Human Systems: Skeletal System

Skeletal system Bones and cartilage Alive and active 206 bones in humans Support and protection Helps maintaining homeostasis Store minerals, make blood cells

Skeletal system Functions of bones Protect organs (ribs protect heart and lungs) Store minerals Role in movement Bone marrow (making blood cells)

Skeletal system

Bone structure Bone is a living organ made up of different types of tissues Connective tissue and minerals Osteoblast cells – mineral deposition Spongy bone – open spaces in bone Compact bone – no visible open spaces Bone marrow – two types Red marrow – red and white blood cells synthesis Yellow marrow – stores fats

Bone structure

Bone growth During development most bones are soft Bone formation initiates as flexible tissue - cartilage As development occurs cartilage is replaced by bone During growth, bones also increase in size During childhood, most bones still have growth plates of cartilage These growth plates provide a place for bones to continue to grow

Joints A place where two or more bones meet is called a joint Some joints, such as fixed joints, allow little or no movement Many of the joints in the skull are fixed joints Other joints, such as your shoulder, allow a lot of movement Joints can be classified based on how the bones in a joint move Gliding or sliding joints Hinge joints Ball and socket joints

Joints

Joints Joints are often placed under a great deal of stress But they can withstand a lot of wear and tear because of their structure Joints are held together by ligaments Ligaments are strong elastic bands of connective tissue They connect the bones in a joint Also, cartilage covers the ends of many bones. Cartilage helps cushion the area in a joint where bones meet.

Injuries and diseases Fracture Dislocation of joint Sprain – ligament stretched or torn Osteoporosis Bone density decreases Bones become weak Arthritis - joints may swell or stiffen Gout – accumulation of uric acid Nutrition and bone heath