basics - terms, structure and neuron classification Flashcards
what are the neuroanatomical terms for the front?
anterior or rostral
neuroanatomical terms for the back end?
posterior/caudal
neuroanatomical term for the bottom vs top?
ventral or inferior vs dorsal or superior
neuroanatomical term for a dissection down the middle, splitting left and right?
sagittal
what is a horizontal dissection?
splits top and bottom / superior and inferior
neuroanatomical term for a dissection splitting the front and back?
coronal
in terms of the spinal cord, what is a transverse and longitudinal dissection?
transverse = separates upper and lower half
longitudinal splits left and right
when using these neuroanatomical terms what must you be mindful of?
some of them, like dorsal/ventral and rostral/caudal change what they are referring to depending on the axis (standing up or lying down for example)
briefly describe the forebrain and its general functions
cerebral hemispheres, thalamus (gateway to the cortex) and hypothalamus (homeostasis)
briefly describe the midbrain and its general functions
colliculi, the tegmentum, and the cerebral peduncles
basic motor control and pain processor
briefly describe the hindbrain and its general functions
pons, cerebellum (motor coordination and movement) medulla (cardiovascular and pulmonary control)
what does the brainstem consist of?
the midbrain, the pons and the medulla oblongata
describe the four sections of the spinal cord
from the top to the bottom:
1) cervical, has an enlargement due to lots of movement in arms so needs to coordinate lots of motor neurons
2) thoracic, autonomic section
3) lumbar, with an enlargement for the legs
4) sacral
distinguish between grey and white matter and where they appear
grey = cell bodies, neurons and glia
white = neuronal axons wrapped in myelin
brain is white on inside grey on outside, spinal cord is the other way around
what two general kind of cells make up the nervous system and what do they do?
neurons = excitable cells that conduct impulses, integrating and relaying information
Glia = supporting cells, the glue, maintaining homeostasis, providing protection and assisting neural function
who distinguished glia and neurons and how?
Nissl Franz, used a positive dye that binds to RNA, in glia this stained the nucleolus, but in neurons it also stained Nissl bodies
this allowed him to observe the distribution of the two (cytoarchitecture)
describe the contents of the soma
all the same stuff as other cells, but there’s more RNA(evident in the staining) and lots of mitochondria (understandable)
define neurite, dendrite and axon
neurite = umbrella term for anything coming off a neuron
dendrite = supper branched, typically receive signals so have postsynaptic terminals
axon = thicker, typically send out signals so have presynaptic membranes
how do you visualise dendrites?
using a Golgi stain (sliver chromate)
what is the composition of neurites and the neuronal cytoskeleton?
made up of microtubules, actin and microfilaments
as well as neuronal filaments (long proteins wound together, super strong)
neurites can be lengthened and shortened over time by polymerisation or depolymerisation
describe the different sections of axons
axon hillock = bit immediately connecting to the soma
axon initial segment = site of action potentials
axon collaterals = axon branches
axon terminal/terminal bouton (aka synaptic boutons, axon terminals are small swellings that are found at the terminal ends of axons. They are typically the sites where synapses with other neurons are found, and neurotransmitters are stored there
axons don’t have a certain organelle - what is it and how do they make up for it?
they don’t have a RER so all proteins must be made in the cell body and transported (this is energy demanding) anywhere from 1mm to 1m
what is immunohistochemistry and what is another method used?
primary antibody + secondary fluorescent antibody, only works on fixed tissue so sometimes live imaging is used
what are the two kinds of presynaptic terminals?
terminal arbour - when one axon splits into many presynaptic terminals
Boutons en passant - a swelling in an axon that continues on after, but this swelling can act as a presynaptic terminal, has all the vesicles and stuff
how are presynaptic terminals specialised?
no microtubules, lots of synaptic vesicles, lots of mitochondria then obviously the synaptic cleft itself
axoplasmic transport - what are the two kinds and how do they work?
anterograde transport = forward transport toward presynaptic membrane, kinesin walks along a microtubule (the meme)
retrograde transport - opposite direction, using dynein not kinesin
how can you locate the soma of a particular axon (or vice versa)?
use an anterograde or retrograde tracer like HRP
explain the structure of dendrites
the combine as branches to form a tree, allowing for the convergence of signals, removing noise
they have dendritic spines (knobbly bits that increase surface area to create space for isolated reactions)
what are the 4 ways you can classify neurons
number of neurites
dendritic geometry
gene expression
type of NT
give an example of a (pseudo)unipolar neuron and what it does
dorsal root ganglion - super specific takes info from skin and inputs it into a spinal cord (one axon that diverges like a T junction)
give an example of a bipolar neuron and how it works
retinal bipolar neurons - photoreceptors pass info onto the bipolar neurons - there are two distinct neurites coming from the cell body, a dendritic one to receive info and an axonal one to send info off
give an example of a multipolar neuron
purkinje neuron - can receive around 150, 000 contacts, has only one axon from the cell body but this branches into many dendrites
what is dendritic geometry used for and what are the two common types?
used to distinguish between multipolar neurons
stellate = star shape, common in the neocortex
pyramidal = common in hippocampus and neocortex, has a basal tree with lots of neurites near the base, and an apical tree with lots of neurites near the brain
what do the following types of neuron connect:
1) sensory
2) motor
3) interneuron
1) periphery to the CNS
2) CNS to periphery
3) between neurons around the CNS (relay or projection neurons go far, local neurons send signals within the same area)
what technique can be used to see where a nerve goes?
reporter gene
what ability do glia maintain throughout their life?
they can proliferate
describe the structure and function of astrocytes
they have a main cell body and some processes that stick out
they stick to their spatial domains
they have a unique marker - glial fibrillary acidic protein (GFAP)
function is homeostatic
what are the different subtypes of astrocyte?
fibrous, protoplasmic, radial glial, muller cells of the retina, ependymal cells like in the choroid plexus
how are astrocytes involved in energy?
they store glycogen, then convert this to lactate to be taken by monocarboxylate transporters to neurons to be used as an energy source
what is a tripartite synapse and what role does the astrocyte play?
synapse with the pre, the post and an astrocyte
astrocytes are involved in terminating NT activity by recycling NTs, they often have receptors too
what do microglia do?
phagocytose cell debris, prune dendrites, send developmental signals and can assist in myelination
what do oligodendrocytes do?
one cell can myelinate multiple axons
what do Schwann cells do?
they myelinate one axon at a time - the Schwann cell wraps around an axon, squeezes, squishing out its own cytoplasm (compaction), leaving the cell membrane and some other proteins that make up myelin
why does myelin remain in contact with the glial cell that made it?
for nutrients purposes
to what part of the nervous system to astrocytes, oligodendrocytes, microglia and Schwann cells belong?
Schwann cells belong to the PNS, the others belong to the CNS
