Overview Of The Nervous System

Question 1

What are the 2 types of pathways in the CNS?

Answer 1

Excitatory pathways - depolarisation is recorded (Excitatory postsynaptic potential)
Inhibitory pathways - hyperpolarises the membrane. Called IPSP, the Cl channel is involved, making an action potential difficult to reach

Question 2

What are the sites of drug action?

Answer 2

Presynaptic actions - synthesis, storage and metabolism of NT, degradation of NT in synapse.
Postsynaptic drug action where it acts in various types of ways

Question 3

What are the amino acid NTs?

Answer 3

Glutamate (Excitatory)
GABA (Inhibitory)
Glycine (Inhibitory)

Question 4

What are the monoamine NTs

Answer 4

Dopamine
Noraderenaline
5-Hydroxytrytamine
Histamine

Question 5

What are the types of receptors that act with regards to acetylcholine?

Answer 5

Metabotropic and ionotropic receptors

Question 6

What are the dopaminergic pathways?

Answer 6

Nigrostriatal (Motor control)
Mesolimbic (Limbic system)
Mesocortical (Emotion)
Tuberoinfudibularc(Endocrine)

Question 7

What is the difference between the dopamine receptors?

Answer 7

D1 and D5 - Stimulate Adenylate Cyclase and increase Cyclic AMP

D2 - D4 - Activate K, Decreases calcium and decreases adenylate cyclase.

Question 8

What are the different noradrenaline receptors?

Answer 8

A1 - postsynaptically binds for NA and produces excitatory effect
A2 - pre and post, high affinity for NA. Inhibitory effects
B (1&2) found in cerebral cortex, low binding affinity with NA and has excitatory effects.

Question 9

What is special of the 5-Hydroxytryptamine-3 receptor?

Answer 9

Its Ionotropic and excitatory, while the rest are metabotropic and are inhibitory receptors.

Question 10

Explain how an action potential is generated?

Answer 10

A signal arrives at the neuron, causing depolarisation in the membrane and voltage-gated Na channels open (sodium comes in). Voltage gated K channels open and K leaves the cell. Sodium channels go inactive but K stay open and the neuron repolarises as the negative gradient is re-established. The relative refractory period happens when the K channels close and the membrane becomes hyperpolarised (reaches -80mV). Depolarisation continues until -55mV, then voltage-gated Ca channels open. This then causes vesicles with neurotransmitter to fuse with the membrane and release neurotransmitters via exocytosis and bind post-synaptically to the neuron.