Chapter 2: LOCOMOTION & SUPPORT

2.1 Support and locomotion in human and animals.Introduction1. Locomotion - ability of an organism to move from one place to another (food, mates & avoid dangers)2. 3 types:

Hydrostatic skeleton Exoskeleton Endoskeleton1. Consist of internal fluid within the body cavity.2. Fluids held under pressure in compartments surrounded by muscles - incompressible skeleton.3. Soft wall rigid - muscles can act against it.Benefits: Maintains shape & support internal organs.Ex: Earthworm, Hydra sp.

1. Cuticle (covered with wax) cover body surface - prevent water loss.2. Rigid external exoskeleton.3. Unsuitable for large animals - exoskeleton (non living) incapable of growth. Arthropods shed it periodically to grow (ecdysis) Benefits: Supports important organs, protects internal structures from damage, allows animal to move.Ex: Insects, crab, molluscs

1. Rigid framework of bone and cartilage.2. Attached to muscles.3. Store minerals e.g. Calcium & phosphorous.Benefits: Maintain body shape, support soft tissue, protect internal organs, produce blood cells.

3. Problems: Gravitational force - overcome by strong supporting structures like limbs. Friction & resistance - streamlining in bodies

Human skeleton: Axial skeleton

1. Encloses and protects the spinal cord. 2. Supports the head & point of attachment for ribs, pelvic girdle & muscles at the back and the neck. 3. Sacrum and coccyx immovable. 4. Intervertebral discs permits movement and absorb vertical shock. 5. Has neural canal/vertebral foramen which the spinal cord lines. 6. Size different because uneven distribution of weight. 7. Functions: (i) Centrum - provides support & absorb shock. (ii) Spinous & transverse process - surface for attachment of muscles, tendons and ligaments (iii) Neural arc - protects the spinal cord.

1. Consist of 22 bones.2. Cranial bones enclose and protect the brain3. Facial bones protect and provide support for entrances to the digestive system & respiratory system.4. Jaw the only freely movable bone in the skull.

Cervical vertebrae (7)1. Have transverse foramen through with blood vessels and nerve pass.2. Atlas - no centrum, joint between atlas and skull allow nodding.3. Axis - forms joint with atlas called pivot joint allow side movement of the head.

Thoracic vertebrae (12) 1. Long spinous and transverse process serve as a point of attachment of muscle and ligaments. 2. Attachment of ribs.

Lumbar vertebrae (5) 1. Largest and strongest in the vertebral column. 2. Bear the weight of lower back. 3. Large centrum for support.

Sacrum/Sacral vertebrae (5) 1. Triangular bone. 2. Transmit weight to pelvic girdle.

Coccyx/Caudal vertebrae (4) 1. Triangular bone.

Ribs & Sternum: Thoracic cage - encloses & protects the organs in the thoracic cavity and upper abdominal cavity.