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Life Sciences 2 Midterm 2 > Chapter 39: Neurons and the Nervous System > Flashcards

Chapter 39: Neurons and the Nervous System Flashcards

1
Q

What is the Nervous system’s purpose? (1)

A

Communication

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2
Q

What does the nervous system do?

A

-Receive, process, send information
- Output is evident in muscle activity
• Use of unique, excitable cells (ability to receive, process, and send electrical activities)

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3
Q

Neuron characteristics

A
  • Differ in shape and function
  • Communicate with other neurons
  • Ability to convert electrical signals to chemical signals
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4
Q

What are glial cells’ functions?

A
  • Guide growth for neurons.

- Glial cell functions Wrap around neurons and form an to prevent interference from other electrical signals.

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5
Q

What is the Soma?

A
  • Part of the neuron that contains the nucleus

- Abundant in protein synthesis organelles

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6
Q

What are dendrites?

A

-part of the neuron that extends out and serves as a receptive site for electrical activites

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7
Q

What are the axon and axon hillock?

A
  • Axon hillock is where major electrical activities are produced
  • Initial branching is called axon hillock
  • Electrical signals travel away and towards the axon terminal which helps with the transport
  • Generate and conduct many electrical activites
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8
Q

What are neurons?

A

Cell body or perikaryon

-Nerve fibers

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9
Q

What does the axon terminal do?

A
  • Axon collateral terminate in many axon terminals

- Contain neurotransmitters filled vesicles

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10
Q

What do the myelin sheaths do?

A
  • Insulate the axon
  • Covers the axon nodes(and thickens the neuron membrane) in order to speed up activities
  • Nodes of Ranvier are gaps in myelin
  • Comes from glial cells
  • Saltatory conductance: jumping from one neuron to the other
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11
Q

What are the Nodes of Ranvier?

A

Nodes of Ranvier are gaps in myelin

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12
Q

Neuron structure

A

Soma, Axon hillock, dendrites, axon, myelin, and axon terminals

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13
Q

Central Nervous system (CNS)

A
  • Afferent Neurons send information to the CNS
  • Interneurons connect neurons within the CNS
  • Efferent neurons send information from the CNS
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14
Q

How are neurons classified?

A
  • Function (sensory, interneurons, motor neurons)

- Structure (Multipolar, bipolar, and unipolar)

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15
Q

Multipolar neurons

A

Have many dendrites and one axon

  • Motor neurons and inerneurons
  • Found in the brain and spinal chord
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16
Q

Bipolar neurons

A
  • Have two extensions only (one is analogous to the dentrite [receive] and the other to the axon [send])
  • Function on sensory neurons
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17
Q

Unipolar neurons

A
  • Have a short single process and splits into two branches

- Function as sensory neurons

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18
Q

What is the synapse?

A

-junction between two neurons
-How neurons communicate
-Synaptic cleft: space in between neurons where they communicate
-PreSynaptic neuron: sending signal
○ Divergent: One neuron sending the signal to many
○ Convergent: Many neurons sending the signal to ONE neuron
-Post synaptic neuron: receiving signal

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19
Q

Define neuron diffusion

A

-Movement of substances from high concentration to low concentration
○ If there is more concentration outside the cell than outside the cell
Will not move high to low since the membrane would have to be permeable to it
(membrane will be permeable or impermeable)

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20
Q

Explain action potential

A

-Action potential = electrical activity
-Y AXIS: VOLTAGE
-X AXIS: TIME
-ACTION POTENTIAL IS A CHANGE IN VOLTAGE OVER A CHANGE IN TIME
○ Start slowly, then takes up very quickly
○ Different properties in the plot
§ Different events occurring in every spot
• -70: resting potential
• -55: threshold (critical point)
• +30 Highest point: Peak potential

Look at graph

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21
Q

What is included in the anatomy of the neuron?

A

-Dendrites and cell body
>Gradient potential: change in electrical activity in the membrane potential
-Axon Hillock and the axon
>Action potential leads to neurotransmitter release

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22
Q

Diffusion in relation to the neuron

A

3 Potassium out
2 Sodium in

Creates a gradient

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23
Q

What is ECP?

A

Electrocellularfluid

○ High sodium concentration

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24
Q

What is ICP?

A

Intercellularfluid

○ High Potassium and anions concentration

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25
Q

Why don’t the membrane potential charges mis?

A

Membrane serves as a charge separator and keeps them apart

26
Q

How are charges able to move across the membrane?

A

Charges can only move through the protein channels
• Gated channels: sometimes lock, sometimes unlocked
• Ungated channels: leak channels
○ Always open

27
Q

When are sodium and potassium slightly more permeable through the membrane?

A

At rest

28
Q

How do proteins facilitate the concentration of ions across the neuronal membrane?

A

Proteins serve as channels that permeate ion transport

29
Q

Resting potential

A

-70mV

30
Q

Threshold

A

-55mV
Voltage needed to open the voltage gated channels
Caused by stimulating event.

31
Q

Peak potential

A

30mV

32
Q

What happens when the the neuron is at rest?

A
  • When neuron is at rest, ions are still moving at a very low amount
    ○ Leak channels (passive transport) (always open, not gated): sodium can still move through
    -There is more sodium outside than inside
    -Sodium will be leaking to the inside -More potassium inside the cell
    -Sodium will be leaking outside the cell

Whatever was leaked will be returned by the pump

33
Q

Why is it unfavorable for neurons to reach an equilibrium through diffusion?

A

They will lose excitability

34
Q

What maintains the gradient?

A

the Na+/K+ PUMP

35
Q

What is depolarization?

A

Any time the neuron shifts it voltage to a higher value (than -70mv)
Increases in positive

36
Q

What is hyperpolization

A

Any time the neuron shifts its voltage to a higher value than -70mv

37
Q

What is repolarization?

A

Returning to the “normal” voltage

38
Q

What has to be done so that the action potential can release neurotransmitters?

A

Action potential must travel down to the post synaptic synapse to release neurotransmitters

39
Q

What is a voltage gated sodium channel?

A

-Specific for sodium
-Not always open (closed at resting potential)
-Voltage triggers open, more permeable
-Once they reach +30mv, they don’t close yet
○ Go into the inactivation state
>Meaning that the channel is not permeable, blocked, but the gate is still open
□ Sodium cannot come in during this stage

40
Q

What is a voltage gated potassium channel?

A
  • Less sophisticated

- Two states: open and closed

41
Q

VGSC

A
  • Resting potential: closed but capable of opening
  • From threshold to peak: open (activity)
  • From peak to resting: closed and not capable of opening (inactivated)
42
Q

VGPC

A
  • Resting potential: Closed
  • Delayed opening triggered at threshold
  • Remains closed to peak potential

Open from peak potential through after hyperpolarization

43
Q

Steps of the action potential

A

-REST: VGSC AND VGPC are closed
-THRESHOLD: VGSC triggered to open and VGPC are still closed
>Sodium ions flow and cause membrane to be depolarized
-Eventually we reach the peak potential (+30) and are VGSC inactivated and VGPC opens
>Potassium starts to come out, loses positive (Repolarization)
-Membrane hyperpolarizes and refactory period occurs
-VGKC closes.
-REST: VGSC and VGPC are closed

44
Q

When does propagation of the action potential occur?

A

Between the presynaptic neuron and the postsynaptic neuron,
-After action potential occurs, depolarization spreads to other parts of the axon which triggers VGSC to open and more action potentials to occur

45
Q

Peripheral nervous system (PNS)

A

Made up of nerves that are located throughout the body, except in the brain and spinal cord

46
Q

What is tetrodotoxin (TTX)?

A

Drug that prevents the generation of action potentials by inhibiting voltage-gated Na+ channels of sensory neurons.

47
Q

What is Novacaine?

A

Drug that blocks sodium channels

48
Q

What kind of cells make myelin in PNS?

A

PNS myelin is produced by Schwann cells (type of glial cell).

49
Q

What kind of cells make myelin in CNS?

A

CNS myelin is produced by special cells called oligodendrocytes (type of glial cell).

50
Q

Where are VGSC and VGPS clustered?

A

Nodes of Ranvier

51
Q

What is saltatory conductase?

A

Shows how the action potential developes, the jumping from one Nodes of Ranvier to another.

52
Q

what happens at the axon terminals?

A
  • Vessicles that contain neurotransmitters in the axon terminal
  • Upon the arrival of the action potential, VGCC will be activated,
  • once calcium enters the neurons, calcium binds to proteins on the vessicle and causes them to move to the membrane and releases contents (exocytosis)
  • The neurotransmitter will bind to ligand gated channel and trigger the formation of a gradient that will lead to action potential in the post synaptic neuron
53
Q

What does the arrival of the axon to the action potential do?

A

The arrival of the axon to the action potential triggers the release of the neurotransmitter

54
Q

What kind of signal does the presynaptic neuron have?

A

Electrical signal

55
Q

What kind of signal does the synaptic cleft have?

A

Chemical signal

56
Q

What kind of signal does the post synaptic neuron have?

A

Electrical signal

57
Q

Excitatory potential

A

Causing depolarization. Depends on the neurotransmitter that is being released. Leads to hyperpolarization in postsynaptic potential

58
Q

Inhibitory postsynaptic potential

A

Has hyperpolarization. Depends on the neurotransmitter that is being released.

59
Q

What is summation?

A

Summing up excitatory or inhibitory potentials in order to have an action potential

60
Q

Leak channels differ from voltage-gated channels in that?

A
  • Leak channels are open when the membrane is at resting potential
  • Voltage-gated channels are inactivated when the membrane is at resting potential

Life Sciences 2 Midterm 2 (6 decks)

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