Lecture Exam 2- Ch. 5 Flashcards
1
Q
regulate and control other systems of the body by communicating through electrochemical impulses
- CNS & PNS
A
nervous system
2
Q
brain and spinal cord
A
Central Nervous system (CNS)
3
Q
- afferent division & efferent division
- sensory & motor
A
peripheral nervous system (PNS)
4
Q
- somatic sensory
- visceral sensory
- special sensory
A
afferent division
5
Q
somatic motor & Autonomic motor (sympathetic, parasympathetic, enteric)
A
efferent divison
6
Q
respond to stimuli, conduct electrical activity, release chemical regulators
-pseudounipolar (unipolar)
-bipolar
-multipolar
A
neuron
7
Q
structural classes of neurons: based on
A
of processes
8
Q
ex: sensory neurons
A
unipolar neuron
9
Q
ex: motor & interneurons
A
multipolar neuron
10
Q
single process of the neuron that carries an electrical signal (action potential) away from the cell body toward a target cell
A
axon
11
Q
one of many branchlike processes that extends from the neuron cell body and functions as a contact for incoming signals (synapses) from other neurons or sensory cells
A
dendrites
12
Q
organizes & keeps the cell functioning
A
cell body
13
Q
protects the cell
A
cell membrane
14
Q
generates an impulse in the neuron
- tapering of the neuron cell body that gives rise to the axon
- enough positives than AP goes through the neuron
A
Axon hillock (initial segment)
15
Q
gap between two myelinated regions of an axon, allowing for strengthening of the electrical signal as it propagates down the axon
A
Node of ranvier
16
Q
lipid-rich layer of insulation that surrounds an axon, formed by oligodendrocytes in the CNS and Schwann cells in the PNS; facilitates the transmission of electrical signals
A
Myelin sheath
17
Q
end of the axon, where there are usually several branches extending toward the target cell
A
axon terminal
18
Q
produces the myelin sheath in PNS
A
Schwann cell
19
Q
glial cell type in the CNS that provides the myelin insulation for axons in tracts
A
Oligodendrocyte
20
Q
Conduct impulses from sensory receptors to the CNS
A
sensory neurons
21
Q
Conduct impulses from the CNS to target organs (muscles or glands)
- somatic & autonomic
A
motor neurons
22
Q
responsible for reflex & voluntary control of skeletal muscles
A
somatic
23
Q
responsible for innervation of smooth muscle, cardiac muscle & glands
A
Autonomic
24
Q
Located completely within the CNS and integrate functions of the nervous system
A
Association Neuron/Interneuron
25
-constitute about half of the cels in the CNS
-can divide by mitosis unlike neurons
-provide physical & metabolic support
glial cells of the CNS
26
-microglia
-ependymal cells
-oligodendrocyte
-astrocytes
types of glial cells in the CNS (CNS glia)
27
immune surveillance & phagocytosis
microglia
28
creating CSF
- regulate production of cerebrospinal fluid
ependymal cell
29
support
- abundant & aid in development
astrocytes
30
insulation, myelination
oligodendrocytes
31
myelin forming cells called _____ in the CNS, ______ cells in the PNS
same function but different name
oligodendrocytes, Schwann
32
- Lipid-rich layer of insulation that surrounds an axon, formed by oligodendrocytes in the CNS & Schwann cells in the PNS
- Facilitates the transmission of electrical signals
myelin sheath
33
a physiological barrier that keeps many substances that circulate in the rest of the body from getting into the CNS, restricting what can cross from circulating blood into the CNS
- Glucose & amino acids can pass through
Blood-brain barrier (BBB)
34
found in the postsynaptic membrane. These open in response to the binding of receptor proteins to their neurotransmitter ligands
chemically regulated channels
35
protein channel in the membrane opening IN response to stimulus of depolarization to a threshold level
Voltage-regulated channels
36
- neurons have a resting potential of -70mV
- established by large negative molecules inside the cells
- Na+/K+ pumps
- permeability of the membrane
at rest, there is a high concentration of K+ inside the cell and Na+ outside the cell
ions constantly move to maintain the concentration gradients
membrane potential
37
opening in response to binding of a chemical ligand to its receptor
- binding of signaling molecules
ligand gated
38
protein channel, when stimulated depolarizes membrane to threshold, specific to an ion
voltage gated
39
open when physical deformation to membrane occurs (like stretching)
mechanical gated
40
changes in membrane potential are controlled by changes in the flow of ions through channels
voltage-gated channels on axons
41
-open at +30mV (inside cell)
-slower to open and close
voltage-gated K+ channels
42
- open at negative values (change from -70mV)
- respond faster at threshold (AP) (-55mV approx.)
- inactivate & close at +30mV, breaking positive feedback loop
voltage-gated Na+ channels
43
-a approximate value for an action potential to occur
-a approximate value where the stimulus strength doesn't matter after passing this point
--strength of stimulus affects frequency of AP and may recruit more neurons to have AP
threshold
44
all or nothing electrical event in a single cell where the membrane potential quickly becomes positive and returns to resting potential
action potential
45
all or nothing electrical event in a single cell where the membrane potential quickly becomes positive and returns to resting potential
action potential function
46
local anesthetics (e.g. novocaine, & lidocaine) bind to voltage-gated Na+ channels & therefore block response to initial depolarization- the channels do not open
ex. epidural
drug facts
47
time during the refractory period when a new action potential can only be initiated by a stronger stimulus than the current action potential because voltage-gated K+ channels are not closed
Relative refractory periods
48
time during an action period when another action potential cannot be generated because the voltage-gated Na+ channel is inactivated
Absolute refractory periods
49
-Na+ channels are inactivated
-as soon as inactivation is removed and Na+ are closed, the channel can reopen to second stimulus
why absolute refractory periods happen
50
change in a cell membrane potential from rest toward zero; inside of the membrane becomes less negative compared to outside of the membrane
depolarization
51
return of the membrane potential to its normally negative voltage at the end of the action potential after depolarization
Repolarization
52
increase in negativity of inside of cell membrane with respect to the resting membrane potential (membrane potential becomes more negative)
Hyperpolarization
53
- depolarization of the first AP is the stimulus for the new AP in the region just ahead of it and so on...
- each AP is its own separate event and is said to be regenerated
- however: positive feedback of Na+ allows the AP to travel without decrement (decrease)(regenerating this AP fully) thus reaching the end with the same amplitude
action potential conduction
54
-myelinated neurons: myelin prevents Na+ and K+ from moving through the membrane
- AP move faster due to 'leaping from node to node; compared to ion channels located ALL along the axon
saltatory conduction
55
the conduction rate is slow because so many AP's are generated, each one an individual event.
unmyelinated
56
more charge arrives at nodes due to myelin insulation preventing charge leaking out, therefore AP moves faster
myelinated
57
due to ions moving only at the nodes and restoring fewer ions, the ion channels do less work, saving energy
AP myelination
58
narrow junction across which a chemical signal passes from neuron to the next, initiating a new electrical signal in the target cell
synapse
59
conducting signal towards synapse
presynaptic
60
conducting signals away from synapse
postsynapse
61
-pre- and post synaptic cells are connected by gap junctions
-current flow continues quickly across the gaps
-found in cardiac, smooth muscle to allow contraction as a unit to occur
functional anatomy of synapse: electrical
62
-the majority
-axon terminals hold synaptic vesicles
-pre-synaptic neurons release neurotransmitters
functional anatomy of synapse: chemical
63
a chemical messenger that travels across the synaptic cleft and binds to receptors on post-synaptic neurons
neurotransmitters
64
calcium ions trigger a change in the SNARE proteins that lead to the fusion & release of the neurotransmitter
-SNARE proteins loosely dock vesicles
mechanisms of neurotransmitter release
65
1. AP arrives at axon terminals
2. voltage-gated Ca2+ channels open & Ca2+ enters the axon terminal (keeping excitement open)
3. Ca2+ entry causes neurotransmitter-containing synaptic vesicles to release their contents by exocytosis
4. neurotransmitter diffuses across the synaptic cleft & bind to ligand-gated ion channels on the postsynaptic membrane
5. binding of neurotransmitter opens ligand-gated ion channels, resulting in graded potentials
6. reuptake by the presynaptic neuron, enzymatic degradation, and diffusion reduce neurotransmitter levels, terminating the signal
neurotransmitter release
66
example of neurotransmitter at the synapse
-remember these channels are ligand-gated (binds the Ach)
acetylcholine
67
-Ach binds @ postsynaptic cell, ex. skeletal muscle cells (how muscles contract)
-binding of 2 acetylcholine molecules opens a channel
--due to electrochemical gradient, more Na+ flows in than K+ out, EPSP (excite) is begun
nicotinic Ach receptors
68
nicotinic Ach receptors: agonist (mimic)
nicotine
69
nicotinic Ach receptors: antagonist (opposite)
curare (poison)
70
-Ach binds at post synaptic cells, ex. digestive cells or cardio cells
-binding at the receptor opens ion channels indirectly by using a G-protein
--dopamine and norepinephrine receptors do this too
muscarinic Ach receptors
71
muscarinic Ach receptors: agonist
muscarine
72
muscarinic Ach receptors: antagonist
atropine
73
1. ACh binds to the receptor
2. G-protein subunit dissociates
3. G-protein binds to K+ channel, causing it to open
Muscarinic ACh receptors- Mechanism
74
- Opening K+ or Cl- channels results in a graded hyperpolarization
- Brings postsynaptic membrane further from threshold(hyperpolarizing)
- Decreasing the likelihood of an action potential
Inhibitory postsynaptic potential (IPSP)
75
- Opening Na+ or Ca 2+ channels results in a graded depolarization
- Brings postsynaptic membrane closer to the threshold (depolarizing)
- Is a graded potential
Excitatory postsynaptic potential (EPSP)
76
change in the membrane potential that varies in size, depending on the size of the stimulus that elicits it
- amplitude decreases as signal moves toward axon hillock
graded potential
77
characteristics of graded potentials
summation & lack of a refractory period
78
graded potential zone
-90mV to -55mV
79
threshold
-55mV
80
when a sensory neuron receives a stimulus that brings it to the threshold, what will it do
- become depolarized
- transduce the stimulus to an action potential
- cause the release fo neurotransmitters onto cells in the central nervous system
81
if an EPSP and IPSP signal is received at the dendrite, will there be an action potential generated at -65mV
no bc it does not meet the threshold (-55mV)
82
synthesized from amino acids
- Ex: dopamine, norepinephrine, epinephrine (not common), all 3 called catecholamines. All use a second messenger system
-- After activating their receptors they are transported back into axon terminal or broken down by enzymes
-- Neurons releasing catecholamines located in the CNS: regulate mood, attention, hormone release, states of consciousness and more
monoamines
83
a monoamine oxidase (enzyme breaking down monoamines) inhibitor may be used.
- It inhibits the process of breaking down the catecholamine by enzymes, therefore, increasing the concentration of dopamine and norepinephrine at a synapse
to treat depression
84
dopamine, norepinephrine, epinephrine
catecholamines
85
neurotransmitter in your brain & spinal cord
- increases alertness, arousal & attention
- constricts blood vessels, which help maintain blood pressure in times of stress
norepinephrine
86
fight-or-flight response; also called adrenaline
- released by your adrenal glands in response to stress
- plays a role in metabolism, attention, focus, panic & excitement
- made by the adrenal medulla
epinephrine
87
localized collection of neuron cell bodies in the peripheral nervous system
ganglion
