Nervous coordination

Question 1

What does the nervous system involve

Answer 1

-detection of stimuli by receptors
-transmission of nerve impulses by neurons
-response by effectors

Question 2

Types of neurons

Answer 2

-sensory neuron
-relay neuron
-motor neuron

Question 3

structure of the neuron

Answer 3

-dendrites
-cell body
-nucleus
-axon
-myelin sheath
-nodes of ranvier
-schwann cell
-terminal end branch

Question 4

function of the nucleus

Answer 4

found in the cell body and contains the DNA which codes for neurotransmitters

Question 5

function of dendrites

Answer 5

extensions of the cytoplasm of the cell body receiving chemical signals from other neurons at the postsynaptic membrane

Question 6

function of cell body

Answer 6

contains the nucleus and groups of ribosomes needed to synthesise neurotransmitters

Question 7

function of axon

Answer 7

long extension of the cytoplasm that transmit impulses away from cell body towards the terminal ends

Question 8

function of myelin sheath

Answer 8

formed as schwann cells grow around the axon
provide electrical insulation
speeds up transmission

Question 9

function of schwann cells

Answer 9

surround peripheral nerves and forms myelin sheath
K+ and Na+ ions cannot diffuse through

Question 10

function of terminal end branch

Answer 10

connect to other neurons or effectors

Question 11

How is resting potential established

Answer 11

high conc of Na+ on outside of neuron
high conc of K+ on the inside of the neuron
many Na+/K+ pumps that move
3 NA+ out and 2K+ in
via ATP hydrolysis

Na+ voltage gated channel proteins are closed
Na+ pumped out cannot diffuse back in
K+ channel proteins are leaky
K+ can diffuse back out

net result= more positive on outside than inside

Question 12

How a nerve impulse is transmitted

Answer 12

membrane is stimulated
action potential is where the membrane reaches a threshold and becomes depolarised
an action potential is the reversal of the resting potential
-70mV to 40mV

Question 13

process of depolarisation

Answer 13

stimulus causes membrane to become more permeable to Na+ ions
Na+ channel proteins are open
higher conc of Na+ outside the cell
Na+ ions rapidly diffuse into the cell via FD
higher conc of Na+ inside the cell reverses action potential
inside is more positive
K+ voltage gated channel proteins remain closed
high conc of + ions is action potential

Question 14

process of repolarisation

Answer 14

once the internal potential reaches +40mV
Na+ ion voltage gated channel proteins close
K+ voltage gated channel proteins open
more K+ ions inside than outside
K+ ions diffuse out down a conc gradient

Question 15

process of hyperpolarisation

Answer 15

K+ ion channel proteins remain open longer than needed to reach action potential
inside of the cell more negative to -90mV
sodium potassium pump restores the resting potential back to -70mV

Question 16

The all or nothing principle

Answer 16

above the threshold the full sized action potential is given regardless of the increase in the size of the stimulus

Question 17

the refractory period definition

Answer 17

the time taken to restore the resting potential potential

Question 18

what is the impulse transmission along the axon

Answer 18

action potential acts as a stimulus to adjacent polarised areas of the membrane and this causes the action potential to be passed along

Question 19

what is saltatory conduction

Answer 19

impulse travels by jumping from one node of ranvier to the next node of ranvier
to increase the rate of transmission

Question 20

how does temperature affect the rate of transmission

Answer 20

increase in temp
increase in kinetic energy
increase in the rate of diffusion
increase the rate of conduction

Question 21

how does axon diameter affect the rate of transmission

Answer 21

the larger the axon diameter
the greater the speed of conductance
larger membrane surface area
increase in number of channel proteins

Question 22

process of synaptic transmission

Answer 22

action potential arrives
ca2+ channel opens
ca+ ion diffuse into the presynaptic neuron via facilitated diffusion
vesicles fuse with presynaptic membrane to release acetylcholine via exocytosis
ACh bind to receptors
Na+ channels open allowing Na+ into postsynaptic neuron
K+ channels open allowing K+ out into the cleft
enzyme acetylcholinesterase hydrolyses acetylcholine into choline and ethanoic acid using water to break the etser bond

Question 23

types of neurotransmitters

Answer 23

excitatory
inhibitory

Question 24

type of inhibitory neurotransmitter

Answer 24

GABA

Question 25

how do inhibitory neurotransmitters work

Answer 25

resting potential hyperpolarized
less likely to reach threshold in postsynaptic membrane
cannot generate action potential

Question 26

what is the neuromuscular junction

Answer 26

a synapse between a motor neuron and a muscle cell
uses acetylcholine which binds to recptors

Question 27

adaptations to muscular junctions that differentiate them from synapses

Answer 27

1. lots of folds, increase in surface area for more enzymes
2. more receptors
3. always triggers a response

Question 28

what is summation

Answer 28

the build up of neurotransmitters within the synapse

Question 29

what are the two types of summation

Answer 29

spatial
temporal

Question 30

process of spatial summation

Answer 30

different neurons converge at a single synapse
action potentials arrive from several different neurons
release of enough neurotransmitter to reach threshold and cause an action potential

Question 31

process of temporal summation

Answer 31

only one presynaptic neuron
impulses arrive in rapid succession giving a cumulative effect
sufficient to depolarise the post synaptic neuron