Cellular communication 6 Flashcards
The brain synthesizes its own histamine from
L-histidine (an amino acid)
One major metabolite of histamine, _______________, can be measured in the urine to determine the amount of histamine that has been released systemically.
imidazole acetic acid
What enzymatic reaction is present in ALL biogenic amine neurotransmitter biosynthesis?
decarboxylation
Biogenic amine neurotransmitters are removed from the synaptic clefty by
reuptake into the presynaptic terminal or uptake into non-neuronal cells and organs
Adrenergic receptors are divided into three main classes with three subtypes each:
alpha 1
alpha 2
beta
Serotonergic neurons play a vital role in
sleep & wakefulness
emotions
cognition
CV
respiratory
& intestinal activities
Derangements of serotonergic pathways contribute to
anxiety
depression
mania
schizophrenia
______________________________- is the target of antagonists that are used to treat postoperative or cancer-chemotherapy-induced nausea and vomiting
the ionotropic 5-HT3 serotonin receptor
Histaminergic neurons play a role in
arousal and attention
memory
learning
mood
L-tyrosine is present in all ______________ and can be synthesized from __________
food products; phenylalanine
Tyrosine is converted into __________ by the rate limiting enzyme _____________-
dihydroxyphenylalanine (DOPA)
tyrosine hydroxylase
Degeneration of dopaminergic neurons in the substantia nigra causes
Parkinson’s disease
Overactive D2-like receptors are implicated in the pathogenesis of
schizophrenia
Two major groups of adrenergic (Epi) neurons have been identified in the CNS:
the rostral ventrolateral medulla
the nucleus tractus solitarius
In the peripheral nervous system, NE is released from most
postganglionic sympathetic neurons onto the target tissues
In the peripheral nervous system, epinephrine is released from
chromaffin cells of the adrenal medulla into the circulation in response to stress
All adrenergic receptors are
metabotropic
What are the alpha 1 subclasses?
alpha1A, alpha1B, alpha1D
What are the alpha 2 subclasses?
alpha2A, alpha2B, alpha2C
What are the beta subclasses?
b1, b2, b3
The adrenergic classes are distinguished by their relative sensitivity to
isoproterenol
Isoproterenol activates _____________receptors, whereas ______________ receptors are very poorly activated by isoproterenol.
beta-adrenergic receptors; alpha-adrenergic receptors
Activation of presynaptic alpha-2 receptors results in _______________- of NE release
inhibition
Three of the four main classes of serotonin receptors are metabotropic and include:
5HT1
5HT2
5HT4
The brain cells synthesize their own histamine from the amino acid
L-histidine
Histidine is ________ to form histamine
decarboxylated
Histamine receptor subtypes are
metabotropic
The largest concentration of dopaminergic neurons in the brain is in what structure?
substantia nigra
What is the substrate for nitric oxide synthase?
a. L-citrulline
b. nitric oxide
c. L-arginine
d. guanosine triphosphate
c. L-arginine
ATP, ADP, and adenosine are __________neurotransmitters
purinergic
Purinergic receptors are
both ionotropic (P2X family) and metabotropic (P1, & P2Y families)
Most neuropeptides are _______ with other transmitters
co-released
All neuropeptides act on ___________ receptors, and most often induce
metabotropic; alterations in the excitability of postsynaptic cells
Nitric oxide is a universal intercellular messenger acting as both an
autocrine and paracrine signaling molecule
Nitric oxide synthase (NOS) converts
L-arginine to L-citrulline and NO
Many effects of NO are mediated locally by soluble
guanylyl cyclase which produces cGMP from GTP
NO plays a role in
central sensitization to pain
At body temperature, NO is a small, lipid-soluble _______
gas that easily permeates lipid membranes, “soaking” the surrounding tissue cells
Conventional neurotransmitters are stored in _______- and released as
synaptic vessels; released as quanta by Ca2+ dependent exocytosis
Nonconventional neurotransmitters cannot be stored in
vesicles and thus are synthesized and released on demand
Purine & pyrimidine nucleotides are key elements in cell physiology because they have the follwoign roles:
precursors of DNA & RNA
components of enzymes
energy currency
allosteric modulators of enzymes
second messengers
auto- and paracrine first messengers
Purine bases are
adenine (A) and guanosine (G)
Pyrimidine bases are
cytosine (C), thymidine (T), and uracil (U)
A nucleotide is a molecule composed of a
5-carbon sugar (a pentose)
a nitrogenous base
& at least one phosphate group
A nucleoside is a molecule composed of a
pentose and a nitrogenous base with no phosphate group
Adenosine plays a role in the
sleep/wake state
-increased promote sleep
A strong increase in ______________ levels in the extracellular fluid is an emergency signal indicating an acute oxygen deficiency (stroke, angina pectoris, MI)
adenosine
Purinergic neurotransmitters are metabolized to ____ to terminate effects.
5’AMP
