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anatomy > Conduction in the Nervous System > Flashcards

Conduction in the Nervous System Flashcards

1
Q

Name the watery medium that surrounds a cell.

A

Plasma Membrane

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2
Q

The _____ _____ separates the cytoplasm from the extracellular fluid.

A

plasma membrane

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3
Q

______: all materials inside the cell and outside the nucleus.

A

cytoplasm

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4
Q

Intracellular fluid (making up the cytoplasm) is known as ________.

A

cytosol

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5
Q

Intracellular structures are collectively known as ___________.

A

organelles

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6
Q

What is the cytoskeleton made of?

A

Proteins organised in fine filaments or slender tubes.

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7
Q

What are the functions of the cytoskeleton?

A

To provide strength and support

Movement of cellular structures and materials

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8
Q

The plasma membrane consists of a _____ bilayer, steroids, _______ and __________.

A

phospholipid, proteins, carbohydrates

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9
Q

Name the 4 functions of the plasma membrane.

A

Physical Isolation
Regulation of Exchange with the Environment
Sensitivity to the Environment
Structural Support

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10
Q

One of the plasma membrane’s roles is physical isolation, what does it act as?

A

Acts as a barrier

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11
Q

The plasma membrane allows ____ and _____ to enter.

A

ions, nutrients

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12
Q

What does the plasma membrane allow to be eliminated and released by the cell?

A

Waste is eliminated and cellular products are released

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13
Q

The plasma membrane can respond to _____ signals.

A

chemical

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14
Q

How does the plasma membrane structurally support the cell?

A

It anchors cells and tissues

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15
Q

Name the components of the plasma membrane that allow it to perform its characteristic functions.

A

Lipids, Proteins and Carbohydrates :)

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16
Q

How are membrane lipids arranged?

A

In a phospholipid bilayer.

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17
Q

The lipid heads are ______.

A

hydrophilic

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18
Q

The plasma membranes contain hydrophilic heads, define what is meant by hydrophilic.

A

They like water- so will face a watery environment.

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19
Q

The lipid tails are _____.

A

hydrophobic

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20
Q

Where are hydrophobic tails found?

A

INSIDE the plasma membrane

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21
Q

What can the phospholipid bilayer act as?

A

It acts as a barrier :)

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22
Q

Name the 2 types of membrane proteins.

A

Integral and Peripheral

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23
Q

Where are integral proteins found?

A

WITHIN the membrane

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24
Q

Where are peripheral proteins found?

A

Bound to the inner or outer surface of the membrane

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25
Q

Anchoring Proteins, Recognition Proteins, Enzymes, Receptor Proteins, Carrier Proteins and Channels are all examples of _____ proteins found in the ______ _______.

A

functional, plasma membrane

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26
Q

What functional proteins attach to inside or outside structures?

A

Anchoring Proteins

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27
Q

What type of protein can label cells as normal or abnormal?

A

Recognition Proteins

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28
Q

What do enzymes do?

A

Catalyse reactions

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29
Q

Receptor proteins bind and respond to ______.

A

ligands

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30
Q

Give 2 examples of ligands.

A

ions and hormones

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31
Q

_____ proteins transport specific solutes through the membrane and _____ regulate water flow and solutes through the membrane.

A

carrier

channels

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32
Q

Membrane _____ make up 3% of the plasma membrane’s weight.

A

carbohydrates

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33
Q

Proteoglycans, glycoproteins and glycolipids are all examples of what?

A

Membrane Carbohydrates

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34
Q

Proteoglycans, glycoproteins and glycolipids extend _______ the cell membrane. What do they form?

A

outside

They form a sticky sugar coat called glycocalyx.

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35
Q

Name the sticky sugar coat extending from the cell membrane, made from membrane carbohydrates.

A

Glycocalyx

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36
Q

What are the functions of Glycocalyx?

A
  • Lubrication and Protection
  • Anchoring and Locomotion
  • Specificity in binding (receptors)
  • Recognition (immune response)
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37
Q

Define Transmembrane Potential.

A

The electrical potential of the cell’s interior relative to its surroundings.

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38
Q

Name this:

The electrical potential of the cell’s interior relative to its surroundings

A

Transmembrane Potential

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39
Q

Charges in a cell are separated, what does this create?

A

This creates a potential difference.

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40
Q

Unequal Charge across the membrane is ________ __________.

A

Transmembrane potential.

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41
Q

What does membrane potential involve?

A

Ion Movement (this sends Electrical Signals.)

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42
Q

All plasma membranes produce _____ _____by _____ _______.

A

Electrical signals, ion movement.

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43
Q

What is membrane potential particularly important to?

A

Neurons.

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44
Q

Name the 5 Main Membrane Processes in Neural Activities.

A 
1-Resting Potential
2-Graded Potential
3-Action Potential
4-Synaptic Activity
5-Information Processing
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45
Q

What is Resting Potential?

A

The membrane potential of a resting cell.

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46
Q

What is Graded Potential

A

Graded Potential is a temporary, localised change in the resting potential caused by a stimulus.

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47
Q

Define Action Potential.

A

Action Potential is an electrical impulse produced by graded potential.

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48
Q

In Action Potential, what happens?

A

An electrical impulse propagates along the surface of the axon to the synapse.

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49
Q

What 2 things does synaptic activity do?

A
  • It releases neurotransmitters at presynaptic membrane

- It produces graded potentials at postsynaptic membrane

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50
Q

What is the final stage of Neural Activities?

A

Information Processing

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51
Q

What happens at the final information processing stage of neural activities?

A

Response (integration of stimuli) of postsynaptic cell.

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52
Q

Chemical gradients and Electrical gradients are _____ forces acting across the membrane.

A

Passive

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53
Q

What is meant by “Chemical Gradients”?

A

The concentration gradients of ions eg. sodium (Na) and potassium (K).

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54
Q

Electrical Gradients _____ charges of _____ and ______ ions which result in a _______ ________.

A

Separate, positive, negative, potential difference.

55
Q

What is the movement of charges in order to eliminate a potential difference known as?

A

Electrical Current

56
Q

The amount of current, ion movements, a membrane restricts is called _______.

A

Resistance

57
Q

What maintains the concentration of sodium and potassium ions across the plasma membrane?

A

The Sodium-Potassium Exchange Pumps

58
Q

The intracellular concentration of potassium ions (K+) is relatively _______.

A

High

59
Q

In what direction do potassium ions (K+) tend to move?

A

They tend to move out of the cell (through potassium leak channels).

60
Q

The intracellular concentration of sodium ions (Na+) is relatively _______.

A

Low.

61
Q

Sodium ions move _____ the cell through sodium leak channels.

A

into

62
Q

What is sodium moving into the cell and potassium moving out of the cell driven by?

A

A concentration gradient (aka. A Chemical Gradient.)

63
Q

Potassium ions leave the ______ more rapidly than sodium ions enter.

A

Cytosol.

64
Q

Why do potassium ions leave the cytosol more rapidly than sodium ions enter?

A

The plasma membrane is much more permeable to potassium than to sodium.

65
Q

Because Potassium leaves the cytosol faster than Sodium ions entering, what does this result in?

A

More positive charges outside the plasma membrane.

66
Q

There are more ________ charges on the cytosol side of the plasma membrane

A

negative

67
Q

With the outside of the plasma membrane being more positive and the inside of the plasma membrane being more negative, what does result in?

A

An electrical gradient across the plasma membrane.

68
Q

What is the resting membrane potential for most neurons?

A

-70mV

69
Q

The inner surface of the plasma membrane is _______ charged with respect to the exterior.

A

negatively

70
Q

-90mV is the equilibrium potential for _____.

A

K+

71
Q

The plasma membrane is highly permeable to ________ions.

A

potassium

72
Q

The electrochemical gradient for sodium ions is very _______ but the membrane’s permeability for sodium is very _______.

A

large, low.

73
Q

Name the ratio of sodium that goes out and potassium that goes into the cell by the action the sodium-potassium pump.

A

3:2

74
Q

What type of channels are always open?

A

Passive Channels.

75
Q

In passive channels, when does permeability change?

A

It changes with the conditions.

76
Q

What are passive channels also known as?

A

Leak Channels

77
Q

When do active channels open/close?

A

Active channels open and close in response to stimuli.

78
Q

At resting potential most ____ channels are closed.

A

Gated (active)

79
Q

What are active channels also called?

A

Gated channels

80
Q

What are the 3 states of gated channels?

A
  • Closed but capable of opening
  • Open (activated)
  • Closed, not capable of opening (inactivated)
81
Q

Name the 3 classes of gated channels.

A
  • Chemically Gated channels
  • Voltage-Gated channels
  • Mechanically Gated channels
82
Q

Name the channel:
• Open in presence of specific chemicals (e.g., ACh) at a binding site
• Found on neuron cell body and dendrites

A

Chemically Gated channels

83
Q

Name the channel:
• Respond to changes in membrane potential
• Have activation gates (open) and inactivation gates (close)
• Characteristic of excitable membrane
• Found in neural axons, skeletal muscle , cardiac muscle

A

Voltage Gated Channels

84
Q

What do Mechanically Gated Channels respond to and where are they found?

A

They respond to membrane distortion

Found in Sensory Receptors (touch,pressure, vibration)

85
Q

An action potential is an ______ event.

A

electrical

86
Q

Name this:

Propagated changes in membrane potential, that once initiated, affect an entire excitable membrane.

A

Action Potential

87
Q

Electrical events are also known as _____ _______.

A

Nerve Impulses.

88
Q

The ______ contains both voltage-gated sodium channels and voltage-gated potassium channels that are closed when the membrane is at the resting potential.

A

axolemma

89
Q

What is the axolemma?

A

The plasma membrane of an axon.

90
Q

Name the 4 steps in the Generation of Action Potentials.

A

Step 1: Depolarization to threshold
Step 2: Activation of Na+ channels
Step 3: Inactivation of Na+ channels and activation of K+ channels
Step 4: Return to normal permeability

91
Q

What happens at the depolarization to threshold?

A
  • The stimulus that initiates an action potential is a graded depolarization large enough to open voltage gated sodium channels
  • The opening of the channels occurs at the membrane potential known as the threshold.
92
Q

When the sodium channel activation gates open, the plasma membrane becomes much more permeable to _______.

A

Na+ (sodium)

93
Q

During stage 2 of generating Action Potential, what happens.

A
  • Driven by the large electrochemical gradient, sodium ions rush into the cytoplasm, and rapid depolarization occurs.
  • The inner membrane is now more positive than the outside of the membrane (+10mV)
94
Q

Name stage 2 of generating an action potential.

A

Activation of Sodium Channels and Rapid Depolarization

95
Q

What happens at Stage 3 (+30mV) of generating an Action Potential?

A
  • Na+ channels are inactivated
  • K+ channels are activated (are opened)
  • Repolarization begins.
96
Q

Describe step 4- Return to Permeability.

A
  • K+ channels begin to close when the membrane reaches normal resting potential (-70mV)
  • K+ channels finish closing, membrane is hyperpolarised to -90mV.
  • Membrane potential returns to resting level
  • Action potential is over.
97
Q

Until all the potassium channels have closed, potassium ions continue to leave the cell, what does this produce?

A

This produces a brief hyperpolarization.

98
Q

Explain the “All or None Principle”.

A

If a stimulus exceeds threshold amount, the action potential is the same, no matter how large the stimulus.

99
Q

Action potential is either _____ or not according to the ____ __ _______ principle.

A

Triggered, All or None principle.

100
Q

All _____ that bring the membrane to _____, generate ____ action ______.

A

Stimuli, threshold, identical, potentials.

101
Q

“The speed and range of the bullet that leaves the gun do not change, regardless the force that you applied to the trigger.”

What principle does this refer to?

A

The All or None principle.

102
Q

What is the refractory period?

A

The time period from beginning of an action potential to return to resting state.

103
Q

During the refractory period, what will the membrane not respond to?

A

Additional Stimuli.

104
Q

Why will the membrane not respond to additional stimuli during the refractory period?

A

Because all the gated voltage sodium channels either are already open or inactivated.

105
Q

What does this example refer to?- think Action Potential

Flushing a toilet, nothing happens while you press the handle, until the water starts to flow.

A

Threshold is reached.

106
Q

What does this example refer to?- think Action Potential
Once you flush the toilet, the amount of water that is released is independent of how hard or quickly you pressed the handle.

A

The All or None Principle

107
Q

What does this example refer to?- think Action Potential

Finally, you cannot flush the toilet again until the tank refills.

A

The Refractory Period.

108
Q

What are the 2 parts of the refractory period?

A

Absolute Refractory Period

Relative refractory period

109
Q

How long does the absolute refractory period last for?

A

0.4-1 msec

110
Q

Name the type of refractory period:

  • Sodium channels open or inactivated
  • no action potential possible
A

Absolute Refractory Period

111
Q

Name the type of refractory period:

  • membrane potential almost normal
  • very large stimulus can initiate action potential
A

Relative Refractory Period

112
Q

What is being described here?
• Moves action potentials generated in axon hillock
• Along entire length of axon

A

Propagation

113
Q

Name the 2 methods of propagating action potentials.

A
  • Continuous Propagation

- Saltatory Propagation

114
Q

Continuous propagation is the propagation of _______ axons.

A

unmyelinated

115
Q

Saltatory propagation is the propagation of _____ axons.

A

myelinated

116
Q

What does continuous propagation affect?

A

It affects one segment of axon at a time.

117
Q

The steps in continuous propagation are as follows:
Step 1- _____ _____ in segment 1
Step 2- _______ second segment to _______.
Step 3- First segment enters ______ period
Step 4- The _____ ______ from segment 2 depolarizes next segment.
This cycle then _____.

A 
action potential
Depolarizes, threshold 
refractory
local current
repeats
118
Q

In continuous propagation, action potential travels in _______ direction/s (1m/sec).

A

one

119
Q

Name the action potential along a myelinated axon.

A

Saltatory Propagation

120
Q

Saltatory propagation is ______ and uses less ______ than continuous propagation..

A

faster, less

121
Q

What does myelin do?

A

It insulates the axon.

122
Q

What propagation does myelin prevent?

A

It prevents continuous propagation.

123
Q

How does the local current travel in saltatory propagation?

A

The local current “jumps” from node to node.

124
Q

In saltatory propagation where can depolarization only occur?

A

It can only occur at nodes.

125
Q

Which component of the plasma membrane is primarily responsible for the membrane’s ability to form a physical barrier between the cell’s internal and external environments?

A

The phospholipid bilayer

126
Q

Which type of integral protein allows water and small ions to pass through the plasma membrane?

A

Channel Proteins

127
Q

Define the resting potential.

A

The resting potential is the transmembrane potential of a normal cell under homeostatic conditions.

128
Q

What effect would a chemical that blocks the voltage gated sodium channels in neuron plasma membranes have on a neuron’s ability to depolarize?

A

The voltage-gated sodium channels couldn’t open so the sodium ions could not flood into the cell, and it would not be able to depolarize.

129
Q

Define action potential.

A

An action potential is a propagated change in the transmembrane potential of excitable cells.

130
Q

What is action potential often initiated by?

A

It is initiated by a change in the membrane permeability to sodium ions.

131
Q

What effect would decreasing the concentration of extracellular potassium ions have on the transmembrane potential of a neuron?

A
  • More potassium would leave the cell
  • The electrical gradient across the membrane (the transmembrane potential) would increase.
  • This condition is called hyperpolarization.
132
Q

The four steps involved in the generation of action potentials are:

(1) _________ to threshold;
(2) activation of ______ channels and rapid depolarization;
(3) _________ of sodium channels and activation of _______ channels;
(4) return to normal _______.

A

Depolarization
Sodium, Depolarization
Inactivation, potassium
permeability

133
Q

What does the transmission speed of the action potential depend on?

A

The diameter of the axon and if it’s myelinated or not.

anatomy (31 decks)

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