Week 3 Nervous system Flashcards
1
Q
What are the two different types of cells Nervous tissue is made up of:
A
neurons and glial cells
2
Q
A neurons function is to :
A
Communicate
3
Q
Neurons are found in the :
A
CNS
4
Q
What are the different types of neurons:
A
sensory, motor, and interneurons
5
Q
Glial cells function are :
A
they are the supporting tissue
6
Q
What are the various types of glial cells?
A
Astrocytes, Oligodendrocytes, Ependymal, Microglia, Satellite cells, Schwann cells
7
Q
Where are glial cells found?
A
some in CNS and some in PNS
8
Q
Oligodendrocyte:
A
(CNS), Myelinate CNS axons, provide structural framework
9
Q
Astrocyte:
A
(CNS)Maintain blood brain barrier, structural support, regulates ion, nutrients, and dissolved gas concentrations, absorbs and recycle neuronstransmitters, FORMS SCAR TISSUE AFTER INJURY
10
Q
Ganglia:
A
Neuronal cell bodies outside of the CNS
11
Q
Ependymal Cells:
A
(CNS) lines ventricles (brain) and central canal (spinal cord), assists in producing CSF
12
Q
Microglia:
A
(CNS) removes cell debris, wastes, and pathogens by phagocytosis
13
Q
Satellite cells:
A
(PNS) surrounds neuron cell bodies in ganglia, regulates O2, CO2, nutrients and neurotransmitter levels around neurons in ganglia
14
Q
Schwann cells:
A
(PNS) are responsible for myelination of peripheral axons in PNS, enclosed in the myelin sheath, participates in repair process after injury
15
Q
Myelin sheath :
A
fatty substance covering the axon, forms in sections, produced by Oligodendrocyte (CNS) & Schwann cells (PNS)
16
Q
Unmyelinated sections are called :
A
Node of Ranvier
17
Q
what is the function of the myelin sheath, why do we need it?
A
speeds up transmission of electrical signal by enabling saltatory conduction, it also insulates axons, & keeps ions in
18
Q
What is saltatory conduction?
A
The process in which the electrical signal hops from one node of ranvier to the next node of ranvier, causing the transmission to speed up
19
Q
Neurons communicate via ____ ____ and _____ _____.
A
chemical signals and electrical signals.
20
Q
Chemical signal are called
A
neurotransmitters
21
Q
Electrical signals are called:
A
action potentials (impulses)
22
Q
Neurons convert _____ _____ into ______ _____.
A
chemical signals into electrical signals . chemical signal->electrical signal->chemical signal
23
Q
Chemical signals are located :
A
between neurons, Axon terminal -> synaptic cleft-> Dendrites/Cell body
24
Q
Electrical signals are located :
A
on neurons, Axon hillock-> Axon body-> Axon terminal
25
What are the two different classes of neurotransmitters:
Excitatory and Inhibitory
26
What is an excitatory neurotransmitter?
Excites the neuron thereby causing an ELECTRICAL signal to be generated.
27
What is an inhibitory neurotransmitter ?
Inhibits the neuron from firing an ELECTRICAL signal.
28
Examples of excitatory neurotransmitters:
Acetylcholine, Dopamine
29
Examples of inhibitory neurotransmitters:
GABA, Serotonin
30
Electrical signals are called ____ _____.
Action potentials
31
where do action potentials occur?
on the axon
32
What triggers an action potential ?
graded potential
33
What do action potentials result in?
neurotransmitter release
34
what is meaning of resting membrane potential ?
Membrane potential of the neuron when it is at rest (not firing any action potentials)
35
What is the value (mv) of resting membrane potential?
-70 mv
36
Action potential will only occur when it reaches _____ mv.
-50 mv, threshold
37
What is the meaning of threshold?
Minimum amount of voltage needed to initiate an action potential
38
How is the membrane able to reach threshold (go from -70mv to -50mv)?
Via graded potential
39
What does graded potential do?
Triggers an action potential to occur
40
What is a graded potential?
Summation of multiple neuronal outputs
41
What is depolarizing graded membrane potential?
When membrane potential becomes POSITIVE and is taken TOWARDS threshold
42
What is another name for depolarizing graded membrane potential?
EPSP (Excitatory post synaptic potential)
43
What causes membrane potential to depolarize?
excitatory neurotransmitters
| Acetylcholine, Dopamine
44
What is hyperpolarizing
| graded membrane potential?
When membrane potential becomes negative and is taken away from threshold
45
What is another name for hyperpolarizing graded membrane potential?
IPSP (Inhibitory post synaptic potential)
46
What causes hyperpolarizing graded potential?
inhibitory neurotransmitters (GABA, Serotonin)
47
What are the two types of graded potential types?
Depolarizing & Hyperpolarizing
48
How do depolarizing graded potentials work?
Excitatory neurotransmitter is released-> binds to receptor->this opens ligand gated NA+ (sodium) channel->NA+ enters-> membrane becomes positive (taken towards threshold)
49
How do hyperpolarizing graded potentials work?
Inhibitory neurotransmitter is released-> binds to receptor-> this opens the ligand gated Cl- (chloride) channel-> Cl- enters-> membrane becomes negative (taken away from threshold, action potential cannot be generated)
50
What are the three phases of an action potential?
Depolarization (D, 1st phase),
Repolarization (E, 2nd phase), &
Hyperpolarization (F, 3rd phase)
51
Graded potential occurs on :
cell body and dendrites
52
Depolarizing action potential is due to :
Opening of Voltage gated sodium Channels and sodium (Na+) enters / influx
53
What is another name for depolarization in action potential?
upstroke
54
At what value do the voltage gated Na+ channels close and depolarization end?
+30 mv
55
At what value does the depolarization process start in action potential ?
-50 mv
56
What is another name for repolarization?
downstroke
57
At what value does repolarization start?
+30 mv
58
At what value does repolarization end?
-70 mv
59
Repolarization is due to :
Opening of Voltage gated Potassium Channels and Potassium (K+) exits / efflux
60
Hyperpolarization is due to :
Voltage gated Potassium Channels being open due to slow closure and thus more Potassium (K+) continues to exit / efflux
61
At what value does hyperpolarization start?
-70 mv
62
At what value does hyperpolarization end?
-90 mv
63
How do you bring the membrane of -90mv back to resting membrane potential of -70mv?
Sodium potassium pump
64
Action potential will always have the _____ _______.
Same appearance
65
What is the all or none phenomenon in action potential
Threshold must be reached for an action potential to be generated (no threshold no action potential).
66
what is the self propagating event in action potentials?
when the action potential propagates itself from axon hillock down to axon terminal
67
What are the two things that increase the speed of an action potential?
increase diameter and increase insulation (more myelin)
68
What are refractory periods in action potentials?
resting periods
69
What are the two refractory period types?
Absolute Refectory Period & Relative Refractory Period
70
What is absolute refectory period?
Another action potential CANNOT be generated regardless of the strength of the stimulus
71
what is relative refectory period?
Another Action potential CAN be generated if the stimulus is stronger than the original
72
In what part of action potential is the absolute refractory period in place?
Depolarization(D) & Repolarization(E), another action potential cannot be generated during Depolarization and repolarization
73
In what part of action potential is the relative refractory period in place?
Hyperpolarization(F), another action potential can be generated during hyperpolarization
74
Why can an action potential be generated in relative refectory period, but not in absolute?
In Absolute refectory period, it is because the sodium channels are already open. In relative refectory period, the sodium channels are closed and inactive. The channels can then be forced open w/ a stronger stimulus.
75
synaptic transmission steps
action potential arrives at axon terminal->voltage gated Ca2+ (calcium) channels open & Ca2+ enters->Ca2+ enters axon terminal causing the neurotransmitter containing synaptic vesicles to release contents via exocytosis->neurotransmitter diffuses across synaptic cleft and binds to specific receptors on post synaptic membrane
76
What will happen to the postsynaptic membrane once the neurotransmitter binds to it? and what type of graded potential?
Graded Potential will be generated. the type of graded potential depends of the type of neurotransmitter released
77
If an excitatory neurotransmitter is released it will bind to a ____ gated ____ channel causing resting membrane potential to move ____ ____.
ligand gated sodium channel, towards threshold.
78
If an inhibitory neurotransmitter is released it will bind to a ____ gated ____ channel causing resting membrane potential to move ____ ____ ____.
ligand gated chloride channel, away from threshold
79
Excitatory neurotransmitters result in a ______ type of graded potential on the _______ ______.
depolarizing, postsynaptic membrane
80
Inhibitory neurotransmitters result in a ______ type of graded potential on the _______ ______.
hyper-polarizing, postsynaptic membrane
81
Neurotransmitters are ____ lived.
short
82
If neurotransmitters aren’t removed from the synaptic cleft they will ____ to the ___ and cause a change to the _____ _____. (stimulate / inhibit)
re-bind, receptors, post synaptic membrane
83
What are the four ways via which the neurotransmitter can be removed?
diffusion, phagocytosis, reuptake mechanisms, and enzyme degradation
84
What is diffusion?
when the neurotransmitters diffuse out of the synaptic cleft
85
What is phagocytosis?
when neurotransmitters are phagocytosed by the WBCs (microglial cell)
86
what is a reuptake mechanism?
Presynaptic membrane will take the neurotransmitter back into its terminal
to be repackaged for a new cycle
87
what is Enzyme Degradation ?
when an enzyme breaks the neurotransmitter into inactive components
88
The autonomic nervous system is the _____ branch of the PNS.
motor
89
The autonomic nervous system regulates _______ ______. (breathing, digestion)
unconscious function
90
what are the two subtypes of the autonomic nervous system, they work opposite of each other.
Sympathetic & parasympathetic
91
What are the two classes of neurons that work in the autonomic nervous system?
preganglionic and postganglionic.
92
Preganglionic neuron starts in the ____ and synapses in the ______.
CNS, ganglion
93
Postganglionic neuron starts in the ______ and goes to the ____ _____.
ganglion, target organs
94
Sympathetic nervous system is activated when the body senses ____ and increases activity of ___ organs.
stress, vital ("fight or flight")
95
Parasympathetic nervous system is activated when the body is ____ and increases activity of _______ organs.
calm, non-vital ("rest & digest")
96
In the sympathetic nervous system, the ganglions are in the ______ _____.
paravertebral chains
97
In the parasympathetic nervous system, the ganglions are in the ______ _____.
target organs
98
Preganglionic neurons in the sympathetic nervous system release:
acetylcholine
99
Postganglionic neurons in the sympathetic nervous system release:
norepinephrine & epinephrine
100
The receptors in the sympathetic system are collectively called the _____ receptors.
adrenergic
101
What are the two main classes of adrenergic receptors?
Alpha (1,2) & Beta (1,2,3)
102
In the parasympathetic nervous system the preganglionic and postganglionic neurons both release
acetylcholine
103
The receptors in the parasympathetic nervous system are collectively called the ______ receptors.
cholinergic
104
What are the two main classes of cholinergic receptors?
Nicotinic (N,M) & Muscarinic (1,2,3,4,5)
