Topic 4-Neurotransmitters

Question 1

Where do neurotransmitters act?

Answer 1

Neurotransmitters act at synapses in the synaptic cleft.

Question 2

How do neurotransmitters affect target cells?

Answer 2

They have direct, rapid effects on specific target cells.

Question 3

How quickly do the effects of neurotransmitters typically occur?

Answer 3

The effects of neurotransmitters usually occur quickly, within milliseconds to seconds, and are usually short-lived.

Question 4

Where do neuromodulators act in relation to the synaptic cleft?

Answer 4

Neuromodulators act at a distance from the synaptic cleft.

Question 5

How do neuromodulators influence cells?

Answer 5

They are released into the extracellular fluid, affecting many cells.

Question 6

What is a notable characteristic of the effects of neuromodulators?

Answer 6

The effects of neuromodulators manifest slowly, over seconds, and typically last longer, ranging from minutes to days.

Question 7

Criteria for classification as a NT: 3

Answer 7

1) Located in presynaptic region (usually in vesicles).
2) Released with activation or depolarization of the presynaptic terminal (Ca 2+ dependent).
3)Specific receptors must be present on the postsynaptic cell.

Question 8

Two Types of NT

Answer 8

1)Small-molecule neurotransmitters (amino acids, acetylcholine, purines and biogenic amines)
2) Neuropeptides

Question 9

Example of Excitatory NT:

Answer 9

1) Glutmate (main fasting acting NT in the CNS)
2) Aspartate

Question 10

Example of Inhibitory NT

Answer 10

1) GABA (major inhibotry) 2) Glycine

Question 11

Small molecule neurotransmitters can act as both

Answer 11

fast-acting neurotransmitters and neuromodulators.

Question 12

Examples of small molecule NT

Answer 12

• Dopamine: Reward
  Norepinephrine: Alertness
  Epinephrine: Stress
  Serotonin: Mood
  Histamine: Wakefulness

Question 13

Where is acetylcholine (ACh) primarily found in the nervous system?

Answer 13

ACh is a major conveyer of information in the peripheral nervous system (PNS).

Question 14

What are the two main receptor subtypes for acetylcholine (ACh)?

Answer 14

ACh has two main receptor subtypes: nicotinic and muscarinic.

Question 15

What is the role of acetylcholine (ACh) in the central nervous system (CNS)?

Answer 15

In the CNS, ACh is slower-acting and involved in neuromodulation, particularly in movement control and the selection of objects of attention.

Question 16

How do nicotinic and muscarinic receptors differ in their action?

Answer 16

Nicotinic receptors are fast-acting, as seen at the neuromuscular junction, while muscarinic receptors are slower-acting, G-protein-coupled receptors. Muscarinic receptors are also found in the CNS.

Question 17

What are the two purines mentioned in neurotransmission?

Answer 17

The two purines are ATP (adenosine triphosphate) and adenosine

Question 18

What is the role of ATP in neurotransmission?

Answer 18

ATP serves as an excitatory neurotransmitter and is coreleased with other neurotransmitters.

Question 19

Is adenosine considered a classical neurotransmitter, and why?

Answer 19

Adenosine is not considered a classical neurotransmitter because it is not stored in vesicles. It is generated from ATP by extracellular enzymes or released in a calcium-dependent manner.

Question 20

How can neuropeptides affect neurosignaling?

Answer 20

Neuropeptides can affect neurosignaling by acting as hormones, neurotransmitters, or neuromodulators.

Question 21

What type of receptors do slow, modulatory neurotransmitters typically act on?

Answer 21

Slow, modulatory neurotransmitters often act on metabotropic receptors. Examples include biogenic amines, ACh (acting on muscarinic receptors), and neuropeptides.

Question 22

Typical Effects of NT: 3

Answer 22

1)Fast Excitatory
2) Fast Inhibitory
3)Slow Modulatory

Question 23

What are examples of neurotransmitters that have fast inhibitory effects and act on ionotropic receptors?

Answer 23

Examples include GABA and glycine (in the spinal cord

Question 24

What are examples of neurotransmitters that have fast excitatory effects and act on ionotropic receptors in the peripheral nervous system (PNS) and central nervous system (CNS)?

Answer 24

Examples include ACh (acting on nicotinic receptors) in the PNS and glutamate in the CN

Question 25

Where are ] Where are small molecule neurotransmitters and larger peptide neurotransmitters typically synthesized?

Answer 25

Small molecule neurotransmitters are synthesized in the nerve terminal.
Larger peptide neurotransmitters are typically synthesized in the soma (cell body) of the neuron.

Question 26

Life Cycle of a NT Steps

Answer 26

1) NT is synthesized in cell body or terminal
2) NT is packaged into vesicles
3) NT is released when vesicles fuse
4) NT binds to and activates post synaptic receptors
5) NT diffuses away and is metabolized and/or trasnported back into the terminal

Question 27

Which direction does neuronal transport occur in and what is the purpose?

Answer 27

-Occurs in both direction
- Allows for the delivery of organelles and macromolecules from the cell body to the axon terminal.

Question 28

Where does the synthesis of neuropeptides, neurotransmitter precursors, and enzymes typically take place?

Answer 28

The synthesis of neuropeptides, neurotransmitter precursors, and enzymes usually occurs in the cell body (soma) of the neuron and is packaged in the Golgi apparatus. These substances are then transported down microtubules to their destinations, such as the axon terminal.

Question 29

NT Production

Answer 29

1,2 - Enzymes for NT synthesis produced in soma & released from Golgi apparatus

3 - Slow axonal transport to presynaptic terminal

4 – NT substrates transported into terminal and assembled using enzymes from soma

5,6 - Packaged in vesicles (5) for release (6)

Question 30

What triggers the link between the membrane and vesicular docking proteins during neurotransmitter release?

Answer 30

The influx of calcium ions (Ca2+) triggers the link between the membrane and vesicular docking proteins.

Question 31

What is the role of the fusion pore in neurotransmitter release?

Answer 31

The formation of the fusion pore allows neurotransmitters (NT) to be released from the nerve terminal into the synaptic cleft, where they can bind to receptors on the postsynaptic neuron and facilitate neurotransmission.

Question 32

What happens to the vesicle membrane after neurotransmitter release into the synaptic cleft?

Answer 32

The vesicle membrane is recycled through a process called endocytosis.

Question 33

Why is the recycling of neurotransmitter precursors important?

Answer 33

The recycling of neurotransmitter precursors ensures a continuous supply of neurotransmitters to refill the vesicles, allowing for sustained neurotransmission.

Question 34

Why is it important to remove neurotransmitters from the synaptic cleft quickly?

Answer 34

To avoid making the receiving cell less responsive to future signals and to protect it from potential harm, i

Question 35

What are the three main methods of neurotransmitter removal from the synaptic cleft?

Answer 35

Neurotransmitters are removed through these methods:

1) Reuptake into neighboring astrocytes (e.g., glutamate).
2) Reuptake into the presynaptic terminal (e.g., dopamine and norepinephrine).
3) Enzymatic breakdown in the synaptic cleft (e.g., acetylcholine).

Question 36

How do most drugs exert their effects in the nervous system?

Answer 36

Most drugs work by either mimicking or blocking the action of neurotransmitters or neuromodulators.

Question 37

What are some ways in which drugs can affect neurotransmitters?

Answer 37

Drugs can influence neurotransmitters by increasing or decreasing their synthesis, altering their release, or affecting receptor binding on the postsynaptic membrane.

Question 38

What is Lambert-Eaton syndrome, and how does it affect transmission at the neuromuscular junction?

Answer 38

Involves antibodies targeting calcium channels, resulting in muscle weakness and affecting neurotransmission at the neuromuscular junction

Question 39

What is Parkinson’s Disease, and what is its primary cause?

Answer 39

Parkinson’s Disease involves the death of neurons that produce dopamine in the substantia nigra.

Question 40

What is Alzheimer’s disease characterized by?

Answer 40

Alzheimer’s disease is characterized by disruptions in the normal function of cholinergic neurons.