Nerves

Front 1

Acetylcholinesterase

Back 1

Enzyme within the synaptic cleft that break down the transmitter substance acetylcholine. This stops the transmission of signals

Front 2

Acetylcholine

Back 2

Transmitter substance that diffuse across the synaptic cleft

Front 3

Transmission across the synase

Back 3

1.An action potential arrives at the synaptic knob

2.The voltage-gated calcium ion channels open

3. Calcium ions cause the synaptic vesticles to move to and fuse with presynaptic membrane

4. Acetylcholine is release by exocytosis and diffuses across the clef

5.acetylcholine molecules binds to the receptor sites on the sodium ion channels in the postsynaptic knob

6.sodium ion channels open and sodium ions diffuse a across the postsynaptic membrane into the postsynaptic node

7.generator potential or excitatory potential is created

8.if suffient generator potential combinr the potential across the postsynaptic membrane reaches the thershold potential

9. A new action potential is created in the postsynaptic neurone

Front 4

Structure of cholinergic synapse

Back 4

Synaptic node

many mitrocondrion

vesticle of chemical transmitters

voltage-gated calcium ion channels

Postsynaptic membrane

specialise sodium ion channels which have special receptors which are complementary to transmitters

Front 5

Myelin sheath

Back 5

soduim and patassium ions cannot diffuse through the fatty layer

swchann cells

gaps = nodes of ranvier

Front 6

Saltory condition

Back 6

Refers to they way that the action potential appears to jump from one node of ranvier to the next

Front 7

Local current

Back 7

1. Sodium ion channel open allowing sodium ion to diffuse into the neurone

2. Localised increase in concentration of sodium ions inside neurone, the action potential

3. Sodium ions diffuse along the axon, away from the region of higher concentration

4. Soduim gate which were initicially closed open because of the movemet of sodium ions allowing the action potential to move along the nerone

Front 8

Sensory nerones

Back 8

Front 9

Motor neurones

Back 9

Front 10

Sensory receptors roles

Back 10

Detect change in enviroment

Energy transducer covert on form of energy to another

Front 11

Ionic movement

Back 11

1. The membrane starts at resting potential it is polarised with the inside of the cell 60mv

2. Soduim ion channels open and sodium ions diffuse out of the cell

3. Membranes depolarise, the inside become less negative and reaches the therahold value of -50mv

4.voltage-gated sodium channels open and many sodium ions diffuse into the cell

5. The potential difference across the plasma membrane reaches +40mv (inside more postive compared with the outside)

6. Sodium ion channels close and patasium ions channels open

7. Patassium ions diffuse out of the cells this is calle depolarisation

8. The potential difference overshoots slightly, makin the cell hypolarised

9. The orignal potential is restored

Front 12

Refactory period

Back 12

Short period where it is impossible to stimulate action potential. Allows cell to recover after action potential and ensures it is transmitted in one direction

Front 13

All or nothing

Back 13

Genrator potential in sensory receptors are depolarisations of the cell membrane

Depolarisation much be large enought to reach thershold potential for action potential to be transmitted

Front 14

Acclimatisation

Back 14

Repeated stimulation a synapes runs out of vesticle containing the trasmitter substance

Front 15

Summation

Back 15

Low-level signals can be amplified. Stimulus is persistent

Front 16

Several presynaptic

Back 16

Converfe to one postsynaptic neurone

Front 17

One presynaptic neurone

Back 17

Diverge to serveral postsynaptic neuronr

Front 18

Synapes

Back 18

Ensure that the signals are transmitted in the correct direction

Only presynaptic knob contaibs vesticles of acetylcholine

Front 19

Unwanted low signals

Back 19

Can be flitter out.

Front 20

Frequency

Back 20

Higher intensity signals the sensory receptirs produce more generator potentials. Action potential is more frequent. When arrived at the synapse they cause more vesticles to be released. Brain determined the intendity of the stimulus from the ferquency of signals arriving.

Front 21

Myelinated and non-mylinated neurones

Back 21

Myelinated

schwann cells are wrapped around the neurones

intervals 1-3mm (node of ranvier)

node is very short

typical speed 100-120ms (rapid reponse to a stimulus)

sensory receptor to CNS and from the CNS to effectors

carries signald over long distances

Non-myelinated

one loosly wrapped schwann cell

2-200ms

shorter

signals carried over short distances

coordinated bodly functions