1. 1st Year Science
THE SKELETAL SYSTEM

2. INTRODUCTION Most animals have a skeleton Plants do not – Why?
Because plant cells have a strong cell wall
Some animals have no skeleton…
Snails, Jelly fish (soft bodied animals)
Crabs have an external skeleton
All other animals have internal skeletons
(e.g. humans, cows etc…)

3. Functions of the skeleton
Why Do We Have A Skeleton???
SUPPORT
MOVEMENT
PROTECTION

4. FUNCTIONS OF THE SKELETON
SUPPORT
The bones of the skeleton keep the body upright.
It gives our bodies it’s distinctive shape.
Without a skeleton we would be a big squishy pile of flesh!!!
Plants have strong cell wall
which helps support them.
FUNCTIONS OF THE SKELETON

5. FUNCTIONS OF THE SKELETON
2. MOVEMENT
The skeleton allows movement.
Movement occurs at the joints.
This is where two bones meet
e.g. the elbow, shoulder, knee etc…
The bones move when muscles contract to pull on the bone.
e.g. the bicep contracts to move the lower arm
FUNCTIONS OF THE SKELETON

6. FUNCTIONS OF THE SKELETON
3. Protection
The skeleton protects the internal parts of the body…
The skull, protects the brain
The backbone (33 vertebrae) protect the spinal cord.
The ribs protect the lungs, heart etc…
These body parts are protected from impacts and other forms of damage
FUNCTIONS OF THE SKELETON

7. Parts of The Human Skeleton
Skull
Jaw
Collar Bone
Humerus
Shoulder Blade
Ulna
(baby finger)
Rib Cage
Vertebrae
Pelvis
Radius
(thumb)
Femur
Knee Cap
Tibia
Fibula
Parts of The Human Skeleton

8. JOINTS There are two main types of joint: 2. Free moving joints:
Fixed joints:
These are fused or immovable joints
e.g. the bones in the skull of an adult are fixed/fused
2. Free moving joints:
Also called synovial joints
Because they contain synovial fluid to help lubricate the joint.
There are two types of free moving joints:
1) Hinge Joints
2) Ball and Socket Joints
Fixed Joint
Hinge joint
Ball & Socket
Ball & Socket

9. Joints
Ball and Socket Joint
Hinge Joint

10. The Skeletal System - Videos
The Knee Joint
Cruciate Ligament
Arthritis
The Skeletal System - Videos

11. Muscles Muscles are made of protein
Muscle are attached to two different bones across a joint
e.g. the biceps & triceps are attached to the humerus and radius bones across the elbow joint.
As the muscle contracts (gets smaller) it pulls on the bone causing the bone to move.

12. Antagonistic Muscles
All muscles work together in pairs.
When one of the pair contracts the other is relaxed
Biceps and triceps in the arm are examples of antagonistic muscles.
Lifting the forearm:
Bicep is contracted
Tricep is relaxed
Lowering the forearm:
Bicep is relaxed
Tricep is contracted

13. Tendons Tendons connect muscle to bone
When a muscle contracts, the pull on the muscle is transferred to the bone by the tendon.
Tendons do not stretch, this is why they can be damaged with vigorous exercise

14. Ligaments Ligaments connect bone to bone.
Elastic fibres that are flexible.
Ligaments protect the joint from being damaged, by reducing the movement between bones.
Examples: The cruciate ligaments in the knee.

15. Healthy Bones
Calcium and Vitamin D are the two main nutrients that contribute to having healthy bones.
Calcium forms the hard part of the bone
Vitamin D is needed to allow calcium to pass from the small intestine into the blood.
A lack of vitamin D or calcium leads to brittle bones.