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Learning objectives

Learning objectives What we will learn in this presentation: How bones form (ossification) and their composition How diet and exercise effect bone density The functions of the skeleton The way bones affect body shape and size and their effect upon weight and performance How bones provide support, movement and protection To recognise and name bones The 5 regions of the vertebral column To classify different types of bones.

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Ossification Ossification is the process by which bone is formed from cartilage. The cartilage cells die off and are calcified to produce bone. In the womb the skeleton of the foetus is initially formed from an elastic tissue called cartilage (except for the clavicle and parts of the cranium).

As a baby grows the cartilage becomes bone and hardens. This is part of the process of bone growth. 2 of 29

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Bone growth

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Bone composition epiphysis

diaphysis

The end (or head) of the bone is called the epiphysis. It is made up mainly of spongy bone which is full of tiny cavities. The shaft of the bone is called the diaphysis. It is hollow and made up of hard, dense compact bone.

epiphysis

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Bone composition

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Bone composition

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Diet and exercise for healthy bones Bones are alive. Old cells and bone tissue are constantly being broken down and replaced by new ones. Certain substances are needed for this process of growth and renewal. These need to be include in your diet. Minerals are important. They are inorganic substances which perform a variety of functions in the body. Calcium is the most important for bone strength. It is found in cereals, milk and other dairy products. Some fish and vegetables also contain calcium. 7 of 29

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Diet and exercise for healthy bones After the age of 35, bone tissue begins to be broken down more quickly than it is replaced. This means that bone density and strength begin to deteriorate. Osteoporosis can occur, where bones become very brittle. As well as a good diet, regular weight-bearing exercise can help to maintain bone density and strength. Weight-bearing exercise can include walking, jogging and ball or racket games. Swimming does not help, as your weight is supported. 8 of 29

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Functions of the skeleton The skeleton performs many functions in the body. 1 Shape – The skeleton gives us our shape and determines our size. 2 Support – The skeleton supports muscles and organs. 3 Protection – The skeleton protects delicate parts of the body like the brain and lungs. 4 Movement – The skeleton allows us to move. Muscles are attached to the bones and move them as levers. 5 Blood cell production – blood cells are made in the bone marrow. 9 of 29

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Shape and size Your skeleton affects your body shape and size. Bones play an important part in determining your height and build. People with long, light bones are usually tall and thin, whilst people with short, thick bones are likely to be short and more heavily built. Some sports are more suited to people of a particular size or body shape. This means that your skeleton and bone size can affect your performance in different sports. For example, weightlifting favours individuals with strong, heavy bones. 10 of 29

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Shape and size

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Support The skeleton acts as a framework. It gives the body support, enabling us to stand and walk upright. The bones of the back and chest support internal organs and help to keep them in place. The bones of the body are held together by ligaments. The skeleton provides a framework for the muscles, which are attached to bones by tendons. Can you imagine what humans would look like if they didn’t have bones to support them? 12 of 29

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Movement Bones work with muscles to produce movement. Muscles are attached to bones by tendons. Bones have surfaces that allow for strong attachment. Tendons fuse with the tough Periosteum membrane on the outside of the bone. Muscle Tendon Periosteum Bone

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Movement

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Protection Some of our body parts, such as the brain, are very delicate and need protection from external forces.

cranium

Bones can protect body parts from impacts and injuries. The cranium protects the brain. It encloses the brain entirely in a shell of bone. The rib cage protects the delicate organs of the chest. Can you think of two reasons why the rib cage has gaps in it rather than being a solid shell of bone? 15 of 29

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Blood cell production Red and white blood cells and platelets are made in the bones. The ends of long bones and some other bones including the ribs, humerus, femur and even vertebrae bones, contain red bone marrow. This is where the blood cells are produced. The shaft of long bones is filled with yellow bone marrow which does not produce blood cells.

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Red marrow embedded in spongy bone

Yellow bone marrow in the shaft

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Naming bones Clavicle (collar bone) Ribs

Cranium (skull) Sternum (breast bone) Humerus

Ilium (part of the pelvis) Patella (knee cap)

Radius Ulna

Femur

Tibia Fibula 17 of 29

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Naming bones Scapula (shoulder blade) Vertebral column (spine)

HAND Carpals Metacarpals

FOOT Tarsals Metatarsals 18 of 29

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Naming bones

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The vertebral column The spine is also known as the vertebral column. It is made up of 33 irregularly shaped bones called vertebrae. Between each vertebra there is a pad of The spine’s cartilage which allows movement inverted ‘s’ shape and prevents the bones grinding gives it strength. together. The vertebrae protect the spinal cord. This important nerve runs up the spine, through the centre of each vertebra. The vertebral column is divided into 5 sections. 20 of 29

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The vertebral column

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Classification of bones – long bones Bones are divided into a number of different categories. So far we have mainly dealt with long bones. Long bones have a long shaft containing yellow bone marrow. They are responsible for a lot of movement and often act as levers.

Long bone

Long bones include the femur, humerus, tibia, fibula, the metatarsals, metacarpals and phalanges. Long bones contain red bone marrow for producing blood cells.

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Classification of bones – flat bones Flat bones perform a variety of functions. These include: protection for delicate areas, for example, the cranium protects the brain. areas for muscle attachment, for example, many of the muscles of the lower back and legs attach to the wide flat bone of the pelvis.

Cranium

They are made up of spongy bone between two layers of hard compact bone. They have a large surface area.

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Classification of bones – short bones Short bones are very light and very strong. They are small and squat in shape.

carpals

They are composed of spongy bone with a thin layer of compact bone on the outside. The carpals in the wrist and the tarsals in the foot are examples of short bones. tarsals 24 of 29

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Classification of bones – irregular bones Irregular bones are specially shaped to perform a particular function.

patella

They are composed of spongy bone on the inside and compact bone on the outside. Examples include the patella and the vertebrae.

The patella is shaped so that the quadriceps tendon slides easily over the knee joint. 25 of 29

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Bones and joint movements

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Exam-style questions 1. Name the process by which bone is formed from cartilage. 2. Bones perform a number of functions in the body. a) Name two functions of the skeleton. b) Give an example of a bone which performs each of the functions you listed above. 3. Karim wants to become a professional basketball player. a) How may Karim’s skeleton affect his performance? b) Suggest two things that Karim could do to make sure that his bones stay healthy as he gets older.

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Can you remember all these keywords? Ossification

Osteoporosis

Cartilage

Vertebral column

Epiphysis

Long bones

Diaphysis

Short bones

Periosteum

Flat bones

Compact bone

Irregular bones

Cancellous bone Growth plate Bone marrow

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Bones