Untitled Flashcards Set

Sensory neuron

A neuron that transmits a nerve impulse toward the central nervous system.

Sodium

An action potential is caused by an influx of these ions into the cell.

Convergent circuits

An afferent neuron from a pain receptor and a neuron from the brain both synapse with a motor neuron.

Stimulus

Any change in the environment, outside or within the body.

Heavily myelinated, large diameter fibers

The speed of nerve impulse conduction is greatest in these fibers.

Threshold

When a stimulus becomes strong enough to activate the neuron.

2, 1, 3, 4

Correct sequence of events that follows a threshold potential: Sodium channels open and sodium ions diffuse inward, the membrane becomes depolarized, the membrane becomes repolarized, potassium channels open and potassium ions diffuse outward.

The spinal and cranial nerves

The peripheral nervous system consists of these.

Receptor, sensory neuron, integration center, motor neuron, effector

Best sequence that represents the course of an impulse over a reflex arc.

Schwann cells

The myelin sheath is formed by these.

Multipolar

The majority of neurons in the body are of this type.

The brain and the spinal cord

The central nervous system is composed of these.

Ions

Electrical conduction in neurons is dependent upon these.

Sensory and motor fibers

A mixed nerve consists of these.

Dendrite, cell body, axon, synapse

The proper pathway for impulse conduction.

Synapse

The site of communication between neurons.

Effectors

Muscles and glands are considered to be these.

Dendrites

The cytoplasmic extensions that provide the main receptive surfaces for neurons.

Greater

In relation to unmyelinated fibers, the conductivity of myelinated fibers is this.

Throwing a ball

All of the following are reflex actions except this.

A neurotransmitter

The substance that is released at axonal endings to propagate a nervous impulse.

Axon of presynaptic neuron, synaptic cleft, dendrite of postsynaptic neuron

The correct path an impulse takes across a synapse.

The outside of the plasma membrane is negatively charged and the inside is positively charged.

True statement regarding an action potential.

Axon

The Schwann cell forms a myelin sheath around this.

Nothing can stop the action potential once the threshold is reached.

Meaning of the phrase 'all or nothing' in relation to an action potential.

Sodium-potassium

The system that restores and maintains the resting membrane potential is this pump.

Neuron

The structural unit of the nervous system.

Sodium ions are higher on the outside of its membrane and potassium ions are higher on the inside.

When a nerve fiber is polarized.

All of these

Drugs that decrease membrane permeability to sodium are used to cause loss in the perception of pain, prevent nerve impulses from passing, and are used as local anesthetics.

Receptors

Special sensory end organs that make us aware of changes in our external environment.

True

Bipolar neurons are rare and can be found in the nervous tissue of the eye (retina).

True

Reflexes are rapid, predictable, and automatic responses to stimuli.

Absolute refractory period

The time between the conduction of one nerve impulse and the beginning of another.

Nodes of Ranvier

Unmyelinated gaps between segments of the myelin sheath.

Interneurons

Neurons that carry impulses between sensory neurons and motor neurons.

Neurolemma

The peripheral, nucleated layer of the Schwann cell that encloses the myelin sheath.