Tay-Sachs disease, is an inherited defect in a lysosomal enzyme causing myelin to accumulate, burying neurons in fat.
The affected child begins to show symptoms by six months of age, gradually losing sight, hearing, and muscle function until death occurs by age four.
[Excess myelin seriously impairs nervous system functioning.]
What are the two cell types of neural tissue?
1.) Neurons
2.) Neuroglia
What are the two divisions of the nervous system and
their parts?
Central Nervous System (CNS)
Consisting of the brain and spinal cord
Peripheral Nervous System (PNS)
Consisting of the nerves (cranial and spinal nerves) that connect the central nervous system to other body parts
What is the name of the drug that decreases membrane permeability to sodium ions?
procaine
What is white matter?
myelinated cells (axons )
What parts of neurons are myelinated? {T}
just the axons (not the cell body or dendrites)
What are the 3 classifications of neurons?
1.) Multipolar neurons
2.) Bipolar neurons
3.) Unipolar neurons
True or False: The diameter of the axon effects the
speed of nerve impulse conduction.
True
Besides the diameter of the axon, what else effects the
speed of nerve impulse conduction?
whether the axon is myelinated or not
MY QUESTION
What are the three structures shared by all neurons?
1.) Dendrites
2.) A cell body
3.) An axon
When were neural stem cells first discovered?
neural stem cells were first discovered in the 1980's
in songbirds - the cells were inferred to exist because the numbers of neurons waxed and waned with the seasons, peaking when the birds learned songs
MY QUESTION
A group of cell bodies clustered together outside the
CNS are called?
the cell bodies of some unipolar neurons
aggregate in specialized masses of nerve tissue called ganglia
located outside the brain and spinal cord
Distinguish between the types of activities that somatic
and autonomic nervous systems control?
of the somatic nervous system
control skeletal muscle contraction
under voluntary (conscious) control
of the autonomic nervous system
control the cardiac and smooth muscle contraction and secretions of glands
under involuntary control
What is IPSP?
IPSP
Inhibitory postsynaptic potential
Graded
Hyperpolarized membrane of postsynaptic neuron
Action potential of postsynaptic neuron becomes less likely
Example:
a different neurotransmitter binds other receptors
increases membrane permeability to potassium ions
these ions diffuse outward, hyperpolarizing the membrane
action potential in now less likely to occur
Some inhibitory neurotransmitters open chloride channels:in this case
if sodium ions enter the cell
negative chloride ions are free to follow
opposing the depolarization
What is the special capillaries that are covered by the
ependymal cells called?
cover specialized capillaries called choroid plexuses
(they associate with the ventricles of the brain, and they help regulate the composition of the cerebrospinal fluid)
MY QUESTION
True or False: A myelinated axon, a nerve impulse, appears to jump from nod to nod.
True
A myelinated axon, a nerve impulse, appears to jump from nod to nod. So what are the nods called?
Nodes of Ranvier
What kind of cell produces a neurilemma? {T}
Schwann cell
What is a neurilemma? {T}
neurilemma (neurilemmalsheath)
contain most of the cytoplasm
nuclei remain outside the myelin sheath
surrounds the myelin sheath
In the central nervous system who makes the myelin? {T}
oligodendrocytes, produce the myelin in the brain and spinal cord in the CNS
Neuroglia cell that is located in the CNS that is responsible for cleaning up dead tissue? {T}
microglia, help support neurons and phagocytize bacterial cells and cellular debris
What are three types of channels used?
1.) chemically gated
2.) voltage gated
3.) mechanically gated
What is neuroma?
a tangled mass of regenerating axons that occurs when there is a gap that exceeds 3 millimeters
What are you at, at resting potential?
RMP = -70mV
What happens when a voltage along an axon changes to a +30? {T}
depolarize
if a membrane becomes less negative (more positive) than the resting potential, the membrane is depolarizing
Hyperpolarized is what? {T}
…the membrane potential becomes more negative
than the resting potential, the membrane is...
There is a time after a nerve has been stimulated than
even threshold stimulus will not cause another stimulus, what is that called?
absolute refractory period
…the time when threshold stimulus does not start another action potential
What is the relative refractory period?
when the membrane reestablishes its resting potential
even though repolarization is incomplete, a threshold stimulus of high intensity may trigger an impulse
Time when stronger threshold stimulus can start another action potential
When you speak about a greater intensity of stimulation,
what are speaking about?
it doesn't mean a stronger impulse, but more impulses per second
True or False: A damaged CNS nerve could not regenerate as easily as a PNS fiber.
True
the oligodendrocytes cannot produce the little buds that the Schwann cells can to regenerate an axon
How long does the excitatory postsynaptic potential tend
to last?
lasts for about 15 milliseconds
"Cortical Spreading Depression" leads to what?
to a migraine
Scattered throughout the cytoplasm are many membranous packets of what?
chromatophilic substance (nissal bodies)
Small cells that have fewer process than other types of
neuroglia are what?
microglia
Where would you find epednamal cells. {T}
in the inner lining of the central canal and the inside spaces of the brain (ventricles)
What is the most abundant type of CNS neuroglia?
astrocytes
What is the area just distal to the cell body where the
axon arises from? {T}
axonal hillock
Around the same area where the axonal hillock is, there
are structures there for support, what are they? {T}
neurofibrils
If axon exits the body and goes one side and the other
the other way, what is that? {T}
collaterals
the axon gives off many branches…
What are dendrites? {T}
they are on the other end from collaterals
typically highly branched
they are receiving only
tiny, thorn-like spines on their surfaces, which are contact points for other neurons
Besides dendrites, where else might have a synapse
communicating with an axon?
?
What type of nerve cell is a Schwann cell and what does
it do?
neuroglia cell
that encases the large axons of peripheral neuron in lipid-rich sheets
…etc...
What neuron brings an impulse to a synapse?
the presynaptic neuron
MY QUESTION
What are satellite cells?
small, cuboidal cells that surround cell bodies of neuron in ganglia
Distinguish between a sensory receptor and a effector.
sensory receptors gather information, by detecting changes inside and outside the body
effectors are outside the nervous system and they include muscles that contract in response to nerve impulse stimulation and glands that secret when stimulated
