week 7- lecture 1 into to pharmacology Flashcards Preview

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Flashcards in week 7- lecture 1 into to pharmacology Deck (23)
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1
Q

Structure from brain to synapse

A

100 billion neurons in the brain
~ 0.15 quadrillion synapses in
the cortex

2
Q

Receptors

A
  • Neurons have a cell “membrane” that acts like a wall preventing things from entering or leaving the neuron.
  • The cell wall as two layers with the fatty inside of each layer sticking together like a sandwich.
  • Because of the fatty inside layer, fluids and other chemicals like neurotransmitters are not able to pass through.
3
Q

types of receptors

A

Receptors located on the outside of the cell membrane allow the released neurotransmitters to influence the post-synaptic neuron.
Two types of receptors:
- Ion Channels
- G-Protein coupled

4
Q

ION channels

A

Ion channels act like a gate.

  • When a neurotransmitter binds to the receptor outside the neuron, this causes the gate to open and ions (positively and negatively charged molecules), can flow through.
  • Channels are normally “selective” and only allow one or a few types of ions to pass through when they are open (e.g. a calcium ion channel).
5
Q

G protein-coupled receptor

A
  • G-Protein receptors have 7 Transmembrane units that cross through the cell membrane.
  • When the neurotransmitter binds to the receptor it activates a “second messenger system” that can either open a channel or cause other things to change within the cell (e.g. DNA being transcribed and new proteins being made).
6
Q

Receptor specificity

A
  • Receptors are very selective (lock and key).
  • Each receptor can generally only be activated by one neurotransmitter (or a drug that is designed to mimic that neurotransmitter).
  • They also have a very specific function/action. When a neurotransmitter binds to the receptor this will trigger the same event every time (either opening a channel or triggering a second messenger event).
7
Q

Receptor specificity

continued

A

In reality receptors are not simple “open-shut” gates… They have complex structures and it is often a small change in their shape that will “open” a channel, or cause it to “do its thing”.

8
Q

Criteria for Defining Neurotransmitters

A
  • Present in presynaptic terminals
  • Released from presynaptic terminals after the neuron fires.
  • Existence of receptors on postsynaptic neurons
9
Q

Chemical cocktail in the brain

A

Multiple Neurotransmitters:
Dopamine, Serotonin, Noradrenaline, Glutamate, GABA, Acetylcholine…. and many more…including gasses & peptides
They can activate, inhibit or modulate neuronal activity
excitatory - Glutamate
inhibitory - GABA

modulatory - ie Serotonin, Dopamine & Noradrenaline

10
Q

Neurotransmission:

A

Either EXCITATORY or INHIBITORY and serves rapid (millisecond), precise, point to point communication.

11
Q

Neuromodulation:

A

Describes slower (milliseconds to seconds) processes that alter the subsequent responsiveness of neurons.

12
Q

Neurotransmitters: Excitatory

A
  • Glutamate is the neurotransmitter released by ALL excitatory neurons.
  • Found in most of the long projection neurons throughout the cortex.
  • Acts on both ion channel and G Protein-Coupled receptors
13
Q

Neurotransmitters: Excitatory

continued

A

Excitatory connections are “point-to-point”.

Many region-specific functions (e.g. connections along the visual pathways)

14
Q

Neurotransmitters: Inhibitory

A

GABA (gamma-amino butyric-acid) is released by inhibitory neurons.
Most short local neurons are inhibitory, so they form a dense web around and between the excitatory neurons

15
Q

Neuromodulation

A
  • Presynaptic: Alters neurotransmitter release
  • Postsynaptic: Alters neurotransmitter action (e.g., alters excitability/ firing pattern)
  • Neuromodulation may produce both neurophysiological and biochemical effects.
16
Q

Psychopharmacology

A

The study of drug induced changes in mood sensation, thinking & behavior.

17
Q

Cycle of Neurotransmitters

A

1 Synthesis

2 Release from synaptic vesicles

3 Binds to receptors

4 +/- influence on post synaptic neuron

5 Broken down by enzymes

6 reuptake of transmitter

7 formation & storage in
synaptic vesicles

18
Q

Drug Action

A

can effect all stages of the cycle

19
Q

Action at the receptor

A
  • Drugs act by “mimicking” natural neurotransmitters or neuromodulators.
  • Can act as AGONISTS activating the receptor like the natural compound.
  • Or can act as an ANTAGONIST blocking the receptor and preventing the natural compound from activating it.
20
Q

Synthesis interruption

A

Neurotransmitter function can be altered by increasing or decreasing synthesis of the neurotransmitter

21
Q

Neurotransmitters: Slow & Fast

A

Synthesis and transport to the synapse is relatively slow. BUT
The neurotransmitter action is extremely fast because it sits ready for release

22
Q

Psychology vs Pharmacology

A

-Pharmacology can effect psychology
Natural neurotransmitters and artificial drugs can clearly effect mood, cognition & behaviour
-Psychology can also effect pharmacology
Emotional or stressful events, thoughts and behaviour effect us BECAUSE they influence our neurotransmitters.
Cognitive therapy and pharmacology acts on the same brain!!

23
Q

summary

A
  • Neurons communicate through neurotransmitter release at synapses
  • Receptors either act as ion channels (gates) or they cause down stream effects within the neuron through a “second messenger”
  • Chemical signals act as “neurotransmitters” in fast/local signals or “neuromodulators” in slower more global signals (still fast, just more sustained) .
  • The action of neurotransmitters can be altered by drugs at many stages in many different ways.