CNS Flashcards
What are the 4 parts of the hypothalamus?
Caudal region (mammillary group) Intermediate region (tuberal group) Rostral region (chiasmatic group): supraoptic and preoptic regions
What is the difference between ionotropic and metabotropic neurotransmitter receptors?
Ionotropic: fast, ligand-gated, receptor is present on ion channel
Metabotropic: slower, G-protein coupled, receptor is separate from ion channel, sends G-protein or second messenger to different receptor on ion channel to make it open
What is the function of the caudal region of the hypothalamus?
Relay station for reflexes related to sense of smell
What is the definition of learning?
The acquisition of abilities or knowledge, a change in behaviour which occurs as a consequence of experience, instruction or both.
What is the definition of memory?
The storage of acquired knowledge or abilities for later recall
What are the 2 types of memory?
Declarative: specific facts, events and places often resulting from a single experience
Procedural: skilled motor movements gained through repetitive training/ how to do things
Where are short-term memories formed?
Hippocampus
Where are short-term memories consolidated to long-term memory?
Hippocampus
Where are long-term memories stored permanently?
Cerebral cortex
Where is accessing and manipulating of long-term memories carried out (through working memory)?
Prefrontal cortex of forebrain
Where are ‘how to’ procedural memories stored?
Cerebellum and relevant cortical regions
How long does short-term memory last?
Seconds to hours
How long does long-term memory last?
Days to years
What is the definition of a synapse?
Junction between neurones and other neurones, or between neurones and their effector cells
What is the definition of a neurotransmitter?
A chemical released by a synapse that diffuses from the pre-synaptic membrane to the post-synaptic membrane
Packed in vesicles
What are the 3 main types of neurotransmitter?
L-type : slow release, high threshold
T-type : transient (fast) release, low threshold
N-type : neither fast nor slow release
What is summation?
Many subthreshold synaptic inputs arriving simultaneously at a synapse to evoke a postsynaptic action potential
What are local anaesthetics used for?
Which fibres do they target?
Give some examples
Analgesia
Target pain fibres
Examples: Procaine, Lidocaine, Bupivacaine, Mepivacaine
What are opioids used for?
Give some examples
Analgesia and sedation
Morphine, codeine, butorphanol
What is a neuroleptanalgesic?
What is it comprised of?
What are its 3 uses?
A drug which causes sedation and profound analgesia
Neuroleptic and opioid
Pre-med, minor surgical procedures, restraint (large animals)
Why should you always wear gloves and use a rifle when administering etorphine as restraint?
Absorption through cuts or self-injection is fatal
What is the Lewis Triple Response?
A cutaneous response that occurs from firm stroking of the skin which produces an initial red line, followed by a flare around that line, then a wheal.
The Lewis Triple Response occurs due to the release of what chemical?
Histamine
What are polymodal receptors?
Receptors which pick up different types of pain
Where does decussation occur for:
Motor and touch
Pain
Motor and touch: at midbrain
Pain: around the spinal cord segment
Nociception only becomes pain when it reaches what?
Thalamus
Which are the fastest nerve fibres? What speeds do they operate at?
Which are the slowest (and what are their speeds)?
Fastest: A-alpha (72-120 m/s)
Slowest: C-fibres (0.4-2 m/s)
First order neurons synapse in which part of the grey matter of the spinal cord?
Substantia gelatinosa (lamina II)
What is meant by an antidromal impulse?
One in which conduction is opposite to that of the normal (orthodromic) direction
Where is the chemoreceptor trigger zone located?
4th ventricle of brain
When is benzodiazepine use contra-indicated?
Liver disease
Discuss diazepam’s mechanism, absorption, distribution, metabolism and elimination
Mechanism: GABA-A agonist
Absorption: IV
Distribution Binds to plasma proteins, also crosses BBB. Half-life=2hrs in dog, longer in cats and horses
Metabolism: First pass metabolism by cytochrome P450. Metabolites include oxazepam
Elimination: Dog=60% kidney
What is a side effect of using benzodiazepines as a sedative?
Respiratory depression
What is the definition of general anaesthesia?
The controlled, reversible loss of consciousness with reduced perception of external stimuli, and motor response to such stimuli (eg loss of consciousness with loss of pain)
Give some examples of inhalation anaesthetics
Nitrous oxide
Isoflurane
Halothane
Di-ethyl ether
Give some examples of intravenous anaesthetics
Barbiturates (not commonly used anymore)
Propofol
Alphaxolone
Ketamine
What 3 agents are included in a pre med?
Parasympathetic
Sedative
Analgesic
The speed of anaesthesia (rate at which concentration of anaesthetic in the brain rises) depends on what 2 things?
The solubility of the agent in the blood
Anaesthetic concentration in the inspired mixture
Which kinds of anaesthetics take longer to work: ones that are more or less blood soluble?
More blood soluble.
Therefore ones that are less blood soluble are more desirable (hit neurones and enter the brain more quickly)
Which is the quickest injectable route for anaesthesia?
Which is the slowest?
Quickest: Intravenous
Slowest: Subcutaneous