THE HUMAN SKELETAL SYSTEM

• STRUCTURE • AND• FUNCTION

STRUCTURE

• The human skeletal system is made up of 206 bones (pg 212)

• It is referred to as an endoskeleton because it is inside the body

• Insects have an exoskeleton; a hard shell like substance that encompasses its body

BONES ARE ALIVE

Bones are hardIt contains calcium salts such as calcium and

phosphateIt is a living organ made up of cells, hence the

reason bones are able to repair themselves if broken

CROSS SECTION THROUGH A NORMAL BONE

• Bone consists of three main layers• Hard outer layer of the bone is known as compact

bone- contains bone cells known as OSTEOCYTES which produce more bone cells, Haversian canals are the channels for blood vessels and nerves, there are also rings and bands of calcified substances (makes bone hard)

• Cancellous internal layer also known as spongy bone has large open space

• Bone marrow (yellow and red)

Function

• Support• Protection• Movement• Blood cells formation• Storage

SUPPORT

• Without the skeleton, the body would have no structure. It allows us to stand upright and support our weight

PROTECTION

• Very important to protect our vital organs• Cranium or skull protects our brain• Vertebral column protects our spinal chord• Ribs protect our heart and lungs

MOVEMENT

• Together with muscle, ligaments and joints, the skeletal system enables us to move our bodies

BLOOD cell FORMATION

• All blood cells are made in the bone marrow• Red blood cells transport oxygen• White blood cells aids in defense against

diseases

STORAGE

• Bones also store minerals such as calcium and phosphorus

• It also stores fatty acids

SUMMARY

• Skeleton can either be endoskeleton or exoskeleton

• There are 206 bones in the adult human body• The bone has three layers, compact, spongy

and marrow• Bones are alive• Five main functions are; support, protection,

movement, blood cells production and storage

REVIEW

• How many bones are there in the human body• What is the name of the bones that protect the

heart• What substance enables bones to be hard• What is the function of marrow• What other components besides the skeletal

system is needed for movement• Name one substance bones store• Where are osteocytes found

ASSIGNMENT

• Create a song or poem on the human skeletal system due 27/05/13