Chapter 4: The Nervous System Flashcards

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1
Q

____ are specialized cells capable of transmitting electrical impulses then translating those electrical impulses into chemical signals.

A

Neurons

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2
Q

Structure of a Neuron

A
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3
Q

The nucleus of a neuron is found in the ____, also called the ____.

A

Cell Body

Soma

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4
Q

Dendrites

A

Recieve incoming messages from the other cells.

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5
Q

Axon Hillock

A

Determins if the action potential will be excited of inhibted.

Ex: If the signal is excitatory enough then it will release an action potential.

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6
Q

Axons carry neural signals ___ from the somas. Dendrites carry neural signals ____ the soma.

A

Away

Toward

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7
Q

Myelin

A

White fatty membrane that covers the axons of neurons.

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8
Q

Myelin Sheath

A

Maintains the electrical signal within one neuron. Speeds it up.

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9
Q

Myelin is produced by ____ in the central nervous system and ____ in the peropheral nervous system.

A

Oligodendrocytes

Schwann Cells

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10
Q

Nodes of Ranvier

A

Small breaks in the myelin sheath that are critical for rapid signal conduction.

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11
Q

Nerve Terminal

A

Structure is enlarged and flattened to maximize transmission of the signal to the next neuron and ensure the proper release of neurotransmitters.

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12
Q

What is the collection of cell bodies called in the CNS? In the PNS?

A

CNS = Nucleus (Nuclei)

PNS = Ganglion (Ganglia)

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13
Q

Which two types of glial cells, if not properly functioning, will make an individual most susceptible to a CNS infection?

A
  • Astrocytes: nourish neurons and form the blood-brain-barrier, which helps protect the brain from foreign pathogens gaining entrance.
  • Microglia: injest and break downwaste products and pathogens.
  • Disruption of either of the mechanisms would increase susceptibility to a CNS infection.
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14
Q

Guillain-Barre syndrome (GBS) is an autoimmune disease that causes demyelination in the peripheral nervous system. What type of glial cell is being target in the GBS?

A

Oligodendrocytes produce myelin in the central nervous system while Schwann cells produce myelin in the peripheral nervous system. Since GBS causes demyelination in the PNS, it can be inferred that Schwann Cells are targeted for immune destruction.

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15
Q

Glial Cells (Neuroglia)

A

Responsible for supporting neurons by nourishment, protection, and getting rid of dead neurons.

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16
Q

5 types of Glial cells and what they do.

A
  1. Astrocytes: Nourish neurons and form the blood brain barrier, which controls the transmission of solutes from the blodstream into nervous tissue.
  2. Ependymal: lines the centricles of the brain and produce cerebrospinal fluid, which physically supports the brain and serves as a shock absorber.
  3. Microglia: Phagocytic cells that ingest and break down waste products and pathogens in the CNS.
  4. Oligodendrocytes: produce myelin around axons in the CNS.
  5. Schwann Cells: produce myeline around the axons in the PNS.
17
Q

Action Potential Generation

A
18
Q

What neural structure initiates the action potential?

A

The Axon Hillock

19
Q
  • What entity maintains the reting membrane potential?
  • What is the approximate voltage of the resting membrane potential?
A
  • The resting membrane potential is maintained by the Na+/K+ ATPase.
  • -70mV
20
Q

Define

  • Temporal Summation
  • Spatial Summation
A
  • The integration of multiple signals close to each other in time.
  • The integration of multiple signals close to each other in space.
21
Q

During the action potential, which ion channel opens first? How is this ion channel regulated? What effect does the opening of this channel have on the polarization of the cell?

  • Ion channel:
  • Regulation:
  • Effect on polarization:
A
  • Ion channel:
    • The sodium channel opens first (around -50mV).
  • Regulation:
    • It is regulated by inactivation, which occurs around +35mV
  • Effect on polarization:
    • Inactivation can only be reverse by repolarizing the cell. The opening of the potassium channel causes depolarizing.
22
Q

During the action potential, which ion channel opens second? How is this ion channel regulated? What effect does the opening of this channel have on the polarization of the cell?

  • Ion channel:
  • Regulation:
  • Effect on polarization:
A
  • Ion channel:
    • The potassium channel opens up second at approximately +35 mV.
  • Regulation:
    • It is regulated by closing at low potentials (slightly below -70mV).
  • Effect on polarization:
    • The opening of the potassium channel causes repolarization and, eventually, hyperpolarization.
23
Q

What is the difference between the absolute and relative refractory period?

  • Absolute Refractory Period
  • Relative Refractory Period
A
  • Absolute Period
    • During the absolute refractory period, the cell is unable to fire an action potential regardless of the intensity of a stimulus.
  • Refractory Period
    • During the relative refractory period, the cell can fire an action potential only with a stimulus that is stronger than normal.
24
Q

What ion is primarily responsible for the fusion of neurotransmitter-containing vesicles with the nerve terminal membrane?

A

Calcium is responsible for fusion of neurotransmitter vesicles with the nerve terminal membrane.

25
Q

What are the three main methods by which a neurotransmitter can be stopped?

A
  1. Enzymatic degradation
  2. Reuptake
  3. Diffusion
26
Q

Resting membrane potential

(Definition)

A

The net electric potential difference that exist across the cell membrane, created by the movement of moelcules across the membrane.

27
Q

Potassium leak channels

A

Allows the slow leak of K+ out of the cell. As K+ continually leaks out of the cell, the cell loses a small amount of positive charge, leaving behind a small amount of negative charge and making the outside of the cell slightly positively charged.

28
Q

What is the equilibrium potential of potassium?

A

-90mV. The negative sign because potassium is moving out of the cell.

29
Q

Sodium leak channels

A

The slow leak of sodium into the cell causes a build-up of electric potential.

30
Q

What is the equilibrium potential of sodium?

A

60mV, it is positive because sodium is moving into the cell.

31
Q

K+ movement pulls the cell potential towards ____, while sodium’s movement pulls the cell potential the opposite way, towards ____. But, neither ion ever “wins” the tug of war. instead, a balance od these two effects is reached at around ____ for the average nerve cell.

A
  • -90mV
  • +60mV
  • -70mV (resting membrane potential)
32
Q

Na+/K+ ATPase

A
  • Continually pumps sodium and potassium back to where they started: K+ into the cell and sodium out of the cell, to maintain their respective gradients.
33
Q

Depolarization

A

excitatory inputs that causes the membrane potential to raise from its resting potential.

34
Q

Hyperpolarization

A

Inhibitory inputs the cause lowering of th membrane potential from its resting potential

35
Q

Impulse Propagation

A

Movement of an action potential down an axon, resulting in neurotransmitter release at the synaptic bouton and transmission of the impulse to the target neuron or organ.

36
Q

Saltatory Conduction

A

Process by which an electrical signal jumps across the Nodes of Ranvier to travel down the axon.

37
Q
  • Presynaptic Neuron
  • Postsynaptic Neuron
A
  • Presynaptic Neuron
    • The neuron before the synaptic cleft
  • Postsynaptic Neuron
    • The neuron after the synaptic cleft.
38
Q

If a neuron signals to a gland or muscle, rather than another neuron, the postsynaptic cleft is teram as an ______.

A

Effector