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Multicellular organisms are things like humans, fish, plants etc. They are made of millions of cells! All the cells work together and perform a specific function to keep the organism alive.
Animals like you and me, are more complex than plants and have a greater variety of cells. Our bodies contain over 50 trillion cells and over 200 different types of cells. Each type of cell, has its own function. These cells have special features that allow them to perform their jobs.
Here are some examples of specialised cells and the features they have to help them with their role:
Muscle cells can help move your body parts and pump your heart. Muscle cells are held together in bundles, which pull together to make muscles contract. Muscles which surround the skeleton help you move around. Your biceps and triceps for example, help control your arm. As you can imagine your muscles are always moving. This means muscles cells need a constant amount of energy. If you see a muscle cell, you’ll notice they have a lot of Mitochondria.
There are actually 3 different types of muscle cells.
Scroll over the diagram to see what the type of muscle looks like.
Skeletal muscle is joined to bones. Its cells contract to make bones move and joints bend. These are known are voluntary muscles because you voluntarily move them and they have a stripped appearance.
Smooth muscle cells make up thin sheets of muscle, such as the stomach lining. They can also be arranged in bundles, or rings. They are called involuntary muscles because they act involuntary of thought. Most don’t have a stripped appearance like voluntary muscles.
Cardiac (heart) muscle cells are branched, and they join together to make a net. Cardiac muscle cells contract rhythmically, even outside the body. They never get tired! While they are also involuntary they have a stripped appearance like voluntary muscles.
Your brain is comprised of nerve cells. They carry information too and from the the brain, in the form of impulses all around the body.
They have long fibres called axons which extended from the cell body. In fact the longest axon in the human body stretches form the base of the base of the spine to the toes and can be over 1 meter long! At each end they have branched connections. These join to other nerve cells, allowing them to pass on messages. To communicate they use a combination of electrical & chemical signals. A fatty (myelin) sheath surrounds the the axon, which helps to increases the speed at which the message can travel.
You’ve probably heard of red & white blood cells before. They flow through your veins, arteries and organs. White blood cells are very different from red blood cells, and play an important part in your immune system. Red blood cells supply oxygen to all the cells in your body.
They are well suited to this function because:
They contain haemoglobin, which carries oxygen molecules.
They don’t have a nucleus, allowing more space to carry oxygen.
They are a flat disc shape (bi-concave) which gives them a large surface area, and the best chance of absorbing as much oxygen as they can.
We have ciliated cells all throughout our body. In our trachea are ciliated cells which push up pathogens and dust caught. The the fallopian tubes are ciliated cells which push the egg. These cilia are like tiny hair or fingers, all moving in the same direction to move something.
Ciliated cells are very similar to crowd surfing.
Imagine if the person crowd surfing is the mucus or pathogen, and each person’s hands are the cilia. Watch as the all work together, moving in a single direction.
Try the drag & drop below.
Plants are also multicellular. They contain lot of different cells, each with a different shape, size & function.
Scroll over each box below to see an image of the cell.
Try the drag & drop below.