MUSCULAR SYSTEM I

1
MUSCULAR SYSTEM I

• pp. 917-920

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FUNCTION

• Support, movement, and protection

3
TYPES

• skeletal muscles that move bones (voluntary)
• smooth involuntary muscles that protect organs
• cardiac involuntary muscles found only in heart

4
MUSCLE STRUCTURE
myofibril ?muscle cell (fiber)?fascicle ?muscle
5

• Two types of proteins (actin and myosin) involved
• actin myosin ? myofibril
• myofibril attaches to Z line
• sarcomere functional unit from Z line to Z line

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MUSCLE CONTRACTION
7

• contraction shortening of sarcomere between Z
  lines
• myosin heads walk along the actin
• this requires ATP to walk and to release the
  myosin after walking

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ENERGY

• Aerobic respiration breaking down organic
  compounds to release energy to be used by the
  body
• OCCURS
• 1. when oxygen is present
• 2. in the mitochondria
• PRODUCES
• ATP

10
MUSCLE FATIGUE

• The inability to contract the muscle due to the
  lack of ATP
• a contraction occurs when heads walk along the
  actin
• The walking requires ATP to contract and release
  the muscle

11

• Read 917-920
• Do problems p 922 1-4, 9, 10
• Look at p 929 7. Define parts of picture 1-4.
• Is this muscle elongated or contracted?