Week 0: NEUROPHYSIOLOGY [part 1] Flashcards
T or F: although neurons a permanent cell, some may grow new axons if the axon is severed particularly in the PNS
True
T or F: when stimulated under normal conditions neurons conducts impulses in one direction, from dendrite to synaptic endings
True
what is a soma
cell body
extend outward from the cell body and arborize extensively to aid their role in receiving incoming signals, processing the information, and then transmitting the information to the soma of the neuron
dendrites
originates from a thickened area of the cell body, which is long and fibrous
axon
The first portion
of the axon is called the
initial segment
They contain
granules or vesicles in which the synaptic transmitters released
by the nerves are stored
synaptic knobs/ terminal buttons
____________ forms from
Schwann cells and surrounds the axon except at its ending
and at the nodes of Ranvier
myelin sheath
_____________ neurons have more than 2 processes, but axons cannot be distinguished from dendrites
anaxonic
_____________ neurons have 2 processes separated by the cell body
bipolar
_____________neurons have a single elongated process within the cell body situated off to the side
Unipolar
____________ neurons have more than 2 processes; there is a single axon and multiple dendrites.
multipolar
Examples include motor neurons, hippocampal
pyramidal cells with dendrites in the apex and base, and
cerebellar Purkinje cells with an extensive dendritic tree in a
single plane.
multipolar cells/ neurons
where multiple local potential changes generated by synaptic connections are integrated; what zone in the neurons
dendritic zone
transmits propagated impulses to the nerve endings`
axonal process
part of the neuron where action potentials cause the release of synaptic transmitters.
nerve endings
Membrane-bound organelles and mitochondria are transported relatively rapidly by (fast/slow) axonal transport.
Substances that are dissolved in cytoplasm (e.g., proteins) are moved by (fast/slow) axonal transport.
fast axonal transport.
Slow axonal transport
Axonal transport occurs in both directions. Transport from the
soma toward the axonal terminals is called _________
axonal transport. this involves what motor protein
anterograde; kinesin
Transport in the opposite direction, which is driven by what protein?;
is called __________ axonal transport. This process returns
recycled synaptic vesicle membrane to the soma for
lysosomal degradation.
dynein; retrograde axonal transport
When an axon is transected, the soma of the neuron may
show ________________
chromatolysis, or “axonal reaction.”
Nissl bodies stain well with
basic aniline dyes
what will happen to the soma when there is a reaction to injury?
swell and may become rounded
However, in the PNS the Schwann cells that had formed the
myelin sheath remain viable, and in fact they undergo cell
division. what do you call this?
wallerian degeneration
herpes zoster virus invades what part of the CNS?
dorsal root ganglion
causative agent of tetanus
clostridium tetani
tetanus toxin vs botulinum toxin, which is flaccid, spastic?
spastic-tetanus; flaccid- botulinum
clostridum tetani MOA?
delivery of toxin to inhibitory neurons; GABA and glycin are not produced; excitatory signal overwhelms and then muscles go extreme spasm.
The difference in voltage (or electrical potential difference) between the interior and exterior of a cell
Membrane potential or transmembrane potential
results from the separation of positive and negative charges across the cell membrane
membrane potential
For a potential difference to be present across a membrane lipid bilayer, two conditions must be met
First, there must be an unequal distribution of ions of one or more type across the membrane (ie, a concentration gradient). Second, the membrane must be permeable to these ions. The permeability is provided by the existence of channels or pores in the bilayer; these channels are usually permeable to a single type of ion
what maintains the separation of charges?
Lipid bilayer
outside the cell which ion has higher concentration? how about inside?
Sodium is high outside; potassium is high inside. (PISO) basta tandaan na ang pumapasok ang sodium pag action potential so siya yung nasa labas.
Is the tendency for the ion to diffuse
diffusion potential
T or F? Equilibrium potential is based on the charge outside the cell.
F; it should be inside the cell.
What is the Physiological Significance of the Membrane
Potential?
No membrane potential no action potential; No membrane potential no returning of ion channels to
inactive states
Potential difference across the axon plasma membrane of a
neuron not sending signals (not firing)
Resting membrane potential
most important and major contributor of the three mechanisms by which Resting Membrane Potential is generated
Transmembrane K gradient thru non gated K leak channels (potassium leak channels)
RMP of a neuron
-70
Three important mechanisms by which Resting Membrane Potential is generated
- Transmembrane K gradient thru non gated K leak channels (potassium leak channels)
- Donnan effect (Gibbs-Donnan Equilibrium)
- Na K ATPase Pump
Used to measure the actual value of RMP
Utilizes the concentration and permeability of ALL THE IONS involved
More accurate
Goldman-hodgkin-katz Voltage equation
a name for the behaviour of charged particles near a semi-permeable membrane that sometimes fail to distribute evenly across the two sides of the membrane.
Donnan effect (Gibbs-Donnan Equilibrium)
Na K ATPase pump: how many sodium and potassium?
3 Na out; 2 K in (Trina, out!!! antu K-in!)
what would happen if sodium potassium pump fails?
Sodium will be trapped inside the cells, water follows and it will lead to lysis.
A shift in membrane potential in positive direction when sodium ions enter the cell
depolarization
is the process of adding things up. In the case of nervous system, it is about adding up the effect of multiple stimuli, that are all individually subthreshold, so that together they can reach suprathreshold or beyond threshold and are able to generate an action potential (a response).
Summation
Fleeting, self-renewing wave of depolarization (positive wave) that propagates without decrement along the entire length of a nerve axon at high speed.
Action potential
Where is Action Potential Generated?
Axon hillock
Period during which a nerve or muscle is incapable of responding to stimulation, especially following a previous stimulation
Refractory Period
Hypokalemia, what symptoms? Hyponatremia?
weakness and eventual paralysis; depressionof sensorium
The Limbic Lobe is surrounded by 3 gyri
Cingulate, Subcallosal, Parahippocampal
Hippocampus is made up of 3 important structures:
Dentate gyrus, hippocampal gyrus, Subiculum or subicular cortex
Sommer’s sector: what sector of hippocampus?
CA1
collateral branches between CA 1 and CA3 is called?
Schauffer Collaterals
CA1 cells are sensitive to anoxia (an absence or deficiency of oxygen reaching the tissues). Why?
CA1 cells produce Glutamate which make the area excitatory therefore needing O2
CA2? CA3? what are the names of these sectors of hippocampus?
Dorsal Resistant Sector; Spielmeyer sector
The axons of the Granule Cell layer project into the CA3 region. They are called
Mossy Fibers
Almond shaped nucleus deep in the medial temporal lobe
Function: Integrative center for emotions, emotional behavior, and motivation
Amygdala
