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Ch 17 CNS
Biology of Drugs
Term | Definition |
---|---|
Central Nervous System: What is it? | Physically: brain and spinal cord Functionally: autonomous, self-organizing, multi-level information processing and control system |
4 Major Cell Types | Neuron, Microglia, Oligodendrocytes, and Astrocytes |
Neuron | Primary information communication, synthesis, and storage cell |
Microglia | Specialized immune cells in the brain |
Oligodendrocytes | Provide insulation for fast electrical transmission |
Astrocytes | Support cells provide metabolic support, cleans up synapse, regulate blood flow, releases immune signaling, etc. |
Neurotransmitters are defined by: | 1) presynaptic presence 2) release initiated by calcium dependent depolarization 3) postsynaptic presence of a specific receptor |
Metabolic Receptors | When neurotransmitter binds it secondary messenger signaling is activated (ex. G-protein coupled receptor, receptor tyrosine kinase ) |
Ionotropic Receptors | When neurotransmitter binds it pore/channel is opened which permits the passage of certain ions. (ex. Na+,K+,Ca2+ and/or Cl-) (ex. NMDA, AMPA, and Kainate Receptor) |
Electric Cells: Diffusion Concentration Gradient is? | the process of particles (dye/ions) moving through a solution or gas from an area with a higher number of particles to an area with a lower number of those particles |
Electric Cells: pumps and channels | Neurons create gradients across the membrane using ion pumps/transporters and channels |
Action Potential 1 | Gradient and voltage is set by pumping out of the cell Na+ (3 ions) in K+(2 ions) |
Action Potential 2 | Neurotransmitter is released and binds opening ligand gated ion channels positively charged ions flow in the postsynaptic neuron |
Action Potential 3 | At an elevated voltage Voltage-gated sodium channels sodium flows in. Goes from -70 to -55. |
Action Potential 4 | At an more elevated voltage Voltage-gated potassium channels open potassium flows out |
Action potential propagation | Saltatory conduction uses myelination of the axon interrupted by nodes of Ranvier where the action potential is regenerated. |
Presynaptic Release 2 | An action potential invades the presynaptic terminal. |
Presynaptic Release 3 | Depolarization of presynaptic terminal causes opening of voltage-gated Ca2+ channels |
Presynaptic Release 4 | Influx of Ca2+ through channels |
Presynaptic Release 5 | Ca2+ causes vesicles to fuse with presynaptic membrane |
Presynaptic Release 6 | Transmitter is released into synaptic cleft via exoxytosis |
Neurotransmitter Reuptake | -Neurotransmitter is released from receptor -Neurotransmitter is taken up by glial and presynaptic neuron transporter -Neurotransmitter is either broken down or repackaged into vesicle |
The Neuron | Store and send info Receive and send signals primarily through chemical synapses (some populations also use electrical synapses) |
Astrocytes/Astroglia | -Provides metabolic support -Regulate blood flow -Remove neurotransmitters from the synapse -Buffers glutamate -Plays a role in mediating restorative properties sleep -Release inflammatory and anti-inflammatory cytokines |
Microglia | Resident macrophages of the brain (immune cells) -Detect damage and respond to inflammatory signaling -Prune synapses -Envelope dead/dying cells |
Oligodendrocytes | Insulating cells Wrap neuron axons in myelin (fatty) sheaths to permit fast transmission of electrical activity though the cells Myelinated tracts are known as ‘white matter’ in the brain |
Oligodendrocytes | One oligodendrocyte can extend processes to ~50 axons Myelination occurs throughout development and may not be finished until ~25-30 years of age in the frontal lobes |
Brainstem | Composed of the midbrain, pons, and medulla |
Cerebellum: What does it do? | -Fine movements -Balance -Coordination -Posture -Motor learning |
Hypothalamus | Important for maintaining homeostasis in the body **Example! Encounter antibodies Fever + sickness behavior |