BIOMEC EXAM 2

• What can nerves be stimulated by?

  electrical stimulus, mechanical stimulus, chemical stimulus, and thermal stimulus
• What are the layers of connective tissue?

  epimysium, perimysuim, and endomysium
• What voltage is resting membrane potential?


  -70mV
• What is the process of polarization (resting membrane potential)?

  it is negative inside because the membrane has NA/K pumps on it continually pumping NA + out of the cells and K + inside the cell (much slower)

  • Na + is building up on the outside
• What is the voltage of action potential?

  -55mV
• What is the process of depolarization + action potential?

  when a neuron (dendrite) gets stimulated it causes NA channel gates on the membrane to open up along the neuron

  -Na + rushes inside the cell because it was accumulated outside when the neuron was at rest

  -the negative polarity (resting polarity) is becoming more positive

  -this causes entire axon to depolarize = action potential
• What is the voltage of repolarization?

  +30mV
• What is the process of repolarization?

  after the neuron polarity reaches +30mV, K+ channels open along neuron membrane

  K+ rushes out of the cell and the negative polarity returns back to normal

  less (+) ions inside neuron

  the NA/K pump will continue to pump out NA after to restore the polarity to -70kV as well
• Excitatory Post-Synaptic Potential 


  neurotransmitter excites the next neuron or muscle activating a contraction or action potential

  EX: adrenaline
• Inhibitory Post-Synaptic Potential 


  neurotransmitter blocks the next neuron or muscle from responding = inhibition

  EX: SLEEP
• What is myelin and its role in nerve conduction?

  FAT TISSUE

  covering over axons, allows to react quick, allow action potential to jump from one spot to another along the axon, makes it much QUICKER (conduction)

  -allows saltatory conduction
• What are the fundamental properties of muscle?

  elasticity, extensibility, excitability, and contractility
• What is the role of contractility?

  tension -- shorten
• What is the role of extensibility? 


  activated (stretched)
• What is the role of elasticity?

  return to normal
• Where does the motor neuron enter and connect to the muscle fiber?

  Neuromuscular Junction (Motor Endplate)
• What role does Calcium + ATP play in muscle contraction?

  Calcium binds to the troponin which pulls the tropomyosin away from the myosin binding site on the actin, the ATP that is on the myosin head gets broken down which provides energy for the myosin head to connect to the actin and pull (power stroke)
• Which ion must be present in a muscle?

  calcium
• Where is ATP stored?

  myosin head
• Where is calcium stored?

  sarcoplasmic reticulum
• What is the phosphagen system?

  ATP-CP stores in the muscle

  quick access, but very limited source

  10 secs of activity

  needs about 7 minutes to completely recover
• What is glycolysis?

  system can make ATP very quickly from glucose

  produces ATP fast but not efficiently (30-90 sec max) and

  produces lactic acid in high amounts when breaking down glucose quickly (which allows muscle cramps)

  2 NET ATP
• If lactic acid builds up in your body does the pH go up or down?

  DOWN
• What is the point at which lactic acid starts to accumulate in the blood stream?

  anaerobic threshold (lactic threshold)
• What is the oxidative system?

  36 ATP

  not ready for the first 30-60 seconds

  body uses O2 to break down glucose, fat, protein to make ATP

  more efficient, but longer to activate

  does require the availability of O2 to the muscle cells

  does not produce the lactic acid at such a fast rate
• What is the sensory reflex in the stretch reflex?

  muscle spindle (intrafuscal fiber)
• What is a sudden, quick change in the length of the muscle spindles causes that muscle to shorten?

  stretch reflex
• Does the stretch reflex excite or inhibit?

  excite
• The muscle on the opposite side of the joint from the muscle contraction will be inhibited allowing the contraction to be unopposed which decreases the chance of injury to the muscle contracting. What is the name of this reflex?

  Reciprocal Muscle Reflex
• What reflex responds to pressure and when a muscle length continues to build the Golgi tendon organ inside the tendon is compressed, so the GTO tells the muscle tissue in that muscle to stop contracting?

  autogenic inhibitory reflex
• Explain the Active Length-Tension Curve

  a muscle has an optimal length at which it can produce the most amount of force (the area of overlap from actin and myosin)

  conversely if a muscle is to short or to long in length, then not as good of force production

  SHORT = no place for actin and myosin to shorten

  LONG = not enough overlap to connect
• The spot during an arc of motion of a joint where gravity would be the most perpendicular? (Hard part of exercise)

  sticking point
• What is no movement? Muscle is not changing in length...

  isometric
• When the contraction causes attachments to get closer together... or slows down the rate of moving apart?

  isotonic
• Eccentric 


  lengthening of muscle
• Concentric 


  shortening of muscle
• What is the contraction of muscle that occurs at the same of motion ?

  isokinetic
• What are the 4 muscle functions?

  agonist, antagonist, stabilize, and synergize
• What is the non-contractile component?

  epimysium, perimysuim, and endomysium
• What is the contractile-component?


  sarcomeres