Lecture 2 Flashcards
challenges of studying neurons
-the size
-obtaining nervous tissue that is sufficiently thin (very soft)
-neurons are generally colourless
parts of a prototypical neuron
soma
axon
nerve terminal
dendrite
dendritic spine
nucleus
cellular membrane
cytoskeleton
soma
-mitochondria
-site of cellular respiration
-krebs cycle
-ATP - cell’s energy source
axon
-electrical transmission of signal output
-branches (collaterals) bifurcating at right angles (90 degrees)
axon hillock
-start of the axon that emerges from the soma
-site of initiation of action potentials
axon (or nerve) terminal
synaptic transmission
differences between axon and soma
-ER does not extend into axon
-protein composition of the axon is unique
differences between nerve terminals and axons
-no microtubules in terminal
-presence of synaptic vesicle
-abundance of membrane proteins
-large number of mitochondria
electric synapses
gap junctions
chemical synapses
release of neurotransmitters
dendrites
-“antennae” of neurons
-processing of information received through synapses
dendritic spines
-dendrites of certain neurons are stubbed with small mushroom or spine-shaped structures
-recieve signals from nerve terminals of other neurons
-postsynaptic compartment contains synaptic receptors
-associated with memory and learning
cell membrane
-barrier that encloses the cytoplasm
-different regions of the neuron cell membrane will contain different types of membrane proteins
-supports electrical and chemical transmission of information
different neuron membranes
-presynaptic membrane
-postsynaptic membrane
-axonal membrane
cytoskeleton
-not static, very dynamic
-3 types of filaments (microtubules, microfilaments (actine), neurofilaments)
microtubules
-movement of organelles
-railroad for molecular motors
microfilaments (actine)
dynamic change of shape
neurofilaments
support and stability
anterograde axoplasmic transport
-from soma to nerve terminal
-requires kinesins interacting with microtubules
-consumes ATP
-used to visualize the postsynaptic connections of neurons of interest
-answers the question: “a neuron speaks to who?”
retrograde axoplasmic transport
-from nerve terminal to soma
-requires dyneins
-consumes ATP
-used to visualize the presynaptic neurons connected to neurons of interest
-answers the question: “a neuron is listening to who?”
anterograde tracing
-labels nerve terminals
-phageolus vulgaris leucoagglutinin
-dextrans
-dil
retrograde tracing
-labels cells that innervate a targetted area
-dextrans
-dil
-horseradish peroxydase (HRP)
-virus
unipolar
a single neurite
bipolar
two neurites
multipolar
multiple neurites
somatic classification
can be oval/spherical or pyramidal cells
dentritic classification
-number of dendrites
-lengths
-branching patterns
golgi type I
projection neurons (long axon)
golgi type II
loccal neurons (short axon)
sensory neurons connectivity
sensory receptors
motoneurons connectivity
muscle or gland
interneurons connectivity
contact other neurons within CNS
glia function
-neuronal support
-insulation
-nourish neurons
-can shape cell signalling
astrocytes
-formed by many projections: star shaped
-most numerous glia in the brain
-fill the space between neurons
-influence neurite growth
-regulate ionic extracellular concentrations
-shape synaptic transmission
oligodendrocytes (CNS)
wrap around multiple axons
schwann cells (PNS)
wrap around a single axon
role of myelin
-insulate axons
-increases the speed of electrical transmission
node of ranvier
-region where the axonal membrane is exposed, high density of sodium channels
-allows for saltatory transmission
microglia
-phagocyte
-immune system
-elimination of cellular waste and dead cells
neurons
-process information
-sense environmental changes
-communicates percieved changes to other neurons
-command corporal responses
