Physical Health: Skeletal and Muscular Systems

The Skeletal System Skeletal System – bones of the body, shields important organs, gives your body shape Skull protects the brain / Ribs Protect your heart and lungs / Back bone protects your spinal cord Approx. 206 bones in the skeletal system Composed of nonliving mineral matter, mostly calcium, and living tissue with blood vessels and nerves

Structure of Bones Before you are born, skeleton appears as cartilage: tough supportive tissue, similar to bone but softer and more flexible Bones grow and go through a process called ossification until you reach 20- 25 years old Ossification: calcium and phosphorus are deposited within most of the cartilage in your body and changes them to bone With age, bones become thinner and do not absorb needed calcium minerals. This process is called osteoporosis Osteoporosis and low bone mass represent 55 percent of the people aged 50 and older in the United States

Structure of Bones All bones are covered with a tough membrane called periosteum Periosteum: contain bone-forming cells that produce new bone for growth and repair Blood vessels run through, branch into the bone, and nourish the cells of the bone Beneath periosteum is a strong outer layer of compact bone. The inner layer is spongy bone composed of hallow spaces which act as shock absorbers Bone Marrow: fills the spaces inside the hollow spaces within the spongy bone Two types – Red Morrow: found in the ends of bones, produces red blood cells and white blood cells - Yellow Morrow: found in the body of bones, composed mostly of fat cells

Structure of Bones Breaking down the human skeleton Two Sections Axial Skeleton: Skull, vertebrae, sacrum, ribs, sternum Appendicular Skeleton: Bones of the arms, legs, shoulders, and hips

Joints Joint: point at which two bones come together. Joints tightly fitted together are considered immovable. Joints which allow the bones to bend, twist, or turn are known as moveable joints. Four types: Ball and Socket: allows movement in all directions (shoulders/hips) Hinge: permit bones to move back and forth (fingers, knees, elbows) Gliding: allows bones to slide over one another. Ligaments: prevent bones from popping apart at these joints. Connect bone to bone (MCL/ACL in the knee) Synovial Fluid: secreted in membranes around the joint reducing wear on the bones (imagine oil for your car engine as an example)

Muscular System Without muscles, you would not be able to walk breath, digest your food, or swallow. Your muscular system even helps you produce heat. Three types – Skeletal, Smooth, and Cardiac Skeletal: Voluntary muscle. You control its movement. Skeletal muscle is connected by think strands of connective tissue called Tendons Smooth: Involuntary muscle. Works automatically to control movements inside your body. Examples: breathing, digestion, and blood circulation Smooth muscle makes up the walls of your stomach, intestines, and blood vessels Cardiac: Involuntary muscle. Only found in the walls of your heart and is the strongest muscle in your body

Muscular System All muscle (skeletal, smooth, cardiac) causes movement by contracting, or becoming shorter and thicker Muscle contraction starts from the nervous system, travel along nerve cells attached to your muscles When a muscle receives a message from a nerve, the muscle contracts. When the message stops, the muscle relaxes, or lengthens Skeletal muscles work in pairs, one contracts as the other relaxes Example in the picture

Disorders of Skeletal and Muscular System Problems arise through consistent use. Most issues are caused by pushing systems beyond their endurance or not properly prepared for an activity Fracture: break in a bone. Bone cracked or broken in two pieces. Closed Fracture: bone does not break through the skin Open Fracture: bone end breaks through surface of the skin Scoliosis: Curvature of the spine. Spine develops an abnormal curvature to one side. Can be inherited or developed during child hood. Dislocated joints, ligaments around a joint stretched or torn. Muscle strains: overstretched or torn ligaments. Occurs when muscles are over worked or stretched too far or too quickly. Muscle Imbalances (ex. Shin splints): calf muscles pulling the front of the foot down overpower the shin muscles that pull the front foot up.

Keeping Muscles and Bones Healthy While your bones and muscles are still forming, include calcium in your diet every day Calcium requires Vitamin D to absorb into bones (Vit.D – milk, bread, cereals, grains) Exercise keeps muscles toned and flexible. Does not increase the number of muscle fibers you have, helps make individual muscle fibers grow In turn causes entire muscle to become larger and thicker To prevent injury always warm up before exercising to increase blood supply to your muscles. Cool down afterwards to prevent muscle injuries.