cells and signaling in nervous system

Question 1

what is the neuron doctrine

Answer 1

Brain composed of neurons connected by functional space (synapses) that communicate with neurochemical signals

Question 2

what are the two main parts of neurons

Answer 2

perikaryon and neurites

Question 3

what are perikaryon

Answer 3

cell bodies (soma) that are metabolic centers

Question 4

what are neurites

Answer 4

cellular fibers that extend off the soma and conduct electrical signals to the body

Question 5

how many neurites can a neuron have

Answer 5

1 or many

Question 6

what are dendrites

Answer 6

branches off the cell body that are the “receptive area”

Question 7

what are dendritic spines and what do they do

Answer 7

mushroom shaped branches off the dendrite that increase SA and are where other cells contact the cell

Question 8

what are axons

Answer 8

single neurite that goes from the cell body and conduct electrical signal

Question 9

what covers axons

Answer 9

mutelin sheath

Question 10

what are myelin sheath made of and what do they do

Answer 10

fat and protein that cover the axons and insulates the electrical signal

Question 11

what produce myelin sheath

Answer 11

schwann cells in PNS and oligodendrocytes in CNS

Question 12

what are presynaptic terminals

Answer 12

bulbs at ends of axons that contain synaptic vesicles to store and release neurochemical signals

Question 13

what does neuron types depend on

Answer 13

number of neurites originating from the soma

Question 14

where does the electrical signal travel

Answer 14

dendrite –> cell body –> axon –> presynaptic terminal

Question 15

what do neurotransmitter receptors do

Answer 15

when they receive neurotransmitters they open up channels for K+ and Na+ to excite or inhibit postsynaptic neuron through electrical charge

Question 16

differences between neurotransmitters and neuropeptides

Answer 16

both are released from synaptic vesicles
transmitters: small molecules where receptor determines effect
peptides: product of genes (5-30 AA long)

Question 17

where can neurons receive input

Answer 17

any place along length of terminal

Question 18

axodendritic synapse

Answer 18

synapse onto dendrite (inc dendritic spine)a

Question 19

axosomatic synapase

Answer 19

onto cell body

Question 20

axo-axonal synapse

Answer 20

onto axon (at nodes of ranvier not myelin)

Question 21

axo synaptic synapse

Answer 21

synapse onto other synapse

Question 22

nuclei vs ganglia

Answer 22

both clusters of neurons but nuclei in CNS while ganglia outside of CNS

Question 23

types of neuroglia

Answer 23

macro and microglia

Question 24

what don’t neuroglia form

Answer 24

synapses

Question 25

types of macroglia

Answer 25

oligodendrocytes, schwann cells, astrocytes

Question 26

relationship of oligodendrocyte to axons and why this relationship

Answer 26

1 olig: N axons 1 axon: N olig CNS has less space than PNS so CNS evolved to have less myelination cells in cranial vault

Question 27

differences between oligodendroytes and schwann cells

Answer 27

both myelinate olig - cNS schwann - PNS

Question 28

relationship of schwann cells to axons

Answer 28

1 schwann: 1 axon 1 axon: N schwann

Question 29

differences between myelin sheaths in cns and pns

Answer 29

Sheaths longer and thicker in PNS

Question 30

types of astrocytes

Answer 30

protoplasmic and fibrous

Question 31

functions of astrocytes

Answer 31

Provide structural support Act as glial guides during dev Maintain ion balance Recycle neurotransmitters Blood brain barrier

Question 32

differences between protoplasmic and fibrous astrocytes

Answer 32

proto --> buchy and branches, grey matter fibrous --> more fibrous, spindly, robust, white matter, long processes in all directions

Question 33

what is a subtype of protoplasmic astrocytes and what do they do

Answer 33

reactive astrocytes --> repair damaged neurons by migrating to site of injury and proliferating. act like scar tissue if too much damage

Question 34

what is glial scarring made of and what can it cause

Answer 34

strong collagen matrix that can cause behavioral changes if too many issues

Question 35

what do microglia do

Answer 35

immune surveillance of CNS by being mobile cells that activate and invade injured zones to fight infection and neural damage

Question 36

where do mobile cells exist

Answer 36

Some exist in CNS and are looking around for damage but some are from the blood and differentiate into microglial when they make their way into CNS

Question 37

where does wallerian degeneration happen

Answer 37

mostly CNS but some PNS

Question 38

what is wallerian degeneration

Answer 38

axon is cut so distal end of axons degenerates so the neuron dies

Question 39

how long does wallerian degeneration take

Answer 39

almost 2 days

Question 40

where does neuron regeneration happen and how does it work

Answer 40

PNS When axon damaged, schwann cell forms guidance tube to guide the regenerating end of axon to target end so damage is temporary.

Question 41

differences between schwann and olig relating to regenerating

Answer 41

schwann produce nerve growth factor olig produce no go factor which inhibits repair factor

Question 42

where does collateral sprouting happening and what does it do

Answer 42

CNS and PNS Neighboring neurons form new collaterals that try to reinnervate end organ to fill vacant synapses when neuron dies to retain function