exam 4 Flashcards
(107 cards)
1
Q
what happens within the nervous system
A
impulses are transmitted along the specialized plasma membranes of nerve cells
2
Q
central nervous system (CNS)
A
includes the brain and spinal cord
3
Q
peripheral nervous system (PNS)
A
includes other sensory and motor components like: cranial nerves, neuromuscular junctions, spinal nerves
4
Q
what are the 2 types of nervous system cells?
A
nerurons and glial cells
5
Q
neurons
A
cells within the nervous system that send and receive electrical impulses
6
Q
glial cells
A
variety of cell types and are abundant in the central nervous system
7
Q
what are the types of neurons
A
sensory neurons, motor neurons, and interneurons
8
Q
sensory neurons
A
are diverse cells specialized for stimuli detection
9
Q
motor neurons
A
transmit signals from the central nervous system to muscles and glands to make synaptic connections
10
Q
interneurons
A
process signals and transmit information between parts of the nervous system
11
Q
what are the types of glial cells
A
microglia, oligodendrites, schwann cells, and astrocytes
12
Q
microglia
A
fight infections and remove debris
13
Q
oligodendrites + schwann cells
A
form insulating myelin sheath around neurons of the CNS and PNS
14
Q
astrocytes
A
control access to blood borne components into extracellular fluid around nerve cells.
15
Q
myelin sheath
A
protective membrane that surrounds CNS and PNS cells
16
Q
processes that receive signals
A
dendrites
17
Q
processes that conduct signals
A
axons
18
Q
nerve
A
tissue composed of bundles of axons
19
Q
fundamental property of all cells
A
membrane potential
20
Q
synapse
A
the point of contact between a nerve cell, gland, or muscle cell.
21
Q
where do synapses usually occur
A
between axon-dendrite, dendrite-dendrite, or axon-axon
22
Q
what is the property of a cell at rest
A
negative charge outside the cell and positive inside the cell
23
Q
potassium ion gradient
A
uneven distribution of potassium ions in and outside the cell
24
Q
electroneutrality
A
ions are present in solutions in pairs, one negative-one positive
25
counter ion
oppositely charged ion in the solution
26
electrical potential
charges are separated so that one part has more positive charges and another has more negative
27
current
movement of ions
28
whats another name for electrical potential
voltage
29
how is current measured
in amperes (A)
30
action potential
stimuli trigger a rapid set of changes in membrane potential
31
what salts are within extracellular fluid
Na+ and Cl-
32
what macromolecules are within cytosol
proteins and RNA
33
Ion channels
form ion conducting pores through a lipid bilayer
34
leak channel
type of ion channel thats always open
35
potassium leak channel
K+ ions leak out of cell, more anions without counterions resulting in negative resting potential
36
Na+/K+ Pump
continuously pumps Na+ ions out of cell and K+ ions into cell
37
how many Na+ and K+ ions are moved in/out of cell
3 Na+ out, 2 K+ in
38
electrical equilibrium
when a chemical gradient is balanced with electrical potential
39
nernst equation
mathematical relationship between ion gradient and equilibrium potential
40
what happens when K+ diffuses out of the cell
membrane potential becomes more negative
41
what happens when Na+ goes into the cell
the membrane potential becomes more positive, polarizing
42
what happens when Cl- diffuses into the cell
its repelled by the negative potential, and enters with positive ions
43
what happens if the membrane is permeable to K+
the membrane potential will be equal to K+ equilibrium potential
44
what happens when the membrane is permeable to Na+
the membrane will be partly depolarized
45
patch clamping
modern technology thats used to record the ion currents passing through channels
46
optogenetics
genetic engineered channel proteins, and ion concentrations thats manipulated by light
47
bacteriorhodopsin
used to suppress neurons
48
channelrhodopsins
used to activate neurons
49
whats the function of voltage gated ion channels
respond to voltage channels across the membrane
50
voltage gated Na+/ K+ channels are
responsible for action potential
51
what do ligand gated ion channels do
open when a certain molecule binds to it
52
what types of voltage gated ion channels are there
voltage gated potassium channels and voltage gated sodium channels
53
how is channel specifity determined
by the size of the central pore and how it interactions with an ion
54
what is channel gating
channels opening rapidly to stimuli then closing
55
what is channel inactivation
voltage gated channels adopting a second closed state
56
what happens during channel inactivation
voltage gated channels can't reopen immediately even when stimulated
57
describe a resting neuron
closed voltage gated channels. 100x more permeable to K+
58
subthreshold depolarizations
depolarizations too small to initiate action potential
59
steps to the depolarization stage
-membrane is depolarized past the threshold potential then Na+ channels activate
-membrane potential shoots upward fast
-the peak is +40mV
60
steps to repolarization stage
-when peaked the membrane repolarizes
-inactivated Na+ channels stay closed while membrane potential turns negative.
-Cell repolarizes until K+ leaves
61
Hyperpolarization stages
-membrane potential drops below resting potential when K+ increases.
-when K+ voltage gated channels close the membrane potential returns to normal
62
what is the refractory period
a few milliseconds after action potential when another cant be triggered
63
absolute refractory period
sodium channels are inactivated and cant open via depolarization
64
relative refractory period
when the membrane potential is below threshold of another action potential
65
what is myelination
the process where axons are coated with myelin, a fatty sheath that insulates and protects nerve fibers.
66
whats the role of myelination
Myelin increases the speed and efficiency of electrical signal transmission along the axon.
67
saltatory propagation
action potentials jump from one node to the next
68
electrical synapse
one neuron (presynaptic) is connected to another neuron (postsynaptic) via gap junctions
69
what are gap junctions
specialized intercellular connections that allow direct communication between nearby cells
70
how do ions move between cells and why is it efficient
through junctions as it allows no delays in transmission
71
presynaptic neuron
sends a signal to another cell at synapse
72
postsynaptic neuron
receives the signal at synapse
73
chemical synapse
presynaptic and postsynaptic neurons are separated by a small space called the synaptic cleft
74
neurotransmitters
chemical messengers that transmit signals across a synapse from one neuron to another
75
How Do Neurotransmitters Work?
- Released from the presynaptic neuron into the synaptic cleft.
-Bind to receptors on the postsynaptic cell.
-Trigger excitatory or inhibitory effects depending on the receptor type.
76
Types of Neurotransmitters
Excitatory
Inhibitory
Modulatory
77
Excitatory
Increase the likelihood of an action potential (e.g., glutamate).
78
inhibitory
Decrease the likelihood of an action potential
79
Modulatory
Regulate broader neural circuits
80
what is the criteria to be considered a neurotransmitter
occur naturally, be released during presynaptic stimulation, induce the correct response when induced to the synaptic cleft
81
what is the most common neurotransmitter in vertebrates and is it excitatory or inhibitory?
acetylcholine and excitatory
82
cholinergic synapses
synapses that use acetylcholine as their neurotransmitter
83
catecholamines
group of neurotransmitters and hormones derived from the amino acid tyrosine
84
adrenergic synapses
synapses that use catecholamines as neurotransmitters
85
glutamatergic neurons
neurons that use glutamate as their neuro transmitter
86
neuropeptides
small protein-like molecules that act as neurotransmitters
87
endocannabinoids
lipid-based neurotransmitters that regulate a variety of physiological processes
88
Steps in Neurotransmitter Secretion
-electrical signal reaches the presynaptic terminal
-Voltage-gated calcium channels open, allowing calcium ions to enter.
-Synaptic vesicles containing neurotransmitters fuse with the presynaptic membrane.
-Neurotransmitters are released into the synaptic cleft.
-Neurotransmitters bind to receptors on the postsynaptic cell, initiating a response.
89
Role of Calcium in Secretion
Calcium ions trigger vesicle fusion with the membrane by interacting with proteins like SNARE complex
90
active zone
region of the presynaptic membrane where synaptic vesicles dock, fuse, and release neurotransmitters
91
neurotoxins
chemical agents that disrupt normal function in the nervous system by damaging neurons or interfering with neurotransmission
92
Compensatory endocytosis
maintains the size of the nerve terminal by recycling membranes
93
kiss and run exocytosis
a vesicle will temporarily fuse with the membrane, release neurotransmitters, then reseal
94
what is endocytosis
cells take in substances from the outside environment by engulfing them with their cell membrane, forming a vesicle.
95
exocytosis
cells expel substances from inside the cell to the outside environment by fusing vesicles with the plasma membrane.
96
antagonist
bind to receptors and inhibit their activity
97
agonist
bind to the receptor and activates it
98
whats the function of the GAB A receptor
when GAB A binds to a receptor the ligand gated channel releases Cl- ions into the cell, inducing hyperpolarization, decreasing the chances of action potential
99
NMDA receptor
glutamate receptor and ion channel that plays a central role in synaptic plasticity, learning, and memory
100
acetylcholinesterase
enzyme that breaks down acetylcholine into acetic acid and choline
101
neurotransmitter reuptake
neurotransmitters are pumped back into the presynaptic neuron after they have been released
102
postsynaptic potentials
changes in membrane potential due to neurotransmitter binding
103
types of postsynaptic potentials (PSP)
excitatory postsynaptic potential, inhibitory postsynaptic potential
104
excitatory postsynaptic potential
depolarizes the membrane making firing more likely
105
inhibitory postsynaptic potential
hyperpolarizes the membrane making firing less likely
106
temporal summation
multiple postsynaptic potentials (PSPs) from the same presynaptic neuron add together over time, leading to a stronger overall signal
107
spatial summation
multiple postsynaptic potentials (PSPs) from different presynaptic neurons are added together at the same time, resulting in a stronger overall signal
