Chapter 2-a Flashcards
Depolarization is to ______ as hyperpolarization is to _____
Excitation inhibition
Increased permeability to which type of ion would most likely result in an IPSP
Potassium
A certain week stimulus produces no reflexive response but a rapid repetition of that stimulus may produce such a response what is this phenomenon called
Temporal summation
What is the primary difference between temporal summation and spatial summation
Spatial summation depends on contributions from more than one sensory neuron
The spontaneous firing rate of a neuron refers to
It’s rate of producing action potential’s even when it is not stimulated
Specialized junctions between neurons are called
Synapses
The decision for a neuron to fire is determined by the
Ratio of EPSP two IPSP
What determines whether a neuron has an action potential
The combined effects of EPSP and IPSP
The circuit from sensory neuron to muscle response is called
The reflex arc
Temporal summation most likely occurs with
Rapid succession of sub threshold excitation
Spatial summation refers to
Multiple week stimulation is that occur at the same time
To measure temporal summation in single cells researchers
Record depolarizations of the postsynaptic neuron
A normal healthy animal never contracts the flexor muscles and the extensor muscles of the same leg at the same time why not
When the interneuron sends excitatory messages to one inhibitory messages go to the other
A graded depolarization is known as an
EPSP
Even at rest most neurons have periodic production of action potential’s known as the
Spontaneous firing rate
What do temporal and spatial summation have in common
Both in able a reflex to occur in response to week stimuli
What is the proper ordering of a reflex arc
Sensory neuron interneuron motor neuron
Which process will most likely result in an IPSP
Chloride ions entering the cell
Which statement is true about the spontaneous firing rates of neurons
EPSPs increase the frequency
Inhibitory synapses of a neuron
Hyperpolarize the postsynaptic cell
An EPSP is to _____ as an IPSP is to ______
Depolarization hyperpolarization
Which statement is true of EPSP
They decay over time and space
What causes and EPSP
The opening of sodium channels
In a reflex arc the coordination between contraction of certain muscles and relaxation of others is mediated by
Interneurons
When a vertebrate animal contract the flexor muscles of a leg it relaxes the extensor muscles of the same leg Sherrington consider this evidence for the existence of
Inhibitory messages
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 lower than a long axons
On the basis of what evidence were the properties of synapses first inferred
Behavioral observations
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
Temporal summation is to ______ as spatial summation is to ______
Time location
The primary difference between an EPSP and an action potential is that
EPSP are sub threshold events that decay over time and space
A temporary hyperpolarization is known as an
IPSP
When an action potential reaches the end of an axon it evokes the release of neurotransmitters by opening what kind of channels in the axon terminal
Calcium
Many neurons release neuropeptides mostly from the
Dendrites
Which event is most likely to be dependent on inotropic effects
Rapid muscle contraction
Inotropic events
May Depol arise or hyperpolarized the postsynaptic membrane
The anterior pituitary is composed of and the posterior pituitary is composed of
Glandular tissue neural tissue
Hormones exert their effects
Similarly to metabotropic neurotransmitters
When an action potential reaches the end of an axon the depolarization causes what ionic movement in the presynaptic cell
Calcium into the cell
The presynaptic terminal stores high concentrations of neurotransmitter molecules in
Vesicles
Releasing hormones are synthesized in the ______ and released in the ______
Hypothalamus anterior pituitary
Which term to refer to a chemical that binds to another chemical
Ligand
The basic building blocks for the majority of neurotransmitters are
Amino acids
The amino acid tryptophan is the precursor to which neurotransmitter
Serotonin
A metabotropic synapse by way of that second messenger
Can influence activity in March or all of the postsynaptic cells
A neuron excretes neurotransmitters through its membrane by a process called
Exocytosis
Which neurotransmitter is released by stimulated neurons to dilate the blood vessels
Nitric oxide
Compared to inotropic effects Metabotrophic effects are
Slower and longer lasting
The primary method for disposal of peptide neurotransmitters is
Diffusion
A hormone is a chemical that is
Conveyed by the blood to other organs his activity it influences
What happens when I neurotransmitter is released by a presynaptic cell
The neurotransmitter passably spreads across the synaptic cleft
ACTH control secretions of the
Adrenal cortex
What do dopamine norepinephrine and epinephrine share in common
They are all synthesized from the same amino acids
Loewi demonstrated that synapses operate by the release of chemicals by
Collecting fluid for my stimulated frogs heart transferring it to another frogs heart and measuring that heart rate
What makes nitric oxide unique among neurotransmitters
It is a gas
The main advantage of a neuron releasing more than one neurotransmitter is that
It can send more complex messages
What happens to acetylcholine after it attaches to a receptor on the postsynaptic cell
It is broken down into two components
You were eating a food containing tryptophan what can you consume with it to increase its entry to the brain
Carbohydrates
Transporter proteins transport neurotransmitters to
Back into the presynaptic neuron
Autoreceptors monitor the
Amount of neurotransmitter released
A drug that inhibits the action of the enzyme acetylcholinesterase will have the effect of
prolonging the action of acetylcholine at its synapses
IN addition to influencing other neurons, ____ increases blood flow to a specific area of the brain
Nitric Oxide
Although slower than an action potential, synaptic transmission is still relatively fast because
the synaptic cleft is very narrow
Avoiding foods with lecithin, such as eggs and peanuts, would affect the levels of which neurotransmitter the most
actylecholine
Vesicles are located in the
presynaptic terminals
The catecholamines include
epinephrine, norepinephrine and dopamine
Neuropeptides are synthesized in the
cell body.
which category of chemicals includes adenosine and several of its derivatives
purines
COMT and MAO are
enzymes that convert catecholamines into inactive chemicals
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
Activation of autoreceptors tends to
decrease further neurotransmitter release
Ionotropic effects are characterized by
rapid and short lived effects
the effect of a neurotransmitter on a postsynaptic neuron is determined by the
receptors on the postsynaptic membrane
In general, a single neuron releases ____ neurotransmitters and can respond to ____ neurotransmitters
several, many
What is the synaptic cleft
the gap between the presynaptic neuron and the post synaptic neuron
Glutamate opens sodium gates, enabling sodium ions to enter the postsynaptic cell. What type of effect is this?
inotropic
A receptor can directly open a channel and thereby exert an ____ effect, or it can produce slower but longer ____
ionotropic. metabotropic
Which one of Sherrington’s inferences about the synapse was WRONG?
Transmission at the synapse is primarily an electrical process
Which process is more typical of a metabotropic effect than an ionotropic effect?
producing long-lasting effects on the post-synaptic cell
the neuron that receives the message is called the
postsynaptic
Professor Deshon is lecturing about EPSPs and IPSPs. He tells the class that in order to produce an IPSP, there needs to be an increase in permeability for
chloride
Nitric Oxide can function as a hormone? True or False
false
An EPSP is to ____ as an IPSP is to _____
Depolarization, hyperpolarization
