neurons and supporting cells Flashcards
1
Q
PNS is composed of
A
cranial and spinal nerves
2
Q
the nervous system is divided into what systems
A
central nervous system, peripheral nervous system, enteric nervous system
3
Q
CNS is composed of
A
brain and spinal cord
4
Q
enteric nervous system is composed of
A
sensory afferent neurons, motor efferent neurons, interneurons
5
Q
what does enteric nervous system do
A
neurons that givern the funstion of the GI tract, playing a critical role in regulating digestive processes such as motility, enzyme secretion, nutrient absorption, and blood flow
6
Q
tissue in the nervous system is composed of 2 types of cells
A
neurons and glial cells (neuroglia)
7
Q
what conducts impulses but generally can not divide. they send/receive signals
A
neurons
8
Q
what support neurons and can not conduct impulses, but can divide
A
neuroglia
9
Q
how many neuroglia in cns and pns
A
4cns, 2pns
10
Q
structural and functional units of the nervous system
A
neurons
11
Q
what gives a charge
A
more protons or neutrons
12
Q
where do you get a brain tumor from
A
glial cells (astrocytes)
13
Q
what are the functions of neurons
A
-respond to chemical and physical stimuli
-conduct electrochemical impulses
-release chemical regulators
-enable perception of sensory stimuli, learning, memory, and control of muscles and glands
14
Q
what are examples of chemical and physical stimuli
A
chem= hormones and neurotransmitters
phys= senses (temp, touch)
15
Q
what are electrochemical impulses
A
how neurons respond
16
Q
what can not divide, but can repair
A
neurons
17
Q
neurons vary in shape and size, but they all have :
A
cell body, dendrites axon
18
Q
receive impulses and conducts a graded impulse towards the cell body
A
dendrites
19
Q
conducts action potentials away from the cell body
A
axon
20
Q
significance of nucleus?
A
regulates the cell by dna; everything starts at the nucleus; collection of neuron cell bodies in cns
21
Q
what are Connected to the cell body by the axon hillock where action potentials are generated
at the initial segment of the —
A
axon
22
Q
what can Can form many branches called axon
collaterals
A
axons
23
Q
what are Covered in myelin with open spots called
nodes of Ranvier
A
axons
24
Q
An active process needed to move
organelles and proteins from the cell body to
axon terminals
A
axon transport
25
during axon transport, fast components move
membranous vesicles
26
during axonal transport, slow components move
microfilaments, microtubules, and proteins
27
what are the classifications of neurons and how are they based
neurons are based on direction impulses are conducted
sensory neurons, motor neurons, association/interneurons
28
which neuron conduct impulses from sensory receptors to the CNS (afferent) (towards brain)
sensory neurons
29
which neuron conduct impulses from the CNS to target organs (muscles or glands;
efferent)
motor neurons
30
what are away from brain and out to body for movement (skel and smooth muscle)
motor neurons
31
located completely
within the CNS and integrate functions of the
nervous system
association/interneurons
32
what is causes the ability to speak?
it takes many neurons to do this
Association/interneurons
33
types of motor neurons
somatic and autonomic
34
responsible for
reflexes and voluntary control of skeletal
muscles
somatic
35
innervate
involuntary targets such as smooth muscle,
cardiac muscle, and glands
autonomic
36
types of autonomic motor neurons
sympathetic and parasympathetic
37
emergency situations; “fight or flight
sympathetic
38
normal functions; “rest and
digest”
parasympathetic
39
what is a deviation from homeostasis and not normal. the output is fast heart rate and adrenalin.
sympathetic
40
41
what is homeostasis based.
ex: stomach tells brain
parasympatheitc
42
structural classifications of neurons are based on the number of processes that extend from the cell body. what are the three ?
pseudounipolar, bipolar neurons, multipolar neurons
43
single short process that
branches like a T to form 2 longer processes;
sensory neurons
pseudounipolar
44
have two processes, one on
either end; found in retina of eye
bipolar neurons
45
several dendrites and
one axon; most common type
multipolar neurons
46
where do nerves originate
spinal cord. they are all in pns
47
what are bundles of axons located outside
the CNS
nerves
48
what are a collection of nerves in pns
ganglia
49
Most are composed of both sensory and
motor neurons and are called mixed nerves
nerves
50
A bundle of axons in the CNS is called a
tract
51
Cells that are non-conducting but support
neurons
neuroglia (glial cells)
52
what 2 types of neuroglia are found in pns
schwann cells and satellite cells
53
(neurolemmocytes): form
myelin sheaths around peripheral axons
schwann cells
54
(ganglionic gliocytes): support
cell bodies within the ganglia of the PNS
satellite cells
55
what are the 4 types of neuroglia found in cns
oligodendrocytes, astrocytes, microglia, ependymal cells
56
form myelin sheaths
around the axons of CNS neurons
oligodendrocytes
57
migrate around CNS tissue and
phagocytize foreign and degenerated material
microglia
58
regulate the external environment
of the neurons
astrocytes
59
line the ventricles and
secrete cerebrospinal fluid
ependymal cells
60
Support functions of neurons within sensory and autonomic
ganglia
sat cells
60
also called neurolemmocytes, produce the myelin sheaths
around the myelinated axons of the peripheral nervous system;
surround all PNS axons (myelinated and nonmyelinated) to form
a neurilemmal sheath
schwann cells
61
Form myelin sheaths around central axons, producing “white
matter” of the CNS
oligodendrocytes
62
Phagocytose pathogens and cellular debris in the CNS
microglia
63
Cover capillaries of the CNS and induce the blood-brain barrier;
interact metabolically with neurons and modify the extracellular
environment of neurons
astrocytes
64
Form the epithelial lining of brain cavities (ventricles) and the
central canal of the spinal cord; cover tufts of capillaries to form
choroid plexuses—structures that produce cerebrospinal fluid
ependymal cells
65
All axons in the PNS are surrounded by a
sheath of Schwann cells called
neurilemma, or sheath of schwann
66
These cells wrap around the axon to form the
myelin sheath in the PNS
schwann cells
67
what gaps between schwann cells are left open
nodes of ranvier
68
small axons are usually
unmyelinated
69
unmyelinated axons in the PNS have a
neurilemma but lack the
multiple wrappings of
the Schwann cell plasma membrane
70
Myelinated axons conduct impulses
more rapidly
71
outer layer of nerv fiber
neurilemma
72
what is the benefit of a myelin
protect and support axon
73
why are nodes of ranvier left open
left open bc allow for rapid transmission of electrical signal along axon
74
In the CNS, the myelin sheath is produced by
oligodendrocytes
75
One oligodendrocyte sends extensions to
several axons and each wraps around
a section of an axon
76
Produces the myelin sheath but not a neurilemma
oligodendrocytes
77
The lack of a neurilemma in the CNS reasons why
why nerve regeneration is limited in the brain and spinal cord.
78
Myelin gives these tissues (axons) a --- color
white color = white matter
79
what colors are cell bodies and dendrites which
lack myelin sheaths
gray matter
80
where are white matter
under gray matter, deep region of brain.
81
what is white matter made up of
myelinated axons and long fobers that connect neurons
82
where is gray matter found
outer layer (cerebral cortex) and central core of spinal cord
83
what does gray matter consist of
consists of cell bodies of neurons and dendrites (process info)
84
gaps in myelin sheath that allow action potentials to regenerate and move along the axon.
vital for speed and timing of impulses btwn neurons
node of ranvier
85
what are found in white matter and repair damaged myelin sheaths after injury/disease
oligodendrocytes
86
what diseases are those in which
the myelin sheaths are specifically attacked
demyelinating diseases
87
the T cells of the
immune system attack the myelin sheaths of the
PNS. This produces rapid onset of symptoms that
include muscle weakness.
guillain-barre syndrome
88
what syndrome damages myelin and This disruption prevents signals from reaching muscles effectively, leading to muscle weakness or paralysis.
Guillain-barre syndrome
89
produced by an
autoimmune attack by T lymphocytes causing
lymphocytes and monocyte-derived macrophages
to enter the brain and target the myelin sheaths.
causing demyelination
multiple sclerosis
90
When an axon in the PNS is cut, the severed
part degenerates, and a regeneration tube is
formed by
schwann cells
91
what axons are not as able to regenerate
cns
92
what receptors form that promote apoptosis of
oligodendrocytes
death receptors
93
what in the myelin sheath prevents
regeneration
inhibitory proteins
94
what is from astrocytes form that also prevent
regeneration
glial scars
95
apoptosis means
cell death
96
bundles of axons
nerves
97
when you experience brain trauma, go to OT, and your brain is able to restore what was lost, how?
new synapse
1 cell sends lots of branches
98
what are like brain construction workers — they clear the mess, build new paths, and make your brain work better again after an injury.
synapses
99
what is the most abundand glial cell
astrocyte
100
Processes with end-feet associate with
blood capillaries and axon terminals
astrocyte
101
Influences interactions between neurons
and between neurons and blood
astrocyte
102
why do astrocyted take up K+ from the extracellular env
maintain ionic environment for neurons
103
axons take up ?
Take up extra neurotransmitter released from
axon terminals, particularly glutamate.
Chemicals are recycled
104
in astrocytes, End-feet around capillaries take up
take up glucose
from blood for use by neurons to make ATP;
converted first to lactic acid
105
what Can store glycogen and produce lactate for
neurons to use
astrocytes
106
Needed for the formation of synapses in the
CNS
astrocytes
107
Regulate neurogenesis in regions of the
adult brain
astrocytes
108
Release transmitter molecules
(gliotransmitters) that can stimulate or inhibit
neurons; includes glutamate, ATP,
adenosine, D-serine
astrocytes
109
how are astrocytes excited
by changes in
intracellular Ca 2+ concentration
110
Capillaries in the brain do not have pores
between adjacent cells but are joined by
tight junctions
111
Substances can only be moved by very
selective processes of diffusion through
endothelial cells, active transport, and bulk
transport
112
Movement is transcellular not paracellular
blood brain barrier
113
what influence the production of ion
channels and enzymes that can destroy
toxic substances by secreting glial-derived
neurotrophic factor
astrocytes
114
Creates problems with chemotherapy of
brain diseases because many drugs can not
penetrate
blood brain barrier
115
is a special wall made of tightly packed cells that lines the blood vessels in your brain. It decides what can and can't enter the brain from the blood.
blood brain barrier
116
why is the blood brain barrier important
protects the brain from harmful subs, and allows the good stuff (oxygen, glucose)
117
Neurons have a resting potential of
-70mV
118
Established by large negative molecules inside
the cell
RMP
119
Permeability of the membrane to positively
charged, inorganic ions
RMP
120
at rest...
there is a high concentration of K +
inside the cell and Na + outside the cell
121
what can change their membrane potential
Neurons and muscle cells
122
ready to respond.
Neurons are always ready to fire signals when they receive the right message (stimulus).
excitability
123
This is the ability of the neuron to actually react to a stimulus and start firing.
It’s like your phone ringing and responding by lighting up and vibrating
irritability
124
Called excitability or irritability
altering memb pot
125
Caused by changes in the permeability to
certain ions
altering memb pot
126
Flow of ions are called ---which occur
in limited areas where ion channels are located
ion currents
127
At rest, a neuron is considered
polarized when
the inside is more negative than the outside
128
When the membrane potential inside the cell
increases (becomes more positive)
depolarization
129
A return to resting potential
repolarization
130
When the membrane potential inside the cell
decreases (becomes more negative
hyperpolarization
131
occurs when positive ions
enter the cell (usually Na + )
Depolarization
132
occurs when positive
ions leave the cell (usually K + ) or negative
ions (Cl − ) enter the cell.
Hyperpolarization
133
Depolarization of the cell is
excitatory
134
Hyperpolarization is
inhibitory
135
Changes in membrane potential are
controlled by changes
in the flow of ions
through channels.
136
what are the two channels in K+
leaky channels and voltage gated K+
137
open when a particular
membrane potential is reached; closed at resting
potential
voltage gated K+ channels
138
what has only voltage-gated channels that are
closed at rest; the membrane is less permeable
to Na + at rest
sodium
139
These channels open if the membrane
potential depolarizes to −55mV
voltage gated Na+ channels
140
also called threshold
Voltage-Gated Na + Channels
141
when does Sodium rushes in due to the electrochemical
gradient
during Voltage-Gated Na + Channels
142
Membrane potential climbs toward sodium
equilibrium potential
Voltage-Gated Na + Channels
143
These channels are deactivated at +30mV.
Voltage-Gated Na + Channels
144
what happens when voltage gated K+ channels are at 30mV
voltage-gated K +
channels open, and K + rushes out of the cell
following the electrochemical gradient
145
This makes the cell repolarize back toward
the potassium equilibrium potential
voltage gated K+ channels
