Cytology Flashcards
cell classification
polarity
functional
polarity classifications
number of poles:
1: multipolar
2: bipolar
3: pseudo-unipolar
bi-polar
specialized- seen in sensory systems
smell, sight, vestibular
multi-polar
most common
predominant kind of neuron in CNS and PNS
pseudo-unipolar
evolves for speed/faster conduction- bypasses cell body so it doesn’t have to travel through
seen for pain/pressure
self propagating
golgi I
LONG axon which projects from one subsystem to another (brain–>SC, SC–>foot)
Golgi II
(interneurons)
SHORT axons
make connections with other neurons in the same subsystem
most numerous; short or no axon;
neurons that integrate things (connect dorsal horn to ventral horn of C5 on the same side)
1: segmental
2: propriospinal
segmental golgi II
project only to the same segment
associative: same side (ipsilateral fiber)
commissural: opposite side (contralateral fiber)
Propriospinal golgi II
project to other SC segments
tract cells
similar to golgi I but reside only in the CNS
forms tracts- collections of axons carrying the same kind of information (project to higher or lower levels of communication; fasiculus)
Functional classifications
1: directional
2: action on other neurons
3: discharge patterns
4: neurotransmitter release
directional classifications
afferent
efferent
interneurons
point of reference is usually the CNS; when it is, then you can refer to them as sensory or motor neurons
afferent=
coming to the point of reference (CNS)
usually “sensory”
efferent=
leaves the point of reference (CNS)
usually “motor” in the sense that it innervates muscles
actions on other neurons
excitatory:
inhibitory:
modulatory:
modulatory=
changes how the system reacts to the next time the stimulus is introduced
endorphins- modulate system to feel less pain to same painful stimulus
discharge patterns
tonic or regular spiking
phasic or bursting
fast spiking
thin spike
tonic (or regular spiking) discharge pattern
firing- always firing at a rhythmic rate and changed by increasing or decreasing firing rate; slow adapting
stimulate a neuron, continue to fire for a long time
phasic (or bursting) discharge pattern
“dynamic”
only on when they are stimulated and go off quickly; quick adapting
stimulate a neuron, fires, stops when stimulus is removed
fast spiking discharge pattern
fast firing rates
neurotransmitter release
cholinergic neurons
GABAergic neurons
glutamatergic neurons
dopaminergic neurons
serotonin
cholinergic neurons
excitatory to muscle
inhibitory to PNS
acetylcholine- usually always excitatory, used to contract muscle and inhibit the heart
GABAergic neurons
primary inhibitors
glutamatergic neurons
excitatory
dopaminergic neurons
excitatory and inhibitory
serotonin
excitatory
nucleus
contains genetic material (chromosomes) including information for cell development and synthesis of proteins necessary for cell maintenance and survival.
covered by a membrane
nucleolus
produces ribosomes necessary for translation of genetic information into proteins
nissl bodies
groups of ribosomes used for protein synthesis
endoplasmic reticulum (ER)
system of tubes for transport of materials within cytoplasm
Rough ER: have ribosomes- important for protein synthesis
Smooth ER: no ribosomes
golgi apparatus
membrane-bound struction important in packaging peptides and proteins (including neurotransmitters) into vesicles
microfilaments/neurotubules
system of transport for materials within a neuron and may be used for structural support
passes nutrients/proteins up and down axon
anterograde
retrograde
mitochondria
produce energy to fuel cellular activities
anterograde
produced in cell, going down to synapse away from home
retrograde
coming back towards nucleus or cell body of neuron
cell hillock
where AP is generated because it has the lowest threshold
function of the intracellular matrix
1: gives the cell its shape and stiffness
2: provides the mechanisms for cell growth and motility
3: provides the internal network over which molecules and organelles are transported
elements of the intracellular matrix
structural- keep axon together
1: actin filaments
2: neurofilament
3: microtubules
actin filaments (don’t memorize)
STRUCTURAL INTEGRITY- gives membranes structure
- closely associated with the cell membrane- forms a dense network
- responsible for developing and maintaining surface irregularities of cells (i.e. dendritic spines) and growing axons
- 3-5 nM in diameter
- key role in the dynamic function of the cell’s periphery (ie motility or growth cones during developmental, formation or pre- and post morphologic specializations
intermediate filaments (neurofilaments (neurons)) (don’t memorize)
(railroad track for structures to move and and down the axon)
gives cells mechanical integrity- bones of the cytoskeleton
give high tensile strength
most numerous
aligned in orderly parallel arrays
10nm in diameter
forms the neurofibrillary tangles of Alzheimer’s
microtubules (don’t memorize)
largest intracellular protein
abundant in all cells
in neurons, provide rigidity by x-linking with neurofilaments
essential in the transport of macromolecules and membrane bound structures
long scaffolds- extend the full length of the neuron
responsible for maintaining the neuron’s processes
axons
not only transports AP but moves fluids
if you take an axon off a muscle the muscle will atrophy
can be up to a meter long!