Drugs and the nervous system

Question 1

What do general anaesthetics mainly act on?

Answer 1

The CNS.

Question 2

Why do we use anaesthetics?

Answer 2

Analgesia, unconciousness, amnesia and loss of reflexes.

Question 3

How do anaesthetics work? (4 things)

Answer 3

1. Act on CNS to promote sensitivity.
2. Usually fat soluble so can cross the blood brain barrier and get into CSF.
3. May act on membrane receptors to reduce excitability of neurones.
4. May act on ion channels.

Question 4

Side-effects of anaesthetics?

Answer 4

1. Nausea/ vomitting.
2. Breathing shallow or rapid.
3. Decrease kindey perfussion.
4. Low BP/CO.
5. Loss of temp control.

Question 5

How is anaesthesia usually induced?

Answer 5

Itravenously.

Question 6

How is anaesthesia usually maintained?

Answer 6

Inhaled.

Question 7

Types of general anaesthetics?

Answer 7

Barbiturates, non-barbiturates, volatile liquids and gases.

Question 8

Name a disadvantage of N2O.

Answer 8

Long term exposure may damage foetus.

Question 9

Name the disadvantages of inhaled anaesthetics.

Answer 9

1. CV depression.
2. Hypotension.
3. Arrhythmias.
4. Can decrease CSF pressure.

Question 10

Disadvantages of propofol?

Answer 10

May cause convulsions or anaphylaxia.

Question 11

Disadvantages of thiopental?

Answer 11

Rapid awakening and long lasting sedation.

Question 12

Disadvantages of ketamine?

Answer 12

Raised BP and HR.

Question 13

Disadvantages of hypnotics?

Answer 13

1. May lead to dependance.
2. May cause respiratory depression.
3. Benzodiazepines interact with alcohol.
4. Cross placenta.

Question 14

What are neuromuscular blocking drugs?

Answer 14

Muscle relaxants.

Question 15

What do neuromuscular blocking drugs do?

Answer 15

1. Block transmission in motor nerves.
2. Reduce need for deep anaesthesia.
3. Relax vocal cords allowing insertion of tracheal tube.

Question 16

What do neuromuscular blocking drugs require?

Answer 16

Assisted respiration.

Question 17

Disadvantages of neuromuscular blocking drugs?

Answer 17

1. Prolonged muscle pain/ paralysis.

2. Histamine release- bronchospasm.

Question 18

What are narcotic (opiod) analgesics?

Answer 18

They are for relieving severe pain usually post op.

Question 19

Disadvantages of narcotic (opiod) analgesics?

Answer 19

1. May cause nausea/ vomitting.
2. Can reduce breathing rate.
3. Small risk of addiction.
4. Can cause constipation.

Question 20

What do local anaesthetics act on?

Answer 20

Specific nerve pathways.

Question 21

What is local anaesthetics mechanism of action?

Answer 21

Blocking transmission of nerve impulses that carry pain from nociceptors to the brain.

Question 22

What is local anaesthetics cellular mechanism of action?

Answer 22

It stops sodium entering the cell.

Question 23

Name the side effects of local anaesthetics.

Answer 23

1. Abnormal heart beat.
2. Restlessness.
3. Convulsions.
4. In severe cases, cardiorespiratory arrest.

Question 24

What is the main aim of vasoconstrictors?

Answer 24

To reduce blood flow to lesson blood loss during surgery.

Question 25

Name the disadvantages of tricyclic antidepressants.

Answer 25

1. Headache.
2. Nausea.
3. Dizziness.
4. Diarrhoea.
5. Convulsions.