SEHS common test 2

• Cell respiration


  The controlled release of energy in the form of ATP from organic compounds in cells
• How adenosine can gain and lose a phosphate molecule


  1. When energy is released from ATP, a phosphate molecule is lost (ATP to ADP)

  2. When ATP is resynthesized using the energy given off from Creatine Phosphate, a phosphate molecule is gained (ADP to ATP)

  
• Role of ATP in muscle contraction


  • ATP is broken down into ADP, releasing energy used for muscle contraction
  • ATP has to be re-synthesized by the 3 energy systems (ATP-PC, Lactic Acid, Aerobic)
• Re-synthesis of ATP by the ATP-PC system


  1. Creatine phosphate has a high energy bond that's broken by creatine kinase

  2. This energy is used to resynthesize 1 molecule of ATP

  3. The phosphate and energy is used to convert ADP to ATP

  
• Production of ATP by the lactic acid system


  1. Glucose is broken down by glycolysis into pyruvate, giving off 2 ATPs

  2. Since oxygen is not present, the pyruvic acid is converted to lactic acid

  3. Lactic acid accumulates and causes fatigue

  
• Oxygen deficit


  The amount of oxygen required during exercise

  
• Oxygen debt


  The amount of oxygen that needs to be repaid after vigorous exercise (EPOC)

  
• Production of ATP from glucose and fatty acids by the aerobic system


  1. Glucose is broken down by glycolysis into pyruvate

  2. Pyruvate is converted to Acetyl CoA and enters the Krebs Cycle and Electron Transport Chain

  3. Krebs Cycle produces 2 ATPs, ETC produces 32-34 ATPs

  4. Fats can also be broken down through beta-oxidation to produce Acetyl CoA

  
• Characteristics of the three energy systems


  • ATP-PC: Fuel source - Creatine phosphate, Duration - 10-15 seconds, Intensity - Maximal, ATPs - 1, By-product - Phosphate and creatine
  • Lactic Acid: Fuel source - Glucose, Duration - 1-2 minutes, Intensity - Maximal, ATPs - 2, By-product - Lactic acid
  • Aerobic: Fuel source - Glucose, fats, and proteins, Duration - Up to 2 hours, Intensity - Sub-maximal, ATPs - 36-38, By-product - Carbon dioxide and water
• Relative contribution of the three energy systems during different types of exercise


  • Baseball: ATP-PC 80%, Lactic Acid 15%, Aerobic 5%
  • Swimming (400m): ATP-PC 20%, Lactic Acid 40%, Aerobic 40%
  • Walking: ATP-PC 0%, Lactic Acid 5%, Aerobic 95%
  • Golf Swing: ATP-PC 95%, Lactic Acid 5%, Aerobic 0%
  • Football: ATP-PC 90%, Lactic Acid 10%, Aerobic 0%
  • Rowing: ATP-PC 20%, Lactic Acid 30%, Aerobic 30%
• Motor unit


  • Dendrite
  • Cell body
  • Nucleus
  • Axon
  • Motor end plate
  • Synapse
  • Muscle

  
• Neurotransmitters stimulating skeletal muscle contraction


  1. Acetylcholine

  2. Increases membrane permeability to sodium ions

  3. Calcium released into muscle cell

  4. Cholinesterase breaks down acetylcholine
• Acetylcholine


  • Transfers action potential from motor unit to muscle cells
  • Allows muscle to contract
• Cholinesterase


  • Enzyme that breaks down acetylcholine
  • Depolarizes membrane to stop muscle contracting
• Skeletal muscle contraction by sliding filament theory


  1. Myosin heads attach to actin active sites

  2. Tropomyosin prevents myosin-actin binding

  3. Troponin neutralizes tropomyosin with calcium

  4. Myosin heads bind actin, ATP breakdown releases energy

  5. Myosin heads swivel, pulling actin over myosin shortening muscle

  6. Calcium removed, muscle returns to original length
• Skeletal muscle contraction


  • Thick myosin filaments have myosin heads
  • Actin filaments have active sites
  • Tropomyosin blocks active sites
  • Troponin neutralizes tropomyosin with calcium
• Skeletal muscle fiber types


  • Slow-twitch (type I)
  • Fast-twitch (type IIa)
  • Fast-twitch (type IIb)
• Slow-twitch (type I) fibers


  • Low in glycogen content
• Fast-twitch (type IIa and IIb) fibers


  • High in glycogen content depending on training status
• Depolarizes


  Refers to the change in electrical potential across a cell membrane, where an action potential depolarizes the muscle fiber membrane and triggers muscle contraction
• Acetylcholine


  A neurotransmitter that transmits signals across a chemical synapse from one neuron to another
• Phosphatase


  An enzyme that removes phosphate groups from molecules
• Creatine kinase


  An enzyme that catalyzes the transfer of a phosphate group from creatine phosphate to ADP, forming ATP and creatine
• Creatine kinase function


  Catalyzes the transfer of a phosphate group from creatine phosphate to ADP, forming ATP and creatine, helping maintain a supply of ATP for muscle contraction and other energy-intensive processes
• ATP


  Adenosine Triphosphate, the energy currency of the cell that gets broken down to release energy for muscle contraction
• ADP


  Adenosine Diphosphate, a byproduct of ATP breakdown that needs to be converted back into ATP through the energy systems
• Aerobic system


  A system that uses oxygen to produce ATP through the breakdown of carbohydrates, fats, and proteins over a longer period of time
• Lactic Acid system


  A system that uses glucose or glycogen to produce ATP in the absence of oxygen, producing lactic acid as a byproduct
• ATP-PC system


  A system that uses creatine phosphate (CP) to re-synthesize ATP for short, intense bursts of activity