Skeletal and Muscular Systems

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Skeletal and Muscular Systems
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Skeletal System

• The framework for your body
• 206 bones
• Os- bone
• Osteo- bone

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Osteocytes are bone cells
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Bone contains

• Minerals especially calcium which provides for
  the hardness of bone
• Collagen fibers which provides strength of bone

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Bone has an excellent blood supply
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Joint

• art- and arthr- mean joint
• Ligaments stabilize joints
• Cartilage caps the bones at the joint for a
  smooth surface

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Cartilage

• chondr- means cartilage
• Healing capability is poorer than bone

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Skeleton Function

• Framework
• Support
• Movement
• Protection
• Blood cell production from bone marrow
• Storage of minerals fat

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Disorders of Skeleton-Osteoporosis
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Incidence

• Common in the U.S.
• Responsible for many fractures each year

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Cause

• Inadequate calcium
• Females, older more commonly
• Sedentary lifestyle
• Poor diet
• Pregnancy giving calcium to fetus
• Menopause lead to calcium withdrawal from bone

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Prevention/Treatment

• Weight-bearing exercise
• Calcium in diet
• Estrogen replacement therapy after menopause
• Drugs, such as Fosamax

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Arthritis

• Rheumatoid arthritis is an autoimmune disease in
  which the immune system attacks the joints in the
  body leading to their gradual destruction

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Arthritis

• Osteoarthritis is the wear and tear arthritis due
  to joint damage and injuries

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Sprain

• Joint injury that stretches or tears supportive
  ligaments
• A severe sprain can result in a dislocation

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Fracture

• Generally bones heal well with proper alignment,
  stabilization, and without infection

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Fractures

• Hairline or greenstick
• Simple
• Compound Open
• Comminuted

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Muscular System

• Myo- means muscle
• Muscle tissue is capable of contraction

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Smooth muscle

• Found in the wall of tubular structures such as
  intestine
• Involuntary
• Smooth appearance microscopically
• Peristalsis is a wave like contraction of smooth
  muscle

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Cardiac Muscle

• Heart muscle
• Involuntary
• Striated, or striped when observed microscopically

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Skeletal Muscle

• Muscle attached to the skeleton
• Voluntary
• Striated microscopically

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Skeletal Muscle

• Tendons attach muscle to bone

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Microscopic Muscle

• Myofiber muscle cell
• Myofibril the striated parts of the muscle cell
• Myofilaments the proteins that make up the
  myofibrils

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Myofilaments

• The two main proteins that comprise the
  myofilaments are
• Myosin very thick protein
• Actin very thin protein

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Sarcomere

• The actin and myosin in the muscle cells are
  arranged in small groups called SARCOMERES
• Since contraction occurs at the microscopic level
  of the sarcomere, the sarcomere is the
  functional unit of contraction

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Sliding Filament Theory

• This describes the mechanics of muscle
  contraction
• The myosin heads grab on to the actin protein
  and pull the actin towards the center of the
  sarcomere, making the sarcomere shorter.

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ATP

• ATP is necessary for muscle contraction
• Running out of ATP leads to muscle fatigue

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Motor Neuron

• Skeletal muscle will not contract unless a motor
  neuron (movement nerve cell) stimulates it to
  contract

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Motor Unit

• A motor neuron plus how every many skeletal
  muscle cells it serves is a motor unit
• A motor unit that has one neuron to one muscle
  cell allows for very precise movements
• A motor unit that has one neuron to 400 muscle
  cells does not provide precise control