nervous tissue Flashcards

The subdivisions of the PNS are the [a], [b], and [c].

The two divisions of the autnomic nervous system are the [a] division and the [b] division

At a chemical synapse between two neurons, the neuron receiving the signal is called the presynaptic neuron, and the neuron sending the signal is called the postsynaptic neuron.

Neurons in the PNS are always capable of repair while those in the CNS are not.

Which of the following statements are TRUE? (1) The sensory function of the nervous system involves sensory receptors sensing certain changes int he internal and external environments. (2) Sensory neurons receive electrical signals from sensory receptors. (3) The integrative function of the nervous system involves analyzing sensory information, storing some of it, and making decisions regarding appropriate responses. (4) Interneurons are located primarily in the PNS. (5) Motor function involves the activation of effectors (muscles and glands)

Which of the following statements are TRUE? (1) The sensory function of the nervous system involves sensory receptors sensing certain changes int he internal and external environments. (2) Sensory neurons receive electrical signals from sensory receptors. (3) The integrative function of the nervous system involves analyzing sensory information, storing some of it, and making decisions regarding appropriate responses. (4) Interneurons are located primarily in the PNS. (5) Motor function involves the activation of effectors (muscles and glands)

A neuron's resting membrane potential is established and maintained by (1) a high concentration of K+ in the extracellular fluid and a high concentration of Na+ in the extracellular fluid. (2) the plasma membrane's higher permeability to Na+ because of the presence of numerous Na+ leakage channels, (3) differences in both ion concnetrations and electrical gradients (4) the fact that there are numeous large, nondiffusible anions int he cytosol, (5) sodium-potassium pumps that help to maintain the proper distribution of sodium and potassium.

Place the following events in a chemical synapse in the correct order: (1) release of neurotransmitters into the synaptic cleft, (2) arrival of nerve impulse at the presynaptic neuron's synaptic end bulb (or varicosity), (3) either depolarization or hyperpolarization of postsynaptic membrane, (4) inward flow of Ca2+ through activated voltage-gated Ca2+ channels in the synaptic end bulb membrane, (5) exocytosis of synaptic vesicles, (6) opening of ligand-gated channels on the postsynaptic plasma membrane, (7) binding of neurotransmitters to receptors in the postsynaptic neuron's plasma membrane.

Several neurons in the brain sending impulses to a single motor neuron that terminates at a neuromuscular junction is an example of a _________ circuit.

Which of the following statements are true? (1) If the excitatory effect is greater than the inhibitory effect but less than the threshold of stimulation, the result is a subthreshold EPSP. (2) If the excitatory effect is greater than the inhibitory effect and reaches or surpasses the threshold level of stimulation, the result is a threshold or suprathreshold EPSP and one or more nerve impulses. (3) If the inhibitory effect is greater than the excitatory effect, the membrane hyperpolarizes, resulting in inhibition of the postsynaptic neuron and the inability of the neuron to generate a nerve impulse. (4) The greater the summation of hyperpolarizations, the more likely a nerve impulse will be initiated.

Which of the following statements are true? (1) The basic types of ion channels are gated, leakage, and electrical. (2) Ion channels allow for the development of graded potentials and action poten-tials. (3) The major stimuli that operate gated ion channels are voltage changes, ligands (chemicals), and mechanical stimulation. (4) Ligand-gated channels may open either directly due to the presence of the ligand molecule itself or indirectly through the activation of a “second messenger” by a G protein. (5) A graded potential is useful only for communication over short distances.

Which of the following statements are true? (1) The frequency of impulses and number of activated sensory neurons encodes differences in stimuli intensity. (2) Larger-diameter axons conduct nerve impulses faster than smaller-diameter ones. (3) Continuous conduction is faster than saltatory conduction. (4) The diameter of an axon and the presence or absence of a myelin sheath are the most important factors that determine the speed of nerve impulse propagation. (5) Action potentials are localized, but graded potentials are propagated.

Neurotransmitters are removed from the synaptic cleft by (1) axonal transport, (2) diffusion away from the cleft, (3) neurosecretory cells, (4) enzymatic breakdown, (5) cellular uptake.

neurons with just one process extending from the cell body; are always sensory neurons

small phagocytic neuroglia

help maintain an appropriate chemical environment for generation of action potentials by neurons; part of the blood–brain barrier

provide myelin sheath for CNS axons

contains neuronal cell bodies, dendrites, axon terminals, unmyelinated axons and neuroglia

a cluster of cell bodies within the CNS

form CSF and assist in its circulation; form blood-c erebrospinal barrier

neurons having several dendrites and one axon; most common neuronal type

neurons with one main dendrite and one axon; found in the retina of the eye

provide myelin sheath for PNS axons

support neurons in PNS ganglia

a cluster of neuronal cell bodies located outside the brain and spinal cord

aggregation of myelinated processes from many neurons

bundles of axons and associated connective tissue and blood vessels lying outside of the CNS

extensive neuronal networks that help regulate the digestive system

a sequence of rapidly occurring events that decreases and eventually reverses the membrane potential and then restores it to the resting state; a nerve impulse

a small deviation from the resting membrane potential that makes the membrane either more or less polarized

period of time when a second action potential can be initiated with a very strong stimulus

the minimum level of depolarization required for a nerve impulse to be generated

the recovery of the resting membrane potential

a neurotransmitter-caused depolarization of the postsynaptic membrane

a neurotransmitter-caused hyperpolarization of the postsynaptic membrane

time during which a neuron cannot produce an action potential even with a very strong stimulus

polarization that is less negative than the resting level

results from the buildup of neurotransmitter released simultaneously by several presynaptic end bulbs

the hyperpolarization that occurs after the repolarizing phase of an action potential

polarization that is more negative than the resting level

results from the buildup of neurotransmitter from the rapid, successive release by a single presynaptic end bulb

the part of the neuron that contains the nucleus and organelles

rough endoplasmic reticulum in neurons; site of protein synthesis

store neurotransmitter

the process that propagates nerve impulses toward another neuron, muscle fiber, or gland cell

the highly branched receiving or input portions of a neuron

a multilayered lipid and protein covering for axons produced by neuroglia

the outer nucleated cytoplasmic layer of the Schwann cell

first portion of the axon, closest to the axon hillock

site of communication between two neurons or between a neuron and an effector cell

form the cytoskeleton of a neuron

gaps in the myelin sheath of an axon

general term for any neuronal process

area where the axon joins the cell body

area where nerve impulses arise

the numerous fine processes at the ends of an axon and its collaterals

interstitial fluid-filled space separating two neurons