Nervous System Lecture 6.1 Flashcards
What is a cluster?
neuronal cell bodies grouped together
What do neuroglia do in cases of injury or disease?
multiply to fill the spaces formerly occupied by neurons
What is a tract?
a bundle of axons located in the CNS. Interconnects neurons in the spinal cord and brain
what is a ganglion?
cluster of neuronal cell bodies located in the PNS. Associated with cranial and spinal nerves
what are the three types of functional classification
sensory/afferent
motor/efferent
interneurons/association neurons
Why do CNS axons display little regrowth after injury
absence of a neurolemma and an inhibitory influence exerted by the oligodendrocytes on axon regrowth
where are pyramidal cells found?
the cerebral cortex
What is grey matter?
contains neuronal cell bodies, dendrites, unmyelinated axons, axon terminals, and neuroglia. Appears grayish because of the nissl bodies and lack of myelination. Located in the center of the spinal cord and the outside of the brain.
what is fast axonal transport?
moves materials in both directions, to and away from the cell body
where are multipolar neurons found?
the brain, spinal cord, and motor neurons
What are the two types of cells in the nervous system?
neurons and neuroglia
What do both types of PNS neuroglia do?
completely surround the axons and cell bodies
What are the 4 types of ion channels?
leak, ligand-gated, mechanically-gated, voltage-gated
List the functions of Schwann cells
form the myelin sheath around axons in the PNS. Only myelinates a single axon. participate in axon regeneration
what is a nucleus in terms of collections of nervous tissue
cluster of neuronal cell bodies located in the CNS
What is the function of dendrites?
receiving or input portions of a neuron
What are the 5 types of structural classification
multipolar, bipolar, unipolar, Purkinje, and pyramidal
what 2 types of neuroglia are in the PNS?
Schwann and satellite
where are most unipolar neurons located?
the ganglia of the spinal and cranial nerves
define motor/efferent neurons
convey action potentials away from the CNS to the effectors (muscles/glands) in the PNS through cranial or spinal nerves. Most are multipolar
What are three things an axon contains?
mitochondria, microtubules, and neurofibrils
What are the two parts of the sensory division?
somatic senses and special senses
what is an electrochemical gradient?
a concentration difference plus an electrical difference
functions of satellite cells
surround the cell bodies of PNS ganglia like shingles on a roof. Provide structural support and regulate exchange of materials between neuronal cell bodies and interstitial fluid
can neurons undergo mitosis?
no
define sensory/afferent neuron functions
stimulus activates a sensory receptor and the sensory neuron forms an action potential and coveys it to the CNS through cranial or spinal nerves. Most are unipolar
What is the myelin sheath?
A multilayered lipid and protein covering around some axons that insulates them and increases the speed of the nerve impulse conduction.
What are the three places an axon can take a nerve impulse?
another neuron, a muscle fiber, or a gland
What is the difference between anterograde and retrograde fast axonal transport?
anterograde (forward) direction moves organelles and synaptic vesicles from the cell body to the axon terminal
retrograde (backward) direction moves membrane vesicles and other cellular materials from the axon terminals to the cell body to be degraded or recycled
What is the name for the fine processes that come off of the axon or collaterals?
axon terminals or telodendria
What type of cells are ependymal cells?
single layer of cilliated/microvilla cuboidal or columnar cells
where are purkinje cells found?
the cerebellum
what are the functions of ependymal cells?
produce, possibly monitor, and assist in the circulation of cerebrospinal fluid. Also form the blood-cerebrospinal fluid barrier
Function of microglia?
fuction as phagocytes
What are the two types of astrocytes?
protoplasmic: found in grey matter
fibrous: found in white matter
What are the three parts of the autonomic nervous system?
sympathetic, parasympathetic, and enteric
What are the functions of neuroglia?
support, nourish, and protect neurons. Maintain interstitial fluid.
What do axons not contain?
endoplasmic reticulum. No proteins are synthesized in the axon.
can neuroglia undergo mitosis?
yes
What is white matter?
primarily composed of myelinated axons. In the spinal cord, it surrounds the grey matter and in the brain, it is deep to the grey matter
Where are ependymal cells found?
they line the ventricles of the brain and the central canal of the spinal cord
what is a bundle?
axons of neurons grouped together
What is the name for the cytoplasm of an axon and the plasma membrane of an axon?
axoplasm and axolemma
What is slow axonal transport?
It moves axoplasm in one direction only, from the cell body to the axon terminals
What is lipofuscin?
A yellow/brown pigment that appears in aging neuron cells. A product of neuronal lysosomes and is not harmful (as far as we know).
What is the name for side branches off the axon at a 90 degree angle?
axon collaterals
What is the function of oligodendrocytes?
forming and maintaining the myelin sheath around CNS axons
What do the processes of astrocytes make contact with?
blood capillaries, neurons, and pia mater
What is a nerve?
a bundle of axons located in the PNS
where are unipolar/pseudounipolar neurons found
they function as sensory receptors
where are bipolar neurons found?
retina, inner ear, olfactory (special senses)
What are the three parts of a neuron?
cell body/soma/perikaryon
dendrites
axon
What percentage does neuroglia make up of the volume of the CNS?
50%
What are the two types of potentials and how are they used?
grade potentials- short distances
action potentials- long distances
How many types of neuroglia are there?
6
In the embryo what do unipolar neurons begin as?
bipolar neurons
What are the 5 functions of astrocytes?
Support neurons
create blood-brain barrier
in the embryo, they secrete chemicals that appear to regulate growth, migration, and interconnection among neurons in the brain
maintain the appropriate chemical environment for the generation of nerve impulses
may play a role in learning and memory
Where is a neurolemma only found?
around axons in the PNS and aids in regeneration by forming a regeneration tube that guides and stimulates regrowth of the axon
Note, that the neurolemma is the plasma membrane of Schwann cells that surrounds the myelinated nerve fibers of the peripheral nervous system
Which 4 types of neuroglia are found in the CNS?
astrocytes, oligodendrocytes, microglia, and ependymal
what are nodes of ranvier
gaps in the myelin sheath that increase action potential speed
define interneurons/association neuron function
mainly located within the CNS between sensory and motor neurons. interneurons process incoming sensory information from the sensory neurons and then elicit a motor response by activating the appropriate motor neurons. Most are multipolar
What is the function of Nissl bodies?
Synthesize proteins that are used to replace cellular components, as material for the growth of neurons and to regenerate damaged axons in the !PNS!.
What are the functions of neurons?
sensing, thinking, remembering, controlling muscle activity, and regulating glandular secretions
