Comprehension Check 2.2: Chemical Events at the Synapse

Question 1

What was Loewi’s evidence that neurotransmission depends on the release of chemicals?

Answer 1

He stimulated one frog’s heart, collected fluid around it, transferred it to another frog’s heart, and saw change in the second’s heart rate

Question 2

The amino acid tryptophan is a precursor to which neurotransmitter?

Answer 2

Serotonin

Question 3

Suppose you want to cause the presynaptic terminal of an axon to release its transmitter. How could you do so without an action potential?

Answer 3

Inject calcium into the presynaptic terminal

Hint: Calcium is used because it causes a depolarization of the presynaptic membrane leading to neurotransmitter release

Question 4

The brain’s most excitatory neurotransmitter is ——— and its most inhibitory neurotransmitter is ——.

Answer 4

Glutamate…..GABA

Question 5

In which of these ways does a metabotropic synapse differ from an ionotropic synapse?

Answer 5

Its effects are slower and last longer

Hint: meta- is a Greek prefix similar to the Latin prefix post-. The prefix post- means “behind”,”after”, “later”,”subsequent to”. As such metabotropic effects would start later and subsequently last longer.

Question 6

What is a second messenger?

Answer 6

A chemical released inside a cell after stimulation at a metabotropic synapse

Question 7

Neuropeptides are released either in —— quantities or —— at all.

Answer 7

Large…..not

Hint: all or none law

Question 8

List the types of neurotransmitters

Answer 8

• amino acids
• Gasotransmitters(Gases)
• Monoamines
• Trace amines
• Peptides(Neuropeptides)
• Purines
• modified amino acids

Question 9

What does a transporter protein do at a synapse?

Answer 9

It pumps used neurotransmitter molecules back into the presynaptic neuron

Question 10

Except for the magnitude and speed of effects, methylphenidate (Ritalin) affects synapses the same way as which other drug?

Answer 10

Cocaine

Question 11

What recreational drug acts by inhibiting the release of neurotransmitters from the presynaptic neuron?

Answer 11

Cannabinoids ( found in marijuana)

Question 12

In contrast to the posterior pituitary, the anterior pituitary——-.

Answer 12

Is a glandular tissue that produces hormones that control the endocrine system

Note: the non-glandular posterior pituitary secretes oxytocin and vasopressin

Question 13

In what way is a neuropeptide intermediate between neurotransmitters and hormones?

Answer 13

A neuropeptide diffuses more widely than other neurotransmitters but less than a hormone

Question 14

Which neurotransmitter is broken down into two pieces to inactivate it after it excites the postsynaptic neuron?

Answer 14

Acetylcholine