Chapter  2 (  Locomotion and support )

 The skeletal system consists of the axial skeleton and the appendicular skeleton.

 The axial skeleton consists of :           a) skull - Bones of the face (facial bones), Cranium           b) vertebral column that consists of cervical vertebrae, thoracic vertebrae, lumbar vertebrae sacrum and coccyx.           c) Sternum and ribs - Rib cage

 Appendicular skeleton consists of :        a) pectoral and girdle that consists of scapula and clavicle        b) forelimb that consists of humerus, ulna, radius, carpals,metacarpals and phalanges.        c) pelvic girdle that consists of two similar hip bones that are joined together: ilium, pubis and ischium.        d) hind limd that consists of femur,tibia, fibula, tarsals, metatarsals and phalanges

 Skeletal muscles, tendons, ligaments, bones and joints work together to allow movement and to provide support.

 Ligaments are elastic and they connect bone to bone, holding them together to form a joint.        

     - Position of the skeletal muscles,ligament :

                                 Tendons are not elastic and they connet muscles to bones.

 Terrestrial animals have muscles and a skeleton that enables them to crwal. walk and jump.

Fish have fins and myotome muscles on both sides of the backbone to enable them to swim in the water.

 Birds are light and have hollow bones and wings to fly in the air.

 Earthworms move through a series of contraction and relaxation of the circular and longitudinal muscles on the body wall that causes changes in the hydrostatic

pressure in the body fluid.

 Grasshoppers have long hind legs that are folded in the shape of Z,which are always ready to jump.Grasshoppers have 2 pairs of wings to enable them to fly.

 Grasshopper has long hind legs that are folded in the shape of Z. When at rest (flexor muscles contract) and the grasshopper is positioned for a jump.The legs pressing againt a resistant surface produces a force which propels the body forwards and upward.

                                               

Aquatic plants are supported by the buoyancy  of water, presence of aerenchyma tissues or air sacs in the stem,petiole and leaves of the plant.

 Terrestrial plans such as herbaceous plants with soft stems are supported by the turgidity of the plant cells.

The parenchyma cells in the herbaceous plants absord water that exist and causes the cells to become turgid.The turgidity of there plant cells gives support to the  plant.

Terrestrial plants with woody stems are supported by xylem tissues,parenchyma tissue,collenchyma tissue and sclerenchyma tissue.

 The xylem tissue,xylem vessels and tracheids are strengthened with lignin.There tissue form annular rings in the stens called growth rings.

The walls of collenchyma tissue are thickened with cellulose and pectin.These tissues acy as supporting tissues in young plants, non-woody stems and leaves.

 Sclerenchyma tissues have walls that are  thickened with lignin to provide support for plants.