SENIOR SCIENCE BIONICS Part 3: The Skeletal System

1 Identify the role of the skeletal system particularly in relation to maintaining an upright stance and protecting vital organs

The Role of The Skeletal System The adult human skeletal system consists of 206 bones, as well as a network of tendons, ligaments and cartilage that connects them.

The Role of The Skeletal System Provides shape and support Enables movement Protects internal organs Produces blood cells Stores certain materials until they’re needed by the body

2 Describe the different types of synovial joints as: - Ball and Socket - Hinge - Double Hinge - Sliding - Pivot and identify their location

For each joint, describe each of the joints range of movement by moving your own joints.

For each joint, describe each of the joints range of movement by moving your own joints.

Joints Spotlight Senior Science Page 177 Write out the different types of joints

3 Describe the role of cartilage and synovial fluid in the operation of joints.

Joint Structures

Joint Structures Ligaments Tough bands of collagen ( a very strong, flexible substance) which hold a joint together by joining bones on one side of a joint to bones on the other side. They act like strong rubber bands, holding bone ends together at the joint. They prevent dislocation but stretch slightly to allow the bones to move.

Joint Structures Tendons Tough, rope–like strands which connect muscle to bone.

Joint Structures Synovial fluid The slippery fluid which lubricates movable joints. It is secreted by the synovial membrane which is a lining on the inner surface of the joint capsule.

Joint Structures Cartilage A rubbery substance which is used to support and protect the body from shocks and impacts. The ends of the bone are covered with cartilage to make a smooth, flexible joint.

4 Identify the properties of silicone that make it suitable for use in bionics

Joints Spotlight Senior Science Page 178 Summarise and draw figure 6.21

5 Explain why silicone joints would be suitable substitutes for small joints in the fingers and toes that bear little force

Silicone Joints

Silicone Joints

Silicone Joints Properties flexible holds a particular shape light weight smooth acid resistant impervious to water cracks under moderate pressure absorbs impacts. It is these properties that make silicone a suitable substitute for small artificial joints in the fingers and toes. The fingers and toes generally bear little force (unless lifting weights). Therefore, it is unlikely silicone joints in the fingers and toes will break or crack.

6 Describe the properties that make ultrahigh molecular weight polyethylene (UHMWPE) a suitable alternative to cartilage surrounding a ball and socket joint in terms of its -Biocompatability with surrounding tissue -Low friction -Durability 7 Explain why artificial joints have the articulating end covered in polyethylene

Ball and Socket Joints Reason for replacement: Arthritis Damage due to impact sports over time Weak due to age or disease

Hip Replacement Then and Now

Hip Replacement

Requirements of Replacement Materials The material should be strong enough and not fracture The material should not corrode inside and warm, salty body fluids It should last as long as possible so that another operation is not needed to replace it The material can not itself harm the body The corrosion or wear products can not harm the body It must produce the smallest immune response possible (biocompatible) The material should not be too dense, so that weight is kept to a minimum

Extra Requirements of Replacement Materials Touching Bone When bone is compressed it shortens; the material in contact should shorten by the same amount. If it is to be cemented into place, then the bone cement must be able to grip the material. If a bone cement is used, it must set without harmful side-products. If no cement is used, the material's surface must be able to grip the bone directly.

UHMWPE Properties: Strong and durable Resistant to abrasion Doesn’t deform easily Good strength against fatigue Lower in density then high-density polyethylene Compatible with surrounding tissue Form a low-friction coating in place of the cartilage

UHMWPE

UHMWPE Used to coat metallic parts, forming the joint to give it a smooth surface. If the metal parts of the joint were in contact and rubbed as the joint moved, metal debris would accumulate in the joint tissues, causing an infection and loosening of the joint.

8 Describe the properties of materials such as ‘superalloy’ that make a ball and stem for the bone components of a large joint including: -High Strength -Low weight -Good compatibility with body tissue -Inertness

Superalloy Superalloy: A mixture of suitable metals that combine to form a metal with greater strength than one metal alone.

Superalloy Mostly used: Cobalt-chromium-molybdenum alloys Titanium alloys Used because: High Strength Low weight Good compatibility with body tissue Inertness

Superalloys Spotlight Senior Science Page 179 Copy Table 6.3

9 Identify that artificial implants can be either cemented or uncemented into place 10 Describe the properties of the cement that is used in implants and discuss how an uncemented implant forms a bond with bone

Cemented and Uncemented Joints Spotlight Senior Science Page 180 Summarise Cemented and Uncemented paragraphs

Critical Question Review Spotlight Senior Science Page 180 To Think About Set 1, 2, 3