3: Synapses Flashcards
1What evidence led Sherrington to conclude that transmission at a synapse is different from transmission along an axon?
a. Chemicals that alter a synapse are different from those that affect action potentials.
b. The velocity of a reflex is slower than the velocity of an action potential.
c. Stains and microscopic observations demonstrate a gap at the synapse.
d. Reflexes can go in either direction, whereas axons transmit in only one direction.
b. The velocity of a reflex is slower than the velocity of an action potential.
Although one pinch did not cause a dog to flex its leg, a rapid sequence of pinches did. Sherrington cited this observation as evidence for what?
a. Temporal summation
b. Spatial summation
c. Inhibitory synapses
a. Temporal summation
- Although one pinch did not cause a dog to flex its leg, several simultaneous pinches at nearby locations did. Sherrington cited this observation as evidence for what?
a. Temporal summation
b. Spatial summation
c. Inhibitory synapses
b. Spatial summation
When a vigorous pinch excited a dog’s flexor muscle, it decreased excitation of the extensor muscles of the same leg. Sherrington cited this observation as evidence for what?
a. Temporal summation
b. Spatial summation
c. Inhibitory synapses
c. Inhibitory synapses
5.During an epsp, the ___ gates in the membrane open. During an ipsp, the ___ gates open.
a. sodium . . . potassium or chloride
b. potassium . . . sodium or chloride
c. chloride . . . sodium or potassium
a. sodium . . . potassium or chloride
In what way were Sherrington’s conclusions important for psychology as well as neuroscience?
a. He demonstrated the importance of unconscious motivations.
b. He demonstrated the importance of inhibition.
c. He demonstrated the phenomenon of classical conditioning.
d. He demonstrated the evolution of intelligence.
b. He demonstrated the importance of inhibition.
What was Loewi’s evidence that neurotransmission depends on the release of chemicals?
a. He applied adrenaline to muscles and saw them contract.
b. He applied drugs at various synapses and observed excitatory and inhibitory postsynaptic potentials.
c. He stimulated one frog’s heart, collected fluid around it, transferred it to another frog’s heart, and saw change in its heart rate.
d. He stimulated certain nerves, collected the fluid around their terminals, and analyzed the contents chemically.
c. He stimulated one frog’s heart, collected fluid around it, transferred it to another frog’s heart, and saw change in its heart rate
Which of the following is NOT one of the brain’s neurotransmitters?
a. Glutamate
b. GABA
c. Glucose
d. Serotonin
c. Glucose
The amino acid tryptophan is a precursor to which neurotransmitter?
a. Serotonin
b. Dopamine
c. Glutamate
d. Acetylcholine
a. Serotonin
Suppose you want to cause the presynaptic terminal of an axon to release its transmitter. How could you do so without an action potential?
a. Decrease the temperature at the synapse.
b. Use an electrode to produce IPSPs in the postsynaptic neuron.
c. Inject water into the presynaptic terminal.
d. Inject calcium into the presynaptic terminal.
d. Inject calcium into the presynaptic terminal.
The brain’s most abundant excitatory neurotransmitter is ______, and its most abundant inhibitory neurotransmitter is ______.
a. GABA . . . serotonin
b. serotonin . . . dopamine
c. Dopamine . . . glutamate
d. Glutamate . . . GABA
d. Glutamate . . . GABA
In which of these ways does a metabotropic synapse differ from an ionotropic synapse?
a. Its effects are slower to start and last longer.
b. Its effects are faster to start and last longer.
c. Its effects are slower to start and briefer in duration.
d. Its effects are faster to start and briefer in duration.
a. Its effects are slower to start and last longer.
What is a second messenger?
a. A chemical released by the presynaptic neuron a few milliseconds after release of the first neurotransmitter
b. A chemical released inside a cell after stimulation at a metabotropic synapse
c. A chemical that travels from the postsynaptic neuron back to the presynaptic neuron
b. A chemical released inside a cell after stimulation at a metabotropic synapse
Which of the following is true of neuropeptides?
a. They are released close to their receptors.
b. A neuron releases them at a steady rate almost constantly.
c. They produce rapid, brief effects.
d. They are released either in large quantities or not at all.
d. They are released either in large quantities or not at all.
Which of these drugs exerts its behavioral effects by binding to the same receptor as a neurotransmitter?
a. Amphetamine
b. Cocaine
c. Nicotine
d. Marijuana
c. Nicotine
Which neurotransmitter is broken into two pieces to inactivate it, after it excites the postsynaptic neuron?
a. Dopamine
b. Acetylcholine
c. Glutamate
d. Serotonin
b. Acetylcholine
What does a transporter protein do at a synapse?
a. It carries neurotransmitter molecules from the presynaptic neuron to the postsynaptic neuron.
b. It carries neurotransmitter molecules from the cell body to the presynaptic terminal.
c. It carries neurotransmitter molecules from neurons that have too much into neurons that need more.
d. It pumps used neurotransmitter molecules back into the presynaptic neuron.
d. It pumps used neurotransmitter molecules back into the presynaptic neuron.
Except for the magnitude and speed of effects, methylphenidate (Ritalin) affects synapses the same way as which other drug?
a. Heroin
b. Cocaine
c. Nicotine
d. Marijuana
b. Cocaine
Which of these drugs acts by inhibiting release of neurotransmitters from the presynaptic neuron?
a. Opiates such as morphine
b. Cannabinoids (found in marijuana)
c. Nicotine
d. Amphetamine and cocaine
b. Cannabinoids (found in marijuana)
In contrast to the posterior pituitary, the anterior pituitary . . .
a. is neural tissue that releases oxytocin and vasopressin.
b. is glandular tissue that releases oxytocin and vasopressin.
c. is neural tissue that produces hormones that control other endocrine organs.
d. is glandular tissue that produces hormones that control other endocrine organs.
d. is glandular tissue that produces hormones that control other endocrine organs.
In what way is a neuropeptide intermediate between neurotransmitters and hormones?
a. A neuropeptide diffuses more widely than other neurotransmitters but less than a hormone.
b. A neuropeptide is larger than other neurotransmitters but smaller than a hormone.
c. A neurotransmitter produces excitatory effects, a neuropeptide produces neutral effects, and a hormone produces negative effects.
d. A neurotransmitter produces slow effects, a neuropeptide produces faster effects, and a hormone produces still faster effects.
a. A neuropeptide diffuses more widely than other neurotransmitters but less than a hormone.
What is the difference between temporal summation and spatial summation?
Temporal summation is the combined effect of quickly repeated stimulation at a single synapse. Spatial summation is the combined effect of several nearly simultaneous stimulations at several synapses onto one neuron.
What was Sherrington’s evidence for inhibition in the nervous system?
Sherrington found that a reflex that stimulates a flexor muscle prevents contraction of the extensor muscles of the same limb. He therefore inferred that an interneuron that excited motor neurons connected to the flexor muscle also inhibited the input to the extensor muscle.
Can an inhibitory message flow along an axon?
No. Only action potentials propagate along an axon. Inhibitory messages—IPSPs—decay over time and distance.
What was Loewi’s evidence that neurotransmission depends on the release of chemicals?
When Loewi stimulated a nerve that increased or decreased a frog’s heart rate, he could withdraw fluid from the area around the heart, transfer it to another frog’s heart, and thereby increase or decrease its rate also.
