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Clinical Neuroscience PT5024
LECTURE 1: NEUROCYTOGOLGY & GROSS ANATOMY
90
Medical
Post-Graduate
01/26/2011

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Term
neurons and neuroglia
Definition
What are the two basic classes of cells of the Central Nervous System
Term
Neurons
Definition
Anatomical and functional units for signal transmission
Term
Neuroglia
Definition
supporting matix for the neurons
Term
Motor, Sensory, Interneurons
Definition
What are the three basic types of neurons
Term
Dendrites
Definition
A region of the neuron where most of the synaptic input is received and thus contains the bulk of postsynaptic sites.
Term
Dendrites
Definition
tapering processes arising from the cell body
Term
Perikaryon
Definition
cytoplasm and organelles
Term
soma
Definition
formed by the nucleus and perickaryon
Term
Soma
Definition
Part of the neuron that is capable of significant protein synthesis and thus contains numerous free ribosomes and rough endoplasmic reticulum
Term
Soma
Definition
part of neuron which forms the gray matter
Term
Soma
Definition
part of the neuron that receives a lot of synaptic contacts (post synaptic)
Term
Axon
Definition
each neuron has one, often very long, thin process that arises from the cell body. It is responsible for the generation and conduction of an action potential
Term
axons
Definition
In the CNS bundles of what form white matter.
Term
funciculi
Definition
a tract of axons
Term
presynaptic terminal
Definition
the terminal end or swelling of an axon containing numerous small vesicles of neurotransmitter
Term
presynaptic terminal
Definition
Forms the presynaptic element of the synaptic complex
Term
receptive zone(in-put), integrative zone(trigger), conducting zone, effector zone (out-put)
Definition
Neurons can be categorized into 4 functional zones what are they
Term
receptive (input) zone
Definition
Which functional zone is the area of cell membrane that receives the presynaptic terminals from other neurons, in other words postsynaptic membrane
Term
the very distal end surface of peripheral sensory neuron axon/the dendritic processes and cell soma/same as motor
Definition
what makes up the receptive zone of a sensory neuron/motor neuron/interneuron
Term
integrative (“trigger”) zone
Definition
functional area of membrane responsible for generation of AP
Term
the first node of Ranvier/the most proximal portion of the axon (the axon hillock)/same as interneuron
Definition
integrative (“trigger”) zone is what in the sesory/interneurons/motor neurons
Term
conducing zone
Definition
The axon is what functional zone of the neron
Term
effector (output) zone
Definition
The persynaptic termainals are what functional zone of a neuron
Term
horns, nuclei / gray lamina, cerebral cortex
Definition
In the CNS neurons are arranged mainly in clusters (ie) , or laminar pattens (ie)
Term
axon hillock/initial segment
Definition
most proximal portion of axon – region of very high concentration voltage-gated ion channels – site where AP is generated (“trigger zone”)
Term
presynaptic” cell
Definition
- the cell that generates the AP & that releases neurotransmitter is called the
Term
postsynaptic cell
Definition
the cell that receives or binds to neurotransmitter is called the
Term
axo-somatic, axo-dendritic, or axo-axonal
Definition
What are three types of synapses
Term
process of relase of neuro transmitters
Definition
Action Potential is conducted down axon and reaches presynaptic terminal – there it results in opening of CA2+ channels – CA2+ flows (“influx”) into terminal – results in binding & fusion of vesicles with presynaptic membrane and release of neurotransmitter into synaptic “cleft” – neurotransmitter diffuses across cleft and binds with receptors on postsynaptic membrane
Term
may open specific voltage-gated channels (which are tunnels thru the membrane) that only allow positively-charged ion (Na+ and K+) inside the cell - this results in “depolarization” (the inside of the cell more positive) of the postsynaptic cell - this is called an “excitatory” synapse because it makes it more likely the postsynaptic cell will generate an AP
Or
may open voltage-gated channels that allow negatively charged ions (Cl-) inside the cell, “hyperpolarizing” the cell, making it less likely it will generate an AP. This is called an “inhibitory” synapse
Definition
what happens to the neurotransmitters once they have bound to the postsynaptic cleft
Term
“excitatory” synapse
Definition
opens specific voltage-gated channels (which are tunnels thru the membrane) that only allow positively-charged ion (Na+ and K+) inside the cell - this results in “depolarization” (the inside of the cell more positive) of the postsynaptic cell -
Term
“inhibitory” synapse
Definition
open voltage-gated channels that allow negatively charged ions (Cl-) inside the cell, “hyperpolarizing” the cell, making it less likely it will generate an AP
Term
unipolar, bipolar, pseudounipolar, multipolar
Definition
What are 4 morphological types of neurons
Term
Unioplar cells
Definition
1 process (an axon)-no dendrites (most found in invertebrates)
Term
bipolar cells
Definition
2 processes 1 axon and 1 dendrite(usually specialized sensory cell)
found in skin muscles joint etc
Term
pseudounipolar cell
Definition
starts as bipolar cell, but processes eventually migrate away from soma and fuse together (DRG)
Term
Multipolar cells:
Definition
1 axon and many dendrites(spinal motor neurons and interneurons)
Term
afferent neurons
Definition
convey signals (action potentials) from periphery (receptors in skin or joints) to CNS
Term
DRG
Definition
what is the primary sensory neuron
Term
efferent neurons
Definition
convey signals from CNS to muscles
Term
interneurons
Definition
most common type- conveys signals from one neuron to another:
Term
Golgi type 1,2
Definition
two types of internuerons
Term
Golgi type 1
Definition
interneuron which sends its axon long distances(aka relay or projection interneurons
Term
Golgi type 2
Definition
interneurons which sends their axon a short distance
(local interneurons)
Term
Receptive region, Integrative, conductile, output region
Definition
What are the 4 functional domains of neurons
Term
the end of the peripheral process of DRG axon
Definition
Where is the imput region of a DRG
Term
graded
Definition
what type of depolarization occurs at the DRG's receptive region
Term
dendrites and soma
Definition
where are the receptor regions of motor and inter neurons found?
Term
graded
Definition
what type of depolariztion occurs at the motor cells receptive region
Term
synaptical potential
Definition
???
Term
synaptical potential ??
Definition
summation of many excitatory post synaptic potentials (epsp).
Term
Receptor potential??
Definition
a graded depolarization small, localized, slowly spreading depolarizations, that vary in strength (maybe weak or strong) of amplitude and duration- are localized- they “damper” out over distance
Term
Integrative region
Definition
where all the receptor or synaptic potentials summate - “trigger zone” (area where concentration of voltage-gated channels highest). Here is where, if all potentials are strong enough, the action potential (AP) is generated.
Term
1st node of Ranvier (an unmyelinated part of the axon)/initial segment or axon hillock
Definition
where are the integrative regions located on primary sensory neurons/motor neurons and interneurons
Term
Conductile region
Definition
where AP is carried or “propagated” away from the Input & Integration domains
Term
the axon
Definition
where anatomically is the conductlie region located on a neuron
Term
presynaptic terminal, the distal end of the axon
Definition
where anatomically is the output region of a neuron located
Term
fusion,neurotransmitter,postsynaptic
Definition
when the AP reaches the terminal it results in the ______ of the vesicles with the pre-synaptic membrane and release of ________ from vesicles into the synaptic cleft. Once the molecules in the cleft they can bind with receptors on the ____________ membrane.
Term
NO, others close channels, inhibiting or hyperpolarizing the postsynaptic cell
Definition
Do all neurotransmitters open channels or depolarize the postsynaptic cell
Term
summation?
Definition
THe more AP's reach the terminal the more vesicles fuse and release more neurotransmitters is an exaple of what
Term
Restiing Membrane potential
Definition
RMP,Vr
Term
-60mV to -70mV
Definition
RMP
Term
when the inside of the cell is more negative than the out (RMP)
Definition
When is the cell thought to be polarized
Term
transport of charged-ions through membrane channels (transmembrane tunnels) and an active transport system.
Definition
How is the steady state of RMP maintained
Term
“gated” ion channels
Definition
what are tunnels that open up specifically following binding with certain chemicals, mechanical deformation, temperature or voltage changes in a neuron
Term
Na+, K+
Definition
When a neuron depolarizes channels are selectively opened to allow more _____ in then ___ can get out.
Term
graded depolarizaions and action potentials
Definition
In what two ways can neurons depolarize themselves
Term
small, localized, slowly spreading depolarizations, that vary in strength (maybe weak or strong) of amplitude and duration- are localized- they “damper” out over distance
Definition
What are “graded-depolarizations
Term
receptor potentials, synaptic potentials
Definition
What are graded depolarizations called in primary sensory neurons and motor neurons respectivly
Term
action potentials
Definition
what are large, rapid changes in potential that occurs in an “all or nothing” manner – not graded- always same amplitude and duration of deplorization – are carried over very long distances
Term
glial cells
Definition
non-neuronal cells that support and protect neurons.
Term
glial
Definition
_______cells do not have axons or dendrites, nor do they make synapses or generate action potentials.
Term
microglia and macroglia
Definition
There are two general classes of glia:
Term
Microglia
Definition
are the smallest of the glial cells. Some act as phagocytes, cleaning up CNS debris following injury, most mediate the immune response in the brain.
Term
astrocytes and oligodendrocytes
Definition
what are the two major types of macroglia in the CNS
Term
astrocytes
Definition
star-shaped non-neuronal cells
Term
protoplasmic and fibrous
Definition
There are two major types of astrocytes,________ (found only in gray matter)__________ (mostly in white matter)
Term
astrocytes
Definition
the function of these cells are to respond to local injury through increased mitosis (to increase their number) and hypertrophy (to increase there size), a process called scarring or gliosis. They clean up debris within the damaged area though a process known as phagocytosis (called “reactive astrocytes”) and isolate or “wall off” the damaged area. Gliosis is a prominent feature of many diseases of the CNS, INCLUDING MS IE SCLEROSIS AND STROKE
Term
oligodendrocytes
Definition
principle function is to produce the myelin sheath in the CNS
Term
myelin sheath
Definition
insulates axons from each other (allows more axons to stuffed closer together
Term
internodal segment
Definition
Each oligodendrocyte myelinates 1 portion (called an ___________ ___________ , each about 1mm in length) of 10-15 axons.
Term
nodes of Ranvier
Definition
What are the unmyelinated “gaps” in between each myelin segment
Term
saltatory propagation
Definition
The myelin sheath acts as insulation to decrease ion leakage and increase AP conduction velocity, through a process known as _________ __________ in which the AP jumps from node to node
Term
axon diameter (thicker axon = thicker myelin = faster AP conduction)
Definition
AP speed of myelinated axons increases linearly with the________ ______ in other words
Term
Schwann cells:
Definition
make myelin in the PNS
Term
form one internodal segment of myelin around only one axon
Definition
Major difference between oligodendrocytes and Schwann cells is
Term
Schwann cells
Definition
what cells make myelin in the PNS,aid in cleaning up PNS debris and guide the regrowth of PNS axons
Term
arrange themselves in a series of cylinders (tubes) that serves as a guide for sprouts of regenerating axons
Definition
how do schwann cells aid in regrowth of nerves in the PNS
Term
3-4 mm
Definition
If one of these sprouts encounters a cylinder the sprout will grow through the tube at the rate of __ __ per day
Term
wither away
Definition
what happens to nonproductive sprouts of neurons in the PNS
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