61 terms

c11-14 The Nervous Tissue and the Nervous System

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reflex
Automatic reaction to stimuli.
autonomic nervous system
Efferent division of the peripheral nervous system that innervates cardiac and smooth muscles and glands; also called the involuntary or visceral motor system.
gray matter
Gray area of the central nervous system; contains cell bodies and unmyelinated fibers of neurons.
afferent neuron
Nerve cell that carries impulses toward the central nervous system; initiates nerve impulses following receptor stimulation.
myelin
Fatty insulating sheath that surrounds all but the smallest nerve fibers.
somatic nervous system
Division of the peripheral nervous system that provides the motor innervation of skeletal muscles; also called the voluntary nervous system.
repolarization
Movement of the membrane potential to the initial resting (polarized) state.
axon
Neuron process that carries impulses away from the nerve cell body; efferent process; the conducting portion of a nerve cell.
neuroglia
Nonexcitable cells of neural tissue that support, protect, and insulate the neurons.
tract
A collection of nerve fibers in the central nervous system having the same origin, termination, and function.
proprioceptors
Receptor located in a joint, muscle, or tendon; concerned with locomotion, posture and muscle tone.
dura mater
Outermost and toughest of the three membranes (meninges) covering the brain and spinal cord.
action potential
A large transient depolarization event, including polarity reversal, that is conducted along the membrane of a muscle cell or a nerve fiber.
efferent neurons
neurons that conduct impulses away from the central nervous system.
depolarization
Loss of a state of polarity; loss or reduction of negative membrane potential.
arachnoid
Weblike; specifically, the weblike middle layer of the three meninges.
neuron
Cell of the nervous system specialized to generate and transmit nerve impulses.
subarachnoid space
a space in the meninges beneath the arachnoid membrane and above the pia mater that contains the cerebrospinal fluid
Pacinian corpuscle (lamellar)
a type of nerve ending located in the subcutaneous layer that is sensitive to pressure
saltatory conduction
Rapid transmission of a nerve impulse along an axon, resulting from the action potential jumping from one node of Ranvier to another, skipping the myelin-sheathed regions of membrane.
Meissner's corpuscle (tactile)
A sensory receptor located in the dermis of the skin, which is sensitive fine touch.
bipolar neurons
neuron with 2 processes extending for it's cell body-- one axon, one dendrite; common in the retina of the eye and olfactory receptors
brain stem
The part of the brain composed of the midbrain, pons, and medulla oblongata and connecting the spinal cord with the forebrain and cerebrum.
thalamus
the structure of the brain that relays messages from the sense organs to the cerebral cortex
synaptic cleft
The gap between two communicating neurons
nuclei
collections of nerve cell bodies inside the central nervous system
oligodendrocytes
a cell that holds nerve fibers together and produces the myelin sheath around axons in the central nervous system
astrocytes
CNS cells responsible for physical support and maintaining blood brain barrier
Schwann cells
Supporting cells of the peripheral nervous system responsible for the formation of myelin.
ependymal cells
Line cavities of brain and spinal cord; secrete and circulate cerebrospinal fluid (CSF).
microglia
are phagocytes, destroys and breaks down damaged cells
interneuron
neuron, serving as part of the conduction pathway between sensory and motor neuron; also called association neurons
diencephalon
Composed of the epithalamus, thalamus, and hypothalamus; begins where midbrain ends
peripheral nervous system
cranial and spinal nerves that extend beyond the CNS
hypothalamus
a neural structure lying below the thalamus; control of temperature, endocrine activity, and thirst via the pituitary gland, and is linked to emotion
white matter
located in the CNS; myelinated axons in bundles (tracts) with few cell bodies
sympathetic nervous system
A subdivision of the autonomic nervous system that activates nerves, glands and visceral muscles in times of stress or threat; fight or flight response
parasympathetic nervous system
the division of the autonomic nervous system that calms the body, conserving its energy; rest and digest response
blood-brain barrier
mechanism that prevents certain molecule from entering the brain but allows others to cross
central nervous system
brain and spinal cord
cerebrospinal fluid (CSF)
fluid found between the layers of the meninges and through cavities inside the brain and spinal cord; provides nutrients and protects brain and spinal cord
choroid plexus
inside the ventricles; tiny masses of specialized capillaries that form CSF
corpus callosum
thick band of myelinated axons that connects the two cerebral hemispheres and acts as a communication link between them
dendrites
branching neuron processes that transmit an electrical signal toward the cell body of a neruon
dorsal root ganglion
group of sensory neuron cell bodies found just posterior to the spinal cord on either side
efferent division
division of nervous system which carries motor commands to muscles and glands
gyri
- gyrus: elevated ridge on cerebrum
meninges
three membranes that cover the brain and spinal cord, consisting of the dura mater, pia mater, and arachnoid mater
nodes of Ranvier
gaps in myelin sheath; between adjacent Schwann cells
polarized
condition in which the inside of a cell is more negatively charged than the outside of the cell
satellite cells
provide physical support to PNS neurons; surround cell bodies of sensory neurons
sulci
shallow grooves of the cerebrum
voltage gated ion channels
a specialized ion channel that opens or closes in response to changes in membrane potential
chemically gated ion channels
also known as ligand gated ion channels; need the binding of another molecule to open the gate
refractory period
after firing when a neuron will not fire again; hyperpolarized
auditory cortex
the area of the temporal lobe responsible for processing sound information
pia mater
thin, delicate inner membrane of the meninges
arachnoid mater
weblike middle layer of the three meninges
nociceptors
Nerve endings that signal the sensation of pain.
mechanoreceptors
respond to touch, pressure, vibration, stretch, and itch
thermoreceptors
respond to changes in temperature