Drugs and the Nervous System Flashcards
The nerve endings send impulses to the brain along what??
Axons
What three areas do drugs target that constitute the nervous system?
Brain
Spinal Cord
Nerves
Name 5 excitatory neurotransmitters (SANDG)
Noradrenaline Dopamine Serotonin (5-HT) Acetylcholine Glutamate
Name 2 inhibitory neurotransmitters (beginning with G)
GABA
glycine
Once the impulse/calcium enters the neuron in the brain, what does it release to the synapse?
Neurotransmitter
Once the neurotransmitter has been released into the synapse, what are the two processes that can happen?
- It is picked up by the postsynaptic receptor to go to the postsynaptic cell
- It is picked up by enzymes in the postsynaptic cleft, where it goes to the reuptake receptor (to be recycled for the next impulse)
What are the main drugs that act on the nervous system?
5 begin with A, 1 begins with N
Anaesthetics Anxiolytic/hypnotic Antidepressant Antiparkinsonian Anticonvulsants Neuromuscular blocking
General anaesthetics work mainly in the central nervous system (on parts of the brain). What are the 2 ways they can be administered?
Inhalation
Intravenously
Is general anaesthetic lipid soluble?
Yes
What 4 things does general anaesthetic promote/do?
Analgesia
Unconsciousness
Amnesia
Loss of reflexes
General anaesthetic is lipid soluble so that it can cross the blood/brain barrier. Once it has done this, what are the 2 ways we think it may work?
Acting on membrane receptors to reduce excitability of neurones
Affecting ion channels (opening/closing)
What are 6 typical side effects of general anaesthetic?
one is specific to pregnant women
Nausea/vomiting Shallow/rapid breathing Decreased cardiac output Decreased kidney perfusion Loss of temperature control Crossing the placenta
If a person is taking anticoagulant drugs and is due to undergo surgery using a general anaesthetic, what should they do?
Stop taking the drugs as it may interact with the anaesthetic
There are two phases of anaesthesia, induction and maintenance.
How are these administered and what are the strengths and weaknesses of each?
Induction: intravenous - rapid unconsciousness, hard to reverse, needles
Maintenance: inhaled - no needles, easier to control, mask over face is claustrophobic
There are 4 stages of anaesthesia. Stage 3 is surgical anaesthesia where skeletal muscle is relaxed and there is a loss of reflexes. We want the person to be in this stage for as long as possible.
What are the other 3 stages?
Stage 1: analgesia
Stage 2: excitement - adrenaline release
Stage 3: surgical relaxation
Stage 4: medullary paralysis - loss of respiratory/vasomotor control
What are the 4 types of general anaesthetic?
Barbiturates
Non-barbiturates
Gases
Volatile liquids (administered through vaporiser)
What is the name of the anaesthetic used to maintain anaesthesia (along with oxygen)?
This is a potent analgesic and must be used in combination with other drugs.
Nitrous Oxide
What anaesthetic can damage a foetus if the mother has low level long-term exposure to it?
Nitrous Oxide
Name 3 general anaesthetics that are inhaled and controlled by concentration of vapour:
(they all end in flurane)
Isoflurane
Desflurane
Sevoflurane
INHALED = FLURANE
What are the side effects of inhaled anaesthetics?
CV depression
Hypotension
Arrhythmias
Decreased CSF pressure
Is hypoxia a potential issue with inhaled anaesthetics?
Yes
Name a non-barbiturate general anaesthetic:
INTRAVENOUS
Propofol
Propofol can be used as a general anaesthesia for day procedures.
Why?
It has a rapid action and a rapid recovery, without ‘hangover’
Propofol can however cause convulsions/anaphylaxis
Name a barbiturate general anaesthetic (one which has a very quick mechanism of action but only lasts 5-10 minutes)
INTRAVENOUS
Thiopental
Very useful for brief procedures as rapid awakening - issues with long lasting sedation however
Etomidate is sometimes used in surgery as it has no hangover effect and causes less hypotension.
What are the drawbacks of this?
Potential muscle movements in surgery and suppression of adrenocortical function
Ketamine is rarely used as a general anaesthetic, but what patient groups do we tend to use it on?
Shocked patients and children.
We do this as it helps increase blood pressure
Scared of horse stampeed
What are the side effects of using ketamine as a general anaesthetic?
Raised heart rate and blood pressure
Bad dreams/hallucinations in recovery
What are anxiolytics and hypnotics called?
When are they used?
Benzodiazepines - calm the patient before surgery
In surgery, what do neuroleptics and anti-emetics do?
Counteract side-effects of anaesthetic such as nausea
In surgery, why do we use antihistamines?
To prevent bronchi from constricting
In surgery, what is the purpose of analgesics (usually opioid)?
To sedate the patient
What do atropine and hyoscine do in surgery?
These are called anticholinergics
They block the effect of the Peripheral Nervous System to prevent the patient from choking