3.2 Chemical Events At The Synapse

Question 0

Sequence of chemical events. 2. action potentials travel down the axon. At the presynaptic terminal, an action potential enables calcium to enter the cell. Calcium releases neurotransmitters from the terminals and into the ____ ____, the space between the presynaptic and postsynaptic neurons.

Answer 0

synaptic cleft

Question 1

Sequence of chemical events. 1. the neuron synthesises chemicals that serve as neurotransmitters. It synthesises the smaller ____ in the axon terminals and synthesises ____ in the cell body.

Answer 1

neurotransmitters : neuropeptides

Question 2

Sequence of events. 3. The released ____ diffuse across the cleft, attach to receptors, and alter the activity of the postsynaptic neurons.

Answer 2

molecules

Question 3

Sequence of events. 4. The neurotransmitter molecules ____ from their receptors.

Answer 3

separate

Question 4

Sequence of events. 5. The neurotransmitter molecules may be taken back into the presynaptic neuron for ____ or they may ____ away.

Answer 4

recycling : diffuse

Question 5

Sequence of events. 6. Some postsynaptic cells send ____ messages to control the further release of neurotransmitters by presynaptic cells.

Answer 5

reverse

Question 6

At a synapse, a neuron releases chemicals that affect another neuron. Those chemicals are known as it ____.

Answer 6

neurotransmitters

Question 7

One neurotransmitter are acids containing an amine group (NH2) called ____ ____.

Answer 7

Amino acids.

Question 8

Another neurotransmitter are chemicals formed by a change in certain amino acids, these are called ____.

Answer 8

monoamines

Question 9

Another neurotransmitter is a chemical similar to an amino acid called ____.

Answer 9

acetylcholine

Question 10

Another neurotransmitter is chains of amino acids called ____.

Answer 10

neuropeptides

Question 11

Another neurotransmitter is a category of chemicals including adenosine and several of its derivatives called ____.

Answer 11

purines

Question 12

Another neurotransmitter are ____ including nitric oxide and possibly others.

Answer 12

gases

Question 13

Neurons synthesise nearly all neurotransmitters from ____ ____, which the body obtains from proteins in the diet.

Answer 13

amino acids

Question 14

____ is synthesised from choline, which is abundant milk, eggs, and peanuts.

Answer 14

Acetylcholine

Question 15

The amino acids ____ and ____, present in proteins, are precursors of dopamine, norepinephrine, and epinephrine.

Answer 15

phenylalanine : tyrosine

Question 16

The amino acid ____, the precursor to serotonin, crosses the blood-brain barrier by special transport system that it shares with other large amino acids. It is present in the foods such as soy and maize.

Answer 16

tryptophan

Question 17

Most neurotransmitters are synthesised in the presynaptic terminal, near the point of release. The presynaptic terminal stores high concentrations of neurotransmitter molecules in ____, tiny near spherical packets.

Answer 17

vesicles

Question 18

It is possible for a neuron to accumulate ____ levels of a neurotransmitter.

Answer 18

excess

Question 19

Neurons that release serotonin, dopamine, or norepinephrine container an enzyme, MAO (____ ____), that breaks down these transmitters into inactive chemicals.

Answer 19

monoamine oxidase

Question 20

At the end of the axon, the action potential itself does not release the neurotransmitter. Rather, the depolarisation opens at ____ ____ ____ in the presynaptic terminal.

Answer 20

voltage-dependent calcium gates

Question 21

Within 1 or 2 milliseconds after calcium enters the presynaptic terminal, it causes ____ – release of neurotransmitter in bursts from the presynaptic neuron into the synaptic cleft that separates one neuron another.

Answer 21

exocytosis

Question 22

After its release from the ____ cell, the neurotransmitter diffuses across the _____ cleft to the _____ membrane, where it attaches to a ____.

Answer 22

presynaptic : synaptic : postsynaptic : receptor

Question 23

The neurotransmitter takes no more than ____ to diffuse across the cleft, which is only ____ wide.

Answer 23

0.01 ms : 20 to 30 nm

Question 24

Although the brain as a whole uses many neurotransmitters, no ____ neuron releases them all.

Answer 24

single

Question 25

Many, perhaps most, neurons release a combination of ___ or ____ transmitters.

Answer 25

two or more