WEEK 4 LECTURE + TUTORIAL

Question 1

Synapses

Answer 1

-Junction between the terminal button of an axon and the membrane of another neuron
-Spaces between the terminal button of one neuron and the dendritic or somatic membrane of another
-Primary means of communication between neurons is synaptic transmission
-Info travels in one direction

Question 2

Structure of a synapse

Answer 2

-presynaptic axon: terminal containing neurotransmitters, mitochondria and other organelles.
-Postsynaptic ending: receptor sites for neurotransmitters
-Synaptic cleft, contains extracellular fluid through which the neurotransmitter diffuses
-two prominent structures are located in the cytoplasm of the terminal button: mitochondria and synaptic vesicles, small, bubble-like structures made of membranes and filled with molecules
-The presence of mitochondria implies that the terminal button needs energy to perform its functions
-A chemical that attaches to a binding site is called a ligand

Question 3

Synaptic Transmission Process:
Part 1

Answer 3

1. Action potential arrives at axon terminal triggering CA2+ ions to move into the cell
   1.Synaptic transmission is initiated when an action potential invades a nerve terminal, opening CA2+ at the active zone
   1.CA2+ triggers synaptic vesicle exocytosis, thereby releasing the neurotransmitters contained in the vesicles and initiating synaptic transmission

Question 4

Synaptic Transmission Process
Part 2/3

Answer 4

• CA2+ Ions cause the migration of vesicles (which contain NTs) to the pre-synaptic membrane
  -The vesicles fuse to the pre synaptic membrane and break open, emptying their neurotransmitters into the synaptic cleft

Question 5

Synaptic Transmission
Part 4/5/6

Answer 5

-Neurotransmitters diffuse across the synaptic cleft towards the post-synaptic membrane, move from an area of high concentration to disperse across the synapse due to the force of diffusion
-Neurotransmitters bind to receptor cites on the post synaptic membrane with the lock and key specificity - specific NT binds to the specific receptor
-The binding opens NT-dependent ion channels which change the excitability of the post-synaptic excitatory or inhibitory

Question 6

Postsynaptic receptors

Answer 6

-Direct receptors (ionotropic)
-Binding site for a NT
-Ion channels open when NT molecule binds, ionotropic receptor

Indirect Receptor (metabotropic)
-Only a binding site for NT
-Activates enzyme
-Called this because it involves steps that require the cell to expend metabolic energy

Question 7

Problems that could occur:

Answer 7

-Too much or not enough of one or more neurotransmitters
-The receptor on the receiver cell isn’t working properly
-The cell receptors aren’t taking up enough neurotransmitter due to inflammation and damage of the synaptic cleft
-NT’S are reabsorbed too quickly
-Enzymes limit the number of neurotransmitters from reaching their target cell
-Problems with other part of nerves

Question 8

Diseases that can occur

Answer 8

-Not enough acetylcholine can lead to the loss of memory that’s seen in Alzheimer’s disease
-Too much serotonin is possibly associated with autism
-An increase in glutamate can cause seizures
-Too much dopamine and abnormal glutamate transmission contributes to mania

Question 9

Endorphins/ Peptides

Answer 9

• Pain relievers and feel good feelings
  -Released by hypothalamus and pituitary gland
  -Inhibitors (opioid receptors)
  -Low levels of endorphins may play a role in fibromyalgia and some types of headaches

Question 10

Amino acids/ glutamate / GABA

Answer 10

-most common excitatory neurotransmitter
-used by brain to synthesise GABA
-most abundant NT in the brain
-Key role in cognitive functions like thinking, learning and memory
-Imbalances in glutamate levels associated with Alzheimer’s disease, dementia, Parkinson’s, Huntington’s, seizures

Question 11

Gamma-aminobutryic acid (GABA)

Answer 11

-Synthesised from glutamate and vitamin B6
-The most common inhibitory neurotransmitter of the nervous system, particularly the brain
-Regulates brain activity to prevent problems in the areas of anxiety, irritability, concentration, sleep and depression
-Contributes to motor control, vision, regulation of anxiety, and many other cortical functions
-Drugs that increase GABA in the brain are used to treat epilepsy and calm trembling in Huntington’s disease

Question 12

NT removal from synapse

Answer 12

1. Reuptake: NT is quickly pumped back into nearby glia or the axon terminal that released it
2. Deactivation: NT destroyed by enzymes near receptors, so its not recognised by receptor
3. Removal: diffuses into surrounding area, blood

Question 13

Enzymatic deactivation

Answer 13

-Enzymatic deactivation is accomplished by an enzyme that destroys molecules of the neurotransmitter
-E.g. Acetylcholinesterase (AChE) deactivates the neurotransmitter acetycholine (ACh) by breaking it into choline and acetate

Question 14

Psychopharmacology definition

Answer 14

Study of the effects of drugs on the nervous system and behaviour

Question 15

What are drugs

Answer 15

-Exogenous chemicals
-Unnecessary for normal functioning
-Alter molecular functions
-Effects are physiological or behavioural
-Natural VS Artificial

Question 16

1. Agonists VS 2. Antagonists

Answer 16

1. Facilitate or mimics action of NT and facilitates postsynaptic effects
2. Inhibit action of a NT and block postsynaptic effects

Question 17

Mechanisms of drug actions

Answer 17

1. Synthesis
2. Storage
3. Release
4. Receptors
5. Reuptake
6. Destruction

Question 18

1. Synthesis

Answer 18

• Alter neurotransmitter synthesis in presynaptic neuron
  -Modifies concentration in synaptic cleft
  -NT produced from specific precursor molecules
  -Enzymes required for change from precursor to NT

Question 19

2. Storage

Answer 19

• Alter neurotransmitter storage in presynaptic terminal
  -Modifies concentration in synaptic cleft
  -Transporter proteins in vesicle membranes move NT from cytoplasm into vesicles
  -Antagonist inactive transporters
  -Vesicles remain empty

Question 20

Release

Answer 20

• Changes NT release from presynaptic cell
  -Modifies concentration in synaptic cleft

Question 21

4. Receptors

Answer 21

-Act on neurotransmitter receptors
-Modify postsynaptic potentials

Question 22

5. Reuptake

Answer 22

-Modify removal of NT from synaptic cleft
-Changes NT concentrations in the cleft
-Agonists reduce or block reuptake

Question 23

6. Destruction

Answer 23

• Modify NT destruction in synaptic cleft
  -Enzymes typically inactivates nt
  -Acetylcholinesterase in post synaptic membrane deactivates ACH

Question 24

Myasthenia Gravis

Answer 24

• A rare autoimmune neuromuscular junction disorder

Question 25

Drugs of abuse

Answer 25

- Central Nervous System depressants -Central Nervous System stimulants -Opiates and Opioids (Narcotics) -Hallucinogens -Marijuana

Question 26

Categories of Psychotherapeutic Drugs:

Answer 26

-The anatomical therapeutic chemical (ACT) Classification system - International Pharmacopeia (WHO) -European Pharmacopeia -United states Pharmacopeia (USP)

Question 27

4 Key Concepts of Pharmacology

Answer 27

-Dose -Tolerance -Sensitivity -Withdrawal

Question 28

Tolerance

Answer 28

-the diminished response to drugs over the course of repeated or prolonged exposure -accounted for by adapting physiological process that achieves stability in a constantly changing environment

Question 29

Types

Answer 29

-Acute/ Tachyphylaxis: Instant short term effect of drug on NT and synaptic junction -Pharmacodynamic (dispositional): Reduction in cellular response to drug -Pharmacokinetic (metabolic): absorption, distribution, metabolism and excretion of drugs - Behavioural (conditioned): Tolerance to a behavioural effect of a drug, occurs through drug-independent learning or as a form of pharmacodynamic tolerance in the brain

Question 30

Sensitivity

Answer 30

-An increased response to a drug with repeated administration. -Amplified effects, including therapeutic benefits and side effects. -Mechanisms behind sensitization are not fully understood but thought to involve neuroadaptive changes. -Understanding tolerance and sensitization is crucial for optimizing drug therapy as they impact dosing, effectiveness, and potential side effects

Question 31

Withdrawal

Answer 31

-With increased tolerance and dependence on a drug the reduction of that drug typically causes an opposite effect to the drug itself. - Internal systems perpetuate homeostasis by using counter regulatory methods to create a new state of balance based on the presence of the drug in the system. - Adaptions include levels of neurotransmitters, hormones, and other substances to adjust for the addition of the drug to the body

Question 32

FACTS

Answer 32

-Fentanyl is 50x stronger than heroin -Caffeine = Antagonist -SSRI = Agonist -Morphine = Agonist - Benzodiazepine = Agonist