Exam 13: A: Nervous System Cells

The action potential is called an all-or-none response because if the threshold potential is surpassed,the full peak of the action is always reached; if the threshold potential is not surpassed,no action potential will occur.

Regeneration of nerve fibers will occur only if the cell body is intact and the fibers have a neurilemma.

The axon hillock is actually part of the cell body of the neuron.

How long a memory lasts is related to what occurs at a synapse.

The word glia means "support," which accurately describes their function in the nervous system.

In a synapse,both the presynaptic cell and postsynaptic cell must be neurons.

Myelinated axons without gaps in the myelin (nodes of Ranvier)conduct impulses more efficiently than axons with nodes of Ranvier.

Only astrocytes,microglia,and oligodendrocytes are found in the central nervous system; Schwann cells and ependymal cells are found in the peripheral nervous system.

Spinal nerves are considered part of the peripheral nervous system.

Action potential and nerve impulse are interchangeable terms.

Part of the function of the astrocyte is to help feed the neurons.

Synapses between axons are the most common synapses in the nervous system.

The lack of dopamine is linked to the symptoms of Parkinson disease.

Oligodendrocytes are found only around dendrites of neurons of the central nervous system.

The microglia engulf and destroy microorganisms and cellular debris.

All reflex arcs contain an interneuron.

The afferent nervous system consists of all outgoing motor pathways.

The neurotransmitter acetylcholine always has an excitatory effect.

Absolute refractory periods occur in the axon of the cell; relative refractory periods occur in the dendrite or soma of the cell.

The central nervous system is composed of efferent nerves only.