Drugs And The Nervous System Flashcards
What is the basic function of the NS?
Recognise changes in the internal and external environment
Process and integrate environmental changes that are perceived
Reactive to the environmental changes by producing an action or response
What is the difference between inhibitory and excitatory?
Inhibitory: slows down
Excitatory: speeds up
Name the neurotransmitters in the brain.
Excitatory: noradrenaline, dopamine, glutamate, 5-HT, AcH
Inhibitory; GABA, Glycine
What are the six drugs that mainly act upon the nervous system?
Anaesthetis Anxiolytics/hypnotics Neuromuscular blockers Anti Parkinson's Anti convulsants Anti depressant
Why use anaesthetics?
Promote: 1 analgesia 2 unconsciousness 3 amnesia 4 loss of reflexes
To much of it can lead to death
What are general anaesthetics?
Act mainly on the CNS
may be given via inhalation or IV
Person unconscious
How does anaesthetics work?
1 work in the CNS to promote insentivity
2 usually fat soluble and so can cross blood brain barrier
3 may act on the membrane receptors to reduce excitation of neurones
4 may affect ion channels
What are the typical side effects of anaesthetics?
Nausea/ vomiting Breathing shallow/rapid Decrease blood pressure/ CO Decrease kidney perfusion Loss of temperature control Crosses placenta
What are the two phases of anaesthesia?
Induction: usually IV
Maintenance: usually inhalation
What are the four stages of anaesthesia?
1- analgesia
2- excitement
3- surgical anaesthisia- skeletal muscle relaxation/ loss of reflexes
4- medullary paralysis- loss of respiratory/ VMC
What are the four types of general anaesthesia?
Gases
Barbiturates
Non-barbiturates
Volatile liquids
What is n20?
Nitric oxide- laughing gas
Used in maintaining anaesthesia with oxygen
Used in combination with other drugs
Potent analgesic
Low level long term exposure may damage foetus
Other inhaled general anaesthetics?
Isoflurane
desflurane
sevoflurane
How is anaesthetics controlled?
Death of anaesthesia is controlled by varying concentration of vapour
What are the side effects of anaesthesia?
CV depression
hypotension
Arrhythmia
Can decrease CSF pressure
What are the commonly used IV anaesthetics drugs?
1- Propofol: non-barbiturate, rapid action, rapid recovery without hang over, may cause convulsions/ anaphylaxis
- Thiopental (thiopentone): barbiturate, useful for brief procedures, rapid awakening, long lasting, sedation problems
What other drugs are used as general IV anaesthetics?
- Etomidate: no hangover effect, less hypotension, muscle movements, suppression of adrenocorticol function
- Ketamine: shocked patients, increased heart rate and blood pressure, hallucination during recovery
Name the 6 drugs used in surgery.
Bezodiapines: anxiolytics, hypnotics Neuroleptics and anti-emetics Analgesics usually opioids Antihistamines Anticholinergics (atropine, hyoscine)
What help ends when you increase the doses of benzodiapines?
Anxiety
Sedation
Hypnosis
Explain the use of benzodiapines.
Oral, IV, IM or rectal
I.e, midazolam- pre med. 20 mins before surgery, can be used in children
Temazepam, diazepam, prior to dental treatment
Doesn’t cause excessive sedation in low doses
Causes amnesia
No analgesic effect
Hypotension
Constipation
What is the mechanism of action for benzodiazepines?
It increases GABA in the brain at the post synaptic cell
What are disadvantages of benzodiapines?
Dependence
Respiratory depression
Interacts with alcohol
Crises the placenta
What does neuromuscular blocking drugs do?
They are muscle relaxants Block transmission in motor nerves Reduces the need for very deep anaesthesia Relaxes vocal cords, tracheal tube Requires assisted respiration Prolonged muscle paralysis/pain Histamine release--bronchospasm
What are AcH antagonists?
Non-depolarising blockers
They compete with AcH with nicotine content receptors at neuromuscular junction
I.e. atracurium-rapid, short acting.
Pancuronium- longer acting
