Download Skeletal and Muscular Systems

Skeletal and Muscular
Systems
Skeletal System
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The framework for your body
206 bones
“Os-” bone;
“Osteo-” bone
Osteocytes are bone cells
Bone contains:
• Minerals – especially calcium which
provides for the hardness of bone
• Collagen fibers which provides strength of
bone
Bone has an excellent blood supply
Joint
• “art-” and “arthr-” mean joint
• Ligaments stabilize joints
• Cartilage caps the bones at the joint for a
smooth surface
Cartilage
• “chondr-” means cartilage
• Healing capability is poorer than bone
Skeleton Function
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Framework
Support
Movement
Protection
Blood cell production from bone marrow
Storage of minerals & fat
Disorders of Skeleton-Osteoporosis
Incidence
• Common in the U.S.
• Responsible for many fractures each year
Cause
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Inadequate calcium
Females, older more commonly
Sedentary lifestyle
Poor diet
Pregnancy giving calcium to fetus
Menopause lead to calcium withdrawal
from bone
Prevention/Treatment
• Weight-bearing exercise
• Calcium in diet
• Estrogen replacement therapy after
menopause
• Drugs, such as Fosamax
Arthritis
• Rheumatoid arthritis is an autoimmune
disease in which the immune system
attacks the joints in the body leading to
their gradual destruction
Arthritis
• Osteoarthritis is the wear and tear arthritis
due to joint damage and injuries
Sprain
• Joint injury that stretches or tears
supportive ligaments
• A severe sprain can result in a dislocation
Fracture
• Generally bones heal well with proper
alignment, stabilization, and without
infection
Fractures
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Hairline or greenstick
Simple
Compound = Open
Comminuted
Muscular System
• “Myo-” means muscle
• Muscle tissue is capable of contraction
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
Cardiac Muscle
• Heart muscle
• Involuntary
• Striated, or striped when observed
microscopically
Skeletal Muscle
• Muscle attached to the skeleton
• Voluntary
• Striated microscopically
Skeletal Muscle
• Tendons attach muscle to bone
Microscopic Muscle
• Myofiber = muscle cell
• Myofibril = the striated parts of the muscle
cell
• Myofilaments = the proteins that make up
the myofibrils
Myofilaments
• The two main proteins that comprise the
myofilaments are:
– Myosin – very thick protein
– Actin – very thin protein
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
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.
0018.exe
ATP
• ATP is necessary for muscle contraction
• Running out of ATP leads to muscle
fatigue
Motor Neuron
• Skeletal muscle will not contract unless a
motor neuron (movement nerve cell)
stimulates it to contract
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