Download Skeletal System - funtastic physics

To support or hold in shape
many living organisms have a
skeletal system.
Organisms may have
1. An exoskeleton – skeleton
on the outside of the body
eg. Insects
2. Endoskeletons – skeletons
on the inside of the body eg.
Humans
The human skeleton is made of
• bones that meet each other
• to form joints,
• covered on each end by
cartilage and
• are moved by the
contraction and relaxation of
muscles
The skeletal system serves five main
functions:
1.Support
2.Movement
3.Protection
4.Making red and white blood cells
5.Storage of some minerals
Bone is made of:
•Mostly mineral substances
such as calcium phosphate
and small amounts of
magnesium salts
•And Collagen fibres (gives it
elasticity). Collagen is a
protein
Bone is
•Alive
•Needs to be supplied with
food and oxygen
•Have different layers:
1. Compact bone – on the
outside
2. Spongy bone – layer
underneath that has
spaces in it to keep the
bone from being too
heavy
3. Bone marrow – in the
centre, has a good blood
supply and is very soft,
red and white blood cells
and platelets are made
here
Cartilage
Joints
•Is much softer than
bone
•Allows bones to move
easily over each other
•Found at the end of
bones
•Contains collagen
There are different kinds of joints:
• Fibrous joints – joins bones by fibres
such as in the skull. These are called
Sutures
• Synovial Joints – found when two bones
need to move freely. The bones are held
together by ligaments. Eg. Elbow or
shoulder. There are two types of
Synovial Joints
1. Hinge joints – such as the elbow work
like a door on a hinge. Allows up and
down movement or side to side
2. Ball and socket joints – such as the
shoulder and hip. A ball end fits into a
socket in the other. Allows circular
movement
There are three kinds of
muscle:
1. Cardiac Muscle (C ) – found only in
the heart
2. Smooth muscle (Sm) -also called
involuntary muscle since we do not
control them consciously. It is
found in organs such as bladder
and alimentary canal
3. Striated muscle (St) – attached to
bones to make bones move by
contraction (the muscle gets
shorter) or relaxation (the muscle
gets longer). These are also called
voluntary muscles because we
control them
Tendons are collagen fibres that
join muscles to bones
• Tendons do not stretch but they
are very strong