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Anatomy > ✅Conduction Of The Nervous System > Flashcards

✅Conduction Of The Nervous System Flashcards

1
Q

What is a plasma membrane?

A

A watery medium that surrounds a cell

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2
Q

What does plasma membrane separate?

A

cytoplasm from the
extracellular fluid

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3
Q

What is cytoplasm?

A

All materials inside the cell and outside the nucleus

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4
Q

What is cytosol?

A

Liquid ( intracellular fluid)

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5
Q

What are organelles?

A

Intracellular structures

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6
Q

What are the four functions of the plasma membrane?

A

Physical isolation
Regulation of exchange with environment
Sensitivity to the environment
Structural support

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7
Q

How does the plasma membrane act as physical isolation?

A

Act as barrier

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8
Q

How does the plasma membrane controls regulation of exchange its the environment?

A

• Ions and nutrients enter
• Wastes eliminated and cellular products released

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9
Q

How does the plasma control sensitivity to the environment?

A

• Extracellular fluid composition
• Chemical signals

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10
Q

How does the plasma membrane act as structural support?

A

Anchors cells and tissues

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11
Q

What components of the plasma membrane all it to perform its characteristic functions?

A

membrane lipids, membrane proteins, and membrane carbohydrates.

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12
Q

How much of the plasma membranes weight is membrane lipids?

A

42%

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13
Q

What are the three sections of phospholipid bilayer in membrane lipids?

A

Hydrophilic heads
Hydrophobic fatty-acid tails
Barrier to ions and water

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14
Q

Where do you find hydrophilic heads?

A

Toward watery environment, both sides

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15
Q

Where do you find hydrophobic fatty-acid tails?

A

Inside membrane

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16
Q

Where do you find the barrier to ions and water?

A

Soluble compounds

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17
Q

How much of the plasma membranes weight is membrane proteins?

A

55%

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18
Q

Where do you find integral proteins?

A

Within the membrane

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19
Q

Where do you find peripheral proteins?

A

Bound to inner or outer surface of the membrane

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20
Q

What do anchoring proteins do? (Stabilisers)

A

Attach to inside or outside structures

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21
Q

What do recognition proteins do? (Identifiers)

A

Label cells as normal or abnormal

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22
Q

What do enzymes do?

A

Catalyse reactions

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23
Q

What do receptor proteins do?

A

Bind and respond to ligand ( ions, hormones)

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24
Q

What do carrier proteins do?

A

Transport specific salutes through membrane

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25
Q

What do channels do?

A

Regulate water flow and salutes through membrane

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26
Q

How much of the plasma membranes weight is membrane carbohydrates?

A

3%

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27
Q

Describe Proteoglycans, glycoproteins, and glycolipids

A

• Extend outside cell membrane
• Form sticky “sugar coat” (glycocalyx)

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28
Q

What are the functions of the glycocalyx?

A
  • Lubrication and Protection
    • Anchoring and Locomotion
    • Specificity in Binding (receptors)
  • Recognition (immune response)
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29
Q

What is transmembrane potential?

A

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

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30
Q

In transmembrane potential what is created when charges separate?

A

Potential difference

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31
Q

What is unequal charge across the plasma membrane?

A

Transmembrane potential

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32
Q

What is membrane potential?

A

Ion movements and electrical signals

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33
Q

How do all cell membranes produce electrical signals?

A

By ion movements

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34
Q

What is membrane potential particularly important to?

A

Neurons

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35
Q

What are the five main membrane processes in neural activities ?

A 
Resting potential 
Graded potential 
Action potential 
Synaptic activity
Information processing
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36
Q

What is resting potential?

A

The membrane potential of resting cell

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37
Q

What is graded potential?

A

Temporary, localised charge in resting potential

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38
Q

How us graded potential caused?

A

By Stimulus

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39
Q

What is action potential?

A

An electrical impulse

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40
Q

How is action potential produced?

A

By graded potential

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41
Q

What does action potential propagate along?

A

Surface of axon to synapse

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42
Q

What does synaptic activity release?

A

Neurotransmitters at presynaptic membrane

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43
Q

What does synaptic activity produce?

A

Graded potentials in postsynaptic membrane

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44
Q

What is information processing?

A

Response ( integration of stimuli) of postsynaptic cell

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45
Q

What are the two passive forces acting across the plasma membrane?

A

Chemical gradients

Electrical gradients

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46
Q

What are chemical gradients?

A

Concentration gradients (chemical gradient) of ions (Na+, K+)

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47
Q

What do electrical gradients separate?

A

Charges of positive and negative ions

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48
Q

What does electrical gradients result in?

A

Potential difference

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49
Q

What is electrical current?

A

Movement of charges to eliminate potential difference

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50
Q

What is resistance?

A

The amount of current, ion movements, a membrane restricts

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51
Q

In passive chemical gradients what do ions do as a result of potassium ions (k+) being relatively high?

A

They moves out of the cell through potassium leak channels.

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52
Q

What do sodium ions do because the extracellular concentration of sodium ions (Na+) is relatively high?

A

Move into the cell through sodium leak channels.

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53
Q

What are the movements of potassium and sodium ions driven by?

A

Concentration gradient, or chemical gradient

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54
Q

What do Sodium–potassium
++
(Na /K ) exchange
pumps maintain ?

A

the concentration of sodium and potassium ions across the plasma membrane.

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55
Q

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

A

because the plasma membrane is
much more permeable to potassium
than to sodium

56
Q

What is the result of Potassium ions leave the cytosol
more rapidly than sodium ions enter?

A

there are
more positive charges outside the plasma membrane

57
Q

Negatively + charged protein molecules within the – cytosol cannot cross the plasma
membrane what does this lead to?

A

more
negative charges on the cytosol side
of the plasma membrane

58
Q

What is the result of more
negative charges on the cytosol side
of the plasma membrane?

A

an electrical
gradient across the plasma + membrane.

59
Q

What happens when positive and negative ions are held apart?

A

A potential difference arises

60
Q

What do we measure potential difference in?

A

mV

61
Q

What is The resting membrane potential for most neurons?

A

About -70 mV

62
Q

What does the minus sign show in -70mV?

A

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

63
Q

What does Potassium permeability 100x more than?

A

Sodium permeability

64
Q

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

A

The sodium-potassium exchange pumps

65
Q

The intercellular concentration of potassium ions (K+) is relatively what?

A

High

66
Q

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

A

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

67
Q

The intracellular concentration of sodium ions (NA+) is relatively what?

A

Low

68
Q

Do sodium ions move in or out of the cell through sodium leak channels?

A

Into

69
Q

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

A

A concentration gradient (aka chemical gradient)

70
Q

Potassium leave what quicker than sodium ions enter?

A

Cytosol

71
Q

Why do potassium ions leave cytosol quicker than sodium ions enter?

A

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

72
Q

Because potassium leaves the cytosol faster than sodium ions entering what does this result in?

A

More positive charges outside the plasma membrane

73
Q

What kind of charges are there more of on the cytosol side of the plasma membrane?

A

Negative

74
Q

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

A

An electrical gradient across the plasma membrane

75
Q

What is the equilibrium potentiometer for K+

A

-90mV

76
Q

The plasma membrane is highly permeable to what kind of ions?

A

K+

77
Q

The electrochemical gradient for sodium ions is large but the membranes permeability for sodium is very what?

A

Low

78
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

79
Q

What type of channels are always open?

A

Passive channels

80
Q

In passive channels when does permeability change?

A

It changed with the conditions

81
Q

What are passive channels also known as?

A

Leak channels

82
Q

When do active channels open/close?

A

Active channels open and close in responsive to stimuli

83
Q

What are active channels also know as?

A

Gated channels

84
Q

What channels are closed at tasting potential?

A

Gated (active)

85
Q

What are the 3 states of gated channels?

A

Closed but capable of opening
Open (activated)
Closed but not capable of opening (inactive)

86
Q

Name the 3 classes of gated channels

A

Chemically gated channels
Voltage gated channels
Mechanically gated channels

87
Q

What channel is being described:

Open in presence of specific chemicals (ACh) at a binding site
Found on Neuton cell body and dendrites

A

Chemically gated channels

88
Q

What channel
Responds to changes in the membrane potential
Has activation gates and inactivation gates
Characteristics of excitable membrane
Found in neural axons, skeletal muscle, cardiac muscle

A

Voltage gated channels

89
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)

90
Q

What kind of event is action potential?

A

Electrical

91
Q

Name this:

Propagated changes in membrane potential?m, that once initiated, affect and entire excitable membrane

A

Action potential

92
Q

Electrics events are also known as what?

A

Nerve impulses

93
Q

The axolemma contains both what?

A

Voltage-gated sodium channels and voltage-gated potassium channels that are closed when the membrane is at the resting potential

94
Q

What is the axolemma?

A

The plasma membrane of an axon and

95
Q

Name the four steps in the generation of action potentials

A

1- depolarisation to threshold
2- activation of NA+ channels
3- inactivation of NA+ channels and activation of K+ channels
4- return to normal permeability

96
Q

What happens at the depolarisation to threshold?

A

The stimulus that initiates an action potential is a grades depolarisation large enough to open voltage gated sodium channels

The opening of the channels occurs at the membrane potential known as the threshold

97
Q

When the sodium channel activation gates open, the plasma membrane becomes much more permeable to what?

A

NA+ (sodium)

98
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 depolarisation occurs.
  • the inner membrane is now more positive than the outside of the membrane (+10mV)
99
Q

Name stage 2 of generating an action potential

A

Activation of sodium channels and depolarisation

100
Q

What happens at stage 3 (+30mV) of generating action potential?

A
  • NA+ channels are inactivated
  • K+ channels are activated (opened)
  • repolarisation begins
101
Q

Describe stage 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
102
Q

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

A

This produces brief hyperpolarisation

103
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

104
Q

According THE the all or none principle the action potential is either what?

A

Triggered or not

105
Q

All stimuli that bring the membrane to threshold generate what?

A

Identical action potentials

106
Q

Relate a gun to the all or none principle

A

The speed a and range of the bullet that leaves the gun do not change, regardless the forces that you applied to the trigger

107
Q

What is the refractory period?

A

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

108
Q

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

A

Additional stimuli

109
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

110
Q

What does this example refer to?

Once you flush the toilet, the amount of water that is released is independent of how hard or quickly you presses the handle

A

The all or none principle

111
Q

What does this example refer to?

Finally you cannot flush the toilet again until the tank refills

A

The refractory period

112
Q

What are the 2 parts of the refractory period?

A

Absolute refractory period

Relative refractory period

113
Q

How long does the absolute refractory period last for?

A

0.4-1msec

114
Q

Name the type of refractory period:

Sodium channels open or inactivated
No action potential possible

A

Absolute refractory period

115
Q

Name the type of refractory period:

Membrane potential almost normal
Very large stimulus can initiate action potential

A

Relative refractory period

116
Q

What is being described here?

Moves action potentials generated in axon hillock
Along entire length of axon

A

Propagation

117
Q

Name the 2 methods of propagating action potentials

A

Continuous propagation

Saltatory propagation

118
Q

Continuous propagation is the propagation of what type of axons?

A

Unmyelinated

119
Q

Saltatory propagation is the propagation of what kind of axons?

A

Myelinated

120
Q

What does continuous propagation affect?

A

It affects one segment of axon at a time

121
Q

What are the 4 steps in continuous propagation?

A

Step 1- action potential in segment 1
Step 2- depolarises second segment to threshold
Step 3- firs segment enters refractory period
Step 4- the local current from segment 2 depolarises next segment
Then the cycle repeats

122
Q

How many directions does action potential travel in in continuous propagation?

A

1

123
Q

Name the action potential along a myelinated axon

A

Saltatory propagation

124
Q

What does myelin do?

A

It insulated the axon

125
Q

What propagation does myelin prevent?

A

Continuous propagation

126
Q

How does the local current travel in saltatory propagation?

A

The local current ‘jumps’ from node to node

127
Q

In saltatory propagation where can depolarisation only occur?

A

At nodes

128
Q

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

A

The phospholipid bilayer

129
Q

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

A

Channel proteins

130
Q

Define the resting potential

A

The resting potential is the transmembrane potential of abnormal cell under homeostatic conditions

131
Q

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

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 depolarise

132
Q

Define action potential

A

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

133
Q

What is action potential often initiated by?

A

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

134
Q

What effect would decreasing the concentration of extra cellular potassium ions have on the transmembrane potential of a neutron?

A

-more potassium would leave the cell
-the electrical gradient across the membrane would increase
This condition is called hyperpolarisation

135
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 (20 decks)

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