Module 3 Chapter 17 Multiple choice questions 17.5

. In which direction do action potentials travel along an axon?

Away from the cell body

Towards the cell body

Both away from and towards the cell body

Action potentials do not travel along axons.

. How does an action potential propagate along an axon?

Distal parts of an axon experience increasing depolarization as the action potential approaches, taking them towards threshold potential and eventually triggering of a full action potential in those more distal sections.

Hyperpolarization at the end of an action potential in one part of an axon induces depolarization further along the axon.

Temperature changes in the axon as a result of depolarization of preceding areas; this propagates the action potential to distal parts of the axon.

Positively charged sodium ions travel along the length of the axon, depolarizing sections of it as they pass through.

. One important characteristic that determines conductance velocity along the axon of a neuron is the myelin sheath. What is the other?

Diameter of the axon

Length of the axon

Shape of the neuronal cell body

Volume of the neuronal cell body

. G-protein-coupled receptors (GPCRs) can be linked to G-protein-activated second messenger signalling systems. What is the effect of a ligand binding to a GPCR that is linked to the Gαq subunit?

Gαq stimulates adenylyl cyclase activity, activating associated intracellular signalling systems.

Gαq inhibits adenylyl cyclase activity, suppressing associated intracellular signalling systems.

Gαq stimulates inositol 1,4,5-trisphosphate (IP₃) and diacylglycerol (DAG) activity, activating associated intracellular signalling systems.

Gαq inhibits inositol 1,4,5-trisphosphate (IP₃) and diacylglycerol (DAG) activity, suppressing associated intracellular signalling systems.

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