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WEEK 3 Flashcards

1
Q

The nervous system can be broken down into the ____ system and the ____ system

A

Central nervous system
Peripheral nervous system

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2
Q

The central nervous system includes which organs? The Peripheral nervous system includes?

A

CNS: Brain and spinal cord
PNS: Cranial nervous 1-10, spinal nerves, the Ears, eyes, sensory organs of smell, sensory organs of taste, and sensory receptors located throughout the skin, joints, muscles, and viscera

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3
Q

Peripheral nerves are regenerative, while CNS cells are considered ____

A

post mitotic

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4
Q

Fill in:
1. There are two types of cells in the nervous system ___ and ___ .

  1. ____ are excitable cells while ____ are not
A
  1. Neurons ; Glia
  2. Neurons; Glia
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5
Q

Name the types of Glia found in the CNS

A

Ependymal cells
Oligodendrocytes
Astrocytes
Microglia

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6
Q

Names the types of glia found in the PNS

A

Satellite Cells
Schwann Cells

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7
Q

Describe Microglia

A
  • CNS glia cell
  • is an immunocompetent phagocytic cell. helps by fighting off foreign objects/material, debris
  • overactive presence of microglia can lead to disease
  • arise from macrophages outside the cell
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8
Q

True or false.
Astrocytes are the most abundant glial cell

A

True

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9
Q

Describe Astrocytes

A
  • a CNS glia cell
  • the most abundant glia cell
  • restricted to the Brain and spinal cord
  • important in forming Blood brain barrier
  • can adopt different shapes
  • regulate neurotransmitter levels
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10
Q

describe oligodendrocytes

A
  • a CNS glia cell
  • produce myelin in CNS
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11
Q

describe Schwann cells

A
  • a PNS glia cell
  • myelinated peripheral axons
  • involved in repairing damaged peripheral nerve fibers
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12
Q

Ependymal cells

A
  • a CNS glia cell
  • form a continuous epithelial sheet that lines the ventricles and central canal of the brain and spinal cord
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13
Q

Excitable cells include

A

Neurons
Muscle cells
Pancreatic beta cells(endocrine cells)

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14
Q

True or false. Sensory neurons detect physical stimuli and relay that information to the CNS while motor neurons carry information from the CNS to specific muscles and organs

A

True

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15
Q

Fill in.
Sensory neurons are a type of _____ neuron

A

pseudounipolar neuron

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16
Q

Fill in.
Motor neurons are a type of _____ neuron

A

multipolar neuron

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17
Q

Describe interneurons

A
  • Connect sensory and motor neurons
  • are neither a sensory or motor neuron
  • housed entirely within the CNS
  • is a type of multipolar neuron
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18
Q

Fill in.
___ houses the metabolic machinery of the cell. it is also a site of integration of incoming signals

A

Cell body/Soma

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19
Q

Describe dendrites

A
  • delicate
  • branched processes that extend off the soma
  • locus of synaptic input to the neuron
  • another site of signal integration
  • brings information to soma via graded potentials
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20
Q

Signal integration occurs in which two places on a neuron

A
  1. Soma
  2. dendrite
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21
Q

describe axons

A
  • a long process that extends from the soma.
  • conducts action potentials away from the soma and toward the presynaptic terminal
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22
Q

describe presynaptic terminals

A
  • where synaptic transmission between a neuron and its target cell occurs
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23
Q

Where are action potentials generated?

A

The Axon hillock

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24
Q

a neuron that has a single process and extends away from the cell body is a _____

A

unipolar neuron

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25
Q

How do dendrites conduct graded potentials

A
  • through ligand gated ion channels and GPCR
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26
Q

what are axon collaterals?

A

Axon branches. Usually found in pseudounipolar neurons

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27
Q

describe bipolar neurons, and multipolar neurons

A

bipolar:
- have two processes that extend from the cell body
- a single dendrite
- a single axon

multipolar:
- have multiple dendritic processes that extend from their cell body
- a single axon
- usually found in muscles

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28
Q

describe psuedounipolar neurons

A
  • common in somatic sensory system
  • have a single process that extends from the cell body. this splits into a dendrite that goes to the periphery (skin) and an axon that goes to the CNS
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29
Q

what is the order of information flow in a neuron?

A
  1. Signal reception
  2. Signal integration
  3. Signal conduction
  4. Signal transmission
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30
Q

what initiates the action potential in a neuron

A
  • a change in membrane potential
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31
Q

What does a synapse refer to?

A

the junction between a presynaptic neuron and postsynaptic target

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32
Q

where does signal conduction occur?

A

On the axon as the action potential is conducted to the axon terminal

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33
Q

What causes a membrane potential?

A
  1. the concentration of different ions in the intracellular and extracellular fluid compartments
  2. the plasma membrane’s permeability to different ions
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34
Q

what is needed to generate and maintain a membrane potential?

A
  1. electrical gradient (charge difference)
  2. chemical gradient (concentration different)
  3. Leak channels essential
  4. Na-k ATPase pump
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35
Q

How does Na-K ATPase contribute to to the membrane potential

A
  • Actively transports Na+ out of the cell and K+ into the cell
  • Helps maintain the ionic gradients
  • Counters effects of the leak channels
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36
Q

the membrane potential of a cell is always measured with respect to what?

A
  • A reference electrode
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37
Q

Increasing the number of negative charges inside the cell, would cause the membrane potential to become _____

A

Hyperpolarized

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38
Q

Increasing the number of positive charges (or decreasing the amount of negative charges) inside the cell would cause the membrane potential to ____

A

depolarize

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39
Q

Fill in. To maintain the concentration gradients needed for resting membrane potential _____ and _____ are essential

A
  • leak channels
  • Na-K ATPase
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40
Q

the relative permeability of ion is calculated relative to ____

A

the permeability for potassium (K+)

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41
Q

Fill in
Pk=
Pna=
Pcl=

A

Pk= 1
Pna= 0.04
Pcl= 0.45

Leak channels are more permeable to K+ and least permeable to Na+

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42
Q

what is the ratio of K+ leak channels to Na+ leak channels

A

4 :1

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43
Q

[Na+ ] is ____ outside and _____ inside the cell.

[K+] is ______ outside and ____ inside the cell.

A
44
Q

What is the Nernst Equilibrium equation

A

R= gas constant
T= temp in kelvin
F= Faradays constant
z= valence of the ion

45
Q

What does the Nernst equation depend on? What does it not depend on?

A

the concentration gradient and valence of the ion

does not depend no the channel properties or permeability of the ion

46
Q

The Nernst equilibrium equation assumes ______

A

permeability

47
Q

When the concentration gradient is balanced by the electrical gradient_____

A

there is no net flux of ions across the membrane

48
Q

True or false.
The Nernst equilibrium potential can be calculated for every ion that has an ion channel through the plasma membrane.

A

True.

49
Q

Fill in.
The Nernst equilibrium defines _____ across a membrane that will _______ a particular concentration gradient of an ion

A

the voltage (electrical potential) ; balance

50
Q

True or false
A lot of ions have to move to set up the potential; concentration gradients are
significantly disturbed in achieving an equilibrium

A

False.
few ions have to move to set up the potential. the concentration gradients are not significantly disturbed

51
Q

What will happen if a membrane is permeable to only one type of ion?

A

the resting membrane potential will move the equilibrium potential of that ion.

52
Q

The resting membrane potential is largely determined by ___

A

K+
*there are minor contributions from Na+ and Cl-

53
Q

permeability of an ion is proportional to what? If there are no open ion channels for a specific ion, its permeability is?

A

the number of open ion channels for that ion; 0

54
Q

What is the equation for the Goldman-Hodgkin-Katz equation?

A

Vm= membrane potential

Pk= permeability of potassium

55
Q

the GHK equation depends on what?

A

the concentration gradients for each ion and their relative permeabilities

56
Q

Fill in.
The greater an ions permeability, the greater its contribution to ____

A

the membrane potential

57
Q

What happens to the resting membrane potential if an ion is very permeable?

A

It will be weighted more towards that ion’s Nernst equilibrium potential

58
Q

At rest, Vm is dominated by what ion?

A

Potassium

59
Q

True or False.
There will be a flux of ions across the membrane of any ion for which the membrane
potential is not at the equilibrium potential

A

True.

60
Q

When is the Vm stable?

A

When no ions are at their potential

61
Q

when is the total net flux of ions across the membrane zero

A

When the membrane potential stable

62
Q

Vdf (driving force) is the difference between the ______ and the ______

A

membrane potential and
equilibrium potential for an ion

63
Q

What is the driving force equation

A
64
Q

A cation that has a (-) driving force flows in what direction

A

Inward

65
Q

A anion that has a (+) driving force flows in what direction

A

Inward

66
Q

a cation that has a (+) driving force flows in what direction

A

outward

67
Q

a anion that has a (-) driving force flows in what direction

A

outward

68
Q

What happens when the Na-K ATPase stops working

A

the sodium and potassium gradients dissipate

69
Q

What would happen if Vanadate or Ouabain inhibited the Na-K ATPase?

A

the concentration gradient would dissipate and would not be able to establish or maintain membrane potential for action potential and other physiological processes.

70
Q

normal resting membrane potential is essential for what physiological processes?

A

Neurons
cardiac muscle
smooth muscle
skeletal muscle
endocrine cells
the concentrative capacity of secondary active transporters

71
Q

SGLT depends on Na-K ATPase and ____

A

low intracellular Na+ concentration

72
Q

SGLT is considered a ____ pump

A

electrogenic pump. It is also a symporter or cotransporter.

73
Q

SGLT is sensitive to resting membrane potential. This means what?

A

If you change resting membrane potential, you change the driving force thus changing glucose absorption.

74
Q

GLUT transports glucose out of the cell to ____

A

the intracellular space. (basement membrane > interstitial fluid > capillary)

75
Q

As the membrane potential decreases what happens to the glucose concentration

A

the ratio of Glucose(inside) to Glucose(outside) increases. meaning more glucose goes into the cell

76
Q

As depolarization occurs what happens to the concentration of the glucose

A

Concentration of glucose inside decreases

77
Q

as polarization occurs what happens to the concentration of glucose

A

Concentration of glucose inside increases

78
Q

Vm < Vrev

A

Na+ and solute will go in

79
Q

Vm > Vrev

A

Na+ and solute will go out

80
Q

action potential in excitable cells is described as what

A

a brief and reversible change in their membrane polarization

81
Q

How do non-excitable cells respond to depolarizing and hyper polarizing stimuli

A

by producing graded changes in their membrane potential

82
Q

In excitable cells, during action potential the membrane potential depolarizes from ____ to ____

A

-70 mV to + 50mV

83
Q

True or false.
action potentials are all or nothing events

A

True

84
Q

What are the different time scales for motor neurons, skeletal muscle, and cardiac ventricles

A

motor neurons: 2 msec
skeletal muscle: 5 msec
Cardiac ventricles: 200 sec

85
Q

Of motor neurons, skeletal muscle, and cardiac ventricle which of the three has the most negative Em and is the most long lasting?

A

Cardiac Ventricle

86
Q

Describe how the following are opened:
- voltage gated ion channel
- ligand gated ion channels
- mechanical gated ion channels

A

Voltage gated- open by change in voltage (depolarization)

Ligand gated- opened by signal molecules binding to the protein

mechanical gated- open by mechanical forces.

87
Q

who developed the Hodgkin-Huxley model

A

Sir Alan Lloyd Hodgkin and Sir Andrew Huxley

88
Q

What is the basis of information processing and transfer in the nervous system

A

action potential

89
Q

overshoot describes what during the depolarization phase

A
  • the reverse in sign of the membrane potential. essentially going from negative to positive.
90
Q

what are the phases of action potential

A
  1. Rising phase or depolarization phase
  2. Repolarization phase
  3. afterhyperpolarization phase
91
Q

voltage gated ion channels are important for ____

A

the different phases of action potential

92
Q

every voltage gated ion channel must have the following:

A
  • a pore with selectivity filter
  • a gated mechanism (this can be a voltage, ligand or mechanical force).
93
Q

what does the selectivity filter of a voltage gated ion channel do?

A
  • it uses amino acids that can use their carbonyl oxygens to act like a cage to strip the ion of water
94
Q

what amino acid code makes for a strong K+ channel

A

G-Y-G

95
Q

when you introduce more channels what happens to the selectivity of K+

A

it will reduce, and more ions will be able to pass through

96
Q

What does the Hodgkin-Huxley model of the action potential say about Na+ channels

A
  • each Na+ channel has 3 identical rapidly responding activation gates (M-gates)
  • each Na+ channel contains a single slower responding inactivation gate (H-gate)
97
Q

the probability of a Na+ gate being open is dependent upon what?

A
  • the voltage across the membrane
98
Q

the probability of the Na+ activation gates being open increases ___

A

increases with depolarization of the membrane potential

99
Q

the probability of the Na+ inactivation gates being open decreases

A

decreases with depolarization

100
Q

At rest the m-gate is ___ and the H-gate is ___

A

m-gate is closed
h-gate is open

101
Q

When the Na+ channel is open the m-gate is _____ and the H-gate is ____

A

m-gate is open
h-gate is open

102
Q

when the Na+ channel is inactive the m-gate is ____ and the h-gate is _____

A

m-gate is open
H-gate is closed

103
Q

the depolarization phase of the action potential is an example of what type of feedback

A

positive feedback
it is called the Hodgkin cycle

104
Q

What is the Hodgkin cycle (depolarization phase)

A
  1. open voltage gated Na+ channels
  2. Pna increases
  3. influx of Na+ ions
  4. Membrane depolarization
105
Q

What happens at the peak of the depolarization phase

A
  • Voltage gated Na+ channels rapidly inactivate
  • voltage gated K+ channels slow activate. K+ leaving contributes to the repolarization phase
106
Q

what did the Hodgkin-Huxley model say about voltage gated K+ channels

A
  • voltage gated K+ channels have slower kinetics
  • voltage gated K+ channel slowly activate. using 4 n-gates
  • these K+ gates remain open for as long as the membrane is depolarized.
  • when the membrane depolarizes the n-gates close and the K+ channel can no longer conduct a current

advanced human physiology (13 decks)

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