Human Biology - EDEXCEL IGCSE - Form and movement

Form and movement

Axial skeleton - skull, ribcage, vertebral column.

Appendicular skeleton - scapula (shoulder blade), clavicle (collar bone), pelvis (under vertebral column) and limbs.

Limbs:

Arm

Leg

Long bones (e.g.  femur, humerus) :

A diagram of a long bone

The functions of the skeleton:

1. Protection (e.g. ribcage)
2. Shape (e.g. femur)
3. Support (e.g. vertebral column)
4. Movement (e.g. radius, fibula)
5. Blood production (produced in the bone marrow of some bones)

Joints:

Joints are needed at the points where two bones meet each other and are needed for movement.

Hinge joint:

1. Present in elbow.
2. Prevents movement through more than 180°. Movement is only in one plane.

Ball and socket joint:

1. Present at the shoulder and hip.
2. Allows for movement in three planes and around 360°.

Cartilaginous Intervertebral Joint:

1. Present at the vertebral column.
2. This is where the discs of cartilage can be squashed to allow for some movement.

Immovable Joints:

1. Present at the joints in the skull.
2. Can not move.

Synovial joint:

1. Most joints are synovial joints and they are needed to allow for the smooth movement of the bones against each other. 
2. It has smooth articular cartilage at the ends of the bones to reduce friction and to act also as a shock absorber.
3. A synovial joint also contains synovial fluid which lubricates the ends of the bones reducing friction.
4. It also contains ligaments which wrap around the two bones. These are used to hold the bones in place.

How a muscle induces movement:

When a muscle contracts, a tendon pulls a bone making it move. Muscles usually work in antagonistic pairs e.g. the biceps moves the radius up and the triceps moves it down. 

Nutrients needed for muscle and bone growth:

Muscles:

1. Protein
2. Vitamin D

Bones:

1. Calcium
2. Vitamin D
3. Phosphate