ELM 7 The ap

Question 1

What is the action potential?

Answer 1

The action potential is a transient reversal of the membrane potential in excitable cells, lasting from a few milliseconds to a few hundred milliseconds, which allows for communication in the nervous system.

Question 2

What is the all-or-nothing principle of the action potential?

Answer 2

According to the all-or-nothing principle, stimuli must exceed a certain threshold (-55 mV) to trigger an action potential, and once triggered, the size of the action potential remains constant regardless of the strength of the stimulus.

Question 3

What ions are involved in the action potential?

Answer 3

Sodium (Na+) ions enter the cell to depolarize it during the rising phase of the action potential, while potassium (K+) ions exit the cell during the falling phase to restore the resting membrane potential.

Question 4

What is the refractory period of the action potential?

Answer 4

The refractory period of the action potential consists of an absolute refractory period during which another action potential cannot be generated, followed by a relative refractory period during which a larger stimulus is required to generate another action potential.

Question 5

What is Dravet syndrome, and what causes it?

Answer 5

Dravet syndrome is a form of epilepsy characterized by prolonged generalized seizures triggered by high temperatures. It is caused by a mutation in the SCN1A gene, which codes for the sodium channel NaV1.1, leading to dysfunction in inhibitory neurons.

Question 6

ow is Dravet syndrome typically treated?

Answer 6

Dravet syndrome is difficult to treat, and most epilepsy drugs have limited effectiveness. Some research suggests that cannabinoids, particularly cannabidiol (CBD), may be effective in reducing the number of seizures. However, obtaining prescriptions for THC-containing medications, which are not licensed in many countries, can be challenging.

Question 7

How does the action potential propagate along a neuron?

Answer 7

The action potential propagates along a neuron by spreading sideways due to the movement of charged ions. The refractory period prevents the action potential from propagating backward.