Neuroscience Flashcards

1
Q

What was Rene Descarte’s framework?

A

Separated the mental processes of the mind and the physical processes of the brain

Physical brain was thought to serve as a connection between mind and body

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2
Q

What category of cells do neurons belong to?

A

Communication

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3
Q

What are the two zones of neurons?

A

Receptive zone

Transmission zone

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4
Q

What is the receptive zone designed to do?

A

To receive signals from other neurons

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5
Q

What is the transmission zone designed to do?

A

Pass on signals to other cells

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6
Q

What is the receptive zone made of?

A

Dendrites branching out of the cell body

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7
Q

What is the transmission zone made of?

A

Axon and terminal ends

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8
Q

Once the neuron recieves a signal in the receptive zone, it is passed down an _______

A

Axon

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9
Q

What is found at the end of an axon (approaching the transmission area)?

A

Cluster of branches called terminal boutons

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10
Q

What do terminal boutons do?

A

Reach out and make connections with the receptive zone of nearby neurons to transmit the signal further

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11
Q

What do glial cells do?

A

Support, nourish, and provide insulation for neurons

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12
Q

What is the resting potential of a typical neuron (in mV) and what is it caused by?

A

-70 mV

Caused by the differing concentrations of ions between the outside and inside of the neuron

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13
Q

What are the two different types of protein channels?

A

Leaky channel

Voltage gated channel

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14
Q

At rest, which side of the membrane is potassium on? Sodium?

A

Potassium = inside

Sodium = outside

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15
Q

What does the leaky channel do?

A

Allows positively-charged potassium to leave the membrane and go out into the neuron

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16
Q

Why is there a voltage at rest?

A

The leaky potassium channel

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17
Q

Where are the chloride ions and why are they there?

A

Primarily on outside

Large charged protein molecules repel them away and keep them on the outside

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18
Q

True or false: voltage-gated sodium is open during rest

A

False

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19
Q

What are dendrites (ie. their structure and function)?

A

Branch out from the cell body

Reach out to other neurons and receive signals to be relayed through the dendritic branch to the cell body. Some signals will be conveyed down the axon

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20
Q

What is the threshold of the action potential? (in mV)

A

-50 mV

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21
Q

Immediately after the threshold of the action potential is reached, what happens? (i.e. what does sodium do?)

A

Sodium gates open

High concentration of sodium on the outside rushes in

The inside of the cell becomes more positive

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22
Q

After the sodium rushes in (in action potential), what happens next? (potassium)

A

Charge is positive on inside so begins to push potassium ions out thru leaky potassium channels

Once the charge inside of the cell is positive enough, the potassium gates open as well and potassium rushes out

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23
Q

What is the peak charge in action potential (in mV)?

A

+40 mV

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24
Q

What happens after the cell reaches its peak charge (in action potential)?

A

Sodium channels close

Sodium stops entering but potassium continues to rush out

Inside charge becomes less positive. Eventually overshoots the baseline charge of -70 mV

Potassium channels close

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25
Q

After the rush of ions is complete (in action potential), what happens?

A

Cell slowly returns to -70mV

Refractory period where no action potential can happen

26
Q

How does the sodium-potassium pump help maintain ion balance?

A

Expels three sodium ions (from in the cell) and replaces them with two potassium ions (from outside)

27
Q

Where does the action potential start?

A

In receptive zone of the neuron, where cell body connects to the axon

Goes towards terminal end

28
Q

Why do action potentials “cascade” down a neuron?

A

Rapid change in one spot leads to change in ion concentrations in the neighbouring spots (bc of increase sodium permeability) and thus an action potential in that spot and so on

29
Q

What is myelin?

A

Fatty, insulating tissue that surrounds the neuron; formed by glial cells

30
Q

What are the different types of glial cells and where are they found?

A

Oligodendrocytes - Central Nervous System

Schwann cells - Peripheral Nervous System

31
Q

What is the purpose of myelin?

A

Allow the action potential to travel down the axon much faster

32
Q

What are the nodes of ranvier?

A

Open regions of the axon not covered by myelin

33
Q

How does myelin work to perform its function?

A

When action potential reaches myelin, it jumps across it via saltatory conduction. Weakens as it jumps thru

At Nodes of Ranvier, it’s strengthened again thru ion channel cascades before jumping thru to next myelin sheath

34
Q

Are the strengths and magnitudes of all action potentials the same?

A

Yes

All or none (no such thing as a half action-potential)

35
Q

How are different types of messages encoded thru action potentials?

A

Encoded by frequency and pattern

Strong signal will fire more action potentials in a short amount of time (still a refractory period tho)

36
Q

What occurs at the synapse? (i.e. once the action potential reaches the end of the axon)

A

Presynaptic neurons have chemicals (neurotransmitters) contained in vesicles

As the action potential reaches the terminal ends, some vesicles start to move towards the cell membrane of the pre-synaptic neuron. Once it fuses with the membrane, it opens and releases neurotransmitters into the extracellular fluid

37
Q

Examples of neurotransmitters?

A

Glutamate

GABA

Serotonin

Dopamine

38
Q

What is the space between two neurons called?

A

The synaptic cleft

39
Q

What happens once the neurotransmitters are released from the pre-synaptic neuron?

A

Neurotransmitters float freely in the synaptic cleft to the postsynaptic neuron. Bind to their specific receptor

40
Q

Once the neurotransmitters bind to the postsynaptic neuron, how does the signal continue to get passed down?

A

Excitatory Postsynaptic Potentials

Inhibitory Postsynaptic Potential

41
Q

Describe the Excitatory Postsynaptic Potential

A

Sodium ion channels open and sodium goes into the postsynaptic cell

Depolarizes the cell; brings it away from -70mV (resting potential) and to -50mV (threshold)

42
Q

Can one EPSP cause the postsynaptic neuron to reach the threshold?

A

No, must be multiple

43
Q

What’s the difference between Temporal Summation and Spatial Summation?

A

Temporal

  • EPSPs occurring one after the other from the SAME presynaptic connection
  • Slow climb to threshold

Spatial
- Multiple EPSPs generated simultaneously from several diff presynaptic neurons, making connections with the same postsynaptic neuron

44
Q

Describe Inhibitory Postsynaptic Potential

A

Inhibits the transmission of a signal

Chloride channels on postsynaptic membrane open. Negatively charged chloride ions enter and hyperpolarize the cell (bring it away from threshold)

45
Q

What happens on Day 18 of conception (neurogenesis)?

A

Day 18: (after conception) outer layer on back of embryo thickens and forms a plate

46
Q

What happens on Day 21 of conception (neurogenesis)?

A

Day 21: Edges of plate curl upward and fuse together, forming the neural tube (groove turns into the neural tube; does not replace the neural plate)

47
Q

What happens on Day 28 of conception (neurogenesis)?

A

Day 28: Neural tube completely closed; brain at top of tube, spinal cord making up the bottom

Ventricular zone (inside neural tube) lined with founder cells. Begin dividing as soon as neural tube is closed

48
Q

What happens on Days 28-42 of conception (neurogenesis)?

A

Day 28-42: cell division is symmetrical; division of each founder cell leads to two identical founder cells

49
Q

What happens on Days 42-125 of conception (neurogenesis)?

A

Day 42-125: cell division is asymmetrical; dividing founder cell produces one founder cell and a neuron or glial cell that migrates outward from ventricular zone

50
Q

True or false: neurons are always produced before glial cells

A

False

ALMOST always; one exception: radial glial cells are produced before neurons

51
Q

What are radial glial cells?

A

Fibers that extend outwards from the ventricular zone (like scaffolding) and end at the outer layer of the cortex

52
Q

What is the function of radial glial cells?

A

Neurons use these cells to migrate from ventricular zone to surface of cortex

53
Q

True or false: the brain grows from the inside out

A

True

Deepest layers are formed before the outermost layers

54
Q

What happens to the radial glial cells as you add more and more neurons? What is the consequence of this?

A

Grow as well so they always end at the outermost surface

Neurons born later have to travel much farther q

55
Q

After reaching its final destination (after migration), what happens to the neuron?

A

Takes on a specific function that is partly det by genetics and partly by environment

56
Q

How does environment influence neuronal differentiation?

A

Input from other cells influence ND

Ex. If emerging neuron connected to neuron from visual cortex, that neuron will end up doing something related to processing vision

57
Q

How do genetics influence neuronal differentiation?

A

Location in the ventricular zone where founder cell originated

58
Q

What is the final step is the development of the neural system (after differentiation)?

A

Neurons receive neurotrophic factors from other neurons in order to survive. Since ventricular zone made too many neurons, there is a limited amount of neurotrophic factors and some neurons are pruned away.

59
Q

What is the trend of the number of synapses (neural connections) after birth?

A

Many are formed at beginning; number peaks at one year of age. The number declines in subsequent years

60
Q

Why does the number of synapses decline later on in life?

A

Improve processing efficiency of brain

Retains only useful connections