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The Way Muscles Work

The Way Muscles Work. By: Meaghan Bence Kelly Hare Leila Kessler Rachel Malinowski Dan Rockwell. Biological Engines. Our muscles can be described as biological engines because movement is produced, fuel (ATP) is used and it has some sort of ignition (calcium ions). Big Picture.

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The Way Muscles Work

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  1. The Way Muscles Work By: Meaghan Bence Kelly Hare Leila Kessler Rachel Malinowski Dan Rockwell

  2. Biological Engines Our muscles can be described as biological engines because movement is produced, fuel (ATP) is used and it has some sort of ignition (calcium ions).

  3. Big Picture • Begins from voluntary activity from brain or involuntary from spinal cord. • Motor neuron in spinal cord activated causing action potential to pass outwards. • Axon branches to muscle fibers called motor unit. • End of motor unit action potential causes release of acetylcholine into the synaptic clefts on surface of muscle fiber. • Causes resting potential to change and initiates action potential which travels along both directions of the muscle fiber. • At the opening of each transverse tubule on the muscle fiber the action potential spreads inside the muscle fiber.

  4. Sliding Filament • Myosin heads attach to binding sites on the actin filaments and the sliding begins. • Each attachment is energized by ATP • Attachment and detachment happens many times during contraction. • This movement generates tension and pulls the actin filament toward the center of the sarcomere. • As this action takes place in the sarcomeres, the muscle cell shortens.

  5. The Role of Calcium • The calcium ions act as a final trigger for contraction • Calcium binds to the regulatory proteins on the actin filament, they change their position and shape on the filament • This makes it possible for the myosin heads to bind to the actin filaments • The myosin heads then rotate from 90° to 45°, which is the final action for contraction.

  6. Types of Muscle Fibers • Fast Twitch • Used in anaerobic metabolism • Strength and speed activities • Slow Twitch • Used in aerobic metabolism • Endurance activities

  7. Sources of ATP • Creatine • Energy from a phosphate group that is attached by a high-energy bond like ATP • Pool of creatine in fiber is ten times that of ATP • Glycolysis • Muscle fiber degrades glycogen by glycolysis • Glycolysis yields 2 ATP/ pair of lactic acid molecules • Cellular Respiration • Required to meet ATP needs for prolonged activity • Allows the body to resynthesize glycogen from the lactic acid produced earlier

  8. Lou Gehrig’s Disease (ALS) • Incurable disease of the nervous system • ALS gradually destroys the nerves that control the muscles • Motor neurons degenerate and lose the ability to transmit impulses. • The muscles they control gradually stop working and then waste away.

  9. References http://education.magnet.fsu.edu/arts/muscle/mechanism.html http://www.mhhe.com/hper/physed/clw/webreview/web11/sld003.htm http://www.ultranet.com/~jkimball/BiologyPages/M/Muscles.html#CardiacMuscle http://school.discovery.com/homeworkhelp/worldbook/atozscience/a/019720.html

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