Human Body Systems

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Human Body Systems

• Skeletal System

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Chapter 17-1 The Skeletal System

• 1. The skeletal system is all of the bones in the
  human body.
• At birth the skeleton contains about 350 bones.
  The adult skeleton has only 206 bones.
• Of these 29 are in the skull, 26 in the backbone,
  25 in the sternum ribs, 64 in the shoulders,
  arms and hands and 62 in the pelvis, legs and
  feet.

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Types of bones

• Bones are classified by shape and size.

Shape/Size Example
Long Femur
Short Carpals
Flat Sternum
Irregular Pelvis
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Bone structure

• 2. Bone is made of layers of living tissue.
• The membrane that covers the bone is called the
  periosteum.
• Large bones are hollow and are filled with bone
  marrow. Bone marrow produces red and white blood
  cells.
• A smooth thick layer of tissue called cartilage
  separates the bones from each other and reduces
  friction.

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• A ligament is a band of tissue that holds bones
  together at the joints.
• 3. Two types of bone
• A. Compact bone is the hard strong layer of bone.
• B. Spongy bone is found at the ends of long bones
  and has open spaces in it to make it lightweight.
• 4. Two types of joints
• Immovable joints allow little or no movement. Ex
  Skull bones.
• Movable joints allow the body a wide range of
  movement.

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Types of movable joints

• 5. Four types of movable joints
• A. Pivot one joint rotates in a ring of another
  joint. Ex Head/neck joint
• B. Ball and Socket One bone has a rounded end
  that fits into a cup-like cavity in another. Ex
  Shoulder and hip joints
• C. Hinge Back and forth movement like the hinge
  of a door. Ex knees and elbows
• D. Gliding One part of a bone slides over
  another bone. This is the most common joint in
  the body.
• Ex wrists and ankles

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Functions of the skeletal system

• 6. The five main functions of the skeletal
  system.
• A. Shape and support the body.
• B. Protects the internal organs.
• C. Gives muscles a place to attach.
• D. Produces blood cells (marrow)
• E. Stores minerals (calcium and phosphorus)

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Bone cells

• 7. Two types of bone cells.
• A. Osteoclasts cells that break (cut) down
  bone.
• B. Osteoblasts cells that build bone up.