Neuronal communication q's

Question 1

outline the ways in which the structures of a sensory neurone and a motor neurone are similar

Answer 1

both have:
- dendrites
- an axon
- a cell body w/ a nucleus
- mylein sheath
- voltage gated channels / sodium - potassium ion pump

Question 2

explain the effect that this sweating will have on the body

Answer 2

• evaporation will have a cooling effect
• heat supplied by body is used for evaporation
• water has a high latent heat of vaporisation

Question 3

suggest why shivering occurs during fever

Answer 3

• to incr body temp as it is lower than the ‘new’ set point even though body is hot
• as the new ‘ normal’ body temp is higher , the body is using shivering to raise the temp of the internal environment

Question 4

explain why it is not a good idea to give alcohol to someone with hypothermia

Answer 4

• vasodilation results in more blood nearer to the skin surface
• will lose more heat
• organs will not be able to maintain function
• ref to lack of enzyme activity

Question 5

why is the pacinian corpuscle described as a transducer

Answer 5

it converts energy into another form of energy

Question 6

deformation of the plasma membrane of the tip of the neurone causes the membrane to become more permeable to Na+ - suggest why

Answer 6

the increased pressure causes the Na+ to open
gaps appear between phospholipids

Question 7

the generation of an AP follows the ‘all of nothing’ law - explain what this means

Answer 7

if the stimulus is not strong enough, then an AP is not generated

Question 8

describe how info about the strength + intensity of a stimulus is communicated to the brain

Answer 8

it is represented by the frequency of the AP
high frequency of AP shows a strong/ intense stimulus

Question 9

suggest an explanation for the fact that AP are not generated constantly whilst wearing clothes

Answer 9

AP not generated bc :
- sodium ion channels remain open
- ions being in the wrong place for correct ion movement across membrane

Question 10

outline the roles of the synapses

Answer 10

• allows cell signalling
• ensure transmission between neurones in one direction only
• allows impulses from more than one neurone to be passed to a single neurone
• allows impulses from a single neurone to more than one neurone
• ensures that only stimulation that is strong enough will be passed on
• prevents over stimulation
• allows many low lever stimuli to be amplified
• presence of inhibitory + stimulatory synapses allow impulses to follow specifc paths
• permits memory

Question 11

name one chemical that transfer a nerve impulse from one neurone to another

Answer 11

• acetylcholine

Question 12

suggest the part of the neurone where the plasma membrane has TRPA1 receptors

Answer 12

post synaptic membranes - TRPA1 prevents attachment of neurotransmitter to its receptor
pre synaptic membrane - TRPA1 prevents release of neurotransmitter

Question 13

Answer 13

A - sinosoid
B - Branch of bile duct
C - Branch of hepatic portal vein
D - Branch of hepatic artery
E - Branch of central vein

Question 14

suggest a reason for the accumulation of high conc of NAPQ1 in liver cells

Answer 14

• bc there is not enough glutathione to metabolise it
• enzymes catalysing glutathione reaction is in short supply
• the NAPQ1 cannot cross the cell surface membrane

Question 15

name the liver cells that can lead to regeneration + type of cell division they carry out

Answer 15

hepatocytes
mitosis

Question 16

Answer 16

A - cytoplams
B- cell surface membrane
C - nucleus

Question 17

explain the diff in the speed of conduction of an AP along the length of a myelinated neurone + non myelinated neurone

Answer 17

in myelinated neurones
- conduction faster
- AP/ Depolarisation can only occur where Na+ channels present
- myelinated neurones have longer sections w/ no Na+ channels present
- ion movement can only take place at the nodes
- longer local circuits
- saltatory conduction / AP jumps from node to node

Question 18

name the part of a neurone from which aCh is secreted

Answer 18

presynaptic membrane

Question 19

suggest w/ reasoons the effects that toxin would have once it has entered a neurone

Answer 19

• vesicle cannot fuse w/ cell membrane + aCh not secreted
• toxin hydrolyses protein
• bc of hydrolysis no binding complec
• microtubulues broken down so vesicle cannot move towards membrane

Question 20

process that causes glycogen to be broken down into glucose

Answer 20

glycogenolysis

Question 21

2 hormones which increase the heart rate

Answer 21

adrenaline
noradrenaline

Question 22

state a way in which the NS decreases the HR

Answer 22

• impulses along parasympathetic nerve
• impulses along vagus nerve
• nerve endings releasing acetlycholine

Question 23

describe and explain how the resting potential is established and how it is maintained in a sensory neurone

Answer 23

pumping active
- sodium - potassium pump uses ATP
- The na/k pump activtely moves 3 Na+ out of + 2K+ into axon

passive/diffusing
- k+ diffuse freely back out of cell
- membrane less permeable to Na+ , so fewer Na+ diffuses back in
- voltage gated na+ channels closed

Question 24

comment on the relationship between the strength of a stimulus + the resulting AP

Answer 24

• only stimulu that reach threshold value produce an AP
• when stimulated AP either occurs or does not
• AP is the same size no matter how strong the stimulus
• strong stimulus produces many AP
• (strong stimulus increases frequency but not magnitude of action potential )

Question 25

outline how the first neurone communicates with the second neurone

Answer 25

acetylcholine released from membrane
diffuses across synaptic cleft
attaches to receptors on post synaptic membrane
acetlycholine broken down in cleft

Question 26

outline the importance of the junctions between neurones in the functions of the nervous system

Answer 26

ensures movement of AP in one direction only
one neurone can transmit impulses to many neurones
allows summation
ensures that only stimulation that is strong enough will be passes on
permits memory
cell signalling