Chapter 48: Neurons, Synapses, and Signaling Flashcards

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1
Q

Neurons

A
  • Nerve cells
  • Transfer information within the body
  • Long and short-distance electrical signals
  • Receive, transmit, and regulate flow of information
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2
Q

Brain

A

Groups of neurons that sort neuronal paths and connections

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3
Q

Ganglia

A

Simpler clusters of neurons

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4
Q

Cell Body

A

Where most of a neuron’s organelles are located

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5
Q

Dendrites

A

Branched extensions of a neuron

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6
Q

Axon

A
  • Each neuron has one
  • Extension that transmits signals to other cells
  • Much longer than dendrites
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7
Q

Synapse

A

Junction that receives transmitted information from the branched end of an axon

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8
Q

Neurotransmitters

A
  • Chemical messengers

- Pass information from a transmitting neuron to a receiving cell at synapses

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9
Q

Glial Cells/Glia

A
  • Supporting cells
  • Nourish neurons
  • Insulate axons of neurons
  • Regulate extracellular fluid surrounding neurons
  • Replenish certain groups of neurons and transmit information
  • There are more of them than neurons
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10
Q

Sensory Neurons

A

Transmit info about an external stimuli (i.e. light, touch, smell, or internal conditions like blood pressure)

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11
Q

Interneurons

A
  • Most of the neurons in the brain

- Form local circuits connecting neurons in the brain

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12
Q

Motor Neurons

A

Transmit signals causing muscle cells to contract

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13
Q

Central Nervous System (CNS)

A
  • In many animals
  • Organization of neurons that carry out integration
  • Brain and spinal cord
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14
Q

Peripheral Nervous System (PNS)

A

Neurons that carry information in and out of the central nervous system

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15
Q

Nerves

A

Bundles of axons of neurons

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16
Q

Membrane Potential

A

Charge difference/voltage because of potential energy from the attraction of opposite charges across the membrane

17
Q

Resting Potential

A
  • Membrane potential of a neuron that isn’t sending a signal

- Usually -60 to -80 mV (millivolts)

18
Q

Sodium-Potassium Pump

A
  • Actively transports K+ in the cell and Na+ out

- Maintains K+ and Na+ gradients

19
Q

Ion Channels

A

Pores formed by clusters of specialized proteins across the membrane

20
Q

Equilibrium Potential (Eion)

A
  • Magnitude of membrane voltage at equilibrium for a particular ion
  • Can be calculated with Nernst equation
21
Q

Gated Ion Channels

A
  • Ion channels that open/close in response to stimuli

- Opening/closing alters membrane’s permeability to ions and therefore alters potential

22
Q

Hyperpolarization

A

Ions flow across the membrane, increasing magnitude of membrane potential

23
Q

Depolarization

A
  • Reduction in the magnitude of membrane potential

- Often involves gated sodium channels

24
Q

Graded Potential

A
  • Shift in membrane potential
  • Magnitude that varies with the strength of the stimulus (larger stimulus causes a greater change in membrane potential)
  • Decays with time and distance from source
25
Q

Action Potential

A
  • Massive change in membrane voltage
  • Have constant magnitude and can regenerate in adjacent regions of the membrane
  • Good for long distance signal transmission
26
Q

Voltage-Gated Ion Channels

A

Open/close when membrane potential passes a particular level

27
Q

Threshold

A
  • Particular value that depolarization increases membrane voltage to
  • In mammalian neurons it’s about -55 mV
28
Q

Refractory Period

A

Time when the second activation potential cannot be initiated (caused by inactivation of sodium channels)

29
Q

Myelin Sheath

A

Electrical Insulation that surrounds vertebrate axons

30
Q

Oligodendrocytes

A
  • Produce myelin sheaths

- In the central nervous system

31
Q

Schwann Cells

A
  • Produce myelin sheaths

- In the peripheral nervous system

32
Q

Nodes of Ranvier

A

Gaps in the myelin sheath

33
Q

Saltatory Conduction

A
  • Mechanism for propagating action potentials

- Action appears to leap from node to node