A&P Class, Exam #5, My Questions From My Notes

  1. The nervous system consists of what?
    • - neural tissue (predominantly)
    • - blood vessels
    • - connective tissue
  2. What is a neuron?
    • - a nerve cell
    • - that reacts to physical and chemical changes in their surroundings
    • - they are the structural and functional unit of the nervous system
  3. What are neuroglia?
    • - they are neuroglial cells
    • - they are the support and nourishment cells
    • - they do many functions, nourishing neurons, sending and receiving messages
  4. What is a dendrite?
    • - small cellular processes
    • - that receive the input
  5. What is axon?
    • - a nerve fiber
    • - carries information away from the cell (in the form of bioelectric signals)
  6. What is a nerve impulse?
    the name of a bioelectric signals
  7. What are nerves?
    they are bundles of axons
  8. What is the synapse?
    • - important part of the nervous system at the cellular level
    • - it is a small space between a neuron
    • - where there is communication with cell(s)
    • - much of the work of the nervous system is done here (messages between neurons and other cells)
  9. What are neurotransmitters?
    • - they are biological messenger molecules
    • - (the actual conveyors of neural information)
  10. What are the divisions of the nervous system?
    • - CNS, Central Nervous System
    • - PNS, Peripheral Nervous System
  11. What is the CNS?
    it consists of the brain and spinal cord
  12. What is PNS?
    consists of the nerves (cranial and spinal nerves) that connect the central nervous system to the other body parts
  13. What are effector organs?
    they are muscles and glands
  14. What is the sensory division of the PNS?
    this is the area the pics up sensory information and delivers it to the CNS
  15. What is the motor division of the PNS?
    carries information to the muscles and glands
  16. What are the divisions of the motor division?
    • - Somatic nervous system
    • - Autonomic nervous system
  17. What does the somatic nervous system do?
    • oversees conscious (voluntary) activities
    • and carries information to skeletal muscle
  18. What does the autonomic nervous system do?
    • controls viscera, subconscious (involuntary) activities
    • and carries information to smooth muscle cardiac muscle, and glands
  19. What are the three general functions of the nervous system?
    • - Receiving stimuli = sensory function
    • - Deciding about stimuli = integrative function
    • - Reacting to stimuli = motor function
  20. Where is the sensory function and what does it do?
    • - at the ends of peripheral neurons
    • - sensory receptors gather information, by detecting changes inside and outside (environmental factors) the body
    • - and they carry information to CNS
  21. Where is the integrative function and what does it do?
    • - at the CNS
    • - signals are integrated = creating sensations
    • - creating sensations, memory, thoughts
    • - decisions are made from the integrations (conscious and subconscious)
  22. Where is the motor function and what does it do?
    - here decisions are acted upon and impulses are carried to the effectors
  23. What are effectors?
    they are muscles, outside the nervous system, that contract in response to nerve impulse stimulation and glands that secret when stimulated
  24. True or False: Neurons vary in size and shape.
  25. True or False: Neurons may differ in length and size of their axons and dendrites.
  26. Neurons share what certain features?
    • - dendrites
    • - a cell body
    • - an axon
  27. Describe the a neuron's cell body?
    - possess glandular cytoplam, nucleus and nucleolus...(lysomes, Golgi apparatus, mitochondria, microtubrials, neurofibrils)

    - characteristic: they do not divide, (we are born with all the neurons we are going to have)
  28. In the neuron cell body what is in the glandular cytoplasm?
    • - cytoplasmic inclusions
    • (glycogen, pigments [melanin], lipids)

    • - chromatophilic substance
    • (nissl bodies) (rough endoplasmic reticulum)
    • they are scattered throughout
    • many membranous packets
  29. What are neurofibrils?
    a network of fine threads that extend into the axon and support it
  30. What are dendrites?
    • usually highly branched, ______,
    • provides receptive surfaces for other processes of neurons to communicate
  31. What are dendritic spines?
    they are tiny, thorn-like spines on the surfaces of dendrites, which are contact points for other neurons
  32. What is axonal hillock?
    it is slight elevation of the cell body
  33. What is an axon?
    • it is slender and cylindrical in shape, with a uniform diameter and nearly smooth surface
    • arises from the axonal hillock
    • it's job is to conduct nerve impulses away from the the cell body
  34. Where are ribosomes found?
    they are found only in the cell body
  35. The cytoplasm of the axon contains what?
    • mitochondria
    • microtubules
    • neurofibrils
  36. The axon gives off many branches called what?
  37. Where is the axon terminal located and what does it do?
    • it is located near the end of the axon
    • they are the many fine extensions of the axon
    • each having a specialized ending called the synaptic knob
  38. Where is the synaptic knob and what does it do?
    it is found at the end of an axon terminal, where it is close to the receptive surface of another cell but is separated by a space (synaptic cleft)
  39. What does the axonal transport do?
    it conveys biochemicals produced in the neuron cell body

    (such as: vesicles, mitochondria, ion, nutrients, and neurotransmitter)

    move from the cell body to the end of the axon
  40. Axons that have myelin sheaths are what?
    myelinated axons
  41. Axons that lack myelin sheaths are what?
    unmyelinated axons
  42. What is white matter?
    • are groups of myelinated axons, causing the appearance of white...
    • found in the PNS
  43. What is gray matter?
    is unmyelinated (nerve tissue) structures, cell bodies, dendrites...

    in the CNS, many unmyelinated axons and neuron cell bodies
  44. What are Schwann cells?
    • are neuroglia = nerve tissue, cells
    • found in the PNS that encase the large axons in lipid-rich sheets, tight coverings, forming as layers of cell membrane, winding around axons (myelin sheaths, neurilemma)
  45. What are Nodes of Ranvier?
    narrow gaps in the myelin sheeth, between Schwann cells
  46. True or False: Neurons and Neuroglia descend form the same neural stem cells.
    • True
    • (they remain associated their entire existence)
  47. What are 5 ways that neurons structurally differ?
    • size
    • shape
    • the lengths and sized of axons
    • the lengths and sizes of dendrites
    • the number of dendrites
  48. What are the 3 major groups that neurons are structurally classified?
    • 1.) Bipolar neurons
    • 2.) Unipolar neurons
    • 3.) Multipolar neurons
  49. What is a bipolar neuron?
    • a neuron that has only 2 processes from the cell bodies
    • that could arises from either end
    • with end being an axon and the other a dendrite
    • but they are similar in structure

    bipolar neurons are found mostly in specialized parts of the eyes, nose, and ears
  50. What are unipolar neurons?
    • a neurons that has only 1 process extending from its cell body
    • has a short distance form the cell body
    • with the process dividing into two branches
    • yet really functioning as a single axon (peripheral process and central process)
    • and has ganglia
  51. Describe peripheral process. (unipolar neuron)
    associated with dendrites near a peripheral body part
  52. Describe central process. (unipolar neuron)
    enters the brain or spinal cord
  53. What is ganglia?
    • the cell bodies of some unipolar neurons,
    • which aggregate in specialized masses of nerve tissue
    • located outside the CNS (of brain and spinal cord)
  54. What are multipolar neurons?
    • neurons with many processes arising from their cell bodies
    • yet they only have 1 axon and all the rest are dendrites
    • * 99% of neurons are multi polar
    • these neurons are found mostly in the CNS
  55. What are 3 ways that neurons are classified functionally?
    • - they carry information into the CNS = Sensory neurons
    • - they carry information completely within the CNS = Interneurons
    • - they carry information out of the CNS = Motor neurons
  56. Describe sensory neurons.
    • carry impulse to the CNS form peripheral body parts
    • their distal ends, act as sensory receptors
    • most are unipolar, or bipolar
  57. Describe interneurons.
    • lie within the CNS
    • forming links between other neurons (transporting impulses from one part of the brain or spinal cord to another)
    • most are multipolar
  58. Describe motor neurons.
    • carry impulses away from the CNS
    • to effectors (of somatic and autonomic nervous system)
    • most are multipolar
  59. Describe somatic nervous system.
    • control skeletal muscle contraction
    • under voluntary (conscious) control
  60. Describe autonomic nervous system.
    • controls the cardiac and smooth muscle contraction and secretions of glands
    • under involuntary control
  61. What are the 2 types of neuroglial cells in the PNS?
    • 1.) Schwann cells
    • 2.) Satellite cells
  62. What are Schwan (remember the difference, only one "n") cells in the PNS?
    • cells that produce myelin that are found in peripheral myelinated neurons
    • these cells speed up neruotransmission
  63. What are satellite cells?
    these cells support clusters of neuron cell bodies called ganglia
  64. What are 4 types of neuroglial cells in the CNS?
    • 1.) Astrocytes
    • 2.) Oligodendrocytes
    • 3.) Microglia
    • 4.) Ependyma
  65. Describe Astrocytes cells.
    • the most abundant type of neuroglial cells in the CNS
    • star-shaped cells* between neurons and blood vessels

    • provide:
    • structural support
    • formation of scar tissue
    • transportation of substances between blood vessels and neurons
    • communication between each other and neurons
    • mop up excess ions and neurotransmitters
    • induce synapse formation
  66. Describe Oligodendrocytes cells.
    • shaped like astrocytes
    • but with fewer processes
    • occurring in rows along axons
    • in the CNS

    • provide:
    • forms myelin sheaths in the brain and spinal cord
    • produce nerve growth factors
  67. Describe Microglia cells.
    • small cells
    • with few cellular processes
    • found throughout the CNS

    • provide:
    • structural support
    • phagocytosis (immune protection)
  68. Describe Ependyma cells.
    • cuboidal and columnar cells
    • in the inner lining of the ventricles of the brain and the central canal of the spinal cord

    • provide:
    • form a porous layer through which substances diffuse between the interstitial fluid of the brain and spinal cord and the cerebrospinal fluid
  69. True or False: Neuroglia comprise more than half of the volume of the brain.
  70. True or False: Neuroglia outnumber neurons 6 to 1.
    • False
    • Neuroglia outnumber neurons 10 to 1
  71. Name 2 disorders that abnormal neuroglia are associated with.
    • - most brain tumors
    • (neuroglia dividing too much)
    • - neurodegenerative disorders
    • (neuroglia that produce toxins)
  72. True or False: Injury to the cell body usually kills the neuron, yet a damaged peripheral axon may regenerate.
  73. Injury to the cell body usually kills the neuron. Why?
    • because mature neurons do not divide
    • the destroyed cell is not replaced unless neural stem cells become stimulated to proliferate
  74. What is the average growth of a regenerating axon?
    3-4 millimeter per day (slow)
  75. Nerve growth factors, secreted by _______, may help direct the growing axon.
    • neuroglia
    • (still may end up in the wrong place) (full function often does not return)
  76. True or False: Axon of neuron of CNS, seperated from the cell body (distor portion of axon) will degenerate more slowly than a seperated axon of PNS.
  77. Axon of neuron of CNS, seperated from the cell body (distor portion of axon) will degenerate more slowly. Why?
    • lack neurilemma
    • oligodendrocytes (myelin-producing) do not proliferate following injury
    • Thus = proximal end of damaged axon that begins to grow, has not tube of sheath cells to guide it
  78. True or False: If the peripheral nerve is severed, it is important that the two ends be connected as soon as possiable.

    (so the regenerating sprouts of the axon can more easily reach the tubes formed by the basement membranes and connective tissue on the distal side of the gap)
  79. What is neuroma and what does it do?
    • when the regenerating axons reach a gap of 3 millimeters or greater the axons may form a tangeled mass
    • this tangled mass composed of sensory axons, is painfully sensitive to pressure
    • Also, sometimes complicating a patient's recovery following limb amputation
  80. Neurons do not divide, so what happens?
    new neural tissue arises from neural stem cells --> which give rise to neural progenitor cells --> that can give rise to neurons or neuroglia
  81. What happens at the synapse?
    nerve impulses pass from neurons to neurons (or other cells)
  82. What does the presynaptic neuron do?
    it brings the impulse to the synapse

    resulting = stimulation or inhibitation of a postsynaptic neuron (muscle or gland)
  83. What does a synaptic cleft do?
    • this gap
    • seperates two cells, which are connected functionally but not physically
  84. What is synaptic transmission?
    the process by which the impulse in the presynaptic neuron signals the postsynaptic cell
  85. Axons usually have several rounded ______ _____ at thier terminals, which dendrites lack.
    synaptic knobs
  86. What are the arry of memberanous sacs that synaptic knobs have called?
    synaptic vessicles
  87. What do synaptic vessicals contain?
    neurotransmitter molecules
  88. When a nerve impulse reaches a synaptic knob, what kind of channels open and what diffuses inward from the extracellular fluid?
    voltage-sensitive calcium channels

    calcium diffuses
  89. What does an increased calcium concentration inside the cell initiate?
    it inititates a series of events that fuses the synaptic vessicles with the cell membrane, where they release their neurotransmitter by exocytosis
  90. Once the neurotransmitter binds to the receptors on a post-synaptic cell, the actions is either ______ or ______.
    • excitatory (turning a process on)
    • or
    • inhibitory (turning the process off)
  91. What is released when the impulse reaches the synaptic knob?
  92. The net effect on the post-synaptic cell depends on the combined effect of the _________ and ___________ inputs from as few as _____ to ___________ or more presynaptic neurons.
    • excitatory
    • inhibitory
    • 1
    • 100,00
  93. A critical part of the synaptic transmission is what?
    the polararization of the membrane
  94. A cell membrane is usually electrically charged or polarized, what does that mean?
    it means that the inside of the membrane is negatively charged, and thus the outside is positively charged
  95. What is polarization due to?
    it is due to unequal distribution of positive and negative ions on either side of the membrane
  96. [Distribution of Ions]

    What are Potassium (K+) ions?
    they are the major intracellular positive ions (cations)
  97. [Distribution of Ions]

    What are Sodium (Na+) ions?
    they are the major extracellular positive ions (cations)
  98. [Distribution of Ions]

    The distribution of ions is largely created by what?
    the Sodium Potassium Pump (Na+/K+ pump)
  99. [Distribution of Ions]

    What does the Sodium Potassium Pump do?
    it actively transports sodium ions out of the cell and potassium ions into the cell
  100. [Distribution of Ions]

    Channels formed by membrane proteins can be selective, what does that mean?
    means a particular channel may allow only one type of ion to pass through and exlude all other ions of different size and charge
  101. [Distribution of Ions]

    Membrane permeability to ions is also due in part to ___________ in the cell membrane.
  102. [Distribution of Ions]

    Both _______ and ______ electrical factors can affect the opening and closing these gated channels.

  103. [Distribution of Ions]

    True or False: Some channels are always open, wheras others may be either open or closed (somewhat like a gate).
  104. [Distribution of Ions]

    The ability of ions to diffuse across cell membranes depends on the presence of what?
    the presence of channels
  105. [Resting Potential]

    What is it called when a nerve cell is not being stimulated to send a nerve impulse?
    a resting nerve cell
  106. [Resting Potential]

    Under resting conditions what determines the membrane permeability to sodium and potassium ions?
    the nongated (always open) channels do
  107. [Resting Potential]

    Sodium and potassium follow what laws?
    the laws of diffusion
  108. [Resting Potential]

    The resting cell membrane is only slightly permable to sodium and potassium ions, yet which one is the membrane more permeable to?
    the membrane is more permeable to the potassium ions than the sodium ions
  109. [Resting Potential]

    What are negatively charged ions called?
  110. [Resting Potential]

    True or False: A resting nerve cell's cytoplasm has many negatively charged ions (phospate, sulfate, proteins) that are synthesized inside the cell but can easily diffuse through the cell membrane.

    these ions cannot diffuse through the cell membrane
  111. [Resting Potential]

    What is potential difference?
    it represents stored electrical energy that can be used to work at some future time
  112. [Resting Potential]

    What is membrane potential?
    the potential difference across the cell membrane
  113. [Resting Potential]

    True or False: With the resting membrane potential established, a few sodium ions and potassium ions continue to diffuse across the cell membrane.
  114. [Resting Potential]

    The negative membrane potential helps and hinders what?
    helps sodium ions to enter the cell despite sodium's low permeability

    hinders potassium ions from leaving the cell despiste potassium's higher permeability
  115. [Resting Potential]

    Describe RMP.
    • RMP = -70 mV (inside to outside of cell)
    • it is a polarized membrane
    • inside of cell is negative, realative to outside of cell (due to distribution of ions inside vs. outside)
    • Na+/K+ pump restores
  116. [Local Potential Changes]

    What does neurons are excitable mean?
    it means they can respond to changes in their surroundings (inside and outside the body)
  117. [Local Potential Changes]

    Environmental changes affect the membrane potential by opening a what?
    a gated ion channel
  118. [Local Potential Changes]

    What is hyperpolarized?
    as a result (nerons are excited, causes change, etc) the membrane potential becomes more negative than the resting potential
  119. [Local Potential Changes]

    What is depolarized?
    the membrane becomes less negative (more positive) than the resting potential
  120. [Local Potential Changes]

    Local potential changes are graded, what does that mean?
    means the degree of change in the restin potential is directly proportional to the intensity of the stimulation
  121. [Local Potential Changes]

    What is threshold potential?
    • approximately -55 millivolts in a neuron
    • when neurons are sufficiently depolarized, the membrane potential reaches a level that is such called
  122. [Local Potential Changes]

    What is action potential?
    • this is the results of the threshold potential being reached
    • (the basis for the nerve impulse)
  123. [Local Potential Changes]

    What is another way threshold potential may be reached and action potential results?
    • if the presynaptic neurons release more neurotransmitter
    • or
    • if other neurons that synapse with the same cell join in the effort to depolarize
  124. [Local Potential Changes]

    What are the 3 ion channels?
    • 1.) chemically gated
    • 2.) voltage gated
    • 3.) mechanically gated
  125. [Action Potentials]

    In a multipolar neuron, the first part of the axon (intial segment), is often referred to as ____________ and why?
    as the trigger zone

    because it contains many voltage-gated sodium channels
  126. [Action Potentials]

    True or False: Voltage-gated sodium channels remain closed at the resting membrane potential.
  127. [Action Potentials]

    What happens to voltage-gated sodium channels when threshold is reached?
    • they open for an instant
    • briefly increasing sodium permeability
  128. [Action Potentials]

    At the peak of the action potential, the membrane potential may reach ________.
    +30 mV
  129. [Action Potentials]

    What is happening when voltage-gated sodium channels are quickly closing?
    the slower voltage gated potassium channels open and briefly increase postassium permeability
  130. [Action Potentials]

    What does the active transport mechanism in the membrane do?
    it works to maintain the original concentrations of sodium and potassium ions
  131. [Action Potentials]

    Which one is capable of action potential and which ones are not?
    Cell body
    Axons are capable

    Cell body and dendrites are not
  132. [Action Potentials]

    When an action potential is at the trigger zone what does it cause?
    it causes an eletrical current to flow further down the axon
  133. [Action Potentials]

    What is the propagation of actions potentials along an axon?
    nerve impulse
  134. [All-or-None Response]

    True or False: Nerve impulse conduction is an all-or=none response.

    (if a neuron responds at all, it responds completely)
  135. What is the refractory period?
    it is a short time following an a nerve impulse, where a threshold stimulus will not trigger another impulse on axon
  136. What are the two periods of the refractory period?
    • - absolute refractory period
    • - relative refractory period
  137. What does the refractory period limit in a neuron?
    it limits how many action potentials may be generated in a neuron in a given period
  138. What is the absolute refractory period?
    time when threshold stimulus doesn not start another action potential
  139. What is the relative refractory period?
    time when stronger threshold stimulus can start another action potential
  140. [Impulse Conduction]

    An unmyelinated axon conducts an impulse over its ________ surface.
  141. [Impulse Conduction]

    Concerning myelinated axons, myelin serves as an ___________ __________ and ___________ almost all flow of ions through the membrane that it encloses.
    • electrical insulator
    • prevents
  142. [Impulse Conduction]

    Why doesn't a myelin sheath not prevent the conduction of a nerve impulse?
    because the sheaths are not continuous

    • (nodes of ranvier between schwann cells, or oligodendrocytes interrupt the sheath)
    • (at the nodes, axon membrane has channels for sodium and potassium ion that open during threshold depolarization)
  143. [Impulse Conduction]

    When a myelinated axon is stimulated, where does the action potential occur?
    at the trigger zone
  144. [Impulse Conduction]

    In a nerve impulse traveling along a myelinated axon, action potentials occur only where?
    action potentials occur only at the nodes
  145. [Impulse Conduction]

    What is saltatory conduction?
    it is when the action potentials appear to jump from node to node
  146. [Impulse Conduction]

    Is conduction on myelinated axons faster than on unmyelinated axons?
    yes, many times faster
  147. [Impulse Conduction]

    Does the diameter of the axon affect the speed of the nerve impulse conduction?
    • Yes,
    • the greater the diameter, the faster the impulse conduction
  148. [Synaptic Transmission]

    Released neurotransmitters molecules diffuse across the _____ _____ and react with specific molecules called ______ in the _______ neuron membrane.
    • synaptic cleft
    • receptors
    • postsynaptic
  149. [Synaptic Transmission]

    What channels respond to neurotransmitter molecules?
    chemically gated channels
  150. [Synaptic Transmission]

    What are the local potential called that are created when there is changes in chemically-gated channels?
    synaptic potentials

    (enable one neuron to affect another neuron)
  151. [Synaptic Potentials]

    What can synaptic potentials do to the receiving cell membrane?
    synaptic potentials can depolarize or hyperpolarize the receiving cell membrane
  152. [Synaptic Potentials]

    What is EPSP?
    • excitatory postsynaptic potential
    • - neurotransmitter binds to a postsynaptic receptor
    • - opens sodium ions channels, that diffuse inward
    • - depolarizing the membrane
    • - possiably, triggering an action potential, more likely
    • - (lasts about 15 milliseconds)
  153. [Synaptic Potentials]

    What is IPSP?
    • inhibitory postsynaptic potential
    • - different neurotransmitter binds other receptors
    • - increase in membrane permeability to potassium ions, that diffuse outward
    • - hyperpolarizing the membrane
    • - action potential is less likely
  154. [Synaptic Potentials]

    True or False: The integrated sum of EPSPs and IPSPs determines whether an action potential results.
  155. [Synaptic Potentials]

    What is the process called when EPSPs and IPSPs are added together?
    it is called the summation
  156. [Synaptic Potentials]

    The integrated sum of EPSPs and IPSPs determines whether an action potential results. How?
    More EPSP's lead to greater probibility of an action potential
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A&P Class, Exam #5, My Questions From My Notes
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