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What is the musculoskeletal system?

In this video, Lesley introduces the key components and functions of the musculoskeletal system.
Before we look at what happens when the musculoskeletal system ages, it is important to have a basic understanding of what the musculoskeletal system does, what it looks like and how it works. The two key components of the musculoskeletal system are the skeleton and skeletal muscle. The skeleton includes bone, cartilage, ligaments, tendons and joints. The nervous system provides a vital link between this system and the brain, ensuring coordinated movements and control. And a good blood supply is also essential, especially to the muscles which consume large amounts of energy. There are 206 bones supporting the weight of our body. The majority have a dense, strong outer layer, called cortical bone.
Inside the cortical bone, there is a spongy bone material called trabecular bone. In this way, the bone is lighter and easier to carry around but still strong to support us. In the trabecular bone, there is a soft tissue substance called bone marrow. The bone marrow, in contact with the bone,
produces all blood cells: red blood cells which carry oxygen all over the body, and white blood cells, which protect us from infection. Bones are made mostly of collagen and calcium. Collagen is a protein that provides a soft structure, and calcium phosphate is a mineral that gives the bone its characteristic strength and hardness. This combination of collagen and calcium makes bones strong enough to support the body and flexible enough to enable movement. Bone is a living tissue with a blood supply. It is constantly being dissolved and reformed, and can repair itself if a bone is broken. Calcium is essential for cell function, without it, cells do not operate properly.
If there is not enough in the blood, special cells called osteoclasts will dissolve small areas of the bone to release calcium into the bloodstream. New bone is formed by cells called osteoblasts, which also regrow and repair the bone if it breaks. Bones grow continually from birth up to our mid-20s. Bone mass is at its maximum density around the age of 30. When bones stop growing, they continue to be maintained by the osteoclasts removing old bone and osteoblasts replacing it with new bone. Bones are linked together by joints. The most common type are called synovial joints, and include hinge joints like the knee and elbow, and ball-and-socket joints like the hip and shoulder.
If two bones just moved against each other, they would eventually wear away. This can happen in people who have a condition called arthritis. To stop this happening, the ends of the bones in a joint are covered with a tough, smooth substance called cartilage, which is kept slippery by a liquid called synovial fluid. Bones are held together at the joints by ligaments and attached to the muscle by tendons. Both are fibrous connective tissue primarily formed of collagen. But whilst ligaments are flexible and help to provide stability, tendons are inelastic and serve to move bones, transmitting the contractive forces generated by the muscle. Skeletal muscle functions to carry out movements and maintain posture.
Muscle is made up of thousands of specialised cells called muscle fibres, each of which can be up to ten centimetres long. The length and diameter of the fibres determines the muscle’s strength and range of movement. Each muscle fibre contains many mitochondria, the sites of energy production in all cells, which are absolutely essential for muscle function. Muscle moves the skeleton by contracting. This contraction is generated using the energy from the mitochondria and by the movement of specialist proteins called myosin and actin, which run along the length of the fibre and give it a striated appearance under the microscope. The muscle fibres are packaged into bundles and kept together by collagen.
There are different types of muscle fibre distinguished by their strength, whether they are fast or slow, and how quickly they fatigue. Each muscle also has a blood supply and is connected to the nervous system. The whole muscle is enclosed by a sheath of connective tissue so that all the muscle fibres work together. The musculoskeletal system has many components which must all work together to allow us to move about in our daily lives. If any of these components start to fail, it can have a serious knock-on effect on the whole system.

In this video, Lesley Iwanejko introduces the key components and functions of the musculoskeletal system.

The musculoskeletal system is made up of bones, muscles, joints, tendons and ligaments which all work together to provide the body with support, protection, and movement.

When they are healthy, they provide support and stability and allow us to move about in our daily life. But if any of these components start to fail, this can have a serious knock-on effect for the whole system.

We cover a lot of information in this video so don’t feel you have to take it all in at once. Remember you can pause and rewind whenever you need to. We have also created a glossary which you can download below. Let us know if you think any key terms are missing and we’ll make sure to add them in!

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The Musculoskeletal System: The Science of Staying Active into Old Age

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FutureLearn - Learning For Life

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