THE SKELETON
|
|
THE SKELETON
Origin of the skeleton. Our bones are made of one of the hardest andmost-resistant materials in nature. The skeleton: a huge manufacturer of blood cells. Characteristics of the human skeleton.
|
INTRODUCTION
The skeleton is a structure which can support heavy weights, allows movement, acts as a store-room, grows and repairs itself.
Animals without an internal skeleton.
Functions of our skeleton.
ORIGINS
The very first animals to develop anything similar to an internal skeleton lived in the seas about 500 million years ago.
Evolution of the skeleton.
Skeleton of cartilage: sharks and rays.
Water compensates a body’s weight. Huge animals as some cetaceans weighing up to 150 tons can live in the sea.
Only 5% of all animals are vertebrates.
Each species has adapted its skeleton to its style of life.
MAN
Our skeleton is perfectly adapted to our needs of support and movement.
How much pressure can our bones support?
Bone is a living tissue which can regenerate itself.
Composition of bone.
The so called “red-marrow”. Its task.
Number of bones in the human skeleton.
Main groups: the axial skeleton (skull, vertebral column and thorax) and the appendicular skeleton (shoulder blades, pelvic girdle, arms and legs).
Shape and size of the human bones.
MOVEMENT
Articulations with and without movement.
Some articulations have hollow spaces which favor movement.
Articulations in our knee. Femur, tibia and patella. Meniscus.
The skeleton of a foetus is made of flexible cartilage.
Physical exercise makes bones stronger and physical inactivity makes them thinner.
Where there is not gravity, man loses an important amount of bone in just a few weeks.
The skeleton stores calcium and phosphate.
SUMMARY |
|
|
|
|
