SUPPORT SYSTEMS IN ANIMALS TYPES OF SKELETONS

RELATIONSHIP BETWEEN STRUCTURE AND FUNCTION OF BONE TISSUE, CARTILAGE, TENDONS AND LIGAMENTS.

BONE Within Spongy bone tissue of the heads of long bones, bone tissue is not laid down in solid masses. Looks more like criss- cross fashion, with many gaps. The shaft is made up of a hollow cavity, surrounded by compact bone. Heads are covered with articulate. cartilage which reduces friction. Bone marrow of the breast bone, skull, hips, ribs and spine contain stem cells which produce blood cells. Process called haemopoiesis.

CARTILAGE Semi-transparent, tough, flexible. Three types of cartilage: white fibro, yellow-elastic and hyaline cartilage. Cartilage made up of a matrix of proteïen chondrin with cartilage cells called chondrocytes within fluid-filled spaces called lacunae. Chondrocytes are either alone, pairs or in groups of four. Functions: Articular cartilage reduces friction forms part of the larynx. C-shaped cartilage keeps trachea open Discs between vertebrae act as shock absorber Cartilage added to rim of sockets deepen them Ear lobe and epiglottis made up of cartilage

CONTINUE Adaptations of cartilage: Softer as bone but still strong enough, acts as a shock absorber and reduces friction. Very flexible.

TENDONS Connect muscle to bone. Made up of white fibrous tissue. White fibrous tissue is made up of a large number of white non-elastic fibers which make the tendon inelastic.

LIGAMENTS Join bone to bone. Made up of yellow elastic tissue, which has a very large number of yellow elastic fibers. These yellow fibers enable the ligaments to stretch.

JOINTS Joints are places at which one or more bones meet. At the joints, ligaments join bone to bone and muscles are attached to the bones by tendons. Three types of joints: – fixed or immovable joints, like in the skull. – Slightly moveable joints, pivot joint formed by the axis and the skull and gliding joints formed by bones of the wrist and ankle – Free movable or synovial joints, ball and socket joints and hinge joints of the elbow.

SYNOVIAL JOINT End of each bone covered with articular cartilage (hyaline cartilage). Reduces friction between bones. Very strong ligament joins two bones. A capsular ligament encloses the whole joint, the capsular ligament is lined by a synovial membrane which secretes synovial fluid.

ROLE OF BONES, JOINTS, LIGAMENTS TENDONS AND ANTAGONISTIC MUSCLES IN MOVEMENT We know that bones of the skeleton are not continuous, i.e. Joints are present. They allow the different parts of the skeleton to work separately.

CONTINUE At joints, ligaments join bone to bone ensuring that the bone stays together and that they can move. Ligaments can also stretch to different directions. At joints, ends of the skeletal muscles are joined to the bones by tendons. Tendons can’t stretch. They allow the tension created in muscles, to be transmitted to the bones where they are attached to. Skeletal muscles arranged in pairs. Two muscles making a pair, work in opposition to each other (one contracts other relaxes). These are called antagonistic muscles. Good example biceps and triceps.

STRUCTURE OF VOLUNTARY SKELETAL MUCLES You find three different types of muscle; smooth, striated and cardiac. – Striated or striped (skeletal) muscles are voluntary muscles, controlled by wil. – Unstriated or smooth muscles are involuntary muscles, can not be controlled by will. – Cardiac muscles found in the heart, they are striated, involuntary and branched.

CONTINUE Muscles attached to skeleton are responsible for all voluntary actions. Striated muscles. Striated muscles are enclosed in a connective tissue called epimysium. Within the epimysium, bundles of muscle fibres occur. Each bundle is enclosed by a perimysium. Each fibre has the following structure: – Enclosed in tough membrane, sarcolemma. – Ground substance within the sacrolemma is the sacroplasm. – Number of oval-shaped nuclei occur within the sacroplasm. – Each fibre has alternate light and dark bands, gives striped appearance. – Each fibre made up of number of myofibrils. – Each myofibril made up of thick myosin filaments and thinner actin filaments. – Muscle contracts, actin filaments slide inward among the myosin filaments. – Myofibril shortens and the entire muscle thus becomes shorter. i.e. Contracts.

DISEASES THAT AFFECT THE SKELETON Rickets and Osteomalacia Osteoporosis Rheumatiod arthritis Osteoarthritis Gout

RICKETS AND OSTEOMALACIA Lack of Vit D in the diet and lack of sunlight causes a disease known as Rickets in children. They have a deformed skeleton. Adults with a lack of Vit D and sunlight show condition called Osteomalacia, softening of bones.

OSTEOPOROSIS Calcium is a mineral salt that is extremely important in our bodies. As soon as we reduce the amount of calcium in our foods, the body draws on calcium from our bones. Pores appear in our bones because of this loss of calcium.

RHEUMATIOD ARTHRITIS Synovial membrane becomes inflamed. Produces certain enzyme. These enzymes cause the articular cartilage to break up. Fibrous tissue replaces the cartilage. Calcium is deposited in the fibrous tissue. Movement reduced until joint is almost fused.

OSTEOARTHRITIS Is caused by the articular cartilage of the joints becoming worn out. Bones at the joints grind together, causing little outgrowths of bone to be produced.

GOUT Sometimes the body produces to much uric acid. Uric acid accumulates in the vorm of crystals in the joints. Mostly found in your toes.