2. Agonists, Antagonists, and Synaptic Transmission

Question 1

What is the function of an agonist?

Answer 1

Agonists mimic neurotransmitters and activate receptors (e.g., nicotine mimics acetylcholine, ACh).

Question 2

What is the function of an antagonist?

Answer 2

Antagonists block neurotransmitter action by binding to receptors without activating them (e.g., curare blocks ACh receptors).

Question 3

How do receptor subtypes influence neurotransmitter effects?

Answer 3

Different receptor subtypes allow varied effects from the same neurotransmitter.
Example: Nicotinic ACh receptors are excitatory and found in muscles and autonomic ganglia.

Question 4

What are the two primary mechanisms of signal termination in synaptic transmission?

Answer 4

Degradation: Enzymes break down neurotransmitters (e.g., acetylcholinesterase degrades ACh).
Reuptake: Neurotransmitters are reabsorbed into the presynaptic terminal via transporters.

Question 5

What is acetylcholinesterase (AChE), and what does it do?

Answer 5

AChE is an enzyme that breaks down acetylcholine (ACh) into components that can be recycled

Question 6

How does faulty neurotransmitter reuptake affect mental health?

Answer 6

Impaired reuptake of neurotransmitters like serotonin or dopamine can contribute to disorders such as depression.

Question 7

What are the different types of synapses in neural circuitry?

Answer 7

Axo-dendritic: Axon to dendrite.
Axo-somatic: Axon to soma (cell body).
Axo-axonic: Axon to axon (modulates presynaptic activity).
Dendro-dendritic: Dendrite to dendrite (coordinates neuronal activity).

Question 8

What is the significance of the knee-jerk reflex in neural processing?

Answer 8

It demonstrates rapid processing due to:

Myelination & large axon diameter for fast action potential conduction.
Direct synaptic pathways connecting sensory to motor neurons.
Efficient central and neuromuscular synapses.

Question 9

What are the seven steps in synaptic transmission?

Answer 9

-Action potential arrival at the presynaptic terminal.
-Ca²⁺ entry into the presynaptic terminal.
-Vesicle fusion and neurotransmitter release.
-Neurotransmitter binds to postsynaptic receptors.
-EPSPs/IPSPs integrate and spread to the axon hillock.
-Signal termination via degradation or reuptake.
-Presynaptic monitoring of neurotransmitter release.

Question 10

What triggers neurotransmitter release?

Answer 10

The entry of calcium ions (Ca²⁺) into the presynaptic terminal.

Question 11

How do neurons process information?

Answer 11

Electrical signals: Processed within neurons.
Chemical signals: Communicated between neurons via neurotransmitter release.