neurons and their structures

Question 1

what are the three main functions of neurons

Answer 1

receive information
conduct information
transmit information

Question 2

what are the two features of output on neurons

Answer 2

synaptic boutons and terminal branches

Question 3

what are two differences with other cell types

Answer 3

large number of proteins are required to be made, hence rER is enteive ‘NIssl substance’
neurons are secretory cells therfore lot of transcription hence larger nucleus

Question 4

what are dendrites

Answer 4

an extension of the cell body

Question 5

what can be found at the base of dendrites

Answer 5

rER and sER

also mitochondria, free ribosomes , microtubules and microfilaments

Question 6

what are dendritic spines

Answer 6

protrusion on dendritic shaft

synapses form here

Question 7

what does number of spines represent

Answer 7

influencedby disease and input

Question 8

what do spines not contain

Answer 8

mitochondria, microtubules, neurofilaments

Question 9

what are axons

Answer 9

single specialised process but branches at the end generally thinner and longer than dendrites

Question 10

what are the four parts of axons

Answer 10

initial segment- axon hillock
axon processes
synaptic boutons
growth cones

Question 11

describe 3 features of initial segment

Answer 11

lacks ribosomes
contains bundles of microtubules and neurofilaments
voltage gated Na channels and other transmembrane proteins

Question 12

where is initial segment located

Answer 12

ends at start of myelination and is beginning of action potential

Question 13

describe 3 features of axon processes

Answer 13

has normal organelles but no ribosomes
diameter varies
can be myelinated

Question 14

what do synaptic boutons contain

Answer 14

neurotransmitter in secretory vesicles, mitochondria but no microtubulues

Question 15

what does the connecting membrane on synaptic bouton contain

Answer 15

large amount of protein

the post synaptic density- PSD

Question 16

what are growth cones have the ability for

Answer 16

the ability to be very motile

capacity to detect environmental cues

Question 17

what happens to growth cone cues

Answer 17

turned into signals that determine rate and direction

Question 18

what are growth cones important for

Answer 18

development of the nervous system

Question 19

describe the structure of growth cones (6)

Answer 19

lamellipodia
filopodia
p-domain
t-domain
c-domain
cones can vary in shape and sizes in these domains

Question 20

what is lamellipoda

Answer 20

flattened at the tip into a thin fan shaped sheet

Question 21

what is filipodia

Answer 21

with many very thin spikes radiating forward

Question 22

what is the p domain

Answer 22

peripheral

lamellipodia and filopodia

Question 23

what is the t- domain

Answer 23

transition

interface of the p and c domain

Question 24

what is the c domain

Answer 24

thicker region containing organelles, vesicles

Question 25

what is present in growth cones

Answer 25

filipodia and lamellipodia

Question 26

what do filipodia and lamellipodia contain

Answer 26

actin filaments, actin devoid in c domain

Question 27

describe neurofilaments in growth cones

Answer 27

extend as far as the axon, do not penetrate into lamellae

Question 28

describe microtubules in growth cones

Answer 28

extend further into the lamellae

Question 29

what are the three processes of axon growth

Answer 29

protrusion engorgment consolidation

Question 30

what is portrusion

Answer 30

rapid extensions of filipodia / thin lamallae containing aactin

Question 31

what is engrogment

Answer 31

microtubules invade protrusions brining vesicles and organelles

Question 32

what is consolidation

Answer 32

actin depolymerises in the neck of the growth cone, membrane shrinks forming cylindrical shaft

Question 33

what are two problems about having really long neurons

Answer 33

transport reterograde but also local synthesis (i.e. if cut, growth cone still grows)

Question 34

what are two cues growth cones can respond to

Answer 34

attracted or repelled

Question 35

what is fasciculation and which neurons undergo it

Answer 35

axons that undergo bundling guidepost cells pioneer axons follower axons

Question 36

what can chemical signals affect

Answer 36

growth factors secreted by cells substrates other cells using adhesion receptors

Question 37

what are three physical signals

Answer 37

tactile electric photonic

Question 38

what are 5 ways to classify neurons

Answer 38

``` number of neurites- axons or dendrites number of dendrites type of connections axinal length neurotransmitter released ```

Question 39

what are ligand gated ion channels and g protein linked receptors

Answer 39

ionotropic and metabotropic

Question 40

what is the structure of neuromuscular junction in pns

Answer 40

junctional folds found on the postsynaptic side of the NMJ increase the number of Ach receptors that are exposed to release of neurotransmitter resulting in very efficient transmission

Question 41

what does removal of neurotransmitter from post synaptic cleft do

Answer 41

prevetns desensitisation of receptor and interference with new incoming signals

Question 42

what are two mechanisms of neurotransmitter removal from post synaptic cleft

Answer 42

enzymatic degredation | acetylocholinesterase

Question 43

what is myasthenia gravia

Answer 43

autoimmune disorder decrease in number of functional Ach receptors in neuromuscular junctions progressive muscular weakness