The Skeletal System

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The Skeletal System
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Formation of Bone

• When you are developing as a baby, your bone
  starts as cartilage.
• As development continues,
• blood vessels stimulate cartilage and turn it
  into potential bone cells.
• These potential bone cells are called
  OSTEOBLASTS!
• Cells secrete hormones that make the bone harden.

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OSTEOBLASTS
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Bone Structure

• COMPACT BONE Outside layer Dense, hard bone
• Supplies oxygen and nutrients to bone cells
• SPONGY BONE Inside layer
• Less dense bone
• Lots of holes and spaces (like a sponge)
• BONE MARROW Innermost layer

Spongy Bone
Bone Marrow
Compact Bone
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Bone Structure
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What is the purpose of bone?
Purpose Video

• Framework upon which muscles and organs rest
• Protection
• Helps with movement by linking muscles and bones
  with joints
• Helps the immune system
• Warehouse for minerals

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How can bones help your immune system?

• Bone marrow has many useful cells!
• Red marrow produces red blood cells which carry
  oxygen throughout the body.
• Red marrow also produces white blood cells to
  fight disease!
• Yellow marrow helps store fats and produces red
  blood cells during major injury.

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The Skeletal System

• More Bones and Joints!

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Lots of Bones!

• The human skeleton has 206 bones!
• These bones are divided into two sections on the
  skeleton.
• Axial
• Appendicular

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Axial Skeleton

• Axial Skeleton
• Skull and bones that support it
• Skull
• Vertebral Column
• Ribs
• Sternum

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AXIAL SKELETON
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Appendicular Skeleton

• APPENDICULAR the bottom half!
• arms
• legs
• pelvic girdle
• shoulders

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APPENDICULAR SKELETON
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Bringing it all together

• JOINTS are the hinges that connect bones to one
  another.
• Most joints are moveable, but
• Stationary joints are called fixed joints.
• Ex Skull
• Joints are held together by LIGAMENTS
• Ligaments are tough bands of tissue
• The ends of bones are covered with cartilage to
  ensure smooth motion.

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JOINTS
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MORE ON JOINTS

• LIGAMENTS Thin bands are tissue that connect
  bone to bone
• TENDONS Thick bands of tissue that connect
  muscle to bone
• BURSA Fluid-filled sac that absorbs shock and
  prevents bones from rubbing together.

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LIGAMENTS
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TENDONS
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BURSA
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Arthritis

• -itis means inflammation
• Arthro- means joint
• Arthritis, therefore, means
• More than 100 types of arthritis
• About 37 million people have arthritis in the US
  1 out of 7 people

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Arthritis
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Popping Your Knuckels

• All joints are surrounded by synovial fluid, a
  thick, clear liquid
• Stretching or bending the finger causes the bones
  of the joint to pull apart which causes the
  connective tissue capsule to stretch increasing
  its volume
• Increasing the volume decreases the pressure of
  the synovial fluid.
• The synovial fluid pressure drops, gases
  dissolved in the fluid become less soluble,
  forming bubbles through a process called
  cavitation.
• When the joint is stretched far enough, the
  pressure in the capsule drops so low that these
  bubbles burst, producing the pop that we
  associate with knuckle cracking.
• It takes about 25-30 minutes for the gas to
  redissolve into the joint fluid. During this
  period of time, your knuckles will not crack.
  Once the gas is redissolved, cavitation is once
  again possible, and you can start popping your
  knuckles again.

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Damage from Popping Knuckles

• Only one in-depth study
• 300 people
• No correlation between popping knuckles and
  arthritis
• Problems they did have soft tissue damage to the
  joint capsule and a decrease in grip strength
• Probably because of the stretching of ligaments
  when creating the popping
• Professional Baseball players experience similar
  effects to their pitching arm

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Osteoporosis

• Osteoporosis means porous bone
• A disease in which bones become less dense and
  fragile.
• Painless until bone breaks
• Can happen in any bone
• Happens typically in hip, spine, and hand
• Women are 4 times more likely then men
• 10 million people in US
• 8 million women
• 2 million men

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Osteoporosis