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PSYCH 251 > Midterm 1 > Flashcards

Midterm 1 Flashcards

1
Q

History of the Neuron

A

Neuron Doctrine
- The nervous system consists
of discrete individual cells
- Santiago Ramón y Cajal
(1888)

Neuron
- Term coined by Heinrich Wilhem Waldeyer (1891)

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2
Q

What are neurons?

A
  • Specialized biological
    cells
  • In the central nervous
    system (CNS) and
    the peripheral nervous
    system (PNS)
  • Whose primary function
    is information processing
    (i.e. computation) and
    transmittal
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3
Q

Neuron Cell Body

A
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4
Q

Structure of a Neuron

A
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5
Q

Axon

A
  • Axon Hillock
  • Myelin sheath & Nodes of Ranvier
  • Axon termain
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6
Q

Connection between neurons: Synapses

A

Axosomatic Synapses
- made in the soma or cell body of a neuron

Axodendric Synapses
- one neuron makes into a dendrite of another neuron

Axo-axonic
- synapses made by one neuron into the synapse of another neuron

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7
Q

Connection between neurons: Synapses Cell

A

Presynaptic cell
- a neuron that sends information to another neuron via synapse

Synaptic cleft
- a gap between the pre and postsynaptic cells

Postsynaptic cell
- a neuron that receives

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8
Q

Cell Membrane

A

Lipid (fatty) bilayer
- Prevents flow of ions, proteins, and other water-soluable

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9
Q

Neuron as a “Battery” Difference of Electrical Potential

A

Extracellular side
- more positive ions

Cytoplasmic side
- more negative ions

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10
Q

Conduits across the membrane

A

Ion channels
- Na+ , K+ , Ca2+ , Cl -
- Passive transport
- Selective permeability
- Can be gated

Ion pumps
- Na+ /K+ , Ca2+
- Active transport
- Require energy (ATP)

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11
Q

Nongated Ion Channels K +

A

K + (potassium) channel

  • Extracellular side
    – Higher electrical potential
  • Membrane
  • Cytoplasmic side
    – Higher potassium concentration

Electrochemical equilibrium
- Electrical gradient down
- Concentration gradient up

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12
Q

Nernst Equation

A
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13
Q

Nongated Ion Channels Na +

A

Na + (sodium) channel
- Higher electrical potential
- Higher Na+ concentration

Influx of ions
- Electrical gradient down
- Concentration gradient

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14
Q

Sodium/Potassium Pump

A

For 1 molecule of ATP
(adenosine triphosphate):
- 2 K+ in
- 3 Na+ out

Result:
- Concentration gradients
– Greater Na+ outside
– Greater K+ inside
- Electrical gradient
– Higher potential outside
26

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15
Q

Resting membrane potential

A

Steady state
- Passive & active transport balance out
- Difference of electrical potential: energy source

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16
Q

Neuronal Signalling Overview

A

Initiation of action potential (axon hillock)

Propagation of action potential (axon)

Synaptic transmission (synapse)

Synaptic intergration (axon hillock)

17
Q

Changes in membrane potential

A

Hyperpolarization
- Inhibitory posynaptic potentials (IPSPs)

Deporlarization
- Excitatory postynaptic potentials (EPSPs)

18
Q

Action Potential (Spike!)

A

● Rapid depolarization
and repolarization
● Occurs at threshold
potential (~-55 mV)
● All or none
- Constant amplitude
(~100 mV above resting)
- Constant timecourse
(~1 ms)
● Refractory period
(~5 ms) 32

19
Q

Voltage-gated Na+ channel

20
Q

Voltage-gated K+ channel

21
Q

Step 1 action potential events

A

At threshold, voltage-
gated Na + channels
open, and positive Na +
ions flow into cell

22
Q

Step 2 action potential events

A

As depolarization continues, even more voltage-gated Na+ channels open, increasing depolarization

23
Q

Step 2 action potential events

A

Voltage-gated K +
channels open, and K +
ions flow out of cell

24
Q

Step 4 action potential events

A

Voltage-gated Na+
channels close, while
voltage-gated K +
channels are still open
During hyperpolarization,
another action potential
cannot be generated
(absolute refractory
period)

25
Q

Step 5 action potential events

A

Voltage-gated K +
channels close when the
membrane is
hyperpolarized (below
resting potential), and
the membrane potential
returns to steady state at
the resting potential
(relative refractory
period)

26
Q

Hodgkin-huxley model

A

Mathematical mode of action potentials
Awarded 1963 Nobel Prize in Physiology or Medicine

27
Q

Electronic Conduction

A
  • Passive
  • Relatively fast
  • Exponentially attenuating
  • Travel short distances
28
Q

Propagation of the Action Potential

A

Self-regenerating propagation
- Active
- Relatively slow
- Self-regenerating
- Travel long distances

29
Q

Myelin & action potential propagation

A

Saltatory Conduction
- Nodes of Rainvier:
– Action Potentials
- Myelinated sections
– electronic conduction

  • relatively fast
    self regenerating
    travel long distances
30
Q

Speed of propagation

A
  • As slow as < 1 m/s
    (3.6 km/h)
  • As fast as > 120 m/s
    (432 km/h)
  • Depends on:
    – Axon diameter
    – Myelination
    – Temperature
    – etc…
31
Q

Action potential as signals

A
  • All or none
  • Neural coding
    – rate
    – duration
    – timing

PSYCH 251 (1 decks)

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