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120 Cards in this Set
- Front
- Back
- 3rd side (hint)
What are the 2 major divisions of the nervous system?
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The Central Nervous System (CNS) and
The Peripheral Nervous System (PNS) |
Pg. 072
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What are Neuroglia cells?
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Supporting cells located in the CNS.
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Pg. 072
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What are the 3 major parts of a Neuron?
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1) The Cell Body
2) Dendrites 3) Axons |
pg. 072
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What type of insulating material surrounds many of the axons?
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Myelin Sheath
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Pg. 072
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What is a myelin sheath?
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A type of insulating material that surrounds many axons.
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Pg. 072
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What is the part of the “structure that conducts impulses away from the cell body” that does not have myelin surrounding it?
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The Axon Hillock
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Pg. 072
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What is the Axon Hillock?
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The initial segment of the axon.
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What does the CNS consist of?
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The Brain and Spinal Cord
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What does the PNS consist of?
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Everything else in the nervous system with the exception of the brain and spinal cord.
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What are nerves?
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Bundles of axons located in the PNS.
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What do the bundles of PNS axons enter into?
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They enter either the brain or spinal cord.
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Pg. 072
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What are the collection of axons called in the CNS?
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Tracts
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What are Ganglia?
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Bundles of neuron cell bodies located in the PNS.
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Pg. 072
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What are groupings of nerve cell bodies in the CNS called?
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Nuclei
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Pg. 072
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What are neurons in the PNS functionally classified as?
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Sensory Neurons
or Motor Neurons |
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What direction do Sensory neurons conduct impulses with regard to the CNS?
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They conduct impulses into the CNS.
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What is another name for Sensory Neurons?
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Afferent Neurons
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What direction do Motor neurons conduct impulses with regard to the CNS?
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They conduct impulses out of the CNS.
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Pg. 072
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What is another name for Motor Neurons?
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Efferent Neurons
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What is the division of efferent neurons that stimulate skeletal muscles called?
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Somatic motor Neurons
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What is the division of motor neurons that stimulate smooth muscles, cardiac muscles and glands called?
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Autonomic Motor Neurons
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Pg. 073
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What are the neurons that stimulate smooth muscles, cardiac muscles and glands subdivided into?
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Sympathetic and Parasympathetic
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True or False. Autonomic motor neurons can be innervate effectors voluntarily.
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False. Autonomic motor neurons innervate involuntary effectors.
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What are neurons whose dendrites, cell body, and axons are located entirely within the CNS known as?
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Association Neurons
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What functions do association neurons have?
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They can: Receive sensory information, integrate and analyze information and stimulate motor neurons.
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Structurally, how are neurons classified?
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They are classified according to their number of extensions, or processes.
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What structurally does a Bipolar neuron consist of?
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2 processes, 1dendrite and 1axon
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What structural classification do most sensory neurons have?
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Most are Pseudounipolar
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What structurally does a Pseudounipolar neuron consist of?
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They have 1 process but it later divides into 2processes.
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What structural classification do neurons whose dendrites, cell body, and axons located entirely within the CNS have?
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Multipolar
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What types of neurons have a multipolar structural classification?
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Motor Neurons and Association Neurons
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What structurally does a Multipolar neuron consist of?
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They have many dendrites and only a single axon.
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Pg. 073
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What is the nervous system’s ratio of supporting cells to neurons?
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There are about 5 times more supporting cells than neurons.
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What are the names of the 2 kinds of supporting cells in the PNS?
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Schwann Cells and Satellite Cells
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What function do Schwann Cells serve in the PNS?
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They form myelin sheaths around many of the axons in PNS.
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What function do Satellite Cells serve in the PNS?
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They support neuron cell bodies in the ganglia of the PNS.
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What are the supporting cells in the CNS known as?
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Neuroglial cells, or (Neuroglia, Glial cells or Glia)
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Pg. 073
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What are the names of the different neuroglial cells?
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Oligodendrocytes
Astrocytes Microglia Ependyma |
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What function do Oligodendrocytes serve?
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They form myelin sheaths around axons in the CNS.
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Pg. 073
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How are Oligodendrocytes and Schwann cells similar and different?
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They both form myelin sheaths around axons.
However Oligodendrocytes = CNS and Schwann cells = PNS. |
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What function do Astrocytes serve?
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Astrocytes have extensions that surround blood capillaries and extensions in close proximity to axons at synapses.
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Pg. 073
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What function do Microglia cells serve?
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They are the nervous system’s phagocytic cells.
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What function do Ependyma cells serve?
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They are an epithelial layer that lines the ventricles of the brain and the central canal of the spinal cord.
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What structures do Ependyma cells line?
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The ventricles of the brain and the central canal of the spinal cord.
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What do the blood capillaries in the brain lack compared to capillaries in other organs?
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They lack pores in their walls.
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What is a consequence of the brain’s blood capillaries lacking pores?
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There is no filtration of fluid out of the capillaries of the brain as compared to what happens with other organs.
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Pg. 073
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How does the brain obtain nutrients and regulatory molecules since there are no pores in the brain’s blood capillaries?
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The Nutrients and Regulatory molecules move through the cytoplasm of the cells by Diffusion, Active Transport, Endocytosis and Exocytosis.
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Pg. 073
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What neuroglial cell has a direct relationship to the selectivity of the brain’s blood capillaries?
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Astrocytes
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Pg. 073
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What is the selective ability of molecules passing from the blood to the brain known as?
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Blood-Brain Barrier
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Pg. 074
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The nervous system contains what kinds or axons?
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Myelinated axons
and Unmyelinated Axons |
Pg. 074
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True or False. Schwann cells only surround myelinated axons in the PNS.
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False. Schwann cells surround both myelinated and unmyelinated axons in the PNS.
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Pg. 074
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What are the term(s) given to describe what is formed when Schwann cells surround myelinated and unmyelinated axons?
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Sheath of Schwann
or Neurilemma |
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What is believed to aid in the ability of damaged axons in the PNS to regenerate and what does it form?
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The Sheath of Schwann by forming a regeneration tube.
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Pg. 074
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What is the difference between myelinated and unmyelinated axons in the PNS?
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In Myelinated axons the Schwann cells wrap themselves around the axon.
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Pg. 074
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What happens as a Schwann cell wraps itself around the axon?
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It’s cytoplasm is squeezed to the outside.
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What is produced by Schwann cells wrapping themselves over and over again around the same section of axon with then a different Schwann cell wrapping itself around the next section and what are they called?
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Gaps are produced.
They are called Nodes of Ranvier |
Pg. 074
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True or False. Oligodendrocytes form myelin sheaths the exact same way in the CNS as Schwann cells do in the PNS.
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False. Oligodendroccytes form myelin sheaths in a similar way except Oligodendrocytes have several extensions that are able to form myelin sheaths around several axons.
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Pg. 074
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What is the direct result of Oligodendrocytes having several extensions enabling formation of myelin sheaths around several axons?
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There is not a continuous Sheath of Schwann or Neruilemma around axons in the CNS the way there is a continuous Sheath of Schwann around axons in the PNS.
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Pg. 074
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What are reason(s) why CNS axons do not commonly regenerate are they are damaged?
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1) There is not a continuous Sheath of Schwann or Neruilemma around the axons of the CNS.
2) Regeneration of CNS axons is also inhibited by molecules produced by Oligodendrocytes and Astrocytes. |
Pg. 074
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True or False. The CNS contains both white matter and gray matter.
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True
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Pg. 074
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What color do the areas of the CNS have that contain mostly axons?
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White
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Why do the areas of the CNS that contain mostly axons have a white color?
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Because of the phospholipids of plasma membranes of the myelin sheaths.
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What does the “white matter” of the CNS contain?
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Axon tracts
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What “major parts of a neuron” compose the “gray matter” of the CNS and why is it gray?
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Cell bodies and Dendrites Because there are no myelin sheaths surrounding the cell bodies and dendrites.
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Pg. 075
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What is the color of the brain’s surface and its inner core?
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Brain’s surface = Gray
Inner core = White |
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What are action potentials?
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They are nerve impulses produced by axons
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Pg. 075
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True or False. Action potentials are all-or-nothing and they do not decrease in amplitude.
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True
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Pg. 075
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In measuring membrane potential what are the leads connected to which indicates voltage and also graphs the rapid changes in the membrane potential?
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Oscilloscope
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Pg. 075
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What is the process called when membrane potential decreases or (goes to zero)?
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Depolarization
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Pg. 075
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What is the process called when membrane potential increases or (goes to a higher voltage which is even more negative on the inside)?
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Hyperpolarization
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Pg. 075
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What direction will an oscilloscope deflection occur in respect to the resting membrane potential during depolarization?
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Upward direction
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What direction will an oscilloscope deflection occur in respect to the resting membrane potential during hyperpolarization?
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Downward direction
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How are gated ion channels in the axon regulated?
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They are voltage-regulated
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Pg. 075
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How are the axon’s Na+ and K+ plasma membrane channels stimulated to open?
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They are stimulated to open by depolarization.
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Pg. 076
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What are other names for the gated Na+ and K+ channels in an axon’s membrane?
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Voltage-Gated Channels or Voltage-Regulated Channels
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Why are gated channels for Na+ and K+ in an axon’s membrane also called Voltage-Gated or Voltage-Regulated Channels?
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Because these channels open in response to a Depolarization Stimulus.
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Pg. 076
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What term is used to identify “the certain level” a depolarization stimulus must reach in order to open the voltage-gated channels?
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The Threshold
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Pg. 075
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What threshold must Voltage-Gated Na+ Channels be depolarized to in order to open?
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They must be depolarized from the RMP of -70 mV to approximately -55 mV.
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Pg. 076
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True or False. A Voltage-Regulated ion channel is only open for about a millisecond before it becomes inactivated.
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True
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Pg. 076
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What is one of the types of polypeptides that may be involved with inactivating a gated ion channel and how do these particular molecules accomplish this?
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Ball and Chain type polypeptide.
They block the channel. |
Pg. 076
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What is the difference between closed and inactivated gated ion channels?
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Closed channels = can be opened by a depolarization stimulus
Inactivated channels = cannot be opened by a depolarization stimulus |
Pg. 076
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Approximately how long does an inactivated channel stay inactivated?
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Approximately 1 millisecond
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Pg. 076
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Where do the “action potentials” or “nerve impulses” generally begin?
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At the axon hillock
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Pg. 076
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Why is the stimulus for an action potential the depolarization of the axon’s plasma membrane?
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1) Because the opening of Voltage-Gated Na+ and K+ channels produces the action potential.
2) Because production of the action potential’s depolarization stimulus originates at the synapse. |
Pg. 076
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What will happen if depolarization is not sufficient enough to reach -55 mV?
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The voltage-Gated ion channels remain closed.
No action potential is produced. The depolarization will gradually decay and will disappear after it travels about 1-2 mm. |
Pg. 077
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What is the term for an axon’s ability to spread potential charge along the axon?
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“Cable Properties”
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Pg. 077
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Why is the spread of potential charge over distance short?
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1) Because charges can leak through the plasma membrane.
2) Because there is internal resistance of the axon cytoplasm to the spread of charges. |
Pg. 077
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True or False. An axon conducts charges equally as well as the conduction of electricity by a wire.
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False
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Pg. 077
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What general action produces an action potential?
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The sequential opening and closing of Na+ and K+ channels.
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Pg. 077
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What kind of mechanism is the effect of Na+ diffusing into an axon causing it to become more polarized and example of?
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Positive feedback effect
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Pg. 077
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What happens at the same time Voltage-Gated Na+ channels become inactivated?
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The Voltage-Gated K+ channels open.
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Pg. 077
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How is the membrane potential of an axon brought back down to RMP from +30 mV?
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Voltage-Gated Na+ channels become inactivated while at the same time Voltage-Gated K+ channels open allowing K+ to flow out of the axon.
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Pg. 077
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How do the voltages change during depolarization?
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There is a rapid change from -70 mV to +30 mV.
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Pg. 077
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What is the process of membrane potential going from +30 mV to -70 mV called?
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Re-polarization
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Pg. 077
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Why is the use of ATP necessary for Depolarization and Re-polarization?
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1) To maintain the concentration gradients
2) To restore the concentration of Na+ and K+ |
Pg. 077
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What are the certain characteristics of Action Potentials?
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1) They are an All-or-None event.
2) The frequency a membrane fires action potentials are determined by the strength of a depolarization stimulus above threshold. 3) They have a Refractory Period |
Pg. 077-078
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What is meant by an action potential being an “all-or-none” event?
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It fires to its maximum amplitude or it does not fire.
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Pg. 078
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What is the Refractory Period of an action potential?
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It is the period of time a plasma membrane has when an action potential has been produced and cannot produce a second one.
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Pg. 078
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What specific term is used to describe the phase a membrane cannot respond, that occurs during the production of the action potential?
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Absolute Refractory Period
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Pg. 078
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Why does the Absolute Refractory Period occur?
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It results from the inactivation of the Na+ channels.
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Pg. 078
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What specific term is used to describe the phase of a membrane immediately following the action potential?
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Relative Refractory Period
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Pg. 078
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What is occurring in the Relative Refractory Period?
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There is a continued outward diffusion of K+
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Pg. 079
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What happens as a result of the continued outward diffusion of K+ that occurs in the Relative Refractory Period?
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It causes the membrane potential to decrease below the RMP and hyperpolarize for a moment.
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Pg. 079
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What does the Refractory Period of an action potential prevent?
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Prevents action potentials from adding together (summate) or running together continuously
and Prevents action potentials from backtracking |
Pg. 078-079
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What are important consequences of the inabilities of action potential’s to run together and to summate?
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Action potentials remain separate, all-or-none events that are able to code for the strength of a stimulus by their frequency of firing.
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Pg. 079
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What is an important consequence of the inability an action potential has to backtrack?
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It means the action potential produced in the axon hillock travels towards the axon terminal not away from.
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Pg. 079
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True or False. Action potentials are not regenerated along the axon.
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False. Action potentials are regenerated along the axon.
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Pg. 079
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Is it correct to say action potentials are conducted along the length of an axon?
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No. Action potentials are regenerated along the length of the axon.
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Pg. 079
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What does it mean for action potentials to be conducted without decrement?
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They do not decrease in amplitude as they are regenerated along the axon from the axon hillock to the axon terminals.
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Pg. 079
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What is meant by an action potential being a local event?
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An action potential occurs only in the small stimulated region of the axon membrane, not in the entire axon.
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Pg. 079
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What is an important result of action potentials being local events?
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It results in a potential difference between the stimulated region of the axon and the adjacent un-stimulated region.
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Pg. 079
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What are important consequences of resultant potential differences caused by action potentials being local events?
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1) Movements of charges can depolarize the next region along the axon.
2) In unmyelinated axons movement of charges are able to bring the immediately adjacent plasma membrane’s region to a threshold depolarization. 3) These above events are able to repeat from the axon’s first segment to the last. |
Pg. 079
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How does conduction of action potentials in myelinated axons differ from unmyelinated axons?
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Myelinated axons can produce action potentials only at the Nodes of Ranvier.
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Pg. 079
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What is the process that produces action potentials in myelinated axons called?
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Salutatory Conduction
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Pg. 080
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What are some consequences of Salutatory Conduction?
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1) Action potentials seem to jump from node to node
2) Each node must be depolarized to threshold by an action potential produced at the previous node 3) A myelinated axon reproduces the action potential fewer times than an unmyelinated axon would in an axon of equal length. |
Pg. 080
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Which type of axon has a faster conduction of action potentials?
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Myelinated axons
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Pg. 080
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What can a deficiency of Ca2+ called and what does this condition cause?
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Hypocalcemia
It decreases the threshold of excitation of neurons by increasing the permeability of sodium channels, causing them to have repetitive responses to a single stimulus. |
Pg. 080
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What does Hypocalcemia in the interstitial fluid impede?
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It impedes the normal release of Acetylcholine by the axon terminal of the neuromuscular junctions, and inhibits muscle stimulation.
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Pg. 080
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What does Hypocalcemia consequently lead to?
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Paresthesia (tingling)
Tetany and Psychiatric disorders in children |
Pg. 080
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How can Hypocalcemia cause inhibit muscle stimulation but still cause tetany?
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Because the increased neuronal excitability overrides the inhibition of muscle contraction.
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Pg. 080
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