Neural Conduction and Synaptic Transmission Flashcards
Action potentials are produced by the
Select one:
a. opening of voltage-activated sodium channels.
b. closing of voltage-activated calcium channels.
c. closing of ligand-activated potassium channels.
d. closing of ligand-activated chloride channels.
e. opening of ligand-activated potassium channels.
a. opening of voltage-activated sodium channels.
Contributing to the unequal distribution of ions on either side of a resting neural membrane
Select one:
a. is random ion movement.
b. are electrostatic gradients.
c. are sodium-potassium pumps.
d. both A and B
e. both B and C
c. are sodium-potassium pumps.
Dopamine is not an effective treatment for Parkinson’s disease because
Select one:
a. Parkinson’s disease is a cholinergic dysfunction.
b. dopamine does not readily penetrate the blood-brain barrier.
c. Parkinson’s disease is a noradrenergic dysfunction.
d. d’Orta is the treatment of choice.
e. dopaminergic neurons are restricted to the PNS.
b. dopamine does not readily penetrate the blood-brain barrier.
Drugs that facilitate the activity of the synapses of a particular neurotransmitter are said to be \_\_\_\_\_\_\_\_\_\_ of that neurotransmitter. Select one: a. endorphins b. antagonists c. autoreceptors d. facilitators e. agonists
e. agonists
IPSP is to EPSP as
Select one:
a. cable properties are to noncable properties.
b. excitatory is to inhibitory.
c. graded is to nongraded.
d. hyperpolarization is to depolarization.
e. presynaptic is to postsynaptic.
d. hyperpolarization is to depolarization.
Na+ ions are encouraged to move into neurons by Select one: a. the sodium-potassium pump. b. nonrandom assignment. c. selective ion channels. d. nonrandom movement. e. electrostatic pressure.
e. electrostatic pressure.
Some of the morphine-like substances that occur naturally in the brain are Select one: a. autoreceptors. b. false transmitters. c. benzodiazepines. d. exogenous. e. endorphins.
e. endorphins.
The wave of absolute refractoriness that follows an action potential
Select one:
a. produces a second, negative action potential.
b. produces saltatory conduction.
c. increases the firing rate.
d. increases the speed of axonal transmission.
e. keeps the action potential from spreading actively back along an axon towards the cell body.
e. keeps the action potential from spreading actively back along an axon towards the cell body.
When a small-molecule neurotransmitter molecule binds to an ionotropic receptor, the
Select one:
a. EPSP gradually increases.
b. cell fires.
c. cell stops firing.
d. associated ion channel opens or closes.
e. ligand is deactivated.
d. associated ion channel opens or closes.
Roberto Garcia d’Orta referred to himself as “a great lizard frozen in a dark, cold, strange world.” He suffered from ________
Parkinson’s disease
Substatia nigra produces a chemical called _______
Dopamine
The difference in electrical charge between the inside and the outside of a cell is called the _______
Membrane potential
The _______ is about -70mV
Resting potential
_______ are the positively and negatively charged particles of salts inside the neuron
Ions
Two factors pressure Na+ ions to enter resting neurons: random _______ and electrostatic pressure
Motion
When a neuron is in a resting state, there is a greater concentration of ______ ions outside the neuron
Sodium
The ______ channels are open in a resting neuron
Potassium
Ions pass through neural membranes via specialised pores called ______
Ion channels
The firing of neurons releases chemicals at their button terminals called _______
Neurotransmitters
Neurotransmitters typically have one of two effects on postsynaptic neurons: they either depolarise them or ______ them
Hyperpolarise
When neurons add or combine a number of individual signals into one overall signal, this is called _______
Integration
_______ is the sum of the postsynaptic potentials produced in rapid succession at the same synapse to form a greater signal
Temporal summation
An action potential is elicited when the depolarisation of the neuron reaches the _______
Threshold of excitation
Unlike the postsynaptic potentials, which are graded, action potentials are _______ responses
All-or-none
Neurons integrate postsynaptic potentials in two ways: through spatial summation and through _______ summation
Temporal
How does axonal conduction differ to the conduction of EPSPs and IPSPs ?
Action potential do not grow weaker as they travel along the axonal membrane
Action potentials are conducted more slowly that postsynaptic potentials
What are the four classes of small-molecule neurotransmitters?
Amino acids
Monoamines
Acetylcholine
Unconventional neurotransmitters
What is the class of large-molecule neurotransmitters called?
Neuropeptides
Which class of neurotransmitter does dopamine belong to?
Monoamine
Which class of neurotransmitter does carbon monoxide belong to?
Unconventional neurotransmitter
Which class of neurotransmitter does glutamate belong to?
Amino acids
Which class of neurotransmitter does GABA belong to?
Amino acids
Which class of neurotransmitter does serotonin belong to?
Monoamines
Which class of neurotransmitter does epinephrine belong to?
Monoamines
What are the five neuropeptides?
Pituitary peptides Hypothalamic peptides Brain-gut peptides Opioid peptides Miscellaneous peptides
What is an absolute refractory period?
a brief period (typically 1 to 2 milliseconds) after the initiation of an action potential during which it is impossible to elicit another action potential in the same neuron
What is acetylcholine?
a neurotransmitter that is created by the addition of an acetyl group to a choline molecule
What is acetylcholinesterase?
the enzyme that breaks down the neurotransmitter acetylcholine
What is an action potential?
a massive momentary reversal of a neuron’s membrane potential from about -70mV to about +50mV
What is an agonist?
drugs that facilitate the effects of a particular neurotransmitter
What are all-or-nothing responses?
responses that are not graded; they either occur to their full extent or no not occur at all
What are amino acid neurotransmitters?
a class of small-molecule neurotransmitters, which includes the amino acids glutamate, aspartate, glycine and GABA
What is anandamide?
the first endogenous endocannabinoid to be discovered and characterised
What are antagonists?
drugs that inhibit the effects of a particular neurotransmitter
What is antidromic conduction?
axonal conduction opposite to the normal direction; conduction from axon terminals back towards the cell body
What is aspartate?
an amino acid neurotransmitter
What is atropine?
a receptor blocker that exerts its antagonistic effect by binding to muscarinic receptors
What are autoreceptors?
a type of metabotropic receptor located on the presynaptic membrane that bind to their neuron’s own neurotransmitters
What is an axon hillock?
the conical structure at the junction between the axon and the cell body
What is an axon initial segment?
the segment of the axon where action potentials are generated - located immediately adjacent to the axon hillock
What is botox?
Botulinium toxin; a neurotoxin released by bacterium often found in spoiled food. It blocks the release of acetylcholine at neuromuscular junctions and has applications in medicine and cosmetics
What is carbon monoxide?
a soluble-gas neurotransmitter
What are catecholamines?
the three monoamine neurotransmitters that are synthesised from the amino acid tyrosine: dopamine, epinephrine, and norepinephrine
What is coexistence?
the presence of more than one neurotransmitter in the same neuron
What are dendritic spines?
tiny protrusions of various shapes that are located on the surfaces of many dendrites
What does depolarise mean?
to decrease the resting membrane potential
What are directed synapses?
synapses at which the site of neurotransmitter release and the site of neurotransmitter reception are in close proximity
What is dopamine?
one of the three catecholamine neurotransmitters
What are endocannabinoids?
a class of unconventional neurotransmitters that are chemically similar to the active components of marijuana
What does endogenous mean?
naturally occurring in the body (e.g. endogenous cannabinoids)
What are endorphins?
a class of endogenous opioids
What are enkephalins?
the first class of endogenous opioids to be discovered
What is enzymatic degradation?
the breakdown of chemicals by enzymes - one of the two mechanisms for deactivating released neurotransmitters
What are enzymes?
proteins that stimulate or inhibit biochemical reactions without being affected by them
What is epinephrine?
one of the three catecholamine neurotransmitters
What are excitatory postsynaptic potentials (EPSPs)?
graded postsynaptic depolarizations, which increase the likelihood that an action potential will be generated
What is exocytosis?
the process of releasing a neurotransmitter
What are G-proteins?
proteins that are located inside neurons (and some other cells) and are attached to metabotropic receptors in the cell membrane
What is GABA?
the amino acid neurotransmitter that is synthesized from glutamate; the most prevalent inhibitory neurotransmitter in the mammalian CNS
What are gap junctions?
narrow spaces between adjacent neurons that are bridged by fine tubular channels containing cytoplasm, through which electrical signals and small molecules can pass readily
What is glutamate?
the most prevalent excitatory neurotransmitter in the CNS
What is glycine?
an amino acid neurotransmitter
What is the golgi complex?
structures in the cell bodies and terminal buttons of neurons that package neurotransmitters and other molecules in vesicles
What is a graded response?
responses whose magnitude is proportional to the magnitude of the stimuli that elicit them
What does hyperpolarise mean?
to increase the resting membrane potential
What are hypothalamic peptides?
one of the five classes of neuropeptide transmitters; it consists of those first identified as hormones released by the hypothalamus
What are indoamines?
the class of monoamine neurotransmitters that are synthesized from tryptophan; serotonin is the only member of this class found in the mammalian nervous system
What are inhibitory postsynaptic potentials (IPSPs)?
graded postsynaptic hyperpolarisations, which decrease the likelihood that an action potential will be generated
What is integration?
adding or combining a number of individual signals into one overall signal
What are ion channels?
pores in neural membranes through which specific ions pass
What are ionotropic receptors?
recepts that are associated with ligand-activated ion channels
What are ions?
positively or negatively charged particles
What are ligands?
a molecule that binds to another molecule; neurotransmitters are ligands of their receptors
What is membrane potential?
the difference in electrical charge between the inside and the outside of a cell
What are metabotopic receptors?
receptors that are associated with signal proteins and G proteins
What are miscellaneous peptides?
one of the five categories of neuropeptide transmitters; it includes those neuropeptides transmitter that don’t fit into one of the other four categories
What are microelectrodes?
extremely fine recording electrodes, which are used for intracellular recording
What are monoamine neurotransmitters?
small-molecule neurotransmitters that are synthesized from monoamines and comprise two classes: catecholamines and indolamines
What are neuropeptide transmitters?
peptides that function as neurotransmitters, of which about 100 have been identified; also called neuropeptides
What are neuropeptides?
short amino acid chains
What is nitric oxide?
a soluble-gas neurotransmitter
What are the nodes of Ranvier?
the gaps between adjacent myelin sheaths on an axons
What are nondirected synapses?
synapses at which the site of neurotransmitter release and the site of neurotransmitter reception are not close together
What is norepinephrine?
one of the three catecholamine neurotransmitters
What are opioid peptides?
one of the five classes of neuropeptide transmitters; it consists of those with a structure similar to the active ingredients of opium
What is orthodromic conduction?
axonal conduction in the normal direction - from the cell body toward the terminal buttons
What is periaqueductal gray (PAG)?
the gray matter around the cerebral aqueduct, which contains opiate receptors and activates a descending analgesia circuit
What are pituitary peptides?
one of the five categories of neuropeptide transmitters; it contains neurotransmitters that were first identified as hormones released by the pituitary
What are receptor blockers?
antagonistic drugs that bind to postsynaptic receptors without activating them and block the access of the usual neurotransmitter
What are receptor subtypes?
the different types of receptors to which a particular neurotransmitter can bind
What are receptors?
cells that are specialized to receive chemical, mechanical, or radiant signals from the environment; also proteins that contain binding sites for particular neurotransmitters
What is a relative refractory period?
a period after the absolute refractory period during which a higher-than-normal amount of stimulation is necessary to make a neuron fire
What is a resting potential?
the steady membrane potential of a neuron at rest, usually about -70mV
What is reuptake?
the drawing back into the terminal button of neurotransmitter molecules after their release into the synapse; the most common mechanism for deactivating a released neurotransmitter
What is saltatory conduction?
conduction of an action potential from one node of Ranvier to the next along a myelinated axon
What are second messengers?
a chemical synthesized in a neuron in response to the binding of a neurotransmitter to a metabotropic receptor in its cell membrane
What is serotonin?
an indolamine neurotransmitter; the only member of this class of monoamine neurotransmitter found in the mammalian nervous system
What is a sodium-potassium pump?
an ion transporter that actively exchanges three Na+ ions inside the neuron for two K+ ions outside
What are soluble-gas neurotransmitters?
a class of unconventional neurotransmitters that includes nitric oxide and carbon monoxide
What is spatial summation?
the integration of signals that originate at different sites on the neuron’s membrane
What are synaptic vesicles?
small spherical membranes that store neurotransmitter molecules and release them into the synaptic cleft
What is temporal summation?
the integration of neural signals that occur at different times at the same synapse
What is the threshold of excitation?
the level of depolarisation necessary to generate an action potential; usually around -65mV
What are transporters?
mechanisms in the membrane of the cell that actively transport ions or molecules across the membrane
What are voltage-activated ion channels?
ion channels that open and close in response to changes in the level of membrane potential
