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Drugs that act in the CNS and are important tools for studying CNS Pharmacology
- TTX tetrodotoxin
- Strychnine
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Pineal Body
circadian rhythm regulation
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Hypothalamus
neuro endocrine regulation
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Cerebral Cortex
- integrates sensory and motor activity
- thought, memory and consciousness
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Limbic system
integrates emotional state with motor coordination
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4 parts of the limbic system
- basal ganglia
- hippocampus
- thalamus
- hypothalamus
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Basal ganglia
forms extrapyramidal motor system
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Hippocampus
incorporates recent memory
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Hypothalamus
- integrates autonomic nercous system
- body temp, blood pressure, water balance...
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Pyramidal system
- controlled by pyramidal neurons
- located in outer cerebral cortex in motor strip
- move limbs according to thought
- voluntary movement
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extrapyramidal system
- located in deep brain structures
- controlls tone & posture
- involuntary
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Brain stem
- contains nuclei of cranial nerves
- major mono-amine containing neurons
- coordinates essential reflexes (swallowing, vomiting, respiration)
- contains reticular activating system and chemoreceptor trigger zone
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Reticular activating system
- located in brain stem
- regulates sleep/wake
- eye movements
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Chemoreceptor Trigger Zone
- in the brain stem
- responds to drugs and causes emesis
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Cerebellum
- body posture in space
- visceral function
- learning and memory
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Spinal cord
- motor neurons
- sensory relay cells
- convey signals between brain and periphery
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Hierarchical neronal system
- directly involved in sensory perception and motor control
- large mylenated fibers
- fast conduction
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Hierarchical neuronal system contains 2 types of neurons:
- relay/projection: excitatory/glutamate
- local circuit: inhibitory/GABA or glycine
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Diffuse or nonspecific neuronal system
- monoamine or peptide containing pathway
- unmylenated axons, slow conduction
- non-specific information
- sleep/wake, attention, appetite & emotion
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Classifications of neurons
- Function
- location
- neurotransmitter
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Feed Forward
Separate neuron inhibits
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Recurrent interaction
- excitatory neuron synapse on inhibitory neuron when inhibits the same excitatory neuron
- Circle system
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Ionotropic receptors
- fast SN
- hierarchical pathway
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Metabotropic receptor
- diffuse neuronal system
- slow
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3 criteria of neurotransmitters
- localization in presynaptic terminals
- released with presynaptic activity
- synaptic mimicry when applied to target cells
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GABA A
- CL- channels
- agonist is muscimol
- antagonist is picrotoxin and bicuculine
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GABA B
- GPCR
- Agonist: baclofen
- Antagonist: 2-OH-saclofen
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Glutamate ionotropic receptor
- excitatory
- NMDA
- Kainate
- AMPA
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Metabotropic glutamate receptors
excitatory and inhibitory
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glycine receptors
- inhibitory
- agonist : taurine, beta-alanine
- antagonist: strychnine
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Acetylcholine system
- sleep/wake
- learning & memory
- deficiency = alzheimers
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Dopamine system
- deficiency = parkinsons
- reward system
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Norepinephrine system
- attention
- sleep/wake
- learning & memory
- anxiety & pain
- mood & metabolism
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Serotonin system
- Raphe nuclei
- sleep/wake & stages of sleep
- mood/emotions
- ascending reticular activating system
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Features of peptide neurotransmitters
- act in concert with co-existing transmitter
- some neurons contain more than two peptide transmitters
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4 ways peptide neurotransmitters differ from monoamine and amino acid transmitters
- translated from mRNA in the ER
- synthesized in the precursor
- transported to the terminals from the perinuclear cytoplasm
- no active reuptake mechanisms
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General or non-specific CNS depressants
- General anesthetics
- some sedative hypnotics
- alcohol
- local anesthetics if applied systemically
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General or non-specific CNS stimulants
- analeptics
- methylxanthines
- amphetamines
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Exampels of analeptics
- strychnine
- pentylenetetrazol
- picrotoxin
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examples of methylxanthines
caffeine
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Selective CNS stimulants and depressants
- anticonvulsants
- anti PD
- opiates
- non-opiate and antipyretics
- muscle relaxers
- anxiolitic/antipsychotics
- antidepressants/anti-manics
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