BIOL G220: Ch. 14 Flashcards
Terms and concepts from Ch. 14: Nervous Tissue
two structural subdivisions of nervous system
central nervous system
peripheral nervous system
central nervous system includes .. (2)
brain
spinal cord
peripheral nervous system includes .. (3)
cranial nerves
spinal nerves
ganglia
general functions of CNS and PNS (3)
- collecting information
- processing and evaluating information
- responding to information
collection information function
detect changes in the internal and external environment; pass the information on to the CNS
processing and evaluating information function
CNS determines the required response
responding to information function
CNS initiates nerve impulses to effectors to react to changes in the body’s environment
two functional subdivisions of nervous system
- sensory nervous system
2. motor nervous system
sensory nervous system is aka
afferent nervous system
sensory nervous system receives ____ information from ___ in the ____ and transmits it to the CNS
sensory; receptors; PNS
two subdivisions of sensory nervous system
somatic sensory
visceral sensory
somatic sensory
general senses such as touch, pain, pressure, vibration, and proprioception
visceral sensory
impulses from viscera
motor nervous system is aka
efferent nervous system
motor nervous systems sends ___ from ____ to ____ and glands
impulses; CNS; muscles
two subdivisions of motor nervous system
somatic motor
autonomic motor
somatic motor
impulses from the CNS that cause contraction of skeletal muscles
autonomic motor
impulses from CNS that regulate smooth and cardiac muscles, as well as glands
cell types within the NS (2)
neurons (nerve cells)
glial cells
neurons (nerve cells)
electrically excitable cells that initiate, transmit, and receive nerve impulses
glial cells
nonexcitable cells that support and protect the neurons
neurons are the ___ structural unit of the NS
basic
neurons conduct ___ from on part of the body to another
impulses
special characteristics of neurons (3)
high metabolic rate
extreme longevity
nonmitotic
main structural regions of neuron (3)
cell body
dendrites
axon
another name for a cell body is the ___
soma
the cell body contains typical organelles such as … (5)
nucleus, nucleolus, mitochondria, free ribosomes, and rough ER (free ribos and rough ER = Nissl bodies)
dendrites
short processes that branch from the cell body and receive nerve impulses to carry them to the cell body
axons
transmit nerve impulses away from the cell body and transmit information to other cells;
neurons have either ____ or no axon at all
one
anaxonic
neurons without an axon
axon hillock
triangular region where the axon connects to the cell body
structures associated with axons (3)
axon collaterals
telodendria
synaptic knobs
axon collaterals
side branches off the main axon
telodendria
fine terminal extensions at the end of the axon and its collaterals
synaptic knobs
expanded regions at the tip of telodendria
cell body
nucleus and surrounding cytoplasm of a neuron (Excluding dendrites and axon)
perikaryon
most often refers to the cytoplasm within the cell body. sometimes used to describe the entire cell body
neurotubules
microtubules that form the cytoskeleton
neurofilaments
intermediate filaments that aggregate to form bundles called neurofibrils
neurofibrils
aggregates of neurofilaments that extend as a complex network into dendrites and axons, their tensile strength provides support for the processes
structural classifications of neurons (3)
unipolar
bipolar
multipolar
structurally, neurons are classified into 3 types, depending on the number of ____ ______ emanating directly form the cell body
cell processes
unipolar
single, short process that branches like a T; common, usually sensory neurons
bipolar
two processes, one dendrite and on axon; uncommon, some special sense neurons
multipolar
many dendrites and a single axon, most common type of neuron; interneurons, motor neurons
functionally, neurons are classified according to the ____ that the nerve impulse is traveling relative to the CNS
direction
functional classification of neurons (3)
sensory (afferent)
motor (efferent)
interneurons
sensory (afferent) fxnl classification
transmit impulse from sensory receptors to the CNS
motor (efferent) fxnl classification
transmit impulses from CNS to muscles or glands
interneurons
facilitate communication between sensory and motor neurons
ganglion
group of cells bodies in PNS
glial cells are sometimes referred to as
neuroglia
glial cells are found in both the
CNS and PNS
glial cells are ____ than neurons and capable of
smaller; mitosis
glial cells function to … (2)
physically protect and nourish neurons
glial cells are more ___ than neurons
numerous
brain tumors are more likely to be derived from ___ than neurons
glial cells
types of glial cells in CNS (4)
astrocytes
ependymal cells
microglial cells
oligodendrocytes
astrocytes are the most ____ glial cells in the CNS
abundant
astrocyte functions (6)
- helping to form the blood-brain barrier (BBB)
- regulating tissue fluid composition
- helping regulate synaptic transmission
- forming a structural network
- replacing damaged neurons
- assisting neuronal development
BBB
provides high level of control of what material leaves blood and enters neurons
protection from toxins through a selectively permeable membrane of the neuron
ependymal cells
ciliated cuboidal epithelial cells that lines that ventricles of the brain and the central canal of the spinal cord
ependymal cells function
produce cerebral spinal fluid (CSF) and form the choroid plexus
microglial cells
small cells that are motile
microglial cells function
wander through the CNS and exhibit phagocytic activity, removing cellular debris from dead or dying cells
oligodendrocytes
associated with CNS axons ONLY; wrap themselves around the axons
oligodendrocytes function
produce myelin, insulator of electrical activity
glial cells of PNS (2)
- satellite cells
2. neurolemmocytes
satellite cells
flattened cells arranged round neuronal cell bodies in ganglia
neurolemmocytes are aka
schwann cells
neurolemmocytes are associated with ___ axons only
PNS
neurolemmocytes ____ themselves around the ___
wrap; axons
neurolemmocytes function
same structure and function as oligodendrocytes; produce myelin, insulator of electrical activity
myelination of axons affects the ability of neurons to conducts ___ _____, also called __ ____
nerve impulses; action potentials
myelination
process of wrapping the axon with a myelin sheath, serving as insulation
myelination is formed by ____ in PNS and ____ in CNS
neurolemmocytes; oligodendrocytes
breaks in myelin are necessary to allow…
action potentials to jump from one spot to the next
spaces in between myelination are called
neurofibril nodes
axon regeneration can occur if…
the cell body is intact and a critical amount of neurilemma remains
regeneration depends on….
extent and site of damage
____ play an important role in the axon regeneration process
neurolemmocytes
wallerian degeneration occurs when…
a proximal portion of a severed axon seals off and swells, while the distal portion of the axon and myelin sheath disintegrate.
in wallerian degeneration, the ___ survives
neurilemma
neurilemme and endonerium will form a ___ _____ during wallerian degeneration
regeneration tube
after axon regenerate and remyleination occurs in wallerian degeneration, _____ to effector is restored
innervation
nerves
cablelike bundle of parallel axons
nerves are surrounded by three connective tissue wrappings called …
endoneurium
perineurium
epineurium
endoneurium
around each axon
perineurium
around individual fascicles
epineurium
around the entire nerve
synapses
specialized junctions between one axon and another neuron, muscle cell, or gland cell
a typical synapse consists of… (3)
presynaptic neuron
postsynaptic neuron
synaptic cleft
action potential in the _____ neuron rising will lead to _____ diffusion across the synpatic ______ which NTs released will be picked up by receptor proteins in the ______ neuron
presynaptic; vesicle; cleft; postsynaptic
