Lecture 4 (anatomy, cells, resting potential) Flashcards

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1
Q

What are the 3 main parts of the neuron?

A
  1. Soma
  2. Axon
  3. Terminal
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2
Q

What are the parts of the soma and its function?

A
  1. dendrites (receive electrochemical signals)
  2. spines (^^)
  3. receptors (on the ends of D&S)
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3
Q

What are the parts of the axon and its function?

A
  1. axon hillock
  2. myelin
  3. nodes of ranvier
    Electrochemical signals move across the axon into the terminal
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4
Q

What are the parts of the terminal and its function?

A
  1. Vesicles
  2. NTs
    The ec signal reaches the terminal, then moves through the membrane to the synapse to bind to the next neuron
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5
Q

3 types of glial cells?

A
  1. astroglial cells
  2. oligodendroglial cells
  3. microglial cells
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6
Q

Astroglial cells –> job? how?

A

Job: form and maintain the blood brain barrier
How: surrounds blood vessels in the brain, plugs/patches holes

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7
Q

Why is the blood brain barrier important?

A

Prevents bad things (bacteria, etc.) from getting into the brain. They stay in the blood vessels to get filtered out by the kidneys/liver

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8
Q

Oligodendroglial cells –> job? how?

A

Job: form and maintain the myelin layer/sheath around the axons of neurons
How: they wrap around, coating the axon

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9
Q

Why is myelin important?

A
  1. insulating layer
  2. Facilitates quicker transmission/communication between neurons
  3. allows electrical impulses to transmit quickly
  4. it is interrupted at the nodes of ranvier
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10
Q

Microglial cells –> job? how?

A

Job: ‘immune system’ or ‘cleaners’ of the brain
eliminate foreign substances OUTSIDE of
neurons (floating in the brain)
How: they form macrophages
Phagocytosis: a cell ingests or engulfs other cells, particles, or bacteria to dispose of them

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11
Q

Why are microglial / macrophages important?

A

Central role in protecting against infection in the brain

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12
Q

3 states of a neuron:

A
  1. Resting
  2. Excited
  3. Inhibited
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13
Q

Define propagation:

A

the movement of signals between neurons

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14
Q

Define resting potential

A

Electrical charge of the cell when it’s doing nothing

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15
Q

What is the charge? Characteristics of RP?

A

-70mV

  • unequal distribution of ions inside and outside
  • inside is MORE NEGATIVE than outside
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16
Q

Ions higher in concentration INSIDE the neuron? (resting)

A

High concentration of K+

also lots of proteins (A-)**
**proteins cannot move through channels, they’re too big

17
Q

Ions higher in concentration OUTSIDE the neuron? (resting)

A

High concentration of:
Na+
Cl-

18
Q

3 forces responsible for ion distribution?

A
  1. concentration gradient
  2. electrical gradient (electrostatic pressure)
  3. Na+ / K+ pump
19
Q

Concentration gradient?

A

Want the same # of ions inside and outside

20
Q

Electrical gradient?

A

Want equal electrical charge inside and outside
Refers to opposite charges attracting each other

21
Q

Concentration gradient for K+ ?

A
  • some K+ channels are open during resting potentials
  • b/c there’s a high concentration of K+ inside, K+ moves OUT
  • neuron loses + charges!!
    –> becomes more negative
22
Q

Electrical gradient for K+ ?

A
  • when K+ leaves the cell (due to concent. grad.), cell becomes even more negative
  • electrical gradient wants to balance in and out
  • elect. grad. pulls K+ back IN
23
Q

Na+ / K+ pump?

A
  • Na+ leaks in due to elect. grad. wanting more positive charge
  • can’t have too much Na+ because the cell needs to be at -70mV to function at RP
  • Na+ / K+ pump replaces Na+ for K+

3Na+ OUT –> 2 K+ IN

** it just needs to pump out something positive, its irrelevant why its Na+
** the pump has channels that allow movement for both Na+ and K+ –> most channels only allow movement for 1 ion

24
Q

What would happen if a toxin blocked the Na+ / K+ pump?

A

The cell would become too positive, it wouldn’t stay at -70mV, it wouldn’t be able to function at resting potential

25
Q

Given that there is a higher concentration of Ca++ outside the neuron than inside (at resting potential), how do the chemical and electrical gradients affect it?

A
  • the chemical gradient would pull the Ca++ inside the neuron to have the same number of ions in/out
  • this would make the neuron more positive
  • the electrical gradient would pull the Ca++ back outside to keep the charge of the neuron at -70mV