Skeletal and Muscular System By: Kim Beach, Melody Bernhardt, Priscilla Lee, and Shannon Vickers

Skeletal System Determines shape or body Protects organs Works with muscles to create movement Over 200 bones in body Made of bones, ligaments, and tendons

Bone Composition Consists of calcium, phosphorus, carbonate crystals, and collagen fibers. Layer of compact bone surrounds layer of spongy bone, except at the marrow cavity At joints, a layer of cartilage covers the end of the bone to prevent friction. Bone marrow fills bone cavities Red marrow produces red blood cells Yellow bone marrow stores fats and produces white blood cells Tendons attach a muscle to a bone and transmit a mechanical force of muscle contraction to the other part They are much like ligaments, and are composed of dense fibrous connective tissue with high collagen content

Bone Growth Endochondral ossification- process of converting cartilage in embryonic skeletons to bone Cells begin depositing minerals and spongy bone forms Osteoclasts remove the material from the center of the bone Perichondrium forms around cartilage and begins forming compact bone Blood vessels form and grow into the perchondrium transporting stem cells into the interior

Muscular System Allows movement Over 600 individual muscles 3 types: skeletal, cardiac, and smooth Voluntary and involuntary muscles

Cardiac Muscle Involuntary (non-controllable) Makes up brain, wall of the heart, mydocardium This muscle is striated and contracts through the sliding filament method Contains branching fibers Attached together instead of bone

Skeletal Muscle Makes up 40% of an adult’s body weight Striated Composed of long muscle fibers; each fiber is a cell with several nuclei Nervous system controls the contraction of the muscle Voluntary muscle Tendons attach muscle to bone

Smooth Muscle Makes up most of our internal organs Controlled by the nervous system and hormones Involuntary muscles Muscles fibers tightly intertwined

Extensor and Flexor Extensor muscles increase the angle of a joint (straightening the elbow, or the triceps). It is usually bent backwards, except at the knee. Flexor muscles decreases the angle of the joint (bends the elbow, or biceps). It is usually directed forwards, except at the knee. To see the flexor and extensor at work click on: nim/arm.html nim/arm.html

Muscle Contraction Neuromuscular junctions are the point where a motor neuron attaches to a muscle. When the nerve impulse reaches the junction the acetycholine is release from the axon of the nerve cell. Electrical changes are produced in the muscle cell when the Ach binds to the receptors of the surface of the cell and changes to Na ions. This is called depolarization. During repolarization the muscle cannot be stimulated. This is the refractory period and once started the action spreads throughout the entire muscle cell. This is the all or none response. To See Muscle Contraction Go to : g/ANIMTNS/muscle.htm g/ANIMTNS/muscle.htm

Joints Immovable joints have tightly interlocked edges like sutures in the skull Partly movable joints allow some movement have cartilage between bones Synovial joints allow greatest amount of movement and ends of bones covered with a connective tissue filled with synovial fluid Synovial joints have an outer surface that strengthens joints and hold bones in place Some joints also have tendons- which link muscle to bone Gliding Joint

Moveable Joints Ball and Socket Joint: a ball shaped end of one bone fits inside the cup shaped end of another. (shoulder or hip) Pivot Joint: the end of one bone rotates inside ring formed by another. (forearm) Saddle Joint: enables a bone to move backwards to forwards and side to side. Hinge Joint: hinge can only move in one direction like a door hinge. (elbow or knee)

Health Osteoporosis, or porous bone, is characterized by low bone mass and structural deterioration of bone tissue. This leads to bone fragility and an increased susceptibility to fractures of the hip, spine, and wrist. There is no known cure at this time, but there are many options of medications that you can take. Paget’s disease results in enlarged and deformed bones; it is a chronic disorder. The excessive breakdown and formation of bone tissue that occurs can cause bone weakening and pain, arthritis, deformities, and fractures. Treatments can lessen symptoms but not cure the disease. Duchenne Muscular Dystrophy (DMD) is characterized by muscular enlargement and by a rapid progression of muscle degeneration. Treatments on mice are promising, and may lead to effective therapies. Myotonic Dystrophy is when the muscles contract but have decreasing power to relax. Due to this, the muscle become weak, and waste away, and it can cause mental deficiency, hair loss and cataracts. Artificial limbs help to restore a normal way of life to people who have had their limbs amputated. Joints, like the knee and hip, can be replaced also so that the person can return to an active life. In the future, technology may be able to recover senses in the artificial limbs.

Bibliography tout.shtml The Ultimate Visual Science Dictionary. Dorian Kindersly (company) The Random House Book of 1001 Questions and Answers About the Human Body. Trevor Day