NEURONES

Question 1

outline the basic nervous pathway

Answer 1

stimulus -receptor - sensory neurone - CNS(relay neurone) - Motor neurone - effector-response

Question 2

function to receptor

Answer 2

recieve stimuli and send it to CNS via sensory neurone

Question 3

what does cns consist of

Answer 3

brain + spinal chord

Question 4

what are 2 types of effects

Answer 4

muscles, glands

Question 5

what is function of dendron

Answer 5

send impulse to the cell body

Question 6

function of cell body

Answer 6

holds organelles and releases neurotransmitters

Question 7

how can we identify the type of neuron

Answer 7

looking at position of cell body

Question 8

function of axon

Answer 8

sends impules away from cell body

Question 9

what is the function of myelin sheath

Answer 9

insulation layer on neurone that helps speed up the rate of nervous transmission

Question 10

what are branches on dendron called

Answer 10

dendrites

Question 11

where is cell body on a sensory neuron

Answer 11

found in the middle of the neurone

Question 12

what are the nodes of ranvier

Answer 12

gaps in neurone that aren’t covered by myelin sheath

Question 13

where is the cell body on a motor neuron

Answer 13

At the start of neurone

Question 14

do motor neurones have a dendron

Answer 14

No have dendrites (as cell body is at start of cell so only have axon)

Question 15

what is the smalllest neurone and where is it found

Answer 15

relay neurone found in CNS

Question 16

what makes the myelin sheath

Answer 16

schwann cells (stretched and wrapped up = myelin sheath)

Question 17

how can we tell apart the different neurones

Answer 17

relay neuron has no myelin sheath
sensory neuron cell body found in the middle of cell
motor neuron cell body found at start of cell

Question 18

function of sensory neurone

Answer 18

transmit nervous impulses from a sensory receptor cell to relay neuron,motor neuron or the brain

Question 19

function of relay neurone

Answer 19

transmit impulese between neurones

Question 20

function of motor neurone

Answer 20

transmit impulses from relay or sensory neurone to an effector

Question 21

myelinated vs unmyelinated neuron - rate and method of transmission

Answer 21

myelinated - faster transmission of electrical impulse as jumps from one node of ranvier to the other
unmyelinated - slower transmission as electrical impulse must pass continuously along neurone.

Question 22

what cells detect changes in the environment

Answer 22

sensory receptors

Question 23

what is meant by sensory receptors are ‘transducers

Answer 23

transducers convert a stimulus into a nerve impulse

Question 24

what are the 2 main features of sensory receptors

Answer 24

• specific to single type of stimulus

- act as transducer(convert stimulus to neve impulse(generator potential)

Question 25

4 type of sensory receptors and what their stimulus

Answer 25

photoreceptor - light thermoreceptor - heat chemoreceptor - chemicals mechanoreceptor - pressure and movement

Question 26

what type of receptor is a pacinian corpuscle

Answer 26

mechanoreceptor(detects changes in pressure or movement)

Question 27

how does structure of pacinian corpuscle allow it to change physical stimulus to generator potential

Answer 27

- end of sensory neurone found within centre of corpuscle - stretch mediated sodium channel and when they change shape- the permeability of sodium ions also change. In normal state - sodium ion channels are too narrow When pressure is applied - change shape allowing more ions to diffuse into neurone - influx of sodium ions depolarises cell resulting in generator potential - generator turns into action potential and then passed along sensory neurone.

Question 28

How does body detect your finger has touched a pin

Answer 28

- pressure exerted onto skin - pacinian corpuscle detects pressure change - change in pressure widens gated sodium channels allowing more ions to diffuse through - influx of ions causes membrane to depolarise - creating general potential that turns into action potential (once threshold is met)and is transmitted along neurones to CNS

Question 29

how does the body detect difference between large and small stimulus

Answer 29

more frequent action potentials

Question 30

Explain synapse mechanism and how excess neurotransmitters are dealt

Answer 30

- action potential arrives - depolarisation of pre-synaptic neurone triggers calcium channel to open - influx of calcium ions causes synaptic vesicles to fuse aginst pre synaptic membrane - vesicles release neurotransmitters into synaptic cleft via exocytosis - neurotransmitters diffuse across and bind onto receptors on post synaptic neurone - causing sodium gated channels on post synpatic neurone to open - influx of sodium ions causes depolarisation and action potential is generated if threshold is met - excess neurotransmitter is broken down by enzmes

Question 31

how does motor neurone cause a post synaptic neurone to depolarise

Answer 31

- action potential reaches pre synaptic neurone - depolarisation of pre synaptic membrane triggers ca2+ channels to open - influx of ca2+ ions causes vesicles to fuse with pre-synaptic membrane - neurotransmitter diffuse across synaptic cleft - bind to to receptors on post synaptic membrane - allows sodium channels to open and sodium ion diffuse into neurone - threshold potential reached - muscle cell contracts

Question 32

what is a cholinergenic synapse

Answer 32

synapses that use acetylcholine

Question 33

what is the post synaptic receptor in cholinergenic synapses

Answer 33

cholinergenic receptors

Question 34

How is an action potential generated

Answer 34

A; resting potential -70mv - Sodium potassium pump open(actively transport 3NA+ out and 2K+ in), gated sodium pump closed (no na+ can diffuse back into axon), potassium pump open(K+ can diffuse out of axon)- inside membrane (-) outside membrane(+) B- energy from stimulus triggers some of sodium gated channels to open allowing sodium ions to diffuse down chemical gradient C - depolarisation -positive feedback so more sodium voltage pump open - allowing influx of sodium ions into membrane - causing more (+) inside membrane (-)outside membrane. Threshold is met- greater number of sodium pumps open(-55mv) +E - repolarised membrane - from +40 mv potassium channel opens, allowing potassium ions to diffuse out of axon to decrease potential difference, sodium gated channels close F-hyperpolarisation -80mv - too much K+ diffused out so more negative potential difference G - repolarisation - K gated channels shut, sodium potassium pump opens , -70mv re-established

Question 35

What is saltatory conduction

Answer 35

Propogation of axon potential along neurone with myelin sheath (saltatory conduction)