Bones and Muscles

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Five Functions of the Skeletal System
#1 Protection - your heart and lungs are shielded by your ribs. Your spinal cord is protected by your vertebrae, and your brain is protected by your skull.

#2 Movement - muscles are attached to bones, which are jointed, to produce movement. When the muscles contract, the bones move. Without bones, you would not be able to run, walk, sit or stand.

#3 Blood Production - red blood cells (to carry oxygen) and white blood cells ( to protect against infection) are produced in the bone marrow of some bones

#4 Shape - gives shape to the body and makes you tall or short

#5 Support - holds your vital organs in place when playing sports. The vertebral column holds the body upright.
Parts of the Bone
Compact Bone
Spongy Bone
Marrow.
Compact Bone
Tough hard bone that can heal itself when broken. The tissue does not have visible open spaces.
Spongy Bone
Tissue that has many open spaces. Provides most of the strength and support for the bone. Contains red marrow which produces red blood cells that carry oxygen and carbon dioxide throughout the body.
Marrow
Soft inner center of bones containing blood vessels and fat cells. It manufactures red blood cells.
Purpose of Cartilage
Cartilage is soft, flexible tissue. Cartilage helps cushion the area where two bones meets.

During childhood, growth plates of cartilage remain in most bones, providing a place for the bones to continue to grow. (You can find it at the end of your nose or the tip of your ear)
Tendons
Muscle to bones

Strands of connective tissue that connect your muscles to bones. When a muscle gets shorter, a pulling action occurs, bringing the bones closer (ex. bicep muscle)
Ligaments
Bone to Bone

Joints are kept together with strong elastic bands of connective tissue called ligaments. A joint is the place where two of more bones meet.
5 Types of Joints
1. Immovable Joint (skull)

2. Sliding joint - fingers, spine

3. Ball and socket joint- shoulders, hip

4. Hinge Joint - elbows, knees

5. Pivot Joint - head, forearm
Immovable Joint
Little or no movement
Skull
Sliding Joint
Fingers or Spine
allows bones in the hand to glide over one another, giving some flexibility to the area.
Ball and Socket Joint
Shoulders and hips

Like and joystick on a computer, the shoulder enables your arm to move freely in all directions. There is a lot of movement.
Hinge Joint
Elbow and knee

Like a hinge on a door, the knee enables you to flew and extend your lower leg.
Pivot Joint
Head, forearm
Allows for rotation around the length of a bone, and only allows for rotation.
Three types of Muscles
Smooth Muscle
Cardiac Muscle
Skeletal Muscle
Smooth Muscle
Found in the digestive tract and the blood vessels.
Moves food through the digestive system
Cardiac Muscle
Special type of muscle found only in your heart. It causes the heart to beat.
Skeletal Muscle
attached to your bones for movement, and they help protect your inner organs.
Voluntary Muscles
Muscle action that is under your control.

When you want to make a movement you cause electrical signals to travel from the brain to the skeletal muscle cells. The muscle cells respond by contracting or getting shorter.

Skeletal muscles are both voluntary and involuntary. An example - Blinking eyes can be both voluntary and involuntary. You can blink your eyes as many times as you want, but your eyes will also blink automatically if you do not think about it.
Involuntary Muscles
Smooth Muscles and Cardiac muscles are involuntary. These are muscle actions that are not under our control. Some examples are heart beating, food digesting, and breathing.
How do Skeletal Muscles Work?
Skeletal muscles work in pairs to cause smooth controlled movements.

Muscle pairs cause bending and straightening.

Muscles that bend are called flexors and muscles that straighten are called extenders.

Muscles that are not exercised enough become smaller. Exercised muscles are stronger, larger and have more endurance.

Resistance Exercises are the most effective form of exercise to develop to size and strength of muscles - sit ups, push ups, pull ups

Aerobic exercises - mostly strengthens the heart, while increasing the endurance of your skeletal muscles. It does NOT increase muscle size greatly. - swimming, jogging, biking
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