Midterm 1 - Nerve Cell Function/Synaptic Transmission Flashcards
1
Q
what does the sensory system consist of
A
sensory nerve fibers from sensory cells
2
Q
what kind of system is the sensory system
A
afferent
3
Q
where is info generated
A
central nervous system
4
Q
what does the CNS consist of
A
brain and spinal cord
5
Q
what is the peripheral nervous system
A
info conveyors
6
Q
what is the somatic motor sytem
A
specialized system that focuses on skeletal muscle
7
Q
what does the somatic motor system consist of
A
motor nerve fibers to skeletal muscles
8
Q
what kind of system is the somatic motor system
A
efferent
9
Q
what two systems are a part of the autonomic system
A
sympathetic nervous system
parasympathetic nervous system
10
Q
what does the autonomic system consist of
A
motor nerve fibers to glands, the heart, and smooth musculature
11
Q
when is the sympathetic nervous system activated
A
during critical situations
12
Q
when is the parasympathetic nervous system activated
A
at rest
13
Q
what type of system is the autonomic system
A
efferent
14
Q
what are the 2 types of cells that compose nervous tissue
A
neurons
glial cells
15
Q
what are the nerve cells able to transmit info
A
neurons
16
Q
what are neutrons composed of
A
cell body and processes (axons and dendrites)
17
Q
what does the axon do
A
move info away from cell body
18
Q
what does the dendrite do
A
moves info towards cell body
19
Q
what does the cell body do
A
integrates in- and outgoing info
20
Q
what can neurons be categorized based on
A
the number of processes
21
Q
what are the 3 categories
A
multipolar
pseudounipolar
bipolar
22
Q
where are multipolar neurons mainly found
A
CNS
23
Q
where are pseudounipolar neurons mainly found
A
PNS
24
Q
where are bipolar neurons mainly found
A
sensory organs
25
what can neurons be classified by
function
26
what type of neuron is from PNS to CNS
sensory (afferent)
27
what type of neuron is from CNS to muscles and glands
motor (efferent)
28
what type of neuron relay info between neurons within the CNS
interneurons (associations)
29
what are specialized "receptors"
transducers
30
what do transducers do
convert stimuli to signal
31
what are glial cells
non-neuronal cells
32
are neurons or glial cells more abundant and by how much
glial cells - 10x more abundant
33
examples of glial cells
oligodendrocytes
astrocytes
ependymal cells
microglia
34
why do we need glial cells
there is no structural support or access to blood without them
35
what do glial cells provide
structural support to nervous tissue
36
what do glial cells participate in
myelin formation
37
what type of glial cells participate in myelin formation
oligodendrocytes
38
what do glial cells secrete
glutamate
39
what does the secreted glutamate do
modulate excitatory level of neurons
40
what type of glial cell modulates excitatory levels of neurons
astrocytes
41
what to microglia possess
phagocytic activity
42
what is special about glial cells
they contact both blood and neurons
43
what do glial cells do due to it being the contact between neurons and blood
transport of nutrients
44
what do neurons not store
glucose
oxygen
45
what does grey matter correspond to
cell bodies
46
what does white matter correspond to
bundles of nueron processes
47
what gives white matter the white appearance
myelin sheaths
48
what are nerves
bundles of axons
49
where do nerves run
to or from the CNS
50
what are ganglia
clusters cell bodies of sensory neurons - outside of the CNS
51
where are cell bodies of motor nerves located
in the CNS
52
what is myelin
white lipid around nerve fibers
53
what is the white lipid of myelin called
sphingomyelin
54
do all fibers have myelin
no, only white matter
55
what are the interruptions in myelin called
nodes of Ranvier
56
what is the distance between nodes of Ranvier
every 1-2 mm
57
what does every cell body possess
resting membrane potential
58
what does the resting membrane potential result from
a difference in charge across the cell membrane (between cytosol and extracellular fluid)
59
what is the charge difference in resting membrane potential
the inside of the membrane is negative RELATIVE to outside
60
what does the difference in absolute value between cell types depend on
amount of charges
ion channels
thickness of membrane
61
what is the average RMP in nerve cells
-70 to -90 mV
62
is resting membrane potential maintained
always
63
where is the charge electro neutral
intra- and extracellular compartments
64
what charges occur in cytosol
negative charges carried by large organic molecules are attracted to the membrane by the positive charges on the outside
65
what maintains the resting membrane potential
selective permeability
Na+/K+ pump
Large anions trapped on inner surface of membrane
66
what is the ratio of Na+ and K+ to maintain RMP
3 Na+ out
2 K+ in
67
what is the selective permeability to maintain RMP
passive based on diffusion - passive ion leakage through channels (concentration gradient)
68
are anions of negative or positive charge
negative
69
why does the RMP not achieve equilibrium
the Na+ / K+ pump
70
is the resting membrane permeable to K+
yes
71
is the resting membrane permeable to Na+, Cl-, and Ca2+
barely - positive charges accumulate outside
72
what does Na+ go against
concentration gradient and against membrane polarity
73
how much energy do ion pumps require
lots: 40% of ATP availability
74
what are excitable cells
cells that can generate electrical impulses (APs)
75
what do excitable cells need in order to generate action potential
stimulation
76
what is the refractory period
the time when neurons cannot be restimulated - until RMP is restored
77
types of gated channels
voltage-gated
ligand-gated
ion-gated
78
what are ligand gated channels
binding cites for neurotransmitters
79
what is each channel composed of
several subunits
80
what does each channel have various degrees of
specificity
81
what rule do nerve cells follow
all-or-none rule
82
what does the all-or-none rule involve
when threshold is met, an AP is generated
83
does the amplitude of AP change per cells
no, it is fixed for that cell
84
what is intensity of a AP encoded by
the frequency of APs, not the amplitude
85
how does an AP work
depolarization and repolarization processes propagate along cell membrane
86
why is the change in potential needed
to reach threshold on the nearby micro domain to trigger opening of gated channels
87
what is the difference between APs in myelinated or unmyelinated axons
myelinated - only occurs at the nodes of Ranvier
88
are myelinated or unmyelinated fibers faster at transmitting connection
myelinated
89
what is saltatory conduction
the current jumping from one node to another due to myelin preventing ion leakage
90
what makes the speed of connection so much faster in myelinated axon
velocity increases as less membrane is affected = less energy required to transport ions
91
what does nerve velocity (AP speed) depend on
dissipation of current
92
factors that effect dissipation of current
thickness of myelin
diameter of the fiber
93
what diameter of the fiber leads to faster AP
thicker = faster
94
what is synaptic transmission
continuity of signal between neurons or between a neuron and a target cell
95
example of target cells involved in synaptic transmission
skeletal muscle (neuromuscular synapse)
96
what is the electric insulator
cell membrane made of phospholipids
97
what is the synaptic gap/cleft
the gap between pre and post synaptic cell membranes
98
gap junction
rarely, direct continuity in electric impulse
99
what are neuronal synapses in vertebrates
predominantly chemical synapses
100
what does electrical activity to get across synaptic cleft
neurotransmitter
101
what are neurotransmitters
molecules able to transmit info from a neuron
102
what do neurotransmitters do
convert electrical signal (AP) into a chemical signal
103
what are neurotransmitters classified on
their molecular size and composition
104
2 classifications of neurotransmitters
small molecules
neuropeptides (3-40 AA)
105
where are small molecule neurotransmitters synthesized
nerve terminals by specific enzymes at level of cell body
106
what are small molecule neurotransmitters
amino acid derivatives ; biogenic amines
107
where are neuropeptides synthesized
cell body
108
where are neuropeptides packaged
secretory vesicles
109
where are neuropeptides transported
site of release
110
where is postsynaptic folding common
in neuromuscular synapse
111
where is postsynaptic folding not common
in interneurons
112
what does postsynaptic folding do
increases surface
113
what is the neuromuscular synapse transmitter
Acetylcholine
114
can receptors get desensitized
yes - when continuously stimulated
115
what does 1 neuron = in the case of neuromuscular synapse
1 neuron = AP = muscle cell depolarization
116
in neuron-neuron synapse, what can 1 neuron receive
impulse from multiple other neurons
117
what are the 2 types of synapses in neuron-neuron synapse
excitatory
inhibitory
118
does 1 impulse always lead to a response in neuron-neuron synapse
no - needs to reach threshold
119
what is excitatory synapse
depolarization = entry of Na+
120
what is inhibitory synapse
hyperpolarization = entry of Cl- and/or outflow of K+
121
does inhibitory synapse raise membrane potential
no
