Neurons Flashcards

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1
Q

Signaling

A

Coordinates body functions

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2
Q

Difference between endocrine system and nervous system?

A

Endocrine system: has hormones as signalers, is slow-acting, prolonged effects

Nervous system: neurotransmitters as signalers, fast-acting, ephemeral effects (stimulus -> action -> over)

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3
Q

Neurons

A

Highly specialized for information processing; has dendrites, cell body w/nucleus, axon hillock, axons covered w/ myelin sheath, nodes of Ranvier, axon terminals, and synapses

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4
Q

Dendrites

A

Top of the neuron that receives signals

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5
Q

Cell body

A

Also called soma contains nucleus

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6
Q

Axon hillock

A

Determines whether or not to fire the signal through the neuron

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7
Q

Axon

A

Includes myelin sheath and nodes of Ranvier where the signal travels through

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8
Q

Myelin sheath

A

Covers the axon and acts as a fatty insulator; makes the signal travel faster)

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9
Q

Nodes of Ranvier

A

Gaps between myelin sheath that the signal lands on after jumping over myelin sheath

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10
Q

Axon terminals

A

End of an axon and has synapses

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11
Q

Synapses

A

Connect w/ another neuron and transfers signal

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12
Q

How many neurons typically make up a circuit?

A

2-3

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13
Q

How many sodium ions are pumped for how many potassium ions?

A

3 sodiums for 2 potassiums

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14
Q

What does it mean when there is more Na+ ions outside and K+ ions inside?

A

More positive outside and more negative inside

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15
Q

Hyperpolarization

A

Removing positive charges and resting potential becomes more negative; cell does not fire

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16
Q

Depolarization

A

Resting potential becomes more positive due to more positive ions being entering the cell; cell does not fire

17
Q

Graded potentials

A

Stimulated neuron but not enough to fire; “false alarm”

18
Q

Action potential

A

Massive energy change when tons of ions flood in and out of cell; enough energy to pass the threshold allowing for neuron to fire; a lot of positive energy

19
Q

List the steps of an action potential.

A
  1. Resting state-all voltage gated channels are closed
  2. Depolarization-stimulus opens some Na channels causing the resting potential to become less negative (Na ions are outside)
  3. Rising phase-membrane voltage exceeds threshold, causes all voltage gated ion Na channels to open
  4. Falling phase-K channels open, Na channels close; becomes more negative as Na+ goes in
  5. Hyperpolarization-K channels remain open longer than Na channels causing potential to return to resting potential (-70 V)
20
Q

All or nothing

A

Either a neuron fires or it does not

21
Q

Unidirectional

A

A signal moves through the neuron unidirectionally (in one direction cannot go back); signal jumps over myelin sheath and lands on Nodes of Ranvier

22
Q

Difference between neuron w/ myelin sheath and w/o.

A

W/ myelin sheath: fast

W/o myelin sheath: slow, increases radius of neuron to offset speed deficiency, in squids and other molluscs

23
Q

Saltatory conduction

A

Speeds up signal propogation

24
Q

What happens once neurotransmitters reach the synapse?

A
  1. Action potential triggers release of synaptic vesicles
  2. Neurotransmitters cross the synaptic cleft and bind to ligand gated channels
  3. Ion channels open and changing of membrane potential occurs on the other neuron
25
Q

What would happen if the membranes directly touched?

A

The action potential will continue to trigger leading to a continuous signal. It will function as one cell. No touching would’ve allowed the signal to stop.

26
Q

Summation

A

Inputs are integrated in the axon hillock

27
Q

Excitatory potential (EPSP)

A

More likely to fire

28
Q

Inhibitory potential (IPSP)

A

Less likely to fire

29
Q

Sub threshold, no summation

A

Not enough to fire; involves excitatory potentials

30
Q

Temporal summation

A

Excite close in time=fire; involves excitatory potentials

31
Q

Spatial summation

A

Signals firing at the same time at diff. Parts of the target cell leads to firing; involves two different excitatory potentials

32
Q

Spatial summation of EPSP and IPSP

A

a lot of neuron signals but no firing; involves excitatory and inhibitory signals

33
Q

How are neurontransmitters returned?

A

Neurotransmitters are cleared from the synaptic cleft to reset the process. This is done by enzymes breaking down inactivated neurotransmitters in the synaptic cleft and the reuptake of neurotransmitters by the presynaptic neuron.

34
Q

Some medications block the reuptake of neurotransmitters by the presynaptic neuron in the synaptic cleft. What happens to the postsynaptic neuron as a result?

Neurotransmitters remain bound to ligand gated ion channels longer, triggering more graded potentials (don’t fire)

The neuron becomes hyper stimulated, increasing the magnitude of action potentials

Neurotransmitters remain bound to voltage gated ions channels longer, triggering more action potentials

The response rate of the postsynaptic neuron stays the same because it does not respond to neurotransmitters

A

Neurotransmitters remain bound to ligand gated ion channels longer, triggering more graded potentials

35
Q

Greater magnitude leads to taller action potentials. T or F?

A

False, greater magnitude means more action potentials