Biology B5

Skeletons

Types of Skeletons

• An internal skelton has many advantages:
• Provides and internal framework for the body
• Grows with the rest of the body
• It is flexible due to the many joints
• Allows easy attatchment of muscles

Cartilage and Bone

• Cartilage and bone are living tissues which contain living cells
• A long bone is a long shaft containing bone marrow with blood vessles. There is a head covered with cartilage at each end
• Long bones are hollow, so they are stronger and lighter than solid bones
• The living tissues can be infected by bacteria and viruses
• They are able to grow and repair themselves
• In the early stages, the skelton is made of cartilage. During ossification, the cartilage is replaced by bone.
• If cartilage remains between the head and shaft, the bone and person is still growing
• Bones can be easily broken by a sharp knock
• Elderly people's bones lack calcium and phosphorous, resulting in osteoporosis, making them prone to fractures
• In an accident it is dangerous to move someone with a suspected fracture
• Broken vertebrae in the backbone can damage the spinal cord, resulting in paralysis or death

Joints

• Synovial joints (ball and socket/hinge) contain synovial fluid, a synovial membrane, ligaments and cartilage
• A ball and socket joint has more movement than a hinge joint, which is restricted to an up-and-down movement
• The forearm is raised and lowered by atagonistic muscles, biceps and triceps
• The synovial fluid acts as a cushion against shock and a lubricant for easy movement
• The synovial membrane holds in synovial fluid
• Cartilage prtects the bone head
• Ligaments hold bones in place

Circulatory Systems / Cardiac Cycle

Ciculatory Systems

• Animals need a blood circulatory system to ensure their cells recieve enough food and oxygen in order to remove waste products (CO2)
• As blood flows through arteries, veins and capillaries, blood pressure decreases
• Veins have valves to stop backward blood flow
• High blood pressure can damage the fragile walls of the capillaries
• Single circulatory system: heart, gills, body
• Double circulatory system: heart and lungs (obtain oxygen), heart and body (deliver oxygen to body cells)
• Double circulatory system = four-chambered heart : two atria to receive blood, two…