Lecture 5: Malfunctions Of The Nervous System That Cause Serious Symptoms

Front 1

What happens if we hold voltage gated Na+ channels open?

Back 1

The channels would not close and reactivate, so the membrane potential would stay near that of Na+. K+ channels would open and bring the membrane potential down and eventually there would be a balance between Na+ and K+

Front 2

What happens if we hold voltage gated Na+ channels closed?

Back 2

No Na+ flows into the cell, and the membrane potential goes back to resting. When K+ channels open the membrane potential goes down faster.

Front 3

What happens if we keep the voltage gated K+ channels open?

Back 3

Smaller action potential with a longer hyperpolarization

K+ would immediately flow out of the cell once AP is fired, and the membrane potential would shoot down

Front 4

What happens if we keep the voltage gated K+ channels closed?

Back 4

Wider action potential

Repolarization would take much longer

Front 5

Tetrodotoxin, TTX

Back 5

- Prevents propagation of action potentials
- Can lead to respiratory arrest, coma, death, paralysis

Front 6

Multiple Sclerosis

Back 6

- Slows down action potentials, then stops them
- Caused by a destruction of the myelin sheath
- Potential causes of myelin degeneration: infection by a slow virus, autoimmune disorder, heredity, or combo of all
- Paralysis, respiratory arrest, coma, death

Front 7

Polio

Back 7

- Kills ventral horn neurons
- Cannot move, sometimes cannot breathe because respiration muscles are affected
- Caused by a virus
- Paralysis, respiratory arrest, coma, death

Front 8

Leprosy

Back 8

- Cannot feel pain or touch
- Kills dorsal root ganglion cells
- Caused by bacteria

Front 9

Rabies

Back 9

- Virus attached to acetylcholine and travels with motor neurons to the brain
- Retrograde spread
- Causes mental depression, spasms of the throat, excessive salivation, fear of water, paralysis, coma, death

Front 10

Botulism

Back 10

- Stops transmission at the neuromuscular junction
- Caused by bacteria
- Paralysis, respiratory arrest, coma, death

Front 11

Tetanus

Back 11

- Stops inhibition of ventral horn motor neuron
- Caused by bacteria
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Front 12

Curare and Cobra Venom

Back 12

- Blocks acetylcholine receptors in the neuromuscular junction