Principles of a+p 1112 session 2 - skeletal system (functions of skeletal system and bone structure)

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Principles of Anatomy and Physiology in Sport

Session 2 – The Skeletal System

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Re-Cap Last Session

• Major bones of the body

• Axial/Appendicular skeleton

• Vertebral column - sections

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Drag the labels to the correct place on the skeleton...

The Skeletal SystemThe Skeletal System

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Aim

• To complete assignment 1

Objectives

• To be able to describe the functions of the skeletal system

• To be able to describe the structure of a typical long bone

• To explain the differences between compact and cancellous bone

Aims & Objectives

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Activity

• With your partner work together to list and briefly describe the 6 functions of the skeleton

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Bone Structure

Bone is the hardest tissue in the body

• Compact Bone– Found at the

shaft or diaphysis of long bones

– External layer of bone that copes with the stresses of PA

• Cancellous Bone– Referred to as

the spongy part of a bone

– Found under the external layer of compact bone

– Bone marrow is found in this part of the bone

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Ossification

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Ossification

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Bones start to grow inside the womb, where they begin as cartilage. Cartilage

Periosteum

Bone Marrow

Spongy Bone

Compact Bone

What are Bones made of?What are Bones made of?

Vitamin D helps build bone.

Calcium is a mineral which helps keep bones strong. Even as a fully-grown adult, the

bone structure is always changing, as vitamins and minerals are constantly replaced.

As you get older this turns into hard bone by a process called ossification. Bones will only grow properly as long as certain minerals and vitamins are eaten:

A poor diet will result in soft bones, whilst a balanced diet and exercise will make the bones harder.

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Structure of a Long Bone• Consists of a diaphysis

(shaft) with a bulge called the epiphysis at either end

• Longitudinal growth occurs between these structures

• The medullary or marrow cavity is situated in middle of the shaft beneath the compact bone; it contains either red or yellow marrow

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Bone Marrow• Age is a dependant factor on

the colour of the marrow. At birth all bones are filled with red bone marrow which produces both red & white blood cells

• With age there is a progressive replacement of the red marrow by that of yellow marrow, which is fatty and non-blood producing

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Periosteum• Each bone is enclosed in a

dense layer of fibrous tissue known as periosteum

• There are 2 layers– Outer layer

• Blood vessels & nerves– Inner layer

• Responsible for bone development

• Bones change in size & shape throughout life and they are denser in males

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Compact Bone• Is dense, has few spaces and appears solid to the naked eye

• Forms the external layer of the bones of the body, and the bulk of the shaft (diaphysis) of long bones

• Provides support & protection and helps the long bones resist the stresses of weight placed upon them

• ‘Haversian Systems’ are patterns that can be seen under a microscope

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Cancellous Bone• Known as spongy bone

• Made up of large interconnected spaces, like comic book cheese

• Is the make up of most flat, short, irregular and the end of long bones

• It has a criss cross structure that gives strength without excess weight, this is known as trabeculae

• The spaces between the trabeculae are filled with red bone marrow

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Essentials• Diaphysis

– Shaft of bone• Periosteum

– Layer around the bone (like a sleeve)

• Compact bone – Found in the bulk of

the shaft• Medullary cavity

– Marrow cavity in the middle of the shaft beneath the compact bone

• Epiphysis– Ends of bone

• Cancellous bone– Has interconnected

spaces (spongy)• Hyaline/Articular

cartilage– Found at the ends of

the epiphysis• Epiphyseal plate

– Appears as a line across the cancellous bone

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Summary

• Functions of skeleton• Ossification• Cartilage• Periosteum• Epiphysis• Bone Marrow• Compact bone• Cancellous bone

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Session objectives

• To be able to describe the functions of the skeletal system

• To be able to describe the structure of a typical long bone

• To explain the differences between compact and cancellous bone

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Next session

• Classifications of bone

• Functions of each classification of bone