Biochemistry of Neurotransmission and Neurotransmitters Flashcards
1
Q
The neuron is the basic functional unit of _______.
A
CNS
2
Q
How many synaptic connections from input fibers are there?
A
2.Few hundred to 200, 000
3
Q
The brain is composed of how many neurons?
A
3.100 Billion neurons
4
Q
How many connections between neurons are there?
A
10 raised to the 16
5
Q
What are the 2 types of signal messengers?
A
- Internal and External messengers
6
Q
The signaling mechanism is regulated by what?
A
6.The amount of action potential that can progress or dampen
7
Q
Signals are received from the ________.
A
dendrites
8
Q
The output from the signals are discharged via the _____.
A
axon
9
Q
The main function of this neuron is to initiate the activity of transmitting the information from the receptors to the CNS through the peripheral nerves.
A
Sensory Neurons
10
Q
The main function of this neuron is to relay the signals of the CNS to the effectors.
A
Motor neurons
11
Q
The skin and glands are actual structures that perform functions dictated by the nerve signals. Collectively, they are called the _______.
A
Effectors
12
Q
The myelinated nerves are composed of cells that lay down myelin or sphingomyelin. These cells are also excellent electrical insulators. What are these cells?
A
Schwann cells
13
Q
Schwann cells (increase or decrease) ion flow through the membrane?
A
Decrease.
14
Q
Between the schwann cells are uninsulated area called the ______.
A
Nodes of Ranvier.
15
Q
True or False. Nodes of Ranvier lets ions pass through the membrane with ease.
A
TRUE
16
Q
True or False. Nodes of Ranvier wastes energy.
A
- False, they conserve energy.
17
Q
What is the speed of the increased transmission velocity brought by the Nodes of Ranvier?
A
100 m/sec.
18
Q
True or False. In the processing of information, unimportant sensory information is also processed.
A
False.
19
Q
In the channeling of information, information is directed to proper regions of brain (unidirectionally, bidirectionally).
A
Unidirectionally.
20
Q
What is the integrative function of the CNS?
A
20.Important sensory information is channeled into proper integrative and motor regions of the brain to cause desired responses.
21
Q
Depolarization of the end terminal opens voltage-gated (Calcium, Sodium, Potassium) channels which triggers the release of neurotansmitter.
A
Calcium
22
Q
Once neurotransmitter is released, it will bind to the receptor to transiently open (Calcium, Sodium, Potassium) channels.
A
Sodium
23
Q
The local depolarization brought by the opening of sodium channels further result to opening of voltage-gated (Calcium, Sodium, Potassium) channels to cause widespread depolarization.
A
Sodium.
24
Q
The widespread depolarization brought by the voltage-gated sodium channels opens voltage-gated (Calcium, Sodium, Potassium) channels.
A
Calcium.
25
Calcium enters to what type of receptors in the SR membrane?
Ryanodine receptors.
26
Once calcium attaches to the ryanodine receptors, they open ________________ in the SR membrane to start muscle contraction.
Ligand-gated Calcium channels.
27
Specialized structure or a junction point that transfers info between neurons
Synapse
28
Who coined the term synapse?
28.Sir Charles Scott Sherrington and colleagues.
29
What are the 2 roles of synapse?
1. to determine the direction of spread of signal. 2. to serve as point of control of synaptic transmission.
30
True or False. Synapses have different capacity to transmit signals.
True.
31
What are the two types of synapses?
Electrical and Chemical Synapses.
32
The mediator in an electrical synapse are the _________ while the mediator in a chemical synapse are the ______.
Connexons in gap junctions; Neurotransmitters
33
Nature of Electrical Synapse?
Direct open fluid channels that conduct electricity
34
Nature of Chemical Synapse?
Presence of vesicles that fuse with the presynaptic vesicles.
35
The communication in an electrical synapse depends on 2 factors:
35.1. gap junctions 2. transmission of signals in either direction
36
The communication in a chemical synapse depends on 3 factors:
36.1. nature of the chemical messenger 2. type of post-synaptic receptor 3. mechanism that couples receptors to effector systems
37
What are the three main components of a synapse?
37.1. presynaptic terminal 2. synaptic cleft 3. postsynaptic neuron
38
How many presynaptic terminals are there and their composition?
10, 000 to 200, 000 where 80-95% on dendrites while 5-20% on soma.
39
True or False. Most of the presynaptic terminals are inhibitory.
False, most are excitatory.
40
An autoreceptor is located in the __________.
presynaptic terminal.
41
Width of the synaptic cleft.
200-300 A width
42
The cholinesterase in synpatic cleft is in the ____________.
42. proteoglycan reticulum
43
What are the 2 types of receptor proteins in a postsynaptic neuron?
43.1. binding compartment 2. ionophore.
44
This protrudes outward from the membrane into the synaptic cleft.
Binding compartment.
45
This passes all the way through postsynaptic membrane.
45. Ionophore.
46
What are the 2 types of ionophore.
1. ion channel 2. second messenger activator
47
The ion channel allows passage of 2 specified types of ions: __________ and __________.
47.cation channel (allow sodium ions to pass; excitatory transmitters) and anion channel (allow chloride ions to pass; inhibitory transmitters).
48
The _________ activates a second neuron by releasing G protein.
48.Secondary messenger activator
49
The G protein is regulated by what pathway?
Receptor-tyrosine kinase pathway.
50
What are the four subsequent possible effects of G protein.
50.1. Opening specific ion channels through the postsynaptic cell membrane 2. Activation of cyclic adenosine monophosphate (cAMP) or cyclic guanosine monophosphate (cGMP) in the neuronal cell. 3. Activation of one or more intracellular enzymes directly activate one or moreintracellular enzymes. In turn the enzymes can cause any one of many specific chemical functions in the cell. 4. Activation of gene transcription- can cause formation of new proteins within the neuron, thereby changing its metabolic machinery or its structure
51
What are the other secondary messengers?
Cyclic AMP, Calcium, Diacylglycerol, Nitric Oxide
52
If you repetitively stimulate an excitatory synapse at a rapid rate, it will result to _______.
Fatigue of synaptic transmission.
53
True or False. Stored neurotransmitters can be exhausted.
True.
54
True or False. Postsynaptic membrane receptors can be progressively inactivated.
True.
55
True or False. Inside the postsynaptic neuronal cell, there is fast development of abnormal concentration of ions.
55.False, it is slow development not fast.
56
Synaptic Transmission is affected by ________.
Change in pH.
57
Alkalosis (increase or decrease) excitability
Increase.
58
pH 7.8 - pH 8 causes ____________.
epileptic seizure.
59
Acidosis (increase or decrease) excitability.
Decrease.
60
pH below 7 causes ____________.
coma
61
Hypoxia for a few seconds can lead to __________.
complete inexcitability.
62
List drugs that increase excitability of neurons:
62.Caffeine, Theophylline, Theobromine, Strychnine
63
How does Strychnine works?
It inhibits inhibitory transmitters like glycine.
64
What is the general action of drugs that increase excitability of neurons?
64.They reduce the threshold for excitation.
65
List a drug that decreases synaptic transmission.
Anesthetics.
66
How does an anesthetic works?
66.It increases the threshold for the excitability of neurons.
67
A low molecular weight compound that is secreted from the terminal of a neuron.
Neurotransmitter.
68
What are the two general categories of neurotransmitter.
68.1. small molecular messengers (less than 10 carbons) 2. large neuropeptides (10 or more carbons)
69
Majority of neurotransmitters are _____ and examples of which include _____.
69.small molecular messengers; amino acids, biogenic amines, nucleotides, nucleoside carriers
70
Examples of large neuropeptides.
Met-enkephalin, leu-enkephalin, endorphins, CGRP messengers
71
True or False. For a chemical to be considered as a neurotransmitter, it must be produced and found within the neuron.
True
72
True or False. For a chemical to be considered as a neurotransmitter, it must always release the chemical.
72. False, it should only release the chemical if it is stimulated or depolarization happened, not always.
73
True or False. A neurotransmitter acts on a post-synaptic receptor to cause a biological effect.
True.
74
True or False. Once the neurotransmitter is released, it must be activated for a long while.
74.False, it should be inactivated through a) a reuptake mechanism b) by an enzyme that stops its action
75
True or False. If the chemical is applied on the post-synaptic membrane, it should have a different effect as when it is released by a neuron.
75.False, same effect should be exhibited.
76
What are the three general types of neurotransmitters?
76. Amino acids, monoamines, peptides
77
Examples of amino acids that serve as neurotransmitters:
77. glutamic acid, GABA, aspartic acid, glycine
78
Examples of monoamines:
78.norepinephrine, dopamine, serotonine, acetylcholine
79
What are the 2 neurotransmitters that serve as work-horse neurotransmitters of the brain:
glutamic acid and GABA.
80
What neurotransmitter performs specialized modulating function that is often confined to specific structures?
Acetylcholine.
81
Peptides are neurotransmitters that perform specialized functions in what part of the brains?
Hypothalamus
82
Peptides also act as cofactors, examples of peptides include:
vasopressin, somatostatin, neurotensin
83
What are the 4 types of neurotransmitter vesicles?
Small synaptic clear vesicles, Small synaptic dense vesicles, large dense-cored vesicles, neurosecretory vesicle
84
Small synaptic clear vesicles are found in both ______ and ____________ neurons.
84.Central; peripheral
85
Small synaptic dense vesicles contain ________.
catecholamines
86
Large dense-cored vesicles are less numerous and they contain ______.
neuropeptides.
87
Large dense-cored vesicles are synthesized and filled in the ____________.
neuromal stroma.
88
Neurosecretory vesicles contain neurohormones that are found in the ______.
88.axon terminals in neurohypophysis.
89
Small molecular neurotransmitters such as acetylcholine are synthesized in the ____.
89.cytosol of axon and axon terminals.
90
Small molecular neurotransmitters such as norepinephrine are synthesized in the ____.
vesicles
91
Neuropeptides are made in the ___ and processed in ______.
soma; vesicles from golgi complex.
92
The release of neurotransmitters is aided by ________and ______.
92.docking proteins and calcium ions.
93
These proteins concentrate neurotransmitters in synaptic vesicles up to 10-1000 times.
93.Transport proteins.
94
The synaptic vesicles are localized in the _________.
active zones
95
What proteins helps in clustering synaptic vesicles?
Synapsin
96
Chemical neurotransmitters act based on ____ and _______.
96.Nature of chemical messenger and type of post-synaptic receptor
97
Examples of excitatory neurotransmitters:
97.Ach, glutamate, serotonin [opens cation channels]
98
Examples of inhibitory neurotransmitters:
GABA and glycine [opens anion channel]
99
What are the four mechanisms that couples receptors to effector systems?
99.Ligand-gated/ion channel-linked, G-protein-linked, Enzyme-linked, Ligand-dependent regulators of nuclear transcription
100
Two types of receptors:
100.cholinergic and adrenergic receptors
101
2 types of cholinergic receptors and function.
101.Nicotinic (excitatory) and Muscarinic (inhibitory)
102
2 types of adrenergic receptors and function.
102.Alpha-adrenoceptor (vasoconstriction) and Beta-adrenoceptor (vasodilation)
103
In the fast transduction mechanism, the postsynaptic receptor is an ion channel associated with small-molecule neurotransmitter. What are the 4 ions involved?
103.Sodium, potassium, calcium, and chloride.
104
In the slow transduction mechanism, the neurotransmitter is a neuropeptide which is tranduced by what type of receptors?
104. G-protein-coupled receptors.
105
In the slow transduction mechanism, the effector is a ____.
105.protein (ion channel or enzyme)
106
What are the two types of receptors?
Ligand-gated and protei-coupled receptors
107
Glycine is an inhibitory neurotransmitter that results to _____.
hyperpolarization.
108
Aspartate is a/an _______ neurotransmitter.
108.Excitatory
109
Glycine and aspartate pair forms in the ______.
ventral spinal cord.
110
_______ is a glycine antagonist which can bind to the glycine receptor without opening the chloride ion-channel (ie, it inhibits inhibition).
110. Strychnine
111
Most common neurotransmitter in the brain.
111.Glutamate and GABA.
112
Major inhibitory neurotransmitter of the brain.
GABA
113
Where is GABA concentrated?
113.substantia nigra & globus pallidus nuclei of the basal ganglia, hypothalamus, periaqueductal grey matter ("central grey") and the hippocampus.
114
GABA is synthesized in the brain from ____.
114.alpha-keto glutarate (reaction is called the GABA shunt)
115
What vitamin is a cofactor in the release of GABA?
115.Vitamin B6
116
As the Kreb’s cycle activity increases, the GABA level _______________.
decreases
117
The GABA receptor is connected to what ion channel?
117.Chloride ion channel.
118
What is the action of benzodiapezines?
118.It increases the frequency of channel opening.
119
What neutralizes the effects of benzodiapezines?
Caffeine.
120
True or False. The GABA concentration in the brain is 200- 1000 times lesser than that of the monoamines or acetylcholine.
120.False, it is greater not lesser.
121
What is the major neurotransmitter in the PNS?
Acetylcholine
122
Dopamine is nearly always inhibitory but its receptors D1 R is ________ and D2 R is ________.
stimulatory; inhibitory.
123
Neurotransmitter involved in regulatory motor activity, mood, motivation, and attention.
Dopamine
124
Too much dopamine.
Schizophrenia
125
Too little dopamine.
Parkinson’s disease.
126
What are the 4 main dopaminergic tracts in the brains?
126.1. nigrostriatial tract 2. tuberoinfundibular tract 3. mesolimbic tract 4. mesocortical tract.
127
What are the 2 adrenergic receptors?
Noradrenalin and serotonin
128
What are the neurotransmitters of the cerebral cortex?
128. 1. glutamate 2. aspartate 3. gamma-aminobutyric acid
129
In glutamate, the pyramidal cells are _______.
excitatory (Glutaminergic)
130
In gamma amino butyric acid, most of the interneurons of the cortex are _____.
inhibitory (GABAergic)
131
Origin and distribution of norepinephrine.
131.Origin - locus ceruleus of pons Distribution - sparsely to all cortical layers.
132
Origin of dopamine.
Substancia nigra-pars compacta and adjacent ventraltegmental area.
133
Origin and distribution of serotonin.
Origin - raphe nuclei Distribution - cortical layers
