Neurotransmitters

Question 1

Acetylcholine

Answer 1

Signal between neuron & striated muscle.

Discovered by Loewi, in the ‘Frogs’ experiment

Question 2

Outline Loewi’s Frog Experiment

Answer 2

Loewi stimulated the vagus nerve of 1 frog’s heart so it beat more slowly, while in a solution. He withdrew some of that solution, & injected it into another frog’s heart. It too began beating more slowly.
Conclusion: a chemical substance must be responsible.
Substance found: acetylcholine

Question 3

Dopamine

Answer 3

Neurotransmitter in the brain.
Effect: rewards certain behaviour patterns.
Precursor: L-tyrosine => L-Dopa => Dopamine. Occurs in the neuron.
Packaged by:
Receptors:
Recycled by:

Question 4

GABA

Answer 4

Inhibitory neurotransmitter, balancing the effects of glutamate.
Precursor:
Packaged by:
Receptors:
Recycled by: Krebs cycle

Question 5

4 stages of neurotransmission

Answer 5

1: Synthesis & storage
2: Transport
3: Receptor activation
4: Neurotransmitter inactivation

Question 6

2 types of neurotransmitter synthesis

Answer 6

Cell-derived neurotransmitters: from mRNA, so made in the cell.
Food-derived neurotransmitters: precursors are present in the blood, taken up by the axon & processed.

Question 7

4 methods of neurotransmitter inactivation

Answer 7

1. diffusion
2. degradation
3. re-uptake
4. astrocyte uptake

Question 8

Features of an electrical synapse

Answer 8

Direct contact between 2 cells
Bidirectional
Mammalian brain
Fast, but not as controlled as chemical
Can't inhibit or modify the signal
No 'learning' of the signal