Practice Q's - Ch 2 Flashcards
Charles S Sherrington was the first to infer properties of
synapses.
Sherrington studies _____ which are automatic muscular responses to stimuli.
reflexes
Joe is in the lab drawing illustrations of neurons in her lab notebook. She labelled the specialized area between two neurons as the _______
synapse.
On the basis of what evidence were the properties of synapses first inferred?
behavioural observations
the circuit from sensory neuron to muscle response is called ____
a relfex arc.
Mary is studying the refelx arc for a quiz. In her notes she wrote down that the proper order is
sensory, inter, motor neuron.
why is the speed of conduction through a reflex arc slower than the speed of conduction of an action potential along an axon?
transmission between neurons at synapses is slower than along axons.
Sherrington deduced that transmission at a synapse must be slower than conduction along an axon. This was based on what kind of evidence?
the speed of reflexive responses
Dr. Andrus studies relfexes and has demonstrated that a certain reflex doesnt occur if there is a single stimulus. He found that there needs to be __________ for the reflex to occur.
temporal summation
Sherrington found that repeated stimuli within a brief time have a cumulative effect. He referred to this as _____
temporal summation.
temporal summation most likely occurs with
rapid succession of threshold excitation.
Charles Sherrington would most likely agree with which statement about reflexes?
repeated stimuli occurring within a brief time can have a cumulative effect.
to measure temporal summation in single cells, researchers ________
record depolarizations of the postsynaptic neuron.
Lin is working in the lab to generate an EPSP, which is a __________
graded depolarization.
which statement is true of EPSP?
they decay over time and space.
the neuron that receives the message is called the _________ neuron.
postsynaptic
Prof Kinsley is lecturing on EPSPs and action potentials. She tells the class that
EPSPs are decremental and action potentials are not.
Depolarization is to _________ as hyperpolarization is to ___________
excitation; inhibition.
Brock is working in the lab and has been able to demonstrate that
the opening of sodium channels causes an EPSP
which process indicates spatial summation?
present two or more weak stimuli at the same time.
spatial summation refers to
multiple weak stimulations that occur at the same time.
What is the primary difference between temporal summation and spatial summation?
spatial summation depends on contributions from more than one sensory neuron.
Kate is in the lab working ans was able to produce a reflexive response by stimulating several different locations all at one time. She successfully demonstrated ______ summation.
spatial
what do temporal summation and spatial summation have in common?
both enable a reflex to occur in response to weak stimuli.
temporal summation is to _______ as spatial summation is to ___________.
time; location.
Jan is in the lab trying o produce action potential in her cultured neurons? What is most likely to work?
using electrical stimulation to produce a rapid sequence of EPSPs.
when a vertebrate animal contracts the flexor muscles of a leg, it relaxes the extensor muscles of the same leg. Sherrington considered this evidence for the existence of _______.
inhibitory messages.
what ordinarily prevents extensor muscles from contracting at the same time as flexor muscles?
inhibitory synapses in the spinal cord.
_______ in the ________ help coordinate contraction of certain muscles and relaxation of others.
motor neurons; peripheral nervous system.
inhibitory synapses on a neuron?
hyper-polarize the postsynaptic ell.
a temporary hyperpolarization is known as an
IPSP.
Tam is working in the lab trying to produce an IPSP in her cultures neurons. what should she do?
encourage chloride ions to enter the cell.
Increased permeabilty to which type of ion would most likely result in an IPSP?
potassium.
an IPSP represents
a temporary hyper-polarization.
In order to produce an IPSP, there needs to be an increase in permeability for _______
chloride.
an EPSP is to __________ as an IPSP is to _________.
depolarization, hyper-polarization.
Even at rest, most neurons have periodic production of action potentials, known as the _________
spontaneous firing rate.
the “decision” for a neuron to fire is determined by the
ratio of EPSP to IPSPs.
the “spontaneous firing rate” of a neuron refers to
its rate of producing action potentials even when it is not stimulated.
_______ increases the frequency of the spontaneous firing rate.
EPSP
what determines whether a neuron has an action potential?
the combined effects of EPSPs and IPSPs.
which one of Sherringtons inferences about the synapse was wrong?
transmission at the synapse is primarily an electrical process.
neuroscienctists first understood that synapses use chemicals to communicate because Dr.Loewi _________
stimulated a frogs heart that was in a fluid bath and then used just the fluid to stimulate a second heart.
the research that firmly established synaptic communication as chemical was ____________
Loewi’s transfer of fluid from stimulated frog hearts.
which category of chemicals included adenosine and several of its derivatives?
Purines
on advantage of nitric oxide is that is
can be made by neurons effieciently
if Vonnie’s body needed to dilate her blood vessels, it would release
nitric oxide.
In addition to influencing other neurons, __________ increases blood flood to a specific area of the brain.
nitric oxide.
what provides the building blocks for synthesizing nearly all neurotransmitters?
proteins found in the diet.
neurotransmitters are synthesized from
amino acids
____________, ___________, and _________ are catecholamines
E, NE, DA
What makes nitric oxide unique among neurotransmitters?
It is a gas.
What do dopamine, norepinephrine, and epinephrine share in common?
They are all synthesized from the same amino acids.
Riva is unable to eat eggs, milk, and peanuts. She might have altered levels of _____ as a result.
acetylcholine
The amino acid tryptophan is the precursor to which neurotransmitter?
Serotonin
- Lita has just eaten a lot of soy, which contains tryptophan. What should she try to consume less of to potentially
increase tryptophan’s entry to the brain?
a. Phenylalanine
Dopamine and norepinephrine are classified as ____.
catecholamines
Insulin increases the entry of tryptophan into the brain by _________
causing certain competing amino acids to enter other cells, outside the brain
Luis is studying for a quiz on neurotransmission. He wrote in his notes that neurotransmitters are typically stored in
_____ in the _____ neuron.
vesicles; presynaptic
Neuropeptides are synthesized in the ____.
cell body
Although slower than an action potential, synaptic transmission is still relatively fast because ____.
the synaptic cleft is very narrow
Vesicles are located ____.
in presynaptic terminals
Neurotransmitters are released from the
presynaptic neuron when the action potential reaches the terminal and opens ______ channels.
calcium
When an action potential reaches the end of an axon, the depolarization causes what ionic movement in the
presynaptic cell?
Calcium into the cell
An action potential causes the release of neurotransmitters by ____.
opening calcium pores in the membrane
A neuron excretes neurotransmitters through its membrane by a process called ____.
exocytosis
Exocytosis is the process by which neurotransmitters are ____.
released from the presynaptic neuron
What is the synaptic cleft?
The gap between the presynaptic neuron and the postsynaptic neuron
What happens when a neurotransmitter is released by a presynaptic cell?
The neurotransmitter passively spreads across the synaptic cleft.
In general, a single neuron releases ____ neurotransmitter(s) and can respond to ____ neurotransmitter(s).
several; many
The main advantage of a neuron releasing more than one neurotransmitter is that:
it can send more complex messages
The effect of a neurotransmitter on a postsynaptic neuron is determined by the ____.
receptors on the postsynaptic membrane
A receptor can directly open a channel and thereby exert a(n) ____ effect, or it can produce slower but longer ____
effect.
ionotropic; metabotropic
Most of the brain’s excitatory ionotropic synapses release ____ while the inhibitory ionotropic synapses release ____.
glutamate; GABA
Glutamate opens sodium gates, enabling sodium ions to enter the postsynaptic cell. What type of effect is this?
Ionotropic
Ionotropic effects ____.
may depolarize or hyperpolarize the postsynaptic membrane
Ionotropic effects are characterized by ____.
rapid and short-lived effects.
Which terms refers to a chemical that binds to another chemical?
Ligand
Raylene is studying for an exam on neurotransmission. She wrote in her notes that one difference between ionotropic
and metabotropic effects is that _____.
metabotropic effects are slower and longer lasting
Which process is more typical of a metabotropic effect than an ionotropic effect?
Producing long-lasting effects on the post-synaptic cell
Receptor molecules for neurotransmitters that exert metabotropic effects are proteins that bind to ____ outside the
membrane, and attach to ____ inside the membrane.
neurotransmitters; G-proteins
“Second messengers” carry their messages to ____.
areas within the postsynaptic cell
A metabotropic synapse, by way of its second messenger, ____.
can influence activity in much or all of the postsynaptic cell
Many neurons release neuropeptides mostly from the ____.
dendrites
A hormone is a chemical that is ____.
conveyed by the blood to other organs, whose activity it influences
Hormones exert their effects ____.
similarly to metabotropic neurotransmitters
The anterior pituitary is composed of ____ and the posterior pituitary is composed of ____.
glandular tissue; neural tissue
Releasing hormones are synthesized in the ____ and released in the ____.
hypothalamus; anterior pituitary
Adrenocorticotropic hormone (ACTH) controls secretions of the ____.
adrenal gland
What is the function of the enzyme acetylcholinesterase?
it breaks acetylcholine down into components for recycling.
What happens to acetylcholine after it attaches to a receptor on the postsynaptic cell?
It is broken down into two components.
Dr. Edmonson is working in the lab with cultured neurons. He applies a drug that inhibits acetylcholinesterase. What
does he expect to have occur?
Acetylcholine will remain active in the synapse longer.
Reuptake is an alternative to which other process?
Breaking down neurotransmitters via an enzymatic process
“Transporter” proteins transport neurotransmitters ____.
back into the presynaptic neuron
COMT and MAO are ____.
enzymes that convert catecholamines into inactive chemicals
The primary method for disposal of peptide neurotransmitters is ____.
diffusion
Professor Leclair is giving a lecture on autoreceptors. She tells the class that _____.
activated autoreceptors decrease neurotransmitter release
Autoreceptors monitor the ____.
amount of neurotransmitter released
