Transcript The Skeleton and Muscles

The Skeleton and Muscles
Why Do We Need A Skeleton?
• It supports our body (creates room for the
lungs etc.)
• It allows us to move
• Protects vital organs
• Why is the skull so thick?
• To protect the brain
• Why do we need ribs?
• To protect the lungs and heart
The Skeleton
There are
about 206
bones in the
average human
body
Babies are
born with 300
bones
Joints
• Joints are
places where
two bones join
• They allow
movement
• Cartilage and
synovial fluid
prevent bones
wearing away
Parts Of The Joint
• Ligaments: Hold two bones together at
a joint
• Cartilage: Connective tissue that prevents
two bones from wearing each other out
• No cartilage or synovial fluid is a cause of
arthritis
• Tendons: Holds muscle to bone
• http://www.kidshealth.org/misc/movie/bodybasics/bodybasics_
knee.html
Types Of Joints
• Ball and socket e.g. hip and shoulder
• Allow lots of movement
•
http://www.bbc.co.uk/science/humanbody/body/factfiles/joints/ball_and_socket_joint.shtml
Types Of Joints
• Hinge e.g. knee, elbow etc.
• Allow forward and backward movement, but no
sideways movement
•
http://www.bbc.co.uk/science/humanbody/body/factfiles/joints/hinge_joint.shtml
Types Of Joints
• Saddle e.g. fingers
• Allow us to grasp things
http://www.bbc.co.uk/science/humanbody/body/factfiles/joints/saddle_joint.shtml
Types Of Joints
• Fixed Joints e.g. the bone in the skull
• These joints do not move
http://www.bbc.co.uk/science/humanbody/body/factfiles/skull/frontal_in_skull.shtml
Types Of Joints
• Slightly moveable joints
e.g. the vertebrae
• Allow limited movement
http://www.bbc.co.uk/science/humanbody/body/factf
iles/spine/lumbar_vertebrae.shtml
Movement
• Bones
cannot move
on their own
• They are
pulled by
muscles
Muscles
• Muscles cannot push, they can only pull
when they contract
• How do we push doors closed?
• Muscles work in antagonistic pairs, the
bicep pulls the forearm up to the upper
arm, the triceps straightens the arms.
We use the triceps to close a door
Antagonistic Pairs
The bicep flexes the
arms
The triceps extend
the arm
Muscles In The Body
There are about
650 muscles in
the human body
Types Of Muscle
• There are three types:
1. Cardiac muscle: beats on it’s own,
never rests
2. Involuntary muscle: this muscle works
without us thinking about it e.g.
breathing, peristalsis, pupil dilation
3. Voluntary muscle: we have to think
about moving these muscles e.g. skeletal
muscles