basics - terms, structure and neuron classification

Question 1

what are the neuroanatomical terms for the front?

Answer 1

anterior or rostral

Question 2

neuroanatomical terms for the back end?

Answer 2

posterior/caudal

Question 3

neuroanatomical term for the bottom vs top?

Answer 3

ventral or inferior vs dorsal or superior

Question 4

neuroanatomical term for a dissection down the middle, splitting left and right?

Answer 4

sagittal

Question 5

what is a horizontal dissection?

Answer 5

splits top and bottom / superior and inferior

Question 6

neuroanatomical term for a dissection splitting the front and back?

Answer 6

coronal

Question 7

in terms of the spinal cord, what is a transverse and longitudinal dissection?

Answer 7

transverse = separates upper and lower half
longitudinal splits left and right

Question 8

when using these neuroanatomical terms what must you be mindful of?

Answer 8

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)

Question 9

briefly describe the forebrain and its general functions

Answer 9

cerebral hemispheres, thalamus (gateway to the cortex) and hypothalamus (homeostasis)

Question 10

briefly describe the midbrain and its general functions

Answer 10

colliculi, the tegmentum, and the cerebral peduncles
basic motor control and pain processor

Question 11

briefly describe the hindbrain and its general functions

Answer 11

pons, cerebellum (motor coordination and movement) medulla (cardiovascular and pulmonary control)

Question 12

what does the brainstem consist of?

Answer 12

the midbrain, the pons and the medulla oblongata

Question 13

describe the four sections of the spinal cord

Answer 13

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

Question 14

distinguish between grey and white matter and where they appear

Answer 14

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

Question 15

what two general kind of cells make up the nervous system and what do they do?

Answer 15

neurons = excitable cells that conduct impulses, integrating and relaying information
Glia = supporting cells, the glue, maintaining homeostasis, providing protection and assisting neural function

Question 16

who distinguished glia and neurons and how?

Answer 16

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)

Question 17

describe the contents of the soma

Answer 17

all the same stuff as other cells, but there’s more RNA(evident in the staining) and lots of mitochondria (understandable)

Question 18

define neurite, dendrite and axon

Answer 18

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

Question 19

how do you visualise dendrites?

Answer 19

using a Golgi stain (sliver chromate)

Question 20

what is the composition of neurites and the neuronal cytoskeleton?

Answer 20

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

Question 21

describe the different sections of axons

Answer 21

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

Question 22

axons don’t have a certain organelle - what is it and how do they make up for it?

Answer 22

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

Question 23

what is immunohistochemistry and what is another method used?

Answer 23

primary antibody + secondary fluorescent antibody, only works on fixed tissue so sometimes live imaging is used

Question 24

what are the two kinds of presynaptic terminals?

Answer 24

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

Question 25

how are presynaptic terminals specialised?

Answer 25

no microtubules, lots of synaptic vesicles, lots of mitochondria then obviously the synaptic cleft itself

Question 26

axoplasmic transport - what are the two kinds and how do they work?

Answer 26

anterograde transport = forward transport toward presynaptic membrane, kinesin walks along a microtubule (the meme) retrograde transport - opposite direction, using dynein not kinesin

Question 27

how can you locate the soma of a particular axon (or vice versa)?

Answer 27

use an anterograde or retrograde tracer like HRP

Question 28

explain the structure of dendrites

Answer 28

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)

Question 29

what are the 4 ways you can classify neurons

Answer 29

number of neurites dendritic geometry gene expression type of NT

Question 30

give an example of a (pseudo)unipolar neuron and what it does

Answer 30

dorsal root ganglion - super specific takes info from skin and inputs it into a spinal cord (one axon that diverges like a T junction)

Question 31

give an example of a bipolar neuron and how it works

Answer 31

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

Question 32

give an example of a multipolar neuron

Answer 32

purkinje neuron - can receive around 150, 000 contacts, has only one axon from the cell body but this branches into many dendrites

Question 33

what is dendritic geometry used for and what are the two common types?

Answer 33

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

Question 34

what do the following types of neuron connect: 1) sensory 2) motor 3) interneuron

Answer 34

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)

Question 35

what technique can be used to see where a nerve goes?

Answer 35

reporter gene

Question 36

what ability do glia maintain throughout their life?

Answer 36

they can proliferate

Question 37

describe the structure and function of astrocytes

Answer 37

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

Question 38

what are the different subtypes of astrocyte?

Answer 38

fibrous, protoplasmic, radial glial, muller cells of the retina, ependymal cells like in the choroid plexus

Question 39

how are astrocytes involved in energy?

Answer 39

they store glycogen, then convert this to lactate to be taken by monocarboxylate transporters to neurons to be used as an energy source

Question 40

what is a tripartite synapse and what role does the astrocyte play?

Answer 40

synapse with the pre, the post and an astrocyte astrocytes are involved in terminating NT activity by recycling NTs, they often have receptors too

Question 41

what do microglia do?

Answer 41

phagocytose cell debris, prune dendrites, send developmental signals and can assist in myelination

Question 42

what do oligodendrocytes do?

Answer 42

one cell can myelinate multiple axons

Question 43

what do Schwann cells do?

Answer 43

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

Question 44

why does myelin remain in contact with the glial cell that made it?

Answer 44

for nutrients purposes

Question 45

to what part of the nervous system to astrocytes, oligodendrocytes, microglia and Schwann cells belong?

Answer 45

Schwann cells belong to the PNS, the others belong to the CNS