5

• Which of the following applies to polarized membranes?

  there is a voltage difference across the membrane
• Why are plasma membranes polarized?

  Because of the pumping of unequal numbers of ions across the membrane
• Which ions play a major role in the formation of a polarized state?

  Sodium and potassium
• What is a depolarization?


  -A change in the Resting Membrane Potential

  -A decrease in the voltage difference across the membrane

  -A change in the distribution of ions across the membrane
• Which of the following are components of the Neuromuscular Junction?

  A nerve terminal

  A synaptic cleft.

  A motor end plate
• Which neurotransmitter is released at the Neuromuscular Junction?

  Acetylcholine
• What happens immediately after a nerve impulse, traveling down a motor neuron, reaches the nerve terminal?

  Ca2+ channels open and allow Ca2+ into the nerve terminal
• What happens after acetylcholine is released into the synaptic cleft by exocytosis?


  It binds to, and activates, acetylcholine receptors
• What is the function of acetycholinesterase?


  It breaks down acetycholine
• Which of the following make up the Central Nervous System (CNS)?

  It breaks down acetycholine
• What is the function of afferent nerves?


  To send impulses to the CNS
• What are Neuroglia?


  They are supporting cells in both the CNS and PNS
• Which of the following neuroglia is the most abundant in the CNS?

  Astrocytes
• Which of the following statements about neurons is FALSE?


  They have a low metabolic rate
• 15. What is the function of dendrites?

  -increase in the surface area of the cell body

  -To receive input signals

  -To transmit graded depolarizations to the axon hillock
• What types of molecules might flow in an Anterograde direction along the axon?

  Replacement proteins for the axolemma
• What type of neurons are the sensory neurons of the PNS?

  unipolar
• Which of the following are not properties of a GRADED response (depolarization)?

  A threshold level of stimulus must be reached to produce a depolarization
• Which of the following are not properties of an action potential?

  The size of an action potential is determined by the size of the stimulus
• What is the threshold level of an action potential?

  It is the membrane potential that triggers an action potential
• What happens when the threshold level of an action potential is reached?

  All sodium channels are activated automatically to open
• What happens during the Repolarization phase?

  The neuron is refractory
• What event leads to repolarization of the membrane?

  The opening of potassium channels
• What restores the ionic distribution (i.e. Na+/K+ ratio) across the resting membrane?

  An increase in activity of the Na+/K+ pump
• Where, in myelinated nerves, do action potentials occur?

  At the Nodes of Ranvier only
• Which of the following are true for the neuromuscular junction but not for the nerve synapse?

  The receptor region is a motor-end -plate
• 28. What is a function of a synapse?

  B. To convert an electrical signal into a chemical signal then back into an electrical signal
• What is the function of the Axon Hillock?

  -To receive graded responses from dendrites

  -To initiate the firing of action potentials

  -To initiate formation of the axon
• Which of the following statements regarding all the synapses of the nervous system is true?

  Some are excitatory and some are inhibitory
• What type of depolarizations occurs at the postsynaptic membrane?

  Graded depolarizations
• What is a hyperpolarization?


  It is when the membrane potential becomes more negative than the Resting Membrane Potential
• What part of the muscle is covered by Endomysium?

  muscle fibers
• What gives skeletal muscle fibers (cells) their striated appearance?

  The arrangement of actin and myosin fibers
• What elements are present in the dark A bands?

  Actin, Myosin, Myomesin
• Which of the following statements is true?

  -Myofilaments are located within the myofibril

  -Myofibrils are located within the muscle fibers

  -Muscle fibers are located within a fascicle
• What is the function of all types of muscle tissue?

  To convert chemical energy into mechanical energy
• What is the name of the connective tissue that covers each skeletal muscle?

  The Epimysium
• Which of the following statements is true?

  Muscle fibers contain glycosome-rich sarcoplasm
• The formation of a cross-bridge occurs when.....?

  The myosin head attaches to its binding site on actin
• 36. Which of the following occur during contraction of a muscle?

  The thin filaments move towards the center of the sarcomere