1. Red blood cells 7 micrometres diameter 2 micrometres thick Full of a red chemical called haemoglobin that contains iron. Haemoglobin allows the red blood cell to carry oxygen from the lungs to all the cells in the body. They have a biconcave shape. This gives a large surface area for carrying oxygen. Healthy adults have about 20,000,000,000,000 red blood cells. People who do not get enough iron in their diet have small, pale red blood cells and feel tired all the time. People who lose a lot of blood have normal red blood cells but too few of them. Red blood cells don’t have a nucleus. This makes more room to carry oxygen. 143 can fit into 1 millimetre Photo credit: visualsonline.cancer.gov

2. White blood cells White blood cells defend the body against disease. More are produced when you have an infection. They have an unusual shaped nucleus. When they catch a microbe they change shape, wrap themselves around it and digest it. They can squeeze out of blood vessels to attack infections in other tissues. 13 micrometres 77 can fit into 1 millimetre They move through blood vessels until they find microbes. SEM of white cell destroying microbes

3. They pass messages from one end of the cell to the other (like a wire carries electricity). They carry information about the body and the outside environment to the brain. Nerve cells cannot divide and are very bad at repairing themselves. If the nerve cells in your spine are damaged, then messages cannot be passed from your skin to your brain. Sensory neurone Nerve cells Some conduct messages from sense organs like your skin to your spine. Message goes this way The peripheral nervous system (PNS) consists of motor and sensory neurons.

4. They carry information from the brain to parts of the body. For example, they carry information to the muscles to make them move. The ones that take messages from your spine to your muscles are very long. Nerve cells cannot divide and are very bad at repairing themselves. If the nerve cells in your spine are damaged, then messages cannot be passed from your brain to your muscles. Motor neurone Nerve cells Up to 1 metre ( 1,000,000 micrometres) message goes this way When there are disruptions in the signals between motor neurons and the muscle, the muscles do not work properly. This is the cause of Motor Neurone Disease.

5. A sperm cell is very small. It has a tail which can move. This allows it to swim and find an egg to fertilise. The nucleus contains genes from the father. These will be passed on to the child. Sperm cell Nerve cells Its head contains enzymes. These are chemicals that help it get into an egg so the sperm and egg can join. Fertilisation is less likely to happen is sperm numbers are low or they cannot swim very well. The middle section of the sperm cell is packed with mitochondria for energy.

6. An egg cell is large and bulky because it doesn’t need to move about. It just sits and waits for sperm to find it. It contains cytoplasm. This provides food for the embryo. Egg cell Nerve cells The nucleus contains genes from the mother. These will be passed on to the child. The egg is released from the ovary and fertilised in the oviduct. Around 400 eggs are released during a women's reproductive life.

7. The cells on plant roots form long ‘hairs’. These stick out into the soil. Root hair cell Nerve cells Each root has millions of these tiny hairs. This gives the plant a big surface area for taking in water from the soil. Root hair cells have really thin cell walls. This makes it easier for the water to move from the soil into the root hair cell. Each root hair is made of a single cell. It is a delicate structure, which survives for a few days until it is replaced with another.

8. Phloem tubes move glucose (a sugar) up and down the stem. Phloem tubes Nerve cells They are made up of cells joined together end to end. The ends of each cell have little holes in them. This means glucose can move from one cell to the next.

9. Xylem tubes carry water and minerals from the roots to the leaves. Xylem tubes Nerve cells They are made up of cells joined together end to end. The cells have no walls between them. This means that water and minerals can move from one cell to the next.

10. During photosynthesis gases need to enter and exit the plant. They do this through tiny holes called stomata. Guard cells Nerve cells Guard cells control the opening and closing of stomata. When the stomata are open, gases can move in and out of the leaf. The guard cells close the stomata when the plant doesn’t have water. This means the plant loses less water vapour through the leaves.

16. Type of cellWhere you find themThe job they doTheir special features Red Blood Cell White Blood Cell Sensory Neurone Motor Neurone Egg Sperm Phloem Tube Xylem Tube Guard Cell Root Hair Cell Specialised Cells & Structures Name………………………………………………..