KEY STAGE 4 BLOOD Boardworks Ltd 2003 Teachers

KEY STAGE 4 BLOOD © Boardworks Ltd 2003

Teacher’s Notes A slide contains teacher’s notes wherever this icon is displayed To access these notes go to ‘Notes Page View’ (Power. Point 97) or ‘Normal View’ (Power. Point 2000). Notes Page View Normal View Flash Files A flash file has been embedded into the Power. Point slide wherever this icon is displayed – These files are not editable. © Boardworks Ltd 2003

What is blood? If blood is separated it no longer looks like the red liquid that we recognise. centrifuge The blood sample separates into two parts. The top half is a straw coloured liquid called Plasma (55%). The bottom half is a dark collection of Blood cells (45%). © Boardworks Ltd 2003

As blood is 55% plasma and only 45% cells, the cells are actually suspended within the plasma, a little like people would be suspended within a swimming pool. blood cell plasma The plasma actually surrounds the cells and carries them along as it flows through the blood vessels. This is the first function of plasma. © Boardworks Ltd 2003

Blood flows around the body, transporting substances from one place to another. it usually picks a substance up from an exchange site takes it to a place where it is used a reaction occurs Reaction a useful product and a waste product is made © Boardworks Ltd 2003

The blood then transports one or both of these substances to another place in the body. blood vessel cell useful/waste product The cycle then starts again. © Boardworks Ltd 2003

Blood has to rely on its plasma to actually carry some of these useful/waste products. For example, plasma carries CO 2 from the cells to the lungs. Magnify blood flowing along a capillary CO 2 blood cell plasma CO 2 blood cell © Boardworks Ltd 2003

The third and fourth roles are also centred around the moving of a substance from one place to another. 3 rd Role: Plasma is responsible for carrying dissolved food. Remember! Our digestive system breaks down the food we eat to release the useful nutrients. © Boardworks Ltd 2003

Mouth food is eaten Sugars Useful products of digestion are absorbed from the digestive system and enter the blood. Amino Acids Glycerol Fatty Acids Anus waste is excreted © Boardworks Ltd 2003

The soluble food dissolves into the plasma and is carried from the small intestine to the cells of the body. Here they diffuse into the cells and are used in various chemical reactions. Glycerol plasma Sugars Amino acids Fatty acids Body cell © Boardworks Ltd 2003

The final role of the plasma is to carry a waste product from the liver to the kidneys. The waste product is called Urea is made in the liver by the breakdown of amino acids. As urea is toxic, it must be removed from the body as quickly as possible! The blood now has to help the body do this. © Boardworks Ltd 2003

This is where the plasma takes control. It carries the urea from the liver to the filtering organs (the kidneys). As the blood passes into the kidney, the urea is removed from the plasma and passes down a tube that takes it to the bladder. kidney blood urea This urea passes to the bladder where it is stored before it is excreted. © Boardworks Ltd 2003

The urea will leave the body within the liquid urine In summary, this tells us that plasma has a principle role in transporting substances around the body. Substance Moving from Going to CO 2 Cells Lungs Cells All over The Body Dissolved food Small intestine Cells Urea Liver Kidney © Boardworks Ltd 2003

We’ve come a long way from calling blood just a red liquid. After all, all this is being carried in just the bloods plasma. Sugar White Blood Cell Platelets Fatty Acids CO 2 Red Blood Cell CO 2 Urea Carbon Dioxide Amino Acids © Boardworks Ltd 2003

Blood cells There are 3 types of blood cell within human blood. They have different shapes and carry out different functions. Red Blood Cells Platelets White Blood Cells (These are actually fragments of cells so we can’t really call them cells) © Boardworks Ltd 2003

Red blood cells Of all the cells these are the most numerous. In fact, every cubic centimetre of blood contains… 1 cm 5 000, 000 cells 1 cm © Boardworks Ltd 2003

Therefore, it is not hard to realise that each red blood cell is extremely small. In fact, each one is only on average 7 micrometers in diameter (one micrometer is a millionth of a metre). This is a basic diagram of a red blood cell. © Boardworks Ltd 2003

Actually, although the red blood cell is a “cell”, it does not contain one of the 3 parts of a “normal” cell. Red blood cells have no nucleus. This may seem odd but, there is a reason for it. Red blood cells also contain a unique substance called Haemoglobin. This is a special iron based pigment whose presence is essential if the red blood cell is to perform its job. And by the way, its job couldn’t be more important! © Boardworks Ltd 2003

Red blood cells carry OXYGEN (O 2). Let’s look at how it performs this job. The story begins in the lungs because this is where the oxygen gas enters the bloodstream. Remember, during the process of breathing, oxygen gas enters the body and is exchanged for carbon dioxide gas. The oxygen gas will be needed for the process of respiration. © Boardworks Ltd 2003

O 2 oxygen is inhaled O 2 It passes through the breathing system and reaches an alveolus. O 2 O 2 alveolus The oxygen gas diffuses across the lining of the alveolus and the capillary. © Boardworks Ltd 2003

Here is a close up showing the diffusion of oxygen gas. As the oxygen gas diffuses across the lining of the alveolus, it dissolves in the moist layer. This speeds up the diffusion process. O 2 moist layer O 2 lining of alveolus lining of capillary red blood cell © Boardworks Ltd 2003

If we now concentrate on one red blood cell, we can see how important the haemoglobin molecule is to the process of transporting oxygen. O 2 each red blood cell contains the pigment. . . The oxygen molecule diffuses into the red blood cell. Haemoglobin + O 2 Oxyhaemoglobin These two molecules bind together to produce this new substance. © Boardworks Ltd 2003

Oxygen + Haemoglobin Oxyhaemoglobin It is important to remember that this reaction is happening in red blood cells at the alveolus. This is how the red blood cells are able to bind hold of the oxygen and carry it within the blood. Oxyhaemoglobin Each red blood cell is now Oxyhaemoglobin loaded with oxygen molecules. Oxyhaemoglobin © Boardworks Ltd 2003

Once these red blood cells reach the cells of the body, they are travelling through tiny capillaries similar to those found in the alveolus. capillary cells It is here that they offload their oxygen. In order for this to happen, the Oxyhaemoglobin molecule must be broken down. © Boardworks Ltd 2003

ENERGY In the cell, the oxygen is used in the process of respiration which produces…. It diffuses across the cell membrane and the lining of the capillary and into the cell. The Oxyhaemoglobin breaks down to release the oxygen molecule. © Boardworks Ltd 2003

Questions Why are red blood cells shaped like this? Well, they are perfectly suited to do their job. They are specialised in the following ways 1 There are vast numbers of them. The more cells there are, the more O 2 can be carried and delivered to the cells. © Boardworks Ltd 2003

2 They have no nucleus. This means they have more room for haemoglobin molecules and therefore each red blood cell can carry more oxygen gas. 3 They have a large surface area compared to their volume. large surface area small volume © Boardworks Ltd 2003

Through having a small volume compared to its surface area, the red blood cell is able to keep the oxygen close to its surface. This means it can quickly release its oxygen by reducing the time it takes for the gas to diffuse out of the cell. The distance for the gas to move is much smaller in a cell shaped like this. O 2 alternative cell design O 2 The overall effect of this means that the blood can cope with the oxygen demands of the body. © Boardworks Ltd 2003

4 The diameter of red blood cells is slightly larger than the average diameter of a capillary. red blood cell capillary This means that the red blood cell is forced to slow down as it passes through the capillary. This means the exchange of the gas will definitely happen. It also means the surface of the red blood cell will be exposed to the surface of the capillary. © Boardworks Ltd 2003

Let’s now consider the white blood cell. The white blood cell is bigger than the red blood cell. It has a much more varied shape and there are different types of white blood cell within the blood. White blood cells play a part in the defence system of the body. They are designed to fight microbes such as bacteria and viruses. © Boardworks Ltd 2003

There are far fewer white blood cells within the blood compared with red blood cells. When the body fights disease, more white blood cells are produced. With some diseases, doctors can establish how healthy someone is by testing their blood to see how many white blood cells they have. Disease Test white blood cell number is low Test Person is Normal Person is suffering from disease white blood cell number is higher © Boardworks Ltd 2003

Our final cell is the platelet. As we mentioned, the platelet is actually a fragment of a cell. Therefore it does not have a nucleus. They are also much smaller than both the white and red blood cells. Their role is to help to clot the blood when the body has a wound. Blood capillary skin © Boardworks Ltd 2003

Multiple choice questions © Boardworks Ltd 2003

Which of these is not a function of blood? A To support the body. B To fight disease. C To carry gases around the body. D To carry hormones to their site of action. © Boardworks Ltd 2003

What is the name of the pigment within red blood cells? A haemoglycin B haemoglobin C haemoglycerol D haemoglucose © Boardworks Ltd 2003

Which of these descriptions best suits the shape of a red blood cell? A a doughnut B a round flat plate C a biconcave disc D a disc shaped shell © Boardworks Ltd 2003

What is missing from a red blood cell? A the nucleus B the cytoplasm C the cell membrane D answers A and B © Boardworks Ltd 2003

What is the name of the straw-coloured liquid in which blood cells are suspended? A haem liquid B cytoplasma C blood fluid D plasma © Boardworks Ltd 2003

What percentage of blood is made up of plasma? A 20% B 40% C

Which of these substances are carried by blood plasma? A oxygen, glucose, urea and amino acids B amino acids, carbon dioxide, oxygen and fatty acids C fatty acids, glucose, oxygen, glycerol D urea, fatty acids, amino acids and carbon dioxide © Boardworks Ltd 2003

Blood plasma. . . A defends the body against invading microbes. B helps the blood to clot. C transports urea from the liver to the kidneys. D binds to oxygen. © Boardworks Ltd 2003

Red blood cells. . . A need oxygen. B attract carbon dioxide. C carry oxygen. D repel carbon dioxide. © Boardworks Ltd 2003

The white blood cells are larger than red blood cells. Their job is to. . . A make the blood clot. B carry oxygen to the cells of the body. C defend the body against invading microbes. D carry carbon dioxide. © Boardworks Ltd 2003