Pharmacology Part 1

Question 1

How many neurones and synapses are there

Answer 1

~100 billion neurones in the brain
~0.15 quadrillion synapses in the crotex

Question 2

Explain the structural relationship between the fatty layers on the neurones and the receptors and the lock and key analogy

Answer 2

Fatty layers are at the end of the neurones to prevent liquid and other substances to enter or leave the neurone

receptor gates are outside of the fatty layers for ions to enter the cell

receptors are the lock as they can only be opened with one key (i.e., ligands)
ligands are the keys as they can open multiple receptors

Question 3

explain the two receptors

Answer 3

ion channels:
when a specific ligand binds at the channel
the channel opens up for ions to enter the cell
only allows one certain ion to enter (e.g., potassium channels = only potassiums)

G protein coupled receptor
their triggering causes a cascade of events
subunits of the GPCR
alpha, beta, gamma
at resting state
the three subunits and the guanosine diphosphate (GDP) binds at the GDCR
When the right ligand comes in, the GDP is released and is replaced by guanosine triphosphate (GTP)
the GTP-alpha unit and the other two subunits leave the GDCR to interact with other components
When the GTP is hydrolised, GDP replaces the GDP and returns to the GPCR

Question 4

Explain neurotransmitters and neuromodulators

Answer 4

Neurotransmitters:
affects one, or at most two, neurons per time
either excitatory or inhibitory
Fast but slow
fast in terms of fast release of the neurotransmitters (i.e., as long as there is an action potential)
slow in terms of the synthesis and transportation of the neurotransmitters to the synapses

Neuromodulators
affects many neurones at the same time and produces long lasting effects
altering the subsequent responsiveness of the neurones
alters the release of neurotransmitters at the pre-synaptic neuron and the effect of the neurotransmitters in the post-synaptic neurons
causes synaptic plasticity if there is enough neuromodulator activities

Question 5

Explain agonists and antagonists

Answer 5

drugs mimic the transmitters to cause an effect on the receptors

Agonists
binds and activates at the receptors like the natural compounds do
they therefore have a basically identical chemical structure as the natural compound

Antagonists
blocks the receptors or prevents natural compounds to bind at the receptor
still need to have similar chemical structure so that the antagonists can dock on the receptors

Question 6

Explain the cycle of neurotransmitters

Answer 6

1. transportation to the synapses
2. Released from the synaptic vesicles
3. binding on the receptors
4. therefore alters the voltage of the post-synaptic neuron
5. broken down by enzymes
6. reuptake back to the pre-synaptic neurone
7. storages back to the synaptic vesicles

Question 7

what are the potential events of the trigger of GPCR

Answer 7

opening other channels, transcribing DNA or producing new protein