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Physiology > Chapter 06: Neuronal Signaling > Flashcards

Chapter 06: Neuronal Signaling Flashcards

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0
Q

What are varicosities?

A

A series of bulging areas along the axon that release neurotransmitters

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1
Q

What are collaterals?

A

Branches that stem off of the axon

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2
Q

What are the myelin-forming cells of the CNS?

A

Oligodendrocytes

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3
Q

What are the myelin-forming cells of the PNS?

A

Schwann cells

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4
Q

How many axons can oligodendrocytes myelinate and connect to?

A

Up to 40

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5
Q

How may axons can Schwann cells myelinate and connect to?

A

Just one

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6
Q

What is the gap between areas of myelinated axon sheath called?

A

Nodes of Ranvier

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7
Q

Kinesin proteins bond __________ to the microtubule in the axon chain.

A

secretory vesicles

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8
Q

Dynein proteins bond _________ to the microtubule in the axon chain.

A

recycled membrane vesicles

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9
Q

Neurons make up _____% of the cells in the CNS but compose ____% of the volume.

A

10% of CNS cells, 50% CNS volume

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10
Q

What are the four types of neuroglial cells?

A

Oligodendrocytes, astrocytes, microglia, and ependymal cells

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11
Q

What are microglia?

A

Macrophage-like cells that perform immune function for CNS

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12
Q

What are the functions of astrocytes?

A

Regulate composition of extracellular fluid, stimulate formation of tight junctions that compose blood-brain barrier, provide glucose and remove ammonia for neurons

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13
Q

What are ependymal cells?

A

Producers and regulators of CSF that line the fluid filled cavities of the CNS

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14
Q

What is the growth cone?

A

Specialized enlargement that forms tip of extending axons that is involved in finding correct route and final destination

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15
Q

What are the growth factors for neural tissue called?

A

Neurotrophic factors

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16
Q

What is apoptosis?

A

Programmed self-destruction of cell

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17
Q

What percentage of newly formed neurons and synapses go through apoptosis?

A

50-70%

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18
Q

current (n.)

A

the movement of electric charge

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19
Q

resistance (n.)

A

hindrance to the flow of electric charge/current

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20
Q

What is the equation for Ohm’s Law?

A

I = V/R

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21
Q

membrane potential (n.)

A

the state of the negative charge of the inside of a cell relative to the outside

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22
Q

What is the range of resting membrane potentials for all cells?

A

-5 to -100 mV

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23
Q

What is the range for RMP in neurons?

A

-40 to -90 mV

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24
What is average RMP for neurons?
-70 mV
25
What are the general permeabilities of K+, Na+, and Cl-?
``` P(K+) = 1 P(Na+) = 0.04 P(Cl-) = 0.45 ```
26
What is the ionic flow of the Na+/K+ ATPase pump?
3 Na+ out, 2 K+ in
27
leak channel (n.)
open channel, the flow of which follows concentration gradient
28
What are the stages of the firing of an action potential?
Depolarization, overshoot, repolarization, hyperpolarization, afterhyperpolarization
29
What is plasticity?
The remodeling of neural tissue in response to stimulation or injury
30
What is the rate of axon regrowth?
1 mm/day
31
electrical potential (n.)
the potential of opposite, separated electrical charges to do work if brought together
32
Which ion has a high concentration intracellularly?
K+
33
Which ion has a high concentration extracellularly?
Na+ (also Cl-)
34
electrogenic pump (n.)
pump that moves net charge across a membrane and contributes directly to membrane potential
35
excitability (n.)
the ability of a cell to generate an action potential
36
inactivation gate (n.)
part of a voltage-gated Na+ channel that blocks flow shortly after the channel opens
37
What is the threshold level for most neurons?
-55 mV
38
relative refractory period (n.)
period during afterhyperpolarization in which only a very strong stimuli will generate an AP
39
graded potential (n.)
change in potential of variable amplitude and duration that is conducted incrementally (no threshold/refractory period) and has a decremental flow of current
40
What is a threshold stimulus?
A stimulus that generates a change in potential ~15 mV more positive than RMP
41
absolute refractory period (n.)
period in which the VG-Na+ channels are open or inactivated; during this period, no stimuli will generate an AP
42
equilibrium potential (n.)
the electrical potential at a membrane at which there is no net flux of the ion
43
What is equilibrium potential for Na+?
+60 mV
44
What does the Nernst equation calculate?
Equilibrium membrane potential for a single ion species based solely on concentration, measured in mV
45
What is the threshold level for most neurons?
-55 mV
46
What is the Nernst equation?
E = 60/Z * log (C(o)/C(i))
47
What is equilibrium potential for K+?
-90 mV
48
What percentage of RMP is contributed by the Na+/K+ATPase pump? What is the charge?
Up to 20%, about -15 mV
49
Where is the first place in the neuron that an action potential can occur?
Axon hillock
50
Where are action potentials found in the neuron?
The axon hillock and along the axon
51
anterograde conduction (n.)
conduction away from the soma/dendrite of the neuron towards the axon terminal
52
retrograde conduction (n.)
conduction away from the axon terminal towards the soma/dendrites
53
At what stage of the conduction of an action potential is the relative refractory period?
Afterhyperpolarization
54
reaction time (n.)
delay between stimulus and response (reflex or voluntary)
55
synaptic delay (n.)
the amount of time it takes to release and bind neurotransmitters and depolarize the membrane to threshold in the postsynaptic axon hillock
56
How large are neuronal synaptic clefts?
roughly 10-20 nm
57
How long is the synaptic delay?
~ 200 ms (0.2 sec)
58
What protein mediates final fusion of vesicles to the synaptic membrane?
Synaptotagmin
59
What does the Goldman equation calculate?
Equilibrium membrane potential for several ions based upon concentration and permeability, measured in mV
60
What is the signal pathway for all parasympathetic innervation?
Preganglionic neuron > nicotinic receptor > postganglionic neuron > muscarininc receptor > gland or smooth muscle
61
What is the signal pathway for most sympathetic innervation?
Preganglionic neuron > nicotinic receptor > postganglionic neuron > adrenergic receptor > glands and visceral organs
62
What is the less common signaling pathway for sympathetic innervation?
Preganglionic neuron > nicotinic receptor > postganglionic neuron > muscarinic receptor > sweat glands and blood vessels
63
What type of receptor is between the preganglionic and postganglionic neurons in the ANS?
Nicotinic receptors
64
What is the signaling pathway in somatic nervous innervation?
Lower motor neuron > nicotinic receptor > skeletal muscle
65
sensation (n.)
sensory information that reaches the consciousness
66
perception (n.)
a person's understanding of the sensation's meaning
67
sensory information (n.)
information process by the sensory system, regardless of whether the information reaches consciousness
68
What kind of receptor does norepinephrine bind to?
Adrenergic
69
What neurotransmitter is released by postganglionic sympathetic neurons?
Norepinephrine
70
What neurotransmitter is released by postganglionic parasympathetic neurons?
Acetylcholine
71
What neurotransmitter is released by preganglionic sympathetic neurons?
Acetylcholine
72
Which type of receptor that binds acetylcholine released by the parasympathetic system is commonly found on cells of effector organs?
Muscarinic
73
What do mechanoreceptors respond to?
Mechanical stimuli (e.g., touch-pressure)
74
What do thermoreceptors respond to?
Sensations of cold and warm
75
What do photoreceptors do?
Convert light energy into graded potentials
76
What do chemoreceptors respond to?
Respond to binding of chemicals to specific receptors on membrane (used in smell, taste, blood O2 and CO2)
77
What do nociceptors respond to?
Respond to a number of painful stimuli including heat and tissue damage
78
What are the five general classes of sensory receptors?
Mechanoreceptors, thermoreceptors, photoreceptors, chemoreceptors, and nociceptors
79
stimulus transduction (n.)
transformation of energy into electrical signal
80
sensory adaptation (n.)
decrease in receptor sensitivity with constant stimulation
81
What do Meissner's corpuscles sense?
Light touch
82
What do Merkle's corpuscles detect?
Medium touch
83
What do free nerve endings detect?
Pain
84
What do lamellated (Pacinian) corpuscles detect?
Deep pressure
85
What do Ruffini corpuscles detect?
Warmth
86
What are nociceptors?
Unspecialized free nerve endings that detect various "painful" stimuli
87
What neurotransmitter would be increasingly released by post-ganglionic sympathetic cells in fight or flight?
Norepinephrine
88
What neurotransmitter would be increasingly released by pre-ganglionic sympathetic cells in fight or flight?
Acetylcholine
89
What does relative refractory period prevent?
Retrograde movement of action potentials
90
What does binding ACh to nicotinic receptors in a single synapse cause in a post-synaptic cell?
Excitatory Post-Synaptic Potential (EPSP)
91
What molecule directly causes GABA exocytosis from a pre-synaptic axon terminal?
Calcium
92
What type of ion channel is associated with the production of graded potentials?
Voltage-gated channel

Physiology (9 decks)

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