Section Two

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Created by
Taylor Pearson

Cards (59)

  • Skeletal muscles are striated and multinuclear. They are attached to the skeleton by tendons and are involved in control of voluntary movement. Activated by lower motor neurons (somatic efferents)
  • Smooth muscle is found in the internal organs and tubes of the body. They are responsible for the movement of material into and out of the body
  • Cardiac muscle is only found in the cardiovascular system.
  • Cardiac and smooth muscle are driven by the autonomic nervous system (visceral efferents)
  • Fascicles are bundles of muscle fibers
  • Myofibrils are overlapping thick and thin filaments
  • Sarcolemma is the muscle cell plasma membrane
  • The sarcoplasm is the muscle cell cytoplasm
  • Sarcoplasmic reticulum is the modified endoplasmic reticulum
  • A motor unit is a motor neuron and all the muscle fibers it innervates.
  • muscle contractile proteins are actin (thin filaments) and myosin (thick filaments)
  • Muscle regulatory proteins are troponin, tropomyosin (located on actin)
  • Level of organization of the muscle:
    1. Muscle body
    2. Fasicle
    3. Muscle fiber
    4. Myofibril
    5. Actin/myosin (organized into sarcomeres)
  • The sarcoplasmic reticulum wraps around each myofibril and has t-tubules that allow action potentials from neuromuscular junction to reach the interior of the cell quickly
  • The thick filament of the muscle is myosin. It is made up of two chains wrapped around each other. It has the capacity to bind actin and ATP
  • The myosin head is also called a crossbridge
  • Myosin's ability to bind ATP is for the breakdown of ATP for energy required for contraction (ATPase activity)
  • The thin filament of a muscle is actin. The contractile protein is formally called G-actin, and the regulatory proteins are tropomyosin and troponin
  • During contraction, the thin filaments slide over the thick filaments toward the center of the sarcomere. So, the length of the sarcomere shortens
  • Excitation-contraction coupling is the sequence of events that links the action potential to muscle contraction
  • Botox works by stopping muscles from contracting where it is injected. The toxin that prevents acetylcholine from being released (and docking/fusing with the axon terminal)
  • There is very little free ATP in the muscle, so the muscle contains a quick energy storage compound called creatine phosphate
  • creatine kinase (creatine phosphokinase) catalyzes creatine phosphate and ADP into creatine and ATP. During activity (when energy is needed) the reaction leans toward creatine and ATP
  • When creatine phosphate is used, one ATP is created and takes about 15 seconds
  • When anaerobic metabolism is used for ATP, approximately 2 ATP/1 glucose molecules are created through glycolysis. This takes about one minute
  • When aerobic metabolism is used for ATP, approximately 36 ATP/1 glucose are created through oxidative phosphorylation. This takes hours and oxygen is required
  • In the first few seconds of exercise, muscles use stored glycogen to make glucose. When there's not enough oxygen, anaerobic metabolism of glucose forms lactate (making only 2 ATP/1 glucose)
  • After about 30 minutes of exercise, the main energy source is fatty acids
  • Force exerted on an object by a contracting muscle is called tension (pull)
  • Force exerted on muscle by an object is the load (resistance to movement)
  • Isotonic contraction is where the muscles shorten while the load remains. This can be seen when picking up a heavy object
  • Isometric contraction is when a muscle develops tension but does not change length. This can be seen with standing
  • Force generated in a whole muscle depends on:
    1. Force generated in individual muscle fibers
    2. The number of muscle fibers contracted
  • The tension an individual muscle fiber generates is directly proportional to the number of crossbridges it makes with actin
  • The number of crossbridges is affected by the frequency of stimulation, fiber diameter, and fiber length
  • The increase in muscle tension is called summation
  • Tetany is the summation of twitches until the maximum tension for that muscle is reached
  • Resting length of muscle ensures that the sarcomeres are at optimal length. So, changing the overlap of the actin and myosin will alter the number of available crossbridges
  • A small motor neuron innervates very few fibers and is responsible for fine control
  • Large motor neurons innervating many fibers is responsible for gross motor control (hamstrings)