Chapter 2: Structure and Functions of Cells of the Nervous System Flashcards
1
Q
A band of white matter composed of many axons crossing between the right and left hemisphere of the brain.
A
Corpus callosum
2
Q
Consists of the parts that are encased by the bones of the skull and spinal column: the brain and the spinal cord.
A
Central Nervous System (CNS)
3
Q
Found outside the bones and consists of the nerves and most of the sensory organs.
A
Peripheral Nervous System (PNS)
4
Q
Bundles of thousands of individual neurons, all wrapped in a tough, protective membrane.
A
Nerves
5
Q
Information, in the form of light, sound waves,
odors, tastes, or contact with objects, is gathered from the environment by specialized cells of the PNS called?
A
Sensory neurons
6
Q
Movements are accomplished by the contraction of muscles, which are controlled by?
A
Motor neurons
7
Q
Neurons that lie entirely within
the CNS; in between sensory neurons and motor neurons.
A
Interneurons
8
Q
Form circuits with nearby neurons and analyze small pieces of information.
A
Local interneurons
9
Q
Connect circuits of local interneurons in one region of the brain with those in other regions.
A
Relay interneurons
10
Q
Information-processing and information-transmitting element of the nervous system.
A
Neuron
11
Q
4 structures or regions of a neuron.
A
Cell body or soma
Dendrites
Axon
Terminal buttons.
12
Q
Contains the nucleus and much of the machinery that provides for the life processes of the cell.
A
Soma
13
Q
Greek word for tree.
A
Dendron
14
Q
Serve as important receivers of these messages that neurons communicate with one another.
A
Dendrites
15
Q
A small space between the terminal buttons of the sending cell and a portion of the somatic or dendritic membrane of the receiving cell.
A
Synapse
16
Q
A long, slender tube, often covered by
a myelin sheath.
A
Axon
17
Q
Basic message the axon carries.
A
Action potential
18
Q
A brief electrical event that starts at the end of the axon next to the cell body and travels toward the terminal buttons.
A
Action potential
19
Q
Little knobs at the ends of the branches.
A
Terminal buttons
20
Q
A chemical that terminal buttons secrete when an action potential traveling down the axon reaches them.
A
Neurotransmitter
21
Q
An active process that propels substances along microtubule “tracks” that run inside the length of the axon.
A
Axoplasmic transport
22
Q
Movement from the soma to the terminal buttons.
A
Anterograde axoplasmic transport
23
Q
What does “antero” mean?
A
Toward the front
24
Q
Anterograde axoplasmic transport is accomplished by molecules of a protein called?
A
Kinesin
25
Movement from the terminal buttons to the soma.
Retrograde axoplasmic transport
26
Retrograde axoplasmic transport is accomplished by a protein called?
Dynein
27
Defines the boundary of the neuron; consists of a double layer of lipid (fatlike) molecules.
Cell membrane
28
A matrix of strands of protein; much like the bones of your skeletal system.
Cytoskeleton
29
Bundles of thirteen protein filaments arranged around a hollow core, thickest protein strand of cytoskeleton.
Microtubules
30
A jellylike, semiliquid substance that fills the space outlined by the membrane.
Cytoplasm
31
Small, specialized structures in the cytoplasm
Organelles
32
A round or oval structure found in the soma; where the nucleolus & chromosomes are resided.
Nucleus
33
Responsible for the production of ribosomes.
Nucleolus
34
Small structures that are involved in protein
synthesis.
Ribosomes
35
Consist of long strands of deoxyribonucleic acid (DNA); contain the organism’s genetic information.
Chromosomes
36
Receives a copy of the information stored at that location.
Messenger ribonucleic acid (mRNA)
37
A process in which information from DNA (which cannot leave the nucleus) is transcribed into a portable form: mRNA.
Transcription
38
A process in which the ribosomes use the information from the mRNA and create proteins.
Translation
39
Are special protein molecules that act as catalysts which direct the chemical processes of a cell by controlling chemical reactions.
Enzymes
40
A network of internal membranes.
Endomembrane system
41
An endomembrane system is comprised of?
Endoplasmic reticulum
Golgi apparatus
Lysosomes
42
2 forms of endoplasmic reticulum.
Rough ER
Smooth ER
43
ER that contains ribosomes.
Rough ER
44
Provides channels for the segregation of molecules involved in various cellular processes; lipid (fatlike) molecules are also produced.
Smooth ER
45
A special form of smooth endoplasmic reticulum; serves as a wrapping or packaging agent; also produces lysosomes.
Golgi apparatus
46
A process in which the membrane-wrapped product migrates to the inside of the outer membrane of the cell, fuses with the membrane, and bursts, spilling its contents into the fluid surrounding the cell.
Exocytosis
47
Small sacs that contain enzymes that break down substances no longer needed by the cell.
Lysosomes
48
Are shaped like oval beads and are formed from a double membrane; inner membrane is wrinkled; considered as the power plants of neurons.
Mitochondria
49
Set of shelves that fill the inside of the bead of mitochondria.
Cristae
50
Special molecule that cells use as their immediate source of energy.
Adenosine triphosphate (ATP)
51
Most important supporting cells of the CNS
Neuroglia/ Nerve glue
52
Surround neurons and hold them in place, controlling their supply of nutrients and some of the chemicals they need to exchange messages with other neurons; they insulate neurons from one another so that neural messages do not get scrambled; and they even act as housekeepers, destroying and removing the carcasses of neurons that are killed by disease or injury.
Glial cells/ Glia
53
3 most important types of glial cells
Astrocytes
Oligodendrocytes
Microglia.
54
Name means “star cell,” which accurately describes the shape of these cells; provide physical support to neurons and clean up debris within the brain; produce some chemicals that neurons need to fulfill their functions; help to control the chemical composition of the fluid surrounding neurons; involved in providing nourishment to neurons.
Astrocytes
55
The chemical produced during the first step of glucose metabolism.
Lactate
56
A carbohydrate that can be broken down to glucose and then to lactate when the metabolic rate of neurons in their vicinity is especially high.
Glycogen
57
A process in which when astrocytes contact a piece of debris from a dead neuron, they push themselves against it, finally engulfing and digesting it.
Phagocytosis
58
Provide support to axons and to produce the myelin sheath, which insulates most axons from one another.
Oligodendrocytes
59
Consists of a series of segments, each approximately 1 mm long, with a small (1–2 μm) portion of uncoated axon between the segments.
Myelin sheath
60
Bare portion of axon.
Node of Ranvier
61
Smallest of the glial cells; act as phagocytes, engulfing and breaking down dead and dying neurons; serve as one of the representatives of the immune system in the brain, protecting the brain from invading microorganisms; primarily responsible for the inflammatory reaction in response to brain damage.
Microglia
62
Provides myelin for only one axon, and the entirety of it surrounds the axon; aid in the digestion of the dead and dying axons.
Schwann cells
63
A barrier exists between the blood and the fluid that surrounds the cells of the brain; selectively permeable.
Blood-brain barrier
64
A part of the brain that controls vomiting.
Area postrema
65
Counteracts the excitatory synapses; supplied by the brain.
Inhibition
66
Decreases the activity of the motor neuron, blocking the withdrawal reflex.
Inhibitory neurotransmitter
67
Electrical recording techniques using very small sensors that can be inserted into a neuron to record changes in electrical activity across the axon membrane.
Microelectrodes
68
Any difference in charge (positive
or negative) across the membrane is called?
Membrane potential
69
Neuron is at rest and not involved in communicating with any other neurons, the membrane potential remains at approximately –70mV.
Resting potential
70
Inside of an axon becomes more negative relative to the outside.
Hyperpolarized
71
Inside of the axon becomes more positive.
Depolarized
72
A set point, for depolarization to trigger the
main electrical event in an axon—the action potential.
Threshold of excitation
73
A burst of rapid depolarization followed by
hyperpolarization.
Action potential
74
The process whereby molecules distribute themselves evenly throughout the medium in which they are dissolved.
Diffusion
75
Substances with a property to split into two parts, each with an opposing electrical charge, when dissolved in water.
Electrolytes
76
Charged particles in which electrolytes decompose.
Ions
77
2 basic types of ions.
Cations
Anions
78
Ions that have a positive charge.
Cations
79
Ions that have a negative charge.
Anions
80
Force exerted by the attraction or repulsion by charged particles.
Electrostatic pressure
81
Fluid within cells.
Intracellular fluid
82
Fluid surrounding cells.
Extracellular fluid
83
Several important ions in the fluids.
Organic anions
Chloride ions
Sodium ions
Potassium ions
84
Negatively charged proteins and intermediate
products of the cell’s metabolic processes; are found only in the intracellular fluid.
Organic anions
85
Ion found predominantly in the intracellular fluid; concentrated within the axon.
Potassium ions
86
Ions found predominantly in the extracellular fluid.
Sodium ions
Chloride ions
87
Ions that are in greatest concentration outside the axon.
Chloride ions
88
Continuously pushes Na+ out of the axon; consists of a large number of protein molecules embedded in the membrane, driven by energy provided by molecules of ATP produced by the mitochondria; actively pumps sodium ions out of the cell and pumps potassium ions into it.
Sodium-Potassium Pump
89
Molecules that exchange Na+ for K+, pushing three sodium ions out for every two potassium ions they push in.
Sodium-Potassium Transporters
90
Contain passages (“pores”) that can open or close.
Ion channels
91
A brief increase in the permeability of the membrane to Na+ (allowing these ions to rush into the cell) is immediately followed by a transient increase in the permeability of the membrane to K+ (allowing these ions to rush out of the cell).
Action Potential
92
What are sodium channels called?
Voltage-dependent ion channels
93
Channels that are only opened by changes in the membrane potential.
Sodium channels
94
The channels become blocked and cannot open again until the membrane once more reaches the resting potential.
Refractory
95
This law states that an action potential either occurs or does not occur.
All-or-none law
96
Refers to the principle that variations in the intensity of a stimulus or other information being
transmitted in an axon are represented by variations in the rate at which the axon fires.
Rate law
97
Decrease in the size of the disturbance.
Decremental conduction
98
Transmission message, hopping from node to node.
Saltatory conduction
99
Primary means of communication between neurons; the transmission of messages from
one neuron to another across a synapse.
Synaptic transmission
100
Brief depolarizations or hyperpolarizations—that increase or decrease the rate of firing of the axon of the postsynaptic neuron.
Postsynaptic potential
101
Neurotransmitters exert their effects on cells by attaching to a particular region of a receptor molecule called?
Binding site
102
A chemical that attaches to a binding site.
Ligand
103
Smooth surface of a dendrite; small protrusions that stud the dendrites of several types of large neurons in the brain.
Dendritic spines
104
Membrane located at the end of the terminal button.
Presynaptic membrane
105
Membrane located on the neuron that receives the message.
Postsynaptic membrane
106
A gap that varies in size from synapse to synapse but is usually around 20 nm wide; contains extracellular fluid, through which the
neurotransmitter diffuses.
Synaptic cleft
107
Small, rounded objects in the shape of
spheres or ovoids; found in the terminal button
Synaptic vesicles
108
Fill vesicles with the neurotransmitter.
Transport proteins
109
Proteins involved in the release of neurotransmitters and recycling of the vesicles.
Trafficking proteins
110
The region from which the neurotransmitter is released.
The release zone
111
Accomplished when clusters of protein molecules attach to other protein molecules located in the presynaptic membrane.
Docking
112
A hole through both membranes that enables them to fuse together.
Fusion pore
113
3 distinct pools of synaptic vesicles.
Release-ready vesicles
Recycling pool
Reserve pool
114
Docked against the inside of the presynaptic membrane, ready to release their contents when an action potential arrives.
Release-ready vesicles
115
Constitute 10–15 percent of the total pool of vesicles; release their contents if the firing increases.
Recycling pool
116
Make up the remaining 85–90 percent of vesicles; release their contents if the firing increases.
Reserve pool
117
A process where the membranes of vesicles in the reserve pool are recycled.
Bulk endocytosis
118
Special protein molecules located in the postsynaptic membrane.
Postsynaptic receptors
119
Permit the passage of specific ions into or out of the cell.
Neurotransmitter-dependent ion channels
120
Contained in the membrane of the axon, less sensitive than voltage-dependent sodium channels; require a greater level of depolarization before they begin to open; open later than sodium channels.
Voltage-dependent potassium channels
121
Junctions between the terminal buttons at the end of the axonal branches of one neuron and the membrane of another.
Synapse
122
A type of synaptic vesicle release where the vesicle opens and closes transiently.
Kiss-and-run fusion
123
Part of an ion channel; when a neurotransmitter bins the receptor, it responds by opening ion channels.
Ionotropic receptor
124
Type of a neurotransmitter that ionotropic receptors are sensitive to.
Acetylcholine
125
Indirectly linked with ion channels through signal transduction mechanisms, such a G proteins.
Metabotropic receptors
126
Molecules that relay signals received at receptors, which causes ion channels to open.
Second messenger
127
Original second messenger; chemical synthesized from ATP.
Cyclic AMP
128
Four major types of neurotransmitter-dependent
ion channels found in the postsynaptic membrane.
Sodium
Potassium
Chloride
Calcium
129
A temporary depolarization of postsynaptic membrane caused by the flow of positively charged ions into the postsynaptic cell.
Excitatory postsynaptic potential (EPSP)
130
A temporary hyperpolarization of postsynaptic membrane caused by the flow of negatively charged ions into the postsynaptic cell.
Inhibitory postsynaptic potential (IPSP)
131
Most important source of excitatory postsynaptic potentials; keeps sodium outside of the cell.
Sodium channels
132
When opened, some cations will follow this gradient and leave the cell.
Potassium channels
133
Will permit chloride ions to enter the cell if the membrane potential has already been depolarized by the activity of excitatory synapses located nearby; opening serves to neutralize EPSPs.
Chloride channels
134
Opening of it depolarizes the membrane, producing EPSPs.
Calcium channels
135
An extremely rapid removal of neurotransmitter from the synaptic cleft by the terminal button.
Reuptake
136
Accomplished by an enzyme that destroys molecules of the neurotransmitter.
Enzymic deactivation
137
Destroys ACh by breaking it into its constituents: choline and acetate.
Acetylcholinesterase (AchE)
138
Refers to the occurrence of an action potential.
Firing
139
The interaction of the effects of excitatory and inhibitory synapses on a particular neuron.
Neural integration
140
Located at the base of the axon.
Axon hillock
141
Receptors that respond to the neurotransmitter that they themselves release.
Autoreceptors
142
Alter the amount of neurotransmitter released
by the terminal buttons of the postsynaptic axon; produce presynaptic modulation: presynaptic inhibition or presynaptic facilitation.
Axoaxonic synapses
143
The activity of the axoaxonic synapse decreases the release of the neurotransmitter.
Presynaptic inhibition
144
The activity of the axoaxonic synapse increases the release of the neurotransmitter.
Presynaptic facilitation
145
Synapses between dendrites.
Dendrodendritic synapses
146
Membranes on both sides contain channels that permit ions to diffuse from one cell to another; common in invertebrates.
Gap junctions
147
Chemicals released by neurons that travel farther and are dispersed more widely than are neurotransmitters.
Neuromodulators
148
Chains of amino acids.
Peptides
149
Secreted by cells of endocrine glands or by cells located in various organs, such as the stomach, the intestines, the kidneys, and the brain.
Hormones
150
Cells that contain receptors for a particular hormone.
Target cells
151
Consist of very small fat-soluble molecules; Examples include the sex hormones secreted by the ovaries and testes and the hormones secreted by the adrenal cortex.
Steroid hormones
