neuronal communication🧠

Question 1

similarities between sensory and motor neurone structure

Answer 1

• cell body with nucleus
• axon
• dendrites
• myelin sheath
• voltage gated channels

Question 2

which neurone transmits impulse from CNS

Answer 2

motor

Question 3

why does shivering occur during fever

Answer 3

to increase body temp as it is lower than new set point

Question 4

alcohol causes vasodilation why would it be bad to give to someone with hypothermia

Answer 4

• vasodilation results in more blood nearer to skin surface
• lose more heat
• lack of enzyme activity

Question 5

why is the pacinian corpuscle described as a transducer

Answer 5

converts energy (mechanical) into a different form of energy (electrical)

Question 6

why does deformation of plasma membrane at tip of neurone cause it to be more permeable to na+

Answer 6

causes Na+ ion channels to open

Question 7

what is the all or nothing law of generating action potentials

Answer 7

• if stimulus is not strong enough then threshold not reached
• action potential not generated

Question 8

how is info about strength of a stimulus communicated to brain

Answer 8

• represented by frequency of action potentials

- high frequency shows strong stimulus

Question 9

why are action potentials not constantly generated when wearing clothes

Answer 9

sodium channels remain open

Question 10

what are the roles of the synapses in the nervous system

Answer 10

• allow communication between neurones
• ensure transmission in one direction
• allow one neuron to connect to many neurones
• allows summation
• ensures only stimulation strong enough will be passed on

Question 11

explain difference in speed of conduction between myelinated and non myelinated neurones

Answer 11

• myelinated has faster conduction
• depolarisation can only occur where Na+ channels present
• myelinated neurones have larger sections with no channels
• ion transfer can only take place at gaps
• saltatory conduction

Question 12

name part of neurone where neurotransmitter is secreted

Answer 12

synaptic knob

Question 13

what effect would a bacterial protease have in a neurone

neurone releases protein

Answer 13

• protease breaks down protein
• microtubules broken down so vesicle cannot move towards membrane
• vesicle cannot fuse with membrane and protein not secreted

Question 14

what type of hormones are released into blood

Answer 14

endocrine

Question 15

insulin is released from what region of pancreas

Answer 15

islets of langerhans

Question 16

process that breaks glycogen down into glucose

Answer 16

glycogenolysis

Question 17

state one way nervous system decreases heart rate

Answer 17

impulses along parasympathetic nerve

Question 18

how is resting potential established and maintained in a sensory neurone

Answer 18

• sodium potassium pump uses ATP
• pumps 3 Na+ out of neurone and 2 K+ in
• K+ diffuse back out of cell
• membrane less permeable to Na+ so fewer diffuse back in
• voltage gated channels closed

Question 19

process that makes voltage positive

Answer 19

depolarisation

Question 20

process that makes voltage negative

Answer 20

repolarisation

Question 21

process that makes voltage more negative than resting potential

Answer 21

-hyperpolarisation

Question 22

minimum voltage for action potential is called

Answer 22

threshold potential

Question 23

relationship between strength of stimulus and resulting action potential

Answer 23

• only stimuli that reach threshold produce action potential
• when stimulated action potential follows all or nothing law
• action potential is same size no matter how strong stimulus is

Question 24

how do neurones communicate across synapse

Answer 24

• neurotransmitter released from pre synaptic membrane
• diffuses across synaptic cleft
• attaches to receptors on post synaptic membrane
• neurotransmitter broken down in cleft

Question 25

differences between motor and sensory neurones

Answer 25

- sensory has dendron, motor does not have dendron - sensory has short axon, motor has long axon - sensory has cell body in the middle, motor has it at the end - sensory dendrites at the end of dendron, motor has dendrites directly connected to cell body

Question 26

action potentials all have the same

Answer 26

size

Question 27

what happens to plasma membrane when neurone is stimulated

Answer 27

depolarisation

Question 28

describe function of the cell that covers axon

Answer 28

- Schwann cell produces myelin - insulation - action potentials can only occur at nodes of ranvier - saltatory conduction

Question 29

how do synapses only allow transmission in one direction

Answer 29

only postsynaptic membrane has receptors

Question 30

atropine has similar shape to acetylcholine, explain how the presence of atropine in the synapse prevents the initiation of an action potential

Answer 30

- atropine binds to receptors on post synaptic membrane - prevents acetylcholine from binding - sodium channels do not open - Na+ cannot enter neurone - no depolarisation - does not reach threshold

Question 31

when is the membrane most permeable to potassium ions

Answer 31

repolarisation

Question 32

why does increase in temp increase speed of conduction

Answer 32

neurotransmitter diffuses across synapse faster

Question 33

outline the events following the arrival of an action potential at synaptic knob until the acetylcholine has been released into the synapse

Answer 33

- calcium channels open - ca2+ diffuse - acetylcholine in vesicle - vesicles move towards presynaptic membrane - vesicles fuse with membrane - release acetylcholine by exocytosis into synaptic cleft

Question 34

specialised cells in retina of eye respond to..

Answer 34

intensity and wavelength of light

Question 35

specialised cells in tongue and nose detect what type of stimuli

Answer 35

chemical