topic 1 (brain cells SUBCELLTYPES)

Question 1

how many different cell subtypes have been found in brain samples?

Answer 1

roughly 100

Question 2

what are 9 major subtypes of neurons?

Answer 2

• von economo neurons
• radial neurons
• pyramidal neurons
• fork neurons
• place cells
• interneurons

Question 3

can microglia replicate?

Answer 3

• they can but they do so at an extremely slow rate

Question 4

what are sennessent cells?

Answer 4

cells that are no longer dividing

Question 5

what are dystrophic cells?

Answer 5

• cells with structural atrophy

Question 6

what are the 4 stages of microglia cells

Answer 6

stage 1: cells are ramified, surveillant, resting and homeostatic

stage 2: cells are activated and reactive

stage 3: cells are senessent

stage 4: cells are dystrophic

Question 7

what is the difference between microglia in white matter and in grey matter?

Answer 7

• microglia in white matter often have a very flattened appearance. This is so they can track more easily up and down the white matter fibres
• (unstimulated) in grey matter have extended processes with many branches projecting in all directions.
• The cell bodies do not tend to move as much from their territories, instead the processes extend and retract to difference places to detect relavent signals.

Question 8

why are CNS tumors relatively rare compared to tumors elsewhere in the body?

Answer 8

• the cancerous genes are normally genes associated with replication and brain cells are largely post mitotic

Question 9

what is apoptosis and why is it good?

Answer 9

• the orderly mechanism of cell death in stressed or dying neuronal cells
• the orderly manner of it limits damage to bystander cells

Question 10

what is necrosis and why is it bad?

Answer 10

• necrosis is a drastic and uncontrolled form of cell death

- this creates much larger regions of damage to surrounding cells

Question 11

what is arborisation?

Answer 11

the degree of branching of the dendrites of the neurons

Question 12

what protrudes across the length of the dendrite

Answer 12

• a series of spines

- these can be removed and reformed as needed

Question 13

what part of the dendrites form synapses?

Answer 13

• the spines of the dendrites form synapses

Question 14

what does the microtubule transport system provide for the cell?

Answer 14

• the rigidity, force and structure for molecules to travel across the cell

Question 15

how are the nuclei in neurons different to other cells?

Answer 15

• neurons tend to have a very large nuclei with a prominent nucleolus
• this reflects their very high level of gene expression compared to other cells
• perhaps this is related to their high level of protein turnover and shifting in activity

Question 16

what is the differences in neurons in terms of where translation occurs

Answer 16

• in most cells translation occurs in the cytoplasm
• in neuronal cells this can occur in other places
• for example some mRNA molecules are transported along the microtubules to the dendrites for translation to occur in the dendrites
• This can offer greater control over which proteins are made and where
• it can also control how long each mRNA is available for translation and can affect how much protein is made from the templates

Question 17

what are the functions and structure of sensory neurons?

Answer 17

• conduct somatosensory information from the body to the spinal chord or brain
• they have a relatively simple structure compared to other neurons

Question 18

what are the functions and structure of interneurons?

Answer 18

• connect sensory and motor activity of the CNS
• they connect to other interneurons, sensory neurons and motor neurons
• They have variable shapes such as pyramidal and purkinje
• They are the most common form of neuron

Question 19

what are 3 things that can be used to classify neuron subtypes?

Answer 19

• morphology
• whole genome expression
• electrical activity

Question 20

what is the function of motor neurons and where are they located?

Answer 20

they carry information from the brain and spinal chord to the muscles

they are located in the lower brain stem and the spinal chord