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PSYC 211 > Chapter 2: COMMUNICATION WITHIN A NEURON > Flashcards

Chapter 2: COMMUNICATION WITHIN A NEURON Flashcards

1
Q

How do neurons conduct signals?

A

-With electrical signals sweeping across axons

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2
Q

What happens when someone touches a hot stove?

A
  1. Dendrites of sensory neurons detect painful stimuli
  2. The interneuron excites a motor neuron causing muscular contraction
  3. The muscle contraction causes withdrawal from source of pain
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3
Q

What happens when someone is holding a warm, but not too hot cup of tea?

A
  1. Dendrites of sensory neuron detect temperature stimuli
  2. An interneuron excites a motor neuron
  3. Another interneuron inhibits the motor neuron preventing muscular contraction
  4. The person doesn’t drop the cup
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4
Q

What is a membrane potential?

A

Any difference in electrical charge (positive or negative) between the inside and the outside of a membrane.
Potential=stored up source of energy

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5
Q

What is the membrane’s resting potential?

A

When the neuron is at rest and not involved with communicating with any other neurons, the membrane’s resting potential is -60 to -70 mV.

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6
Q

Astrocytes resting potential?

A

-80 to -90 mV

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7
Q

Skeletal muscle resting potential?

A

-95 mV

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8
Q

Smooth muscle resting potential?

A

-60 mV

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9
Q

What are the three ways you can measure electrical potential of axons?

A
  • electrode: apply electrical stimulation or record electrical potentials
  • microelectrode: record activity of individual neurons
  • membrane potential: electrical charge across cell membrane
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10
Q

What are the 3 key players for maintaining resting potential?

A
  • neuronal membrane
  • fluid
  • ion channels (protein) in the neuronal membrane
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11
Q

What are the functions of the neuronal membrane?

A
  • enclose cytoplasm and cytosol
  • establish the electrical potential of the cell
  • control the flow of ions into and out of the cell
  • conduction of nerve impulse
  • sense neurotransmitters
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12
Q

cytosol vs cytoplasm?

A
  • cytosol is the fluid present inside the cell membrane

- cytoplasm is a cell component present outside the cell membrane

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13
Q

What are cytosol and extracellular fluid composed of ?

A

-Water and electrically charged ions (cations +, anions -)

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14
Q

What are the properties of the water that composes the cytosol and extracellular fluid?

A
  • Key ingredient: polar molecule that make water an effective solvent for charged or polar molecules
  • spheres of hydration: clouds formed around ions because they attract water molecules, which insulates the ions from one another
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15
Q

What are the properties of the neuronal membrane, knowing that it is a “sheet” of phospholipids?

A
  • hydrophobic: does not dissolve in water due to even electrical charge, because lipid are hydrophobic
  • also hydrophilic (neuronal membrane is semipermeable because permeable to certain ions and also depending on if it is depolarized or not)
  • Lipids contribute to resting and action potential
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16
Q

What are ion channels composed of ?

A
  • Channel proteins: pore formed by 4 to 6 membrane-spanning proteins. Each structure is called a subunits.
  • Each subunit: has hydrophilic and hydrophobic regions, determines properties of ion channels
17
Q

On what factors can ion channels be selective?

A
  • charge
  • size (diameter of the pore)
  • gating: channels can open or close based upon local microenvironments.
18
Q

What are ion pumps and what do they do?

A
  • ion pumps are also situated on the axon, and are active.

- They use ATP (adenosine triphosphate) to pump ions in and out of the cell.

19
Q

What does the force of diffusion do?

A
  • distribute the molecules evenly throughout the medium in which they are dissolved.
  • molecules ultimately attain balance
20
Q

What does the force of electrostatic pressure do?

A

-Pulls ions of opposite charges together and pushes ions with the same charges apart.

21
Q

What are the 2 factors electrostatic force is determined by?

A

-electrical potential (voltage): force exerted on charged particle, difference in charge between anode and cathode
-electrical conductance (g):
R is electrical conductance, R= 1/g, relative inability of an electrical charge to migrate

22
Q

What is the movement of electrically charged ion determined by?

A
  • concentration gradient

- difference in electrical potential across the membrane

23
Q

What is osmosis?

A

The diffusion of water from a hypotonic solution to a hypertonic solution across a semipermeable membrane.

24
Q

What is osmotic balance?

A

It ensures optimal concentration of ions in intracellular and extracellular fluids.
Balance reached when electrical force pulling an ion in/out is equal to diffusion force pushing an ion in/out

25
Q

What would the RMP equal to if it depended only on K+ or Na+?

A
  • K+= -80mV

- Na+= 62 mV

26
Q

Why is an ion not easily maintained at its equilibrium potential?

A
  • Membranes are leaky
  • K+ always leaking out and Na+ always leaking in
  • This interferes with concentration gradient required to maintain RMP
27
Q

What is the solution to the leaky membrane?

A

The sodium-potassium pump

28
Q

What does the sodium-potassium pump do ?

A
  • It is made of sodium-potassium transporters that exchanges 3 Na+ (push them out) for 2 K+ (take them in)
  • So it keeps the concentration of Na+ low in side the membrane by increasing the concentration of K+ by a little bit
29
Q

How is the membrane with regards to potassium (K+)?

A

Very permeable to K+ (very leaky to K+)

Small change in extracellular= big change in intracellular

30
Q

What is depolarization?

A

A change in membrane potential from a resting value to a less negative value

31
Q

What are the two mechanisms that regulate the external concentration of potassium?

A
  • blood-brain barrier

- Potassium spatial buffering by astrocytes

32
Q

How does the blood-brain barrier regulate external concentration of potassium?

A

-astrocytes take up K+ when extracellular levels are high (K+ pumps)

PSYC 211 (45 decks)

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