The Skeletal System

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The Skeletal System
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The Skeletal System

• Your skeletal system has five
• major functions
• Provides shape support
• Enables you to move
• Protects your internal organs
• Produces blood cells
• Stores certain materials until your
  body needs them

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• vertebrae the 26 small bones that make up your
  backbone
• Your bones are strong and living!
• The spaces in bone contain a soft connective
  tissue called marrow.
• cartilage a connective tissue that is more
  flexible than bone.
• As an infant much of your skeleton was cartilage
  which is replaced with bone as you grow.

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BonesStrong and Living

• Bones are complex living structures that undergo
  growth and development.

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Joints of the Skeleton

• joint - a place in the body where two bones come
  together
• Joints allow bones to move in different ways.
• There are two kinds of joints in the body
• Immovable joints joints in the body
  that connect
  bones in a way that
  allows little or no movement
• Example the skull and the joints that attach
  the
  ribs to the sternum
• Movable joints joints that allow the
  body to make
  a wide range of
  movements
• Most of the joints in the body are movable
  joints.

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Movable Joints

• Ball-and-socket joint allow the greatest range
  of motion
• hips
• Pivot joint allows one bone to rotate around
  another
• head connected to your neck
• Hinge joint allows extensive forward or
  backward motion (hinge of a door)
• knee
• Gliding joint allows one bone to slide over
  another
• wrist ankles

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Joints of the Skeleton

• A joint is a place in the body where two bones
  come together. Joints allow bones to move in
  different ways.

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Ligaments
ligament the bones in movable joints are held
together by this strong connective tissue
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Taking Care of Your Bones

• It is important to take care of your bones.
• Eat a well-balanced diet
• Calcium is very important in strong
  bones which can be found in dairy
  products
• Get plenty of exercise
• osteoporosis a condition in which the bodys
  bones become weak and break easily

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Common Skeletal System Injuries

• fracture a break in a bone
• sprain occurs when ligaments are stretched too
  far and tear in
  places
• dislocation occurs when a
  bone comes out of its
  joint

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X-rays

• x-rays a form of energy
  that travels in waves.
  The energy
  in waves
  passes through some
  living
  tissue, but does
  not pass through bones.
• X-rays are used to detect
  bone injuries only!

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MRI

• Magnetic resonance imaging (MRI) new method for
  taking clear images of both the bones and soft
  tissues of the body

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Preventing Skeletal System Injuries

• You can prevent skeletal injuries by
• Warming up before exercising
• Wearing appropriate protective equipment
• Exercising in safe places

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Fun Facts About Skeletons

• They repair themselves.
• At birth the human skeleton is made up of 275
  different bones.  As the body matures some of
  these bones, such as wrist and ankle bones, fuse
  together leaving only 206 bones in the adult
  body. 
• The smallest bones are in your
  ear. The largest bone, the
  femur, is found
  in your thigh.
• ?The human skeleton contains 206 bones!

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The Skeletal System
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The Skin
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The Skin

• The Skin
• Covers the body and prevents the loss of water
• Protects the body from injury and infection
• Helps to regulate body temperature
• Eliminates waste
• Gathers information about the environment
• Produces Vitamin D

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• epidermis the outermost layer of the skin
• Cells in the epidermis live for about two weeks
  and then they die. The dead cells of the
  epidermis protect the body.
• melanin a pigment that gives skin its color
• dermis the lower layer of the skin
• Contains nerves and blood cells
• Sweat glands produce perspiration which reaches
  the surface
  through openings
  
  called pores.
• Strands of hair grow
  within the
  dermis in
  structures called
  follicles.

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Caring for Your Skin

• Four simple habits can help you keep your skin
  healthy
• Eat properly
• Drink enough water
• Limit your exposure to sun
• cancer a disease in which some body cells
  divide uncontrollably
• Keep your skin clean and dry
• acne a bacterial infection of the skin

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Fun Facts About Your Skin!

• As an adult, you may have more than 20 square
  feet of skin -- about the size of a blanket.
• You are likely to shed some 40 pounds of skin in
  a lifetime.
• Right now there are over a million dust mites,
  microscopic critters invisible to the naked eye,
  on your mattress and pillow, chomping on the dead
  skin cells that fell off you last night!

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Dust Mite Army
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The Muscular System
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Muscle Action

• Involuntary Muscles the muscles that are not
  under your conscious control
• breathing
• digesting food
• Voluntary Muscles the muscles that are under
  your control
• smiling
• running

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Types of Muscles

• Your body has three types of muscle tissue
• Skeletal muscle attached to the bones of your
  skeleton
• tendon a strong connective tissue that attaches
  muscle to bone
• Smooth muscle involuntary muscles found mostly
  on the inside of your internal organs
• Digestive system
• Cardiac muscle involuntary
  muscles that does not get tired
• heart

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Muscles at Work

• Muscle cells can only contract, not extend.
• So Skeletal muscles
  must work in pairs.
• While one muscle
  contracts, the other
  muscle in the
  pair
  returns to its original
  length.