The Skeletal System HLTAP301A

Skeletal System Consists of bones, joints, cartilage and ligaments Bone tissue is living and active

Functions of the skeletal system Gives body shape and support Bones provide an internal framework Support and anchor soft tissue Provide points of attachment for skeletal muscles Protects internal organs Bones protect soft body organs Cranial bones / brain Vertebrae / spinal cord Rib cage / organs of the thorax Provides movement and leverage Muscles attach to bone When they contract they pull on bones and produce movement

Functions of the skeletal system Mineral homeostasis Bones release minerals into blood to maintain mineral balance Calcium must be present in blood for nervous system to transmit messages, muscles to contract and for blood to clot Blood cell production Red bone marrow produces red and white blood cells and platelets Storage Lipids are stored in yellow bone marrow for energy Mineral storage Calcium Phosporous

Structure of skeletal system Bone is living tissue with a blood supply Productive factory and store house Hardest connective tissue Known as osseous tissue 206 bones

Bone tissue Compact bone Hard and dense Forms shaft of bone and outer surfaces of other bone Haversian canals are where osteocytes are arranged in circles around blood vessels and surrounded by protein fibres, calcium and other minerals

Bone tissue Cancellous bone tissue is hard but less dense than compact bone Honey comb appearance Contains red bone marrow and produces blood cells Found in ends of long bones and middle of short flat and irregular bones

Bone tissue Yellow marrow is mainly found in centre of long bones and is mainly made of fat The name of the membrane covering the bone is periosteum Inner layer contains cells called osteoblasts that are essential for bone formation

Bones of the skeleton Two parts to the skeletal system Axial skeleton Upright central part of the body Consists of skull, vertebrae, ribs and sternum Appendicular skeleton bones of lower and upper limbs, shoulders and pelvic girdle

Classification of bones Long bones Shaft with head at both ends Mostly compact bone Femur Tibia Fibula Humerus Ulna Radius

Classification of bones Short bones Roughly cubed shaped ends No cavity Wrist Ankle

Classification of bones Flat bones Thin flattened and usually curved Two thin layers of compact bone with layer of cancellous in between Skull Ribs Sternum

Classification of bones Irregular bones Have 2 or more different shapes Vertebrae Hip Some facial bones

Did you know? When you hit your elbow and get a sharp pain associated with the “ funny” bone that you are actually hitting the ulnar nerve This nerve is unprotected and lies over the distal end of the humerus Probably called funny because it is associated with the humerus

Joints (articulations) Point of contact where 2 or more bones meet Provide flexibility to the skeleton Help together by ligaments

Ligaments Bundles of dense, fibrous tissue forming rope like structures Contain a few elastic fibres enabling limited stretching and great strength Function is to attach bone to bone providing stability to joints and limit the range of movement

Cartilage Firm smooth slightly flexible tissues forming pads in some joints Vertebrae Knee Covers ends of bones with smooth lining Between ribs and sternum Main function is to keep bones aligned

Classification of joints Immovable joints (synarthroses) Mainly axial skeleton Suture lines in bones of skull Slightly movable joints (amphiarthroses) Between vertebrae or symphysis pubis Freely moveable (diarthroses) Variety of shapes Mainly in limbs Allow several types of movement

Classification of joints Structural Fibrous bones Held together by fibrous connective tissue Teeth in sockets Cartilagenous Bones help together by cartilage Synovial All joints of limbs between ends of bones

Synovial joints All synovial joints have common characteristics Articular cartilage (hyaline) Covers the ends of bones forming the joint Fibrous articular capsule Capsule of fibrous connective tissue Lined with synovial membrane Secretes synovial fluid Encloses joint surfaces

Synovial joints All synovial joints have common characteristics Joint cavity contains sinovial fluid Lubricates the bones in the joint Enclosed by articular capsule Supporting ligaments Reinforcing the fibrous capsule Stabilise the joint

Synovial joints Examples Ball and socket (hip) Hinge (elbow) Saddle (thumb) Ellipsoid (wrist) Pivot (neck) Gliding (vertebrae)

Disorders Arthritis – inflammation of a joint Bursitis – inflammation of bursae – small sac of fibrous tissue containing synovial fluid which reduces friction Cancer – commonly myeloma Dislocation – displacement Osteomyelitis – inflammation of bone with infection Osteoporosis – porous bone