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Bio 273 > Unit 2: Neurophysiology > Flashcards

Unit 2: Neurophysiology Flashcards

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1
Q

The nervous system is one of two key __________ _________

A

control structures (the other being the endocrine system)

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2
Q

List some functions of the nervous system related to information

A

receives info, integrates info, and transduces info

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3
Q

What is the pathway of signalling in order

A

stimulus, sensor, afferent pathway, integration centre, efferent pathway, target, response

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4
Q

What are the two main parts of the nervous system

A

CNS (central nervous) and PNS (peripheral nervous)

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5
Q

What is the CNS made up of

A

brain & spinal cord

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6
Q

What is the PNS made up of

A

sensory (afferent) and motor (efferent) neurons (parts of nervous system outside of the brain/spinal cord)

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7
Q

What are the two cell types of the nervous system

A

neurons and glial cells

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8
Q

What are neurons

A

information messengers that generate and transmit signals over long distances

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9
Q

What are neurons made up of

A

soma, dendrites, axon, and axon terminals

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10
Q

What is the soma of a neuron

A

“cell body” of the neuron, that contains the nucleus and all biosynthetic materials

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11
Q

Why is the soma of a neuron so important

A

center for all chemical processes that keeps the neuron functioning and alive

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12
Q

Clusters of cell bodies in the CNS are called

A

nuclei

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13
Q

Clusters of cell bodies in PNS are called

A

ganglia

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14
Q

What are dendrites

A

the projections of the soma that receive information (dendron = “tree”; look like the ‘branches’ of the soma)

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15
Q

What direction do dendrites relay info

A

TOWARD the soma (opposite to axons)

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16
Q

What is an axon

A

cytoplasmic extension that relays information

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17
Q

What are bundles of axons in the CNS called

A

tracts

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18
Q

What are bundles of axons in the PNS called

A

nerves

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19
Q

In which direction do axons relay info

A

AWAY from the soma (opposite to dendrites)

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20
Q

What is an axon terminal

A

self-explanatory; the ends of an axon that connect the neuron to other cells

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21
Q

What is the state of an axon terminal and what process does it contribute to

A

presynaptic: contributes to the synapse

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22
Q

What is a synapse

A

the region where an axon terminal connects to its postsynaptic target cell

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23
Q

What is the state of the target cell in relation to synapse

A

postsynaptic

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24
Q

What is the connection between the presynaptic axon terminal and the postsynaptic target cell

A

synaptic cleft

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25
Q

What are the 5 structural classifications of neurons

A
  1. pseudounipolar
  2. bipolar
  3. anaxonic
  4. multipolar-CNS
  5. multipolar-efferent
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26
Q

What are pseudounipolar neurons

A

somatic sensory neurons
- axon and dendrites fuse during development into a single long process

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27
Q

What are bipolar neurons

A

smell/vision sensory neurons
- single axon & dendrite

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28
Q

What are anaxonic neurons

A

interneuron with no apparent axon (anaxonic - meaning not axonic)

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29
Q

What are multipolar-CNS neurons

A

interneuron of the CNS
- highly branched neurons with numerous dendrites
- no long extension for the axon

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30
Q

What are multipolar-efferent neurons

A

contains 5-7 dendrites and a single long axon (similar to multipolar-CNS but has one extension vs none)

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31
Q

What are the 3 functional classifications of neurons

A
  1. Afferent neurons
  2. Interneurons
  3. Efferent neurons
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32
Q

What does the term interneuron mean

A

in the CNS

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33
Q

What are afferent neurons

A

receive info from the receptor cells and transmit sensory info TOWARD the CNS
- cell bodies located outside the CNS
- has long cytoplasmic extensions that transmit info to the cells

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34
Q

What are interneurons

A

located inside of the CNS (96% of all neurons), which transmit info within the CNS and integrate information received by afferent neurons and transmit signals to efferent neurons
(basically the connection of signalling info from afferent to efferent)
- main role is to figure out what to do with information and transmit the signal forward

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35
Q

What are efferent neurons

A

receive info FROM interneurons and carry AWAY from CNS
- cell bodies located within CNS
- cytoplasmic extensions transmit information to the effectors/targets

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36
Q

What are glial cells

A

associated with neurons as helpers, but do not carry signals over long distances like neurons do, they communicate only with each other and with nearby neurons

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37
Q

What are the two ways glial cells contribute to neuron function

A
  1. aid in nerve impulse conduction
  2. maintain the microenvironment around neurons
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38
Q

What are the 2 PNS glial cell types

A

Schwann cells & satellite cells

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39
Q

What do Schwann cells form

A

myelin (layers of membrane)

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40
Q

What is myelin

A

layers of membrane that act as an electrical insulator (formed by Schwann cells in the PNS)

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41
Q

What are satellite cells

A

non-myelinating Schwann cells

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42
Q

What do satellite cells do instead of create myelin

A

support nerve cell bodies (soma)

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43
Q

What do Schwann cells secrete

A

neurotrophic factors

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44
Q

What is the node of ranvier

A

section of unmyelinated axon membrane between two Schwann cells

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45
Q

What is the myelin sheath

A

Schwann cells wrapped around a single PNS axon

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46
Q

What are the 4 types of CNS glial cells

A
  1. oligodendria (oligodendrocytes)
  2. astroglia (astrocytes)
  3. microglia
  4. ependymal cells
    (review figures 2.4 & 2.5**)
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47
Q

What are oligodendrocytes

A

CNS version of Schwann cells
- wrap around axons & forms myelin to insulate CNS axons

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48
Q

What are astrocytes

A

small star-shaped cells that contact blood vessels and neurons to maintain the microenvironment to help maintain homeostasis in extracellular fluid

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49
Q

What are microglia

A

small specialized immune cells (like macrophages) that function to remove damaged cells and foreign invaders

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50
Q

What are ependymal cells

A

epithelial cells that produce cerebral spinal fluid (CSF)
- creates selectively permeable barriers between compartments of the brain

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51
Q

Review and write out the concept map for the nervous system unit

A

(found on LEARN page under concept maps)

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51
Q

**Review and write out the concept map for the nervous system unit

A

(found on LEARN page under concept maps**)

nervous system = CNS and PNS
CNS = brain & sinal cord
PNS = afferent (sensory) & efferent (motor)
Efferent (motor) = somatic & autonomic
Autonomic = sympathetic & parasympathetic

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52
Q

What is the ONLY target of somatic motor neurons

A

skeletal muscle

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53
Q

What are the main targets of autonomic motor neurons

A

cardiac muscle & smooth muscle
(main focus for this course, but there are others eg. adipose tissues)

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54
Q

How do neurons transmit electrical impulses

A

via energy, stored as an electrochemical gradient

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55
Q

The human body is electrically ____________

A

neutral

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56
Q

Separating positive and negative charges requires ________

A

energy

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57
Q

How does the body specifically separate charges

A

the cell membrane acts as an electrical insulator

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58
Q

A difference in charge between the ICF and the ECF creates an ____________ ________________

A

electrical gradient

59
Q

What structure allows for movement of charge through the membrane

A

ion channels

60
Q

The difference of +ve (cations) vs -ve (anions) charge between inside and outside of cell is called…

A

membrane potential

61
Q

What does it mean when saying all living cells have a membrane potential?

A

they are polarized electrically (to varying extents)

62
Q

Which cells are able to use changes of membrane potential to complete a function

A

excitable cells
(eg. neurons are excitable b/c changes in membrane potential allow them to relay information)

63
Q

What unit is membrane potential quantified in

A

millivolts (mV)

64
Q

What two factors determine membrane electrical properties

A
  1. an unequal distribution between the inside (ICF) and outside of the cell (ECF)
    - eg. Na+, Ca2+, & Cl- are higher in ECF while K+ is higher in ICF [anions (large, negatively charged proteins) usually higher in ICF]
  2. selective movement of these ions across the membrane
    - eg. because of size, anions cannot move across membrane
65
Q

IN CLASS REVIEW: Clusters of cell bodies in the PNS are known as…
a. ganglia
b. nuclei
c. tracts
d. nerves
e. ganglia and nerves

A

a. ganglia
(ganglia=soma in PNS, whereas nuclei=soma in CNS)
(tracts=bundles of axons in CNS, nerves=bundles of axons in PNS)

66
Q

What are the 4 types of selective ion channel

A

K+ channel
Na+ channel
Cl- channel
Ca2+ channel

67
Q

What is higher concentration in ICF

A

K+

68
Q

What is higher concentration in ECF

A

Na+, Ca2+, & Cl-

69
Q

What are anions

A

large, negatively charged intracellular molecules in ICF

70
Q

What are cations

A

large, positively charged extracellular molecules in ECF

71
Q

Why do anions not move across the membrane

A

because of their size

72
Q

What are leak channels

A

passive transport channels (don’t require energy input and are not gated)

73
Q

Does K+ or Na+ have a greater concentration of passive channels in the membrane

A

K+: there are more passive K+ channels so K+ can move much more freely across the membrane compared to Na+

74
Q

What is equilibrium potential

A

membrane potential that exactly opposes the concentration gradient of an ion (this is where the electrical and chemical forces acting on the ion are equal and opposite)

75
Q

What is the Nernst equation

A

E(ion) = (61/z) log ([ion]out/[ion]in)

(looks at what the membrane potential would be for the membrane to be permeable to only one ion)

76
Q

What does the value E(ion) represent

A

equilibrium potential

77
Q

What does the value z represent

A

electrical charge of the ion

78
Q

What are the equilibrium potentials for K+ and Na+ in a typical neuron

A

K+ : -90mV
Na+ : +60mV

79
Q

What is the basic concept of the Nernst equation

A

looks at what membrane potential would be if the membrane was only permeable to one ion

80
Q

What is the deviation between the Nernst equation and living cells

A

the Nernst equation focuses on only one ion but living cells have multiple ion types crossing the membrane

81
Q

What concentrations do you need to know in order to complete the Nernst equation

A

concentration of ion IN & concentration of ion OUT

82
Q

What is resting potential

A

the charge difference between ICF and ECF at rest

83
Q

What is typical resting potential for a neuron

A

-70mV

84
Q

When is the neuron no longer at resting membrane potential

A

when it sends a signal

85
Q

What determines a cells resting membrane potential

A

the concentrations of ions (K+ greater in ICF, and Na+, Cl-, and Ca2+ greater in ECF) and their relative permeabilities to the membrane

86
Q

What is meant by “excitable” in relation to a cell

A

the cell will change its membrane potential to complete a job

87
Q

The ion contribution to the resting membrane potential is proportional to _______________

A

permeability
- this means the more permeable to the membrane, the more important it is for resting membrane potential

88
Q

What type of molecule cannot contribute to the resting membrane potential

A

molecules that cannot move across the cell membrane (ie. Ca2+ because it moves via gated channels)

89
Q

What is the purpose of the GHK equation

A

predicts membrane potential using multiple ions (more relative to living cells)

90
Q

What does the value Vm represent

A

resting membrane potential

91
Q

What does P represent

A

permeability of the membrane to a specific ion

92
Q

What is the permeability of Ca2+ (remember Ca2+ travels via gated channels NOT leak channels)

A

0; it does not cross the membrane via leak channels (therefore is excluded from membrane potential equations)

93
Q

What does the K+-Na+ pump offset

A

the passive flow of Na+ and K+ at rest

94
Q

What is depolarization

A

decrease in membrane potential difference, membrane becomes LESS negative

95
Q

What is hyper polarization

A

increase in membrane potential, membrane becomes MORE negative

96
Q

What are the 3 types of gated channels

A
  1. mechanically gated: found in sensory neurons (open in response to physical force)
  2. chemically gated: respond to ligands like neurotransmitters
  3. voltage-gated: respond to changes in voltage (important in conduction of electrical signals along axons)
97
Q

The gated channels in neurons are for which 4 ions

A

K+, Na+, Ca2+, and Cl-

98
Q

What are the two types of signal generated by neurons

A

short-distance signals & long-distance signals

99
Q

IN CLASS ACTIVITY: match the ion to its associated change in the membrane…
1)Na+
2)Cl-
3)K+
4)Ca2+
…predicting whether it will hyper-polarization or depolarization the cell

A

1) depolarizing (adding positive charges will take it from -70 to less negative)
2) hyper-polarize (adding negative charges will take from -70 to more negative)
3) hyper-polarizing (taking away positive charges will make it more negative)
4) depolarizing (adding positive charges will take it from -70 to less negative)

100
Q

What are graded potentials

A

can be depolarizing or hyper-polarizing, and occur in the dendrites of the neuron
- triggered by opening or closing of ion channels
- started by ions entering the cell from the ECF

101
Q

Why are graded potentials called “graded”

A

the amplitude of the potential is relative to the strength of the triggering event

102
Q

Why do graded potentials lose strength as they travel

A
  1. current leak: some charges leak back with the depolarization wave
  2. cytoplasmic resistance: cytoplasm resists the movement of the current
103
Q

Since graded potentials lose strength as they move, what distance are they travelled

A

short distances

104
Q

What causes an ion to enter the cell

A

initiates by ions binding to membrane receptors and opening ion channels

105
Q

What events occur after neurotransmitters bind

A

Ion channel opens, ions move in/out, and depolarization/hyper-polarization spreads through the cell

106
Q

What determines signal strength

A

the number of ions entering/exiting the cell

107
Q

As graded potential travels, ________ is decreased

A

strength

108
Q

What is another (simpler) term for graded potential

A

signal

109
Q

What is the different type of signalling used for long distances?

A

action potential

110
Q

What are characteristics of action potential

A
  • action potentials don’t deviate, they are identical (no variation in strength, on or off only)
  • action potentials don’t diminish in strength as they travel, the signal remains strong the entire distance
111
Q

How is action potential initiated

A

at the trigger zone (otherwise known as the integrating centre)

112
Q

Where is the trigger zone in a neuron

A

it varies depending on the type of neuron

113
Q

Where is the trigger zone in sensory neurons

A

adjacent to the receptor

114
Q

In relation to action potential, if only one action potential occurs, what is the effect on the cell

A

barely any effect, concentration gradient remains essentially unchanged
- therefore LOTS of action potentials are needed to change the gradient

115
Q

When is the Na+ channel activated during the action potential time frame

A

at threshold (absolute refractory period)

116
Q

When is the Na+ turned off and when is K+ channel opened during action potential time frame

A

Na+ closes after threshold, and K+ channels open (absolute refractory period)

117
Q

When do K+ channels close during action potential time frame

A

relative refractory period

118
Q

Recite the phases of action potential! This is important for the midterm*

A

do this on a whiteboard and check answers in course notes

119
Q

What are the two key refractory periods

A

absolute and relative refractory periods

120
Q

When does the absolute refractory period begin

A

as soon as Na+ channel is opened

121
Q

When does relative refractory period begin

A

at hyper-polarization (when action potential is lower than -55mV)

if this is unclear look at the graph in course notes and study the curve!

122
Q

What types of channels are the Na+ and K+ channels in action potential

A

voltage-gates channels

123
Q

What are nodes of ranvier concentrated with?

A

Na+ channels

124
Q

What is the term used to describe when signals jump from node to node on a myelinated axon

A

saltatory conduction

125
Q

How is myelin insulation significant

A

hyperpolarization within the axons is strong enough by the time it hits the next myelinated area

126
Q

Describe the events that occur at the synapse! this is an important concept for the midterm*

A

check course notes and study this area if unclear

127
Q

What is the space in between the axon terminal and the post-synaptic cell

A

synaptic cleft

128
Q

When action potential arrives at the axon terminal and the docking protein is activated, what happens?

A

the docking protein moves off of the axon terminal and becomes a synaptic vesicle, calcium entry from the voltage-gated channels instigates exocytosis of the neurotransmitters, which end up binding to receptors on the postsynaptic cell to relay a signal

129
Q

Summarize somatic, sympathetic, and parasympathetic neurons and their functions. This is important for the midterm*

A

Read figure 11.9 in course notes and study it

130
Q

What is the target tissue for the autonomic pathway

A

cardiac and smooth muscle (involuntary muscle types)

131
Q

What is the target tissue for the somatic pathway

A

skeletal muscle

132
Q

For autonomic pathways, how many neurons are involved?

A

2

133
Q

Know the receptors released by the pre and post ganglionic neurons and what receptors they each bind to!

A
134
Q

For parasympathetic preganglionic neurons, what neurotransmitter is released

A

acetylcholine (binds to nicotinic receptor)

135
Q

For parasympathetic postganglionic neurons, what neurotransmitter is released

A

acetylecholine (binds to muscarinic receptor)

136
Q

For sympathetic preganglionic neurons, what neurotransmitter is released

A

acetylcholine (binds to nicotinic receptor)

137
Q

For sympathetic postganglionic neurons, what neurotransmitter is released

A

norepinephrine (binds to A, B1, and B2 adrenergic receptors)

138
Q

What is another term for sympathetic (think response)

A

fight or flight

139
Q

For adrenal sympathetic preganglionic neurons, what happens

A

acetylcholine is released from the axon terminals to the chromaffin cells on the adrenal medulla (on the adrenal gland), then epinephrine is released by the chromaffin cells on the adrenal medulla into the bloodstream

140
Q

For adrenergic receptors, do cells contain multiple types of receptors or just one?

A

cells only project 1 type of receptor (different cell types have different receptor types)

141
Q

What do B1 and B2 (beta) receptors initiate

A

cAMP production

142
Q

What do A (alpha) receptors initiate

A

increase Ca2+ levels in the cytoplasm

143
Q

Nicotinic receptors act via ___ __________

A

ion channels

144
Q

Muscarinic receptors act via __ __________

A

G proteins

145
Q

What type of neuron is a chromaffin cell

A

a modified postganglionic neuron

146
Q

For somatic neurons, what neurotransmitter is released and what receptor is it bound to

A

acetylcholine, binds to nicotinic receptors (for skeletal muscles)

Bio 273 (8 decks)

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