Chapter 12- nervous tissue
Which ion has the greatest influence on the resting membrane potential of most neurons?
potassium
an electrical potential is a form of what type of energy?
potential energy
At a synapse, the neuron that releases neurotransmitter is the ______ neuron.
presynaptic
Which term refers to the period of time after a nerve cell has responded to a stimulus in which it cannot be excited by a threshold stimulus?
refractory peropd
which are usually found inside the cell body (or soma) of a mature neuron?
rough endoplasmic reticulum nucleus mitochondria
Which neuroglial cell is found in the peripheral nervous system?
satellite cell
Which type of glial cell produces the myelin sheath in the PNS?
schwann cell
Which type of glial cell aids in regeneration of damaged peripheral nerve fibers by forming a regeneration tube to help reestablish the former connection?
schwann cells
The release of a neurotransmitter is an example of which physiological property exhibited by a neuron?
secretion
Afferent neurons are ______ neurons.
sensory
List the three functional classes of neurons.
sensory neurons interneuons motor neurons
The sensory and motor divisions of the peripheral nervous system are further split into which two subdivisions?
somatic and visceral
Which division inhibits digestion?
sympathetic
The autonomic nervous system is subdivided into the ______ division which tends to arouse the body for action and the ______ division which tends to have a calming effect.
sympathetic, parasympathetic
Which term refers to the microscopic physical gap between the presynaptic and postsynaptic neurons at a chemical synapse?
synaptic cleft
At its distal end, an axon has an extensive complex of fine branches called a(n) ______.
terminal arborization
Which statements characterize neurotransmitters?
they are released in response to stimulation they bind to receptors and alter the physiology of the postsynaptic cell. they are synthesized by presynaptic neurons.
Which statements are true about Schwann cells?
they assist in the regeneration of damaged nerve fibers they form the myelin sheath in the PNS they form the neurilemma
Which lists the structural categories of neurons?
unipolar, bipolar, anaxonic, multipolar
Which best describes an electrical potential?
a form of potential energy that can produce current
axon hillock
a mound located on one side of the soma from which the axon originates
Which term refers to a synapse that releases acetylcholine from the presynaptic axon terminal?
cholinergic
The processes that branch from the somas of most neurons are called ______.
dendrites
_____are the processes of a neuron that usually receive signals from other neurons.
dendrites
which factors influence the speed of nerve signal conduction?
diameter of axon presence of myelin
At a synapse, the neuron that responds to the neurotransmitter is the ______ neuron.
postsynaptic
Choose the characteristics of neuroglia.
they protect the neurons and help them function they bind neurons together and provide a supportive scaffold
unipolar neurons
a single process
which best describes signal conduction in unmyelinated axons?
a wave of depolarization opens more voltage-gated channels immediately distal to the action potential
indicate which of the following statements are true about signal conduction along unmyelinated fibers?
a zone of depolarization excited voltage-gated channels immediately distal to the action potential unmyelinated fibers have voltage-gated channels along their entire length
The refractory period in which no stimulus of any strength will trigger a new action potential is the ______ refractory period.
absolute
Two organ systems are dedicated to internal coordination, communication between the other systems, and maintaining the overall homeostasis of the body. They are the system, which communicates by means of hormones, and the system which sends quick electrical and chemical messages from cell to cell.
endocrine, nervous
In electrical synapses, electrical signals move quickly from cell to cell through which of the following?
gap junctions
Which is true about a neuron with a large diameter, myelinated axon as compared to a neuron with a small diameter, unmyelinated axon?
signal conduction will be faster
What is the primary function of the myelin sheath?
to increase the speed of signal conduction in the axon
True or false: Action potentials occur only where there are voltage-gated ion channels.
true
______ cells protect the neurons and help them function.
GLIAL
Which of the following contributes to the development of the resting membrane potential in neurons?
K+ is more concentrated in the ICF than in the ECF
Which process of a neuron is specialized for rapid conduction of nerve signals to structures relatively far away from the neuron cell body?
axon
Which term applies to the small swellings at the distal end of the axon of a neuron that contain synaptic vesicles?
axon terminals
Which term refers to the passage of proteins, organelles and other materials along an axon?
axonal transport
axon collateral
branch that originates from an axon
What are the two major anatomical subdivisions of the nervous system?
central and peripheral nervous systems
The brain and spinal cord are components of the ______ nervous system, while the nerves and ganglia are components of the ______ nervous system.
central, peripheral
Which fundamental physiological property of neurons allows them to send signals quickly over long distances?
conductivity
axoplasm
cytoplasm of the axon
which are characteristics of local potentials
decremental, graded
True or false: Electrical synapses are able to integrate information and make decisions more rapidly than chemical signals.
false
ependymal cells
in the CNS; line cavities of the brain and spinal cord; secret and circulate csf
microglia
in the CNS; phagocytize microorganisms, foreign matter and dead nervous tissue
schwann cells
in the PNS; form neurilemma around all PNS fibers and myelin around most of them; aid in regeneration of damaged nerve fibers
satellite cells
in the PNS; surround somas of neurons in ganglia, provide electrical insulation, and regulate the chemical environment of neurons
How do neuromodulators alter synaptic transmission?
increasing the release of neurotransmitters by presynaptic neurons adjusting the sensitivity of postsynaptic neurons to neurotransmitters altering the breakdown and or reuptake of a neurostransmitter
Which correctly describe axonal transport?
it is bidirectional (retrograde and anterograde transport) it involves transport of proteins within the axon
the myelin sheath is composed mostly of which of the following?
lipids
Which term refers to decremental changes in electrical potential along a dendrite or the soma?
local potentials
The ______ (the cell body of a neuron) gives rise to branch-like processes called ______, which are the primary sites for receiving signals from other neurons.
nerosoma, dendrites
Which two organ systems are primarily responsible for coordinating the other bodily systems so as to maintain homeostasis?
nervous system and endocrine system
Which term describes the ability of neurons to process information, store and recall it, and make decisions?
neural integration
which are names for the cell body of a neuron?
neurosoma, soma
Stimulation of the postsynaptic neuron will end when nerve signals stop arriving at the presynaptic axon terminal or when which of the following occurs?
neurotransmitter is removed from postsynaptic receptors
anaxonic neurons
no axon; multiple dendrites
which are properties of action potentials?
nondecremental (signal maintains amplitude) all or none self-propagating
which types of glial cells are found in the central nervous system?
oligodendrocytes ependymal cells astrocytes microglia
mulitpolar neurons
one axon; multiple dendrites
bipolar neurons
one axon; one dendrite
Taken together, the sensory and motor subdivisions make up which of the following?
peripheral nervous system
axolemma
plasma membrane of the axon
