High School Biology : Understanding Neurotransmitters

Study concepts, example questions & explanations for High School Biology

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Example Questions

Example Question #1 : Understanding Neurotransmitters

Where do neurotransmitters attach following release into the synaptic cleft?

Possible Answers:

The presynaptic dendrites

The presynaptic membrane

The postsynaptic membrane

The axon hillock

Correct answer:

The postsynaptic membrane

Explanation:

Vesicles of neurotransmitter are located at the axon terminal of the presynaptic neuron. Upon stimulation, they are released into the synapse and flow across the gap between neurons. Neurotransmitters attach to receptors located on the postsynaptic membrane after being released into the synaptic cleft. This allows the action potential to continue on to the next neuron.

Example Question #2 : Understanding Neurotransmitters

Dendrites have receptors that produce electrical signals when they bind with which of the following?

Possible Answers:

Proteins

Enzymes

Electrolytes

Neurotransmitters

Hormones

Correct answer:

Neurotransmitters

Explanation:

In the neuron, dendrites respond to the chemical neurotransmitters released by other local neurons. These dendrites have receptors in their membranes that bind specific neurotransmitters and produce electrical signals as a result of this binding. Binding of a neurotransmitter can either excite or inhibit the neuron, influencing its ability to transmit a signal.

A hormone is a chemical that is synthesized by one group of cells, secreted, and then carried in the bloodstream to other cells whose activity is influenced by reception of the hormone. An electrolyte is a solutution that conducts electricity and generally contains ions. Enzymes are proteins that speed up chemical reactions. Proteins are organic molecules composed of amino acids that are necessary for growth and repair of tissues.

 

Example Question #3 : Understanding Neurotransmitters

Which of the following is released when an axon is excited and acts by inhibiting or exciting a target cell?

Possible Answers:

Ion

Electrolyte

Enzyme

Neurotransmitter

Interleukin

Correct answer:

Neurotransmitter

Explanation:

A neurotransmitter is a chemical agent that relays messages from one nerve cell to the next. An enzyme is a protein that causes other substances to change. Enzymes regulate the rate of chemical reactions. An electrolyte is a substance that, when dissolved, forms electrically charged particles. Ions have lost one or more electrons and have a positive charge, or gained one or more electrons and have a negative charge. In aqueous solutions, ions are called electrolytes because they permit the solution to conduct electricity. Interleukin is a type of protein that enables communication among cells active in inflammation or the specific immune response.

Example Question #4 : Understanding Neurotransmitters

Which of the following ions is required for vesicles containing neurotransmitters to be released into the synaptic cleft?

Possible Answers:

Correct answer:

Explanation:

Vesicles containing neurotransmitters must bind to the membrane at the axon terminal in order to release their contents into the synapse. This binding is dependent upon an influx of calcium ions that occurs with an action potential. The other ions listed are important for other parts of the action potential, but it is calcium that is crucial for this particular step. 

Example Question #5 : Understanding Neurotransmitters

Fill in the blanks with the best answers:

__________ gated potassium channels are the primary mediators of __________ of the neuronal membrane. They permit the postively charged potassium ions to flow out of the cell once the peak of the action potential has been reached. 

Possible Answers:

Ligand . . . repolarization

Ligand . . . permeabilization 

Voltage . . . repolarization

Voltage . . .  depolarization

Voltage . . . equilibration 

Correct answer:

Voltage . . . repolarization

Explanation:

Voltage-gated potassium ion channels are responsible for bringing the membrane potential back to or below resting the potential. This is achieved when these channels open, which can only happen at very positive voltages (hence voltage-gated), and as the potassium ions rapidly leave the cell, the cell repolarizes to a negative potential.

Example Question #33 : Nervous System

Which of the following receive messages from other neurons?

Possible Answers:

Neurotransmitters

Nodes of Ranvier

Axons

Dendrites

Synapses

Correct answer:

Dendrites

Explanation:

The dendrites receive the messages sent from other neurons. Neurotransmitters are released into synaptic clefts between two neurons and bind receptors on the postsynaptic neuron's dendrites. Axons are nerve fibers that carry electrical impulses away from the cell body of a neuron. The nodes of Ranvier are unmyelinated spots on myelinated axons that facilitate conduction of a nerve impulse down an axon.

Example Question #6 : Understanding Neurotransmitters

Which of the following mechanisms would prolong the effects of the neurotransmitter acetylcholine?

Possible Answers:

More receptors on the post-synaptic membrane

Adding acetylcholinesterase, an enzyme that degrades acetylcholine

More acetylcholine re-uptake receptors on the pre-synaptic membrane

More acetylcholine re-uptake receptors on the post-synaptic membrane

Inhibiting acetylcholinesterase, an enzyme that degrades acetylcholine

Correct answer:

Inhibiting acetylcholinesterase, an enzyme that degrades acetylcholine

Explanation:

The effect of acetylcholine is terminated by acetylcholinesterase breaking down acetylcholine. If acetylcholinesterase is inhibited, the degradation of acetylcholine would not occur, and the effects of acetylcholine will be prolonged. 

Example Question #7 : Understanding Neurotransmitters

In the human brain, what is the primary inhibitory neurotransmitter?

Possible Answers:

Glycine

GABA

Acetylcholine

Glutamate

Norepinephrine

Correct answer:

GABA

Explanation:

GABA is only found in the brain and has an inhibitory function. Although glycine is also inhibitory and found in the central nervous system, it's mainly concentrated in the spinal cord and brainstem. Glutamate and acetylcholine are also found in the central nervous system, but are excitatory. Norepinephrine is excitatory and associated with the adrenal glands, not the central nervous system. 

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