19.5

Question 1

In epilepsy, there is excess firing of the ___ cortex.

Answer 1

Motor

Question 2

In treatment of epilepsy, ___ are used to enhance GABA (inhibitory) receptor activity.

Answer 2

Benzodiazepines!

Question 3

In treatment of epilepsy, ___ is used to reduce excitatory input (glutamate) by limiting excitatory nerve activation.

Answer 3

Phenytoin

Question 4

In treatment of epilepsy, ___ is used to reduce excitatory input (glutamate) by inhibiting T-type Ca2+ channels.

Answer 4

Ethosuximide

Question 5

In treatment of epilepsy, ___ is used to reduce excitatory input (glutamate) by inhibiting the NMDA receptor.

Answer 5

Felbemate

Question 6

Benzodiazepines are ___ modulators of the ___ receptor, that ___ activity.

Answer 6

Allosteric modulators of GABA receptor, enhances activity -> increases inhibition.

Question 7

Why is phenytoin esp. effective in epilepsy?

Answer 7

Phenytoin selectively targets AP generation in nerves firing excessively!!!

Question 8

Local anaesthetics are weak ___ that differ in onset, duration and toxicity, and include ___, ___ and ___.

Answer 8

Weak bases.

Aminoesters, aminoamides and benzocaine.

Question 9

Aminoesters vs. aminoamides?

Answer 9

Aminoesters e.g. procaine are shorter acting, and is hydrolysed by esterases.
Aminoamides e.g. lignocaine, bupivacaine, ropivicaine are longer acting and is inactivated by hepatic metabolism.

Question 10

Benzocaine is relatively ___ and is esp. useful in the ___.

Answer 10

Weak

Useful in the throat e.g. for cough suppression, etc.

Question 11

Local anaesthetics selectively bind to the ___ channel, and bind ___ with no nerve damage.

Answer 11

Na+ channel.

Reversible binding.

Question 12

The sensitivity of sensory fibres to local anaesthetics is ___ compared to motor fibres!!!

Answer 12

Sensitivity of sensory fibres > sensitivity of motor fibres.

Question 13

Local anaesthetics bind ___ the channel, and therefore require access to the channel for effect.

Answer 13

INSIDE - NOT outside like toxins can!

Question 14

There are two general types of anaesthetics that influence their mechanism of action: ___ and ___

Answer 14

Hydrophobic and hydrophilic.

Question 15

Hydrophobic local anaesthetics act ___ and are NOT dependent on activity of the channel.

Answer 15

Fast!

Question 16

Benzocaine is a ___ local anaesthetic.

Answer 16

Hydrophobic

Question 17

Hydrophilic local anaesthetics act ___ and ARE dependent on activity of the channel.

Answer 17

Slow

Question 18

Aminoesters and aminoamides are ___ local anaesthetics.

Answer 18

Hydrophilic

Question 19

Why are sensory fibres more sensitive to local anaesthetics than motor fibres?

Answer 19

Sensory fibres are thin and motor nerves are thick and often myelinated - there is less distance for diffusion of local anaesthetics across membranes of sensory fibres!

Question 20

Only the ___ form of hydrophilic local anaesthetics can cross the membrane.

Answer 20

Uncharged/non-charged.

Question 21

After the non-charged form of a hydrophilic local anaesthetic crosses the membrane via the Na+ channel, it forms a ___ form.

Answer 21

Charged

Question 22

The ___ form binds to the Na+ channel with higher affinity.

Answer 22

Charged!

Question 23

The charged form of hydrophilic local anaesthetics can only bind when the Na+ channel is ___

Answer 23

OPEN

Question 24

Local anaesthetics have a greater effect in a ___ medium.

Answer 24

Basic - because weak bases in a basic medium are mostly in uncharged form and can cross the membrane.

Question 25

Use of local anaesthetics in ___ states may be less effective.

Answer 25

Acidic!

There will be more charged form - it cannot cross the membrane!

Question 26

There are 2 theories for the mechanism of action of general anaesthetics: ___ theory and ___ ___

Answer 26

Lipid theory and receptor interaction.

Question 27

Meyer Overton states that…

Answer 27

Anaesthesia is caused by volume expansion of membrane lipids, and the effect can be reversed by pressure.