Cellular Communication Flashcards
1
Q
Types of intercellular communication by chemicals
A
Endocrine
Paracrine
Autocrine
2
Q
Signaling molecule is secreted by a cell and transported through the circulation where it acts on a distant target cell
A
Endocrine cell signaling
3
Q
Chemical signaling molecule is released by one cell and acts locally to regulate the behavior of a neighboring cell
A
Paracrine cell signaling
4
Q
A cell responds to a signaling molecule that it also produced
A
Autocrine cell signaling
5
Q
Any chemical that binds to a receptor is a ____
A
Ligand
6
Q
What is another name for ligand?
A
First messenger
7
Q
What results from signal recognition and transduction of an extracellular message ?
A
Second messenger or
Catalytic cascade
8
Q
Four types of receptor-based signal transducers
A
- Transmembrane G protein couple receptors
- Transmembrane ligand-gated ion channels
- Transmembrane enzyme-linked receptors
- Soluble intracellular (nuclear) receptors
9
Q
What are the four categories of small, hydrophilic chemical messengers?
A
Amino acids
Biogenic amines
Choline esters
Idothyronines
10
Q
Four examples of amino acid chemical messengers
A
Glycine
Glutamate
GABA
Aspartate
11
Q
Five examples of biogenic amine chemical messengers
A
Dopamine
Norepinephrine
Epinephrine
Serotonin (5-HT)
Histamine
12
Q
Example of a choline ester
A
Acetylcholine
13
Q
Two idothyronines
A
Thyroxine (T4)
Triiodothyronine (T3)
14
Q
What chemical messengers are derived from tyrosine?
A
Dopamine
Norepinephrine
Epinephrine
Idothyronines (T4 and T3)
15
Q
What are some general features of small, hydrophilic chemical messengers?
A
Polar molecules that are ionized at physiologic pH
Need cell-surface receptors to cross plasma membranes
Stored in vesicles in the cells that synthesized them
Typically released by exocytosis (excluding T3 and T4)
16
Q
Three general categories of lipophilic chemical messengers
A
Steroids
Eicosanoids
Other
17
Q
Examples of endogenous steroids
A
Aldosterone
Cortisol
Testosterone
Progesterone
Estrogens
18
Q
Examples of eicosanoids
A
Prostaglandins
Leukotrienes
Thromboxanes
19
Q
Two miscellaneous lipophilic chemical messengers
A
Vitamin D3
Retinoids
20
Q
What are general characteristics of peptide and protein chemical messengers?
A
Usually polar (hydrophilic)
Do not readily cross plasma membranes = usually bind to cell surface
Synthesized as precursor molecules
Stored in vesicles in the cells that synthesized them
Circulate in the blood stream as unbound molecules
21
Q
What is the sequence of signal transduction through G protein-coupled receptors?
A
First messenger (ligand) > GPCR > Effector > Second messenger > Cellular response
22
Q
What are the three components of signal transduction through GPCRs?
A
- A plasma membrane receptor with seven transmembrane helical segments
- A guanosine nucleotide- binding protein activates the effector enzyme or pathway
- An effector (usually an enzyme) in or associated with the plasma membrane that generates an intracellular second messenger
23
Q
What are the heterotrimeric G protein families?
A
Gs
Gi
Gq
G12, 13
24
Q
Enzyme that produces cyclic adenosine monophosphate
A
Adenylyl cylase
25
Enzyme that produces inositol triphosphate (IP3) and diacylgycerol (DAG)
Phospholipase C
26
Enzyme that produces eicosanoids
Phospholipase A2
27
Intercellular junction that helps the nervous system communicate
Synapse
28
Two types of synapses
Chemical
Electrical
29
Which type of synapse is most prevalent?
Chemical
30
Signals flow directly from one cell to another in a bi-directional fashion
Electrical synapses
31
Signal travels in one direction from the presynaptic membrane to the postsynaptic membrane across a synaptic cleft
Chemical synapses
32
Two types of receptors at chemical synapses
Ion channels (ionotropic)
Heterotrimeric G proteins (metabotropic)
33
Three signals that open pores in gated ion channels
Membrane voltage (electrical)
Chemicals (ligands)
Pressure (mechanical)
34
Primary neurotransmitter of peripheral efferent neural pathways
Acetylcholine
35
Where does ach synthesis take place?
Presynaptic nerve terminal
36
Type of Ach receptor that is ionotropic
Nicotinic
37
Type of Ach receptor that is metabotropic
Muscarinic
38
Ach substrates
Acetyl-CoA
Choline
39
Primary excitatory neurotransmitter in the brain
Glutamate
40
Responses to glutamate
Motor neuron activation
Pain pathway transmission
Elevated pain sensation (hyperalgesia)
Memory formation
Cerebral neurotoxicity
41
Primary inhibitory neurotransmitter in the brain
GABA
42
Primary inhibitory neurotransmitter in the spinal cord and lower brainstem
Glycine
43
Where is glutamate synthesized?
In the brain (it cannot cross BBB)
44
What alpha G protein subunit results in the increased production of cAMP from adenylyl cyclase?
Gs
45
What G protein alpha subunit stimulation results in decreased production of cAMP from adenylyl cyclase?
Gi
46
What enzyme produces cAMP?
Adenylyl cyclase
47
What enzyme produces inositol triphosphate?
Phospholipase C (PLC)
48
What enzyme produces diacylglycerol?
Phospholipase C
49
What enzyme produces eicosanoids?
Phospholipase A2 (PLA2)
50
What is the precursor for cAMP?
Adenosine triphosphate (ATP)
51
What is the precursor for DAG and IP3?
Phosphatidylinositol 4,5-bisphosphate (PIP2)
52
What G protein and substance are responsible for DAG and IP3 production?
Gq
Ca++
53
What second messenger binds to Ca++ channels on the endoplasmic reticulum resulting in Ca++ release from ER into the cytoplasm?
IP3
54
What second messenger acts as a docking site for and activator of protein kinase C (PKC)?
DAG
55
What second messengers leave the cell and bind to GPCR on the surface of target cells?
Eicosanoids
56
What enzyme liberates arachidonic acid from the cell membrane?
Phospholipase A2 (PLA2)
57
What is the precursor for prostaglandins, thromboxanes, leukotrienes, and CYP450 monooxygenases?
Arachidonic acid
58
What is the precursor for endocannabinoids?
Arachidonic acid
59
What family of enzymes catalyze the addition of phosphate groups to their groups?
Kinases
60
Ion movement during direct excitatory response
Na+ into the cell
Ca++ into the cell
61
Ion movement during direct inhibitory response
Cl- into the cell
62
Signal transduction of Nm ACh receptors
Opens nonselective cation channels > Na+ influx
63
Signal transduction of Nn ACh receptors
Opens nonselective cation channels > Na+ influx
64
Location of Nm ACh receptors
Skeletal muscle at the neuromuscular junction
65
Location of Nn ACh receptors
Autonomic ganglia
Adrenal medulla
CNS
66
Response to Nm ACh receptor stimulation
End-plate depolarization and skeletal muscle contraction
67
Response to Nn ACh receptor stimulation
Depolarization of postsynaptic postganglionic neuron
Secretion of catecholamines
Arousal, attention, analgesia
68
Signal transduction pathway of M1 ACh receptor
Gq > PLC > increase IP3 & increase DAG > increase Ca++ > increase PKC
69
Signal transductions (2) of M2 ACh receptor
Beta/ gamma subunit of Gi > increase K+ channel (GIRK) opening
Gi > inhibits AC > decrease cAMP
70
Signal transduction of M3 ACh receptor
Gq > PLC > increase IP3 & increase DAG > increase Ca++ > increase PKC
71
Signal transductions (2) of M4 ACh receptor
Beta/ gamma subunit of Gi > increase K+ channel (GIRK) opening
Gi > inhibits AC > decrease cAMP
72
Signal transduction of M5 ACh receptor
Gq > PLC > increase IP3 & increase DAG > increase Ca++ > increase PKC
73
Locations of M1 ACh receptors
Autonomic ganglia
CNS
74
Locations of M2 ACh receptors
Cardiac nodal tissue
Cardiac muscle tissue
75
Locations of M3 ACh receptors
Smooth muscle
GI
76
Locations of M4 ACh receptors
CNS
77
Locations of M5 ACh receptors
CNS
78
Response to M1 ACh receptor stimulation
Autonomic- excitatory
Arousal, attention, analgesia
79
Response to M2 ACh receptor stimulation
Slowed spontaneous depolarization (decrease chronotropy); hyperpolarization
Decreased contractility (inotropy); Decreased Dromotropy
80
Response to M3 ACh receptor stimulation
Smooth muscle contraction
Increased salivary secretions
81
Response to M4 ACh receptor stimulation
Presynaptic autoreceptors > negative feedback to suppress ACh release
82
Response to M5 ACh receptor stimulation
Promotes dopamine release, dilation of cerebral arteries
83
Two of the main ionotropic glutamate receptors
NMDA
AMPA
84
How are AMPA receptors activated?
Binding of two glutamate molecules
85
What conditions must be met for full NMDA activation?
Binding of two glutamates
Binding of two glycine molecules
Depolarizing voltage change
86
Glutamate receptor that has non-selective cation channels that are highly permeable to Na+, but poorly permeable to Ca++
AMPA receptor
87
Glutamate receptor that has non-selective cation channels that are highly permeable to Ca++, but poorly permeable to Na+
NMDA receptor
88
Glutamate receptor that has Mg++ bound in the resting state
NMDA receptor
89
Glutamate receptor that depolarizes the postsynaptic membrane d/t glutamate release
AMPA receptor
90
How is the Mg++ block relieved on the NMDA receptor?
Depolarization caused by AMPA receptor activity
91
How is glutamate receptor activation terminated?
1. Transmitter reuptake by presynaptic glial transporters
2. Transmitter diffusion out of the synaptic cleft
3. Receptor desensitization
92
What is exicitoxicity?
Neuronal injury initiated by excessive glutamate receptor activity
93
The majority of hypnotics target what receptor?
GABAa receptor
94
Pentameric ligand-gated Cl- channel
GABAa receptor
95
How are GABAa receptors activated?
By binding of two GABA molecules
96
What type of receptor are GABAb receptors?
Metabotropic
97
Amino acid neurotransmitter formed from serine in an enzyme-catalyzed reaction
Glycine
98
Glutamate is converted to GABA by what type of enzymatic reaction?
Decarboxylation
99
The 5 biogenic amine neurotransmitters
Dopamine
Norepinephrine
Epinephrine
Serotonin
Histamine
100
The 3 catecholamines
Dopamine
Norepinephrine
Epinephrine
101
Most biogenic amine neurotransmitter receptors are what type of receptor?
Metabotropic
102
What type of receptor is the 5-HT3 serotonin receptor?
Ionotropic
103
All catecholamines are synthesized from what amino acid?
L-tyrosine
104
Serotonin is synthesized from what amino acid?
Tryptophan
105
Histamine is synthesized from what amino acid?
Histidine
106
How is tyrosine generated if tyrosine supply is low?
Cells can generate tyrosine from phenylalanine by hydorxylation
107
What is the rate limiting step to in catecholamine synthesis?
Tyrosine hydroxylation by the enzyme tyrosine hydroxylase to form L-DOPA
108
What two enzymes metabolize catecholamines?
Monoamine oxidase
Catechol-O-methyltransferase (COMT)
109
What is the end-product of catecholamine metabolism?
Vanillylmandelic acid (VMA)
110
What is the major metabolite of dopamine?
Homovanillic acid (HVA)
111
What is the metabolite of serotonin?
5-hydroxyindoleacetic acid (5-HIAA)
112
What cells synthesize histamine in the periphery?
Mast cells
Basophils
113
What is the major metabolite of histamine?
Imidazole acetic acid
114
What enzymatic reaction is present in ALL biogenic amine neurotransmitter biosynthesis?
Decarboxylation
115
Where is the largest concentration of dopaminergic neurons in the brain?
Substantia nigra
116
Where is the major concentration of noradrenergic neurons in the CNS?
Locus coeruleus in the pons
117
Where are the two major groups of adrenergic neurons in the CNS?
Rostral ventrolateral medulla
Nucleus tractus solitarius
118
Describe the release of norepinephrine in the peripheral nervous system
From the postganglionic sympathetic neurons onto target tissues
119
Describe the release of epinephrine in the peripheral nervous system
From chromaffin cells of the adrenal medulla into the circulation in response to stress
120
What is the relationship between isoproterenol and alpha- and beta- adrenergic receptors?
Isoproterenol activates beta adrenergic receptors, but alpha adrenergic receptors are poorly activated by isoproterenol
121
Norepinephrine preferentially binds to what receptors?
Alpha 1
Alpha 2
Beta 1
122
Low concentrations of epinephrine has predominantly what effects?
Beta
123
Higher concentrations of epinephrine has predominantly what effects?
Alpha-1
124
Where are serotonin receptors located?
Rostral raphe nuclei > thalamus, limbic system, and cortex
Caudal raphe nuclei > spinal cord and within brainstem
125
Where is the highest density of histamine-containing neurons?
Turberomammillary region of the hypothalamus
126
D2, D3, D4 alpha subunit
Gi
127
Alpha-1 alpha subunit
Gq
128
Alpha-2 alpha subunit
Gi
129
Beta (1,2,3) alpha subunit
Gs
130
5-HT1 alpha subunit
Gi
131
5-HT2 alpha subunit
Gq
132
5-HT4 alpha subunit
Gs
133
Molecule composed of 5-carbon sugar (pentose), a nitrogenous base, at least one phosphate group
Nucleotide
134
What are the main pruinergic transmitters?
ATP, ADP, and adenosine
135
What does a sharp increase in adenosine levels in the extracellular fluid indicate?
Acute oxygen deficiency (stroke, MI, angina pectoris)
136
How are purinergic neurotransmitters metabolized?
5'-AMP
137
Role of P2X receptors on sensory nerves
Detecting and signaling tissue damage and inflammation
138
How is platelet aggregation induced?
ADP binding to P2Y receptors
139
What signaling complex activates nitric oxide synthase?
Ca++/ Calmodulin
140
The 5 types of enzyme-linked receptors
1. Receptor guanyly cyclases
2. Receptor tyrosine kinases
3. Tyrosine kinase-associated receptors
4. Receptor serine/ threonine kinases
5. Receptor tyrosine phosphatases
141
Cytosolic, heme-containing enzyme activated by nitric oxide
Soluble guanylyl cyclase
142
Guanylyl cyclase ligands
Atrial natriuretic peptide (ANP)
Brain atrial natriuretic peptide (BNP)
C-type natriuretic peptide (CNP)
143
Group of enzyme-linked receptors that work in pairs
Receptor tyrosine kinases
144
Receptor tyrosine kinases' ligands
Hormones
Growth factors
145
Genetically regulated cell death
Apoptosis
