Synpases

Question 1

Structure of a synapse
Draw structure
What/how forms the synaptic knob?
What is present in the cytoplasm of the synaptic knob?
Where is the material in the bulb made and how does it get to the bulb and what is this called? What does it require?
What happens in the presynaptic memb when it is active? Whats this known as?
What does the presynaptic knob have for calcium movement?
What 3 things does the post synaptic memb have for its role?

Answer 1

Terminal ends become swollen
Mitochondria,vesicles, SER
Cell body and travels down axon, axoplasmic transport,large amounts of energy
Vesicles release neurotransmitter,exocytosis
Ion channels 
Receptors for neurotransmitter 
Ion channels for Na+ and K+ 
Enzymes to breakdown neurotransmitter

Question 2

Properties of synapses

What are the four properties?

Answer 2

Excretory and inhibitory
Summation
Adaptation
Neurotransmitters

Question 3

Excretory and inhibitory
What does the neurotransmitter of excretory synapses do to the post synaptic membrane?
What does the neurotransmitter of inhibitory synapses do to the post synaptic membrane?

Answer 3

Raises resting potential until it depolarises and causes AP

Lowers resting potential making it more difficult to depolarise

Question 4

Summation
Spatial summation
What is this?
What is wrong with impulse from one presynaptic memb?
What does having 2 different neurones cause?
What’s a situation where spatial summation would be good?

Temporal summation
What’s the problem with the impulse in the presynaptic membrane?
What is he neurotransmitter therefore not enough to cause?
Second impulse comes along later and the same effect is seen but what happens if the impulse comes shortly after the first?
What does it filter out?

Answer 4

When 2 synapses release transmitter at the same time
Not enough to depolarise memb and and cause AP so impulse not propagated
Depolarises memb,above threshold,causes AP,impulse propagated
Amplify weak important stimuli

Carried at low frequency
Action potential
First impulse not subsided,second adds to it,creates local potential causing AP
Weak stimuli that’s not needed

Question 5

Adaptation
What may continuous activity lead to?
So that what’s what happens?
What are situations where this may occur?

Answer 5

Exhaustion of transmitter
Pathway no longer responds
Ticking clock, smell of the perfume

Question 6

Neurotransmitters: cholinergic and adrenergic
What are the two active transmitters?
What are the two enzymes?
What are the inactive transmitters?
What are the type of neurones?
How do drugs and toxins from pathogens block receptors?

Answer 6

Acetylcholine and noradrenaline 
Choline esterase and monoamino oxidase 
Choline and ethanoic acid 
Cholinergic and adrenergic
May be similar shape

Question 7

Synapse
What is a disadvantage of having a synapse?
When is this particularly bad?

What are the advantages of a synapse however?

Answer 7

Slows down impulse
In electrical impulses where pathways speed is critical

Impulses travel one direction
Weed out useful stimuli
Protect nerve network by not firing when over stimulated

Question 8

Synaptic transmission

Sequence of events a presynaptic membrane.

Answer 8

AP arrives at pre synaptic bulb
Opens calcium channels
Calcium rushes in
Synaptic vessels move towards and fuse with membrane
Release neurotransmitter into synaptic cleft

Question 9

Synaptic transmission at post synaptic neurone explain

Answer 9

Neurotransmitter diffuses across synaptic cleft
Bonds to receptors on membrane
Opens sodium channels
Influx sodium
Creates excretory post synaptic potential
If this builds up to threshold there’s AP
Another transmitter opens potassium channels and potassium moves out
Causes inhibitory post synaptic potential
If EPSP is greater than IPSP can exceed threshold and cause AP
Once neurotransmitter has acted is broken down by enzymes
Neurotransmitter is taken up again by membrane and recombined using ATP from mitochondria and synapse can transmit another impulse

Question 10

What do the simplest nerve pathways consist of?
What do most nerve impulses consist of?
What forms a: sensory nerve
                       Motor nerve
                       Mixed nerve 
What is the definition of a synapse?
What is the neurone: before 
                                  after 
the synapse?
What is the synapse between the motor neurone and muscle cell called?

Answer 10

2 neurones- sensory and motor
3 neurones- sensory,relay,motor
A nerve with only a sensory neurone
A nerve with only a motor neurone 
A nerve with both a sensory and motor neurone
Junction between 2 neurones 
Presynaptic neurone
Postsynaptic neurone 
Neuromuscular junction