exam 3 part 2

  1. Which of the following would occur as a result of a single muscle contraction?
    • Answer: Twitch
    • Why: A 'twitch' is a quick, single contraction of a muscle — like a single blink.
  2. Which of the following is true during the resting membrane potential?
    • Answer: Potassium is concentrated primarily inside the cell.
    • Why: Potassium (K+) is mostly inside the cell when it’s at rest — like water stored in a tank.
  3. The capacity of a muscle cell to shorten forcefully is known as.
    • Answer: Contractility
    • Why: Contractility means a muscle can shorten and pull — like when you flex your arm.
  4. A student is characterizing a muscle tissue sample in lab. She discovers that it is autorhythmic and contains striations. What type of muscle tissue is she working with?
    • Answer: Cardiac muscle
    • Why: Cardiac muscle is in the heart. It beats on its own (autorhythmic) and has stripes (striations).
  5. When threshold is reached, depolarization of the same magnitude occurs for all action potentials.
    • Answer: The all-or-none law
    • Why: Once the signal hits the threshold, it fires fully — like flipping a light switch. All or nothing.
  6. A collapsed intervertebral foramen could affect all of the following spinal nerves EXCEPT:
    • Answer: C1
    • Why: C1 exits above the first vertebra, so it’s not squeezed by a collapsed foramen.
  7. Structures called …..are involved in electrical synapses.
    • Answer: Gap junctions
    • Why: Gap junctions are like doorways between cells for quick electrical messages.
  8. Synaptic vesicles contain neurotransmitters and are present in the:
    • Answer: Presynaptic terminals
    • Why: The presynaptic terminals are where the message chemicals (neurotransmitters) wait to be released.
  9. Indicate whether each statement is true or false regarding action potentials and the all-or-none principle:
    • Once the threshold is reached, an action potential will proceed without stopping.
      • Answer: True
      • Why: Action potentials either fully fire or not at all. They’re the same throughout the cell.
  10. The action potentials will be different in different parts of the cell.
    • Answer: False
    • Why: Converging circuits combine signals from different sources (like eyes and ears) to one brain area.
  11. If threshold is not reached, an action potential will occur, but it will be weaker.
    • Answer: False
    • Why: Once threshold is hit, every action potential looks the same — like pressing a play button.
  12. If threshold is not reached, an action potential will not occur.
    • Answer: True
    • Why: Skeletal muscle moves your body parts, like feet during walking.
  13. The equilibrium centers of the brain receiving information from both inner ear structures and the retina of the eyes is an example of a:
    • Answer: Converging circuit
    • Why: Smooth muscle can react differently based on which chemical attaches — it’s not one-size-fits-all.
  14. According to the all-or-none principle, all action potentials are identical.
    • Answer: True
    • Why: These are the correct steps for how signals travel across a chemical synapse.
  15. Which of the following actions is caused by contraction of skeletal muscle?
    • Answer: Moving your feet in walking
    • Why: Muscle movement creates heat, which helps keep your body warm.
  16. The type of neurotransmitter or hormone that binds to receptors on smooth muscle plasma membranes determines the response of the muscle
    • Answer: False
    • Why: Neurotransmitters (message senders) are released from the presynaptic terminal.
  17. The events occurring at a chemical synapse, in the correct order, are:
    • Answer: 1. Action potentials arriving at the presynaptic terminal cause voltage-gated Ca2+ channels to open.
      1. Ca2+ diffuses into the cell and causes synaptic vesicles to undergo exocytosis, releasing neurotransmitter molecules.
      2. Neurotransmitter molecules diffuse from the presynaptic terminal across the synaptic cleft.
      3. Neurotransmitter molecules bind their receptor sites, causing ligand-gated Na+ channels to open. Na+ diffuses into the cell or out of the cell, causing a change in membrane potential.
    • Why: Each pair of spinal nerves covers a skin zone — called a dermatome.
  18. What is Body temperature.
    • Answer: Results from the heat produced when muscles contract.
    • Why: The electrical signal moves along the nerve by triggering the next spot, like dominoes.
  19. Neurotransmitters are released from the
    • Answer: Presynaptic terminal.
    • Why: A reverberating circuit sends the signal in a loop, keeping it going for a while.
  20. A dermatome is the area of skin supplied with sensory innervation by?
    • Answer: A pair of spinal nerves.
    • Why: Your body converts lactate (leftover from muscle work) back into sugar (glucose).
  21. Continuous conduction of action potentials means that?
    • Answer: An action potential in one site generates local currents causing depolarization to threshold at the adjacent site.
    • Why: The signal travels from dendrites to the axon end — like down a wire.
  22. The sensory root of a spinal nerve is also referred to as …… root?
    • Answer: Dorsal
    • Why: The dorsal (back) root handles incoming sensory messages to the spinal cord.
  23. Concentric contractions occur when?
    • Answer: The muscle produces increasing tension as it shortens.
    • Why: Cardiac muscle cells have branches — helping them connect and beat together.
  24. A change in the resting membrane potential has the following characteristics: non-propagated, graded, can summate. This type of change can?
    • Answer: Be a local potential and a consequence of an increase in the permeability to Na+.
    • Why: Isotonic means the tension stays the same while the muscle changes length.
  25. Because the stretch reflexes can be traced back along certain spinal nerve routes?
    • Answer: They are helpful when determining at what level of the spinal cord damage may have occurred.
    • Why: Hypertrophy means muscle fibers get bigger, but the number stays the same.
  26. Which type of muscle tissue has cells that branch?
    • Answer: Cardiac muscle
    • Why: At rest, the inside of the muscle cell (sarcolemma) is more negative than the outside.
  27. An isotonic contraction is described as?
    • Answer: A muscle produces constant tension during contraction.
    • Why: Endomysium is the layer that wraps around each single muscle cell.
  28. Hypertrophy means that there is a/an
    • Answer: Increase in the size of the muscle fibers, and there is usually no change in the number of
    • Why: No matter how strong a signal is, during the absolute refractory period the nerve won’t respond.
  29. At rest, the inside of the sarcolemma is ……relative to the outside.
    • Answer: Negatively charged
    • Why: Smooth muscle cells are long and skinny like spindles.
  30. Which connective tissue wrapping separates individual muscle fibers?
    • Answer: Endomysium
    • Why: The message crosses the synapse from the presynaptic terminal to the postsynaptic membrane.
  31. During the absolute refractory period, a stimulus of high intensity may trigger a nerve impulse.
    • Answer: False
    • Why: Neuromodulators can boost the amount of neurotransmitter released.
  32. Which type of muscle tissue has spindle-shaped cells?
    • Answer: Smooth muscle
    • Why: During a muscle contraction, the distance between the bands gets smaller.
  33. The correct sequence of the structures as they are involved in activity at a chemical synapse.
    • Answer: Presynaptic terminal; synaptic cleft; postsynaptic membrane
    • Why: After contraction, calcium (Ca2+) leaves the troponin so the muscle can relax.
  34. Identify the mechanisms by which neuromodulators alter synaptic transmission.
    • Answer: Increasing amounts of neurotransmitter released
    • Why: Intercostal nerves (between ribs) come from the front branches of thoracic spinal nerves.
  35. Check all of the terms below that will correctly complete this statement. During a muscle fiber contraction, the ……
    • Answer: Decreases in size: The A band and Z zone
    • Why: On myelinated nerves, signals jump between gaps (nodes of Ranvier) to move faster.
  36. After contraction has occurred, the Ca2+ are
    • Answer: Released from troponin
    • Why: C5 to C11 nerves form the brachial plexus, which controls the arms.
  37. Intercostal nerves are formed from the?
    • Answer: Ventral rami of thoracic spinal nerves.
    • Why: Gap junctions allow fast electrical signals between cells.
  38. Along myelinated axons of the peripheral nervous system, ion currents must cross the plasma membrane of the neuron.
    • Answer: At nodes of Ranvier.
    • Why: Presynaptic terminals are the part of a nerve that releases chemical messages.
  39. Spinal nerves C5-11 make up the…… plexus.
    • Answer: Brachial
    • Why: Local potentials grow or shrink depending on how strong the signal is.
  40. Structures called… are involved in electrical synapses.
    • Answer: Gap junctions
    • Why: If the resting potential is more negative, the cell is less likely to fire — that’s hyperpolarization.
  41. The……….of a neuron release(s) neurotransmitters.
    • Answer: Presynaptic terminals
    • Why: The A band stays the same size — it doesn't shrink during contraction.
  42. A local potential?
    • Answer: Increases or decreases in direct proportion to the stimulus strength.
    • Why: The musculocutaneous nerve is part of the brachial plexus and controls arm movement.
  43. In a laboratory experiment, the resting membrane potential of a muscle is measured and is found to be more negative. Which of the following has occurred?
    • Answer: Hyperpolarization
    • Why: The I band is the lighter zone on each side of the Z line, around the thin filaments.
  44. In a contracted muscle, the A bands narrow because the length of the myosin myofilaments changes.
    • Answer: False
    • Why: With age, slow-twitch fibers reduce more than fast ones. Total number of fibers usually stays the same.
  45. Which of the following nerves is part of the brachial plexus?
    • Answer: Musculocutaneous
    • Why: The Z disk anchors the sarcomere parts, and the I band includes only thin filaments.
  46. Each…includes a Z disk and extends from each side of the Z disk to the ends of the myosin myofilaments.
    • Answer: I band
    • Why: The Z disk to end of thick filaments defines part of the I band — like bookends around the working part.
  47. Check all that occur to skeletal muscle with advanced age.
    • Answer: Slow-twitch muscle fibers decrease in number more rapidly than fast-twitch fibers.
      The number of muscle fibers remains relatively constant.
    • Why: With aging, muscle types change more than the total number — slow fibers shrink faster than fast ones.