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30 Cards in this Set
- Front
- Back
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General Anaesthetics cause...
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descending depression of the CNS
decreased awareness and response to pain |
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toxic effect of general anaesthetics
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depress blood pressure and respiration
liver / kidney damage |
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how awareness and response to pain is reduced by general anesthetics
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loss of consciousness
suppression of skeletal muscle reflexes and tone |
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ideal characteristics of a general anesthetic
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quick induction (low blood solubility), high potency (high lipid solubility), reversibility, good analgesia, amnesia, no hangover, lower / harmless metabolism, non-flammability, muscle relaxation, low toxicity
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why are combinations of several agents used as general aesthetics?
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because not one agent has all the ideal characteristics
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describe volatile/ gaseous anaesthetics
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simple, unreactive compounds, with numerous, small molecules
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Halothane
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volatile / gaseous general anaesthetic
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Nitrous Oxide
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laughing gas, volatile anaesthetic
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two types of general anaesthetic
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volatile / gaseous
intravenous |
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intravenous agents
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through injection
very rapid with short duration repeat dose for longer analgesia induction processes, short procedures |
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examples of IV agents
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1) Thiopentane
2) ketamine (barbituates) |
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thiopentane
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low TI
depress heart and respiration; medullary collapse |
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ketamine
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horse tranquiliser
dissociative amnesia barbituate, IV agent |
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mechanisms of anaesthetics
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1) synaptic transmission
2) reticular formation 3) Thalamus 4) hippocampus 5) lipid solubility |
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reticular formation causes...
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analgesia, unconsciousness
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thalamus causes...
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analgesia
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hippocampus causes...
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amnesia, unconsciousness
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lipid solubility
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interacts with hydrophobic structures
volume expansion of membranes protein binding |
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opening of chloride channels is encourages by?
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receptors e.g. GABA
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opening of chloride channels causes..
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Cl- entry into neurone
hyper polarisation inhibition (no Action Potential) |
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general anaesthetics do what to the opening of chloride channels?
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enhance it
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premedication drugs used in surgery
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hyosine, morphine, lignocaine, tubocurarine, soxamethonium
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muscle relaxants
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tubocurarine
soxamethonium interfere with muscarinic and nicotinic receptors |
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hyosine
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muscarinic receptor antagonist
dries up saliva secretions and bronchal mucus |
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morphine
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opiate analgesic
prevents post op pain |
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lignocaine
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local anaesthetic
blocks conduction in sensory nerves |
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muscarinic receptors affect:
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smooth gut muscle
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nicotinic receptors affect:
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Ach, skeletal muscle
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Tubocurarine
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non depolarising
competes with Ach long lasting reversible with ChE inhibitor |
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Soxamethonium
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depolarising
cation channels stay open short acting not reversible with ChE inhibitor |
