity than women. If you are older, about 25 – 45 than is your lung capacity the largest. That’s because you grow if you are a child, and if you become older, your lung capacity will be a little smaller. You have also a bigger lung capacity if you do lots of sport.

If you are resting, you take about 16 breaths a minute. If you just did exercise, than you take more breaths because you need more oxygen, because they move faster.

When you doing exercise, you produce more carbon dioxide. Your brain sends messages via the nerves to your chest muscles. Then they know that they have to work harder to lower the carbon dioxide in your blood.

Page 80

If someone has a accident their breathing might stop. Artificial respiration is a way of starting their breathing again for them. This is also called mouth-to-mouth ventilation (mond op mond beademing) or kiss of life. Than you breath oxygen into the mouth of the person who needs oxygen. Your oxygen goes into the windpipe, or trachea, and than they can get oxygen again. It can save your life.

Page 81

Sometimes we can respire without oxygen. That is called anaerobic respiration. Many microbes can respire without oxygen. When it respires without oxygen it is called fermentation.

Glucose à alcohol + carbon dioxide + energy

© Eric and Nina , B2a & B2b

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