Neurobiology of Nerve Impulses and Neurotransmitters

What is the primary action of local anesthetics on nerve cells?

Which neurotransmitter is NOT listed among the common neurotransmitters in the brain and spinal cord?

What condition can result from excessive nerve impulses?

Where does the herpes simplex virus lie dormant before reactivation?

Which effect is NOT associated with the use of local anesthetics?

What is the term for a nerve impulse that runs towards the brain and central nervous system?

What initiates a nerve impulse?

Which structure stores neurotransmitters prior to their release?

What occurs at the synapse?

How is the action of a neurotransmitter typically characterized?

What process releases neurotransmitters into the synaptic cleft?

What happens to neurotransmitters after they act on the receptor sites?

What describes the journey of a neurotransmitter from synthesis to action?

Nerve Impulses

Nerve impulses are initiated by either sensory nerve ending stimulation or the passage of impulses from another nerve.
Afferent (sensory) impulses travel towards the brain and central nervous system (CNS).
Efferent (motor) impulses travel away from the brain and CNS.
Synapses are the points where nerve impulses jump from one nerve to another.
- There are approximately 1000 trillion synapses in the brain.
Synaptic knobs contain spherical, membrane-bound synaptic vesicles that store neurotransmitters.

Neurotransmitters

Neurotransmitters are chemicals released into the synaptic cleft.
The journey of a neurotransmitter:
- Synthesized by nerve cell bodies.
- Actively transported along axons.
- Stored in synaptic vesicles.
- Released by exocytosis in response to action potential.
- Diffuse across the synaptic cleft.
- Act on specific receptor sites on the postsynaptic membrane.
- Short-lived action.
- Inactivated by enzymes or taken back into the synaptic knob.
More than 50 neurotransmitters exist in the brain and spinal cord.
- Some examples include:
  - Noradrenaline
  - Adrenaline
  - Dopamine
  - Histamine
  - Serotonin
  - Acetylcholine

Drugs & Nerve Impulses

Drugs can increase the excitability of neurons or inhibit neurotransmitters.

Local Anaesthetics

Local anaesthetics block nerve transmission to pain centres in the CNS by binding to and inhibiting the function of sodium channels in the cell membrane of nerve cells.
- This action obstructs the movement of nerve impulses near the site of injection.

Neuralgia

Excessive nerve impulses can lead to neuralgia, with trigeminal neuralgia being the most common.

Herpes Simplex Virus

The herpes simplex virus (HSV) lies dormant in the trigeminal ganglion.
When reactivated, HSV travels down the trigeminal nerve, emerging on the lip and potentially causing a cold sore.

Test your knowledge on the mechanisms of nerve impulses and neurotransmitter functions. This quiz covers the roles of afferent and efferent impulses, synapses, and the journey of neurotransmitters in the nervous system. Challenge yourself with these essential concepts in neurobiology!