1. The Skeletal, Muscular, and Nervous Systems
Body Systems
The Skeletal, Muscular, and Nervous Systems

2. The Skeletal System
Consists of 206 bones and the attached connective tissues
The connective tissues cushion bones, attach bone to bone, and attach bone to muscle
Functions of the skeletal system include
Providing support for the body
Protecting internal tissues and organs from damage
Acting as a framework for attached muscles
Allowing movement for limbs and fingers
Producing new red and white blood cells
Storing fat and minerals, such as calcium and phosphorus

3. Bones, Connective Tissue, and Joints
Bones - made up of living tissues formed into layers
Outer layer is hard, densely packed, compact bone
Beneath that is spongy bone, a less dense bone with cavities filled with red bone marrow; where blood cells are produced
Some bones contain yellow marrow, connective tissue that stores fat
Connective tissue - three types include cartilage, ligaments, and tendons
Cartilage is a strong, flexible connective tissue that acts as a cushion between bones to reduce friction
Also acts as a flexible structure for soft parts of the body
All bones begin as cartilage and harden into bone during ossification

4. Bones, Connective Tissue, and Joints
Connective tissue - three types include cartilage, ligaments, and tendons
Ligaments are bands of fibrous, slightly elastic connective tissue that attaches bone to bone
Ligaments attach to bones to create joints
A tendon is a fibrous cord that attaches muscle to bone

5. Caring for the Skeletal System
Your overall health depends on the health of the skeletal system.
Foods high in calcium, vitamin D, and phosphorus help prevent skeletal disorders
During regular check-ups, your doctor can screen you for skeletal disorders
Scoliosis - a lateral or side-to-side curvature of the spine
Fracture - any type of break in a bone
Compound fracture - broken end of the bone breaks through the skin
Simple fracture - broken bone does not break through the skin

6. Skeletal System Injuries
Fractures
Hairline - parts of the bone do not separate
Transverse - the fracture is completely across the bone
Comminuted - bones shatters into more than two pieces

7. Injuries to Joints
Dislocation - when a bone slips out of place, tearing the ligaments
Torn cartilage - sharp blow to a joint or severe twisting of a joint
Bursitis - painful inflammation of bursa, a fluid-filled sac that helps reduce friction
Bunions - painful swellings of the bursae in the first joints of the big toe
Arthritis - inflammation of a joint resulting from an injury, natural wear and tear, or autoimmune disease

8. The Muscular System
Muscles are elastic, stretching to allow a wide range of motion
Some muscles in the body are always at work
Help you breathe
Make your heart beat
Move food through the digestive system
A muscle is made up of hundreds of long cells called fibers
Fibers are stimulated by nerve impulses
Contract, or shorten, and extend, or stretch

9. Types of Muscles
Smooth muscles - act on the lining of the body’s passageways and hollow internal organs
Found in:
Digestive tract
urinary bladder
Lining of blood vessels
Passageways that lead to the lungs
Smooth muscles are involuntary muscles

10. Types of Muscles
Skeletal muscles - attached to bone that cause body movements
Look striated, or striped, under a microscope
Most muscle tissue falls under this category
Most skeletal muscles are voluntary

11. Types of Muscles
Muscle pairs work opposite of one another to perform a task
Flexor - muscle that closes a joint
Extensor - muscle that opens a joint

12. Types of Muscles
Cardiac muscle - striated (striped) muscle that forms the wall of the heart
Involuntary
Responsible for the contraction of your heart

13. Caring for Muscles Get regular exercise
Eat high protein foods to build and repair muscle tissue
Practice good posture to strengthen back muscles
Use proper equipment and wear appropriate clothing to protect muscles during any physical activity
Warm up properly and stretch before exercising; cool down after exercising to prevent an injury

14. Understanding Muscular Problems
Bruises - areas of discolored skin that appear after an injury, causing blood vessels beneath the skin to rupture
Strains and sprains - result when muscles are stretched or partially torn from overexertion
Tendinitis - inflammation of a tendon due to injury, overuse, or natural aging
Hernia - organ or tissue protrudes through an area of weak muscle
Muscular dystrophy - fibers are progressively distroyed