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Neurobiology Test 2
| Question | Answer |
|---|---|
| Presynaptic | cell before the synapse |
| Postsynaptic | after synapse |
| synaptic cleft | space between cells in chemical synapses |
| gap junctions | connections between two cells in electrical symnapses |
| connexons | Gap junctions are formed by these proteins |
| Chemical synapses | most neuron-neuron; all neuron-muscle |
| Otto Lowei (1926) | tested the idea that cells communicate by releasing chemicals; experimented on the vagus nerve through the frog heart. |
| Chemical Response (1-5) | 1. Neurotransmitter synthesized and packed into vesicles in the terminal. 2. Action potential through synaptic bouton. 3. Presynaptic terminal depolarized; opens Voltage gated channels. 4. Ca2+ influx. 5. Ca2+ helps vesicles fuse w/membrane. |
| Chemical Response (6-10) | 6. Neurotransmitter released. 7. Diffuses across cleft and bind to receptor proteins in PostSyn. 8. Binding leads to channels opening. 9. Resting membrane poten. changes as ions move. 10. NT removed or inactivated from cleft. 11. Vesicle membrane recycled |
| Neurotransmitter | 1. Must be present w/in the presynaptic neuron. 2. Must be released in response to presynaptic depolarization and the release must be calcium dependent. 3. Must bind to specific receptors on the postsynaptic cell. |
| Examples of Neurotransmitters | Acetylcholine, Serotonin, Dopamine, Substance P. |
| ACh binds to AChR | AChR is activated and becomes an open channel. K+ out and Na+ influx. Depolarization in post synaptic cell (causes muscle contraction). |
| Acetylcholinesterase (AChE) | The enzyme that recycles ACh and allows the receptors to close |
| Miniature Endplate Potentials (MEPPs) | Falt & Katz. Caused by random calcium causing a few vesicles to fuse and stimulate the channels to open. Proves vesicle size is uniform at 1 mV--quantal release (packet release) |
| Endplate potential | another term for an action potential that is exclusive to neuron and muscle interaction |
| Quantal release | the release of neurotransmitters in packets |
| Neurotoxins | chemicals that negatively impact the ability of neurotransmitters or the neural system, i.e. EDTA, Botulinum, black widow spider venom, bungarotoxin |
| Calcium Influx blockers (vesicle fusion and ACh release) | EDTA (binds calcium), Ca Ionophores (create artificial calcium channels) |
| Vesicle Fusion (Dockin and exocytosis) | botulinum prevents docking, black widow spider venom causes all vesicles to dock and release |
| Block AChR | bungarotoxin (binds to the site), Curare |
| Block AChE | atropine gives a longer last muscle response, belladona |
| Compound action potential | summation of many cells (recording from many nerves) |
| End plate current (EPC) | the measure of ion flow across the membrane, inward flow of sodium down, outward flow of potassium up |
| EPSP (excitatory post synaptic potential) | takes cells closer to threshold (all EPP in muscle cells) |
| IPSP (inhibitory post synaptic potential) | keeps cells from reaching threshold by opening channels to bring - ions (chloride) in |
| Muscle cells | always excitatory, always have one input |
| Temporal summation | time (closer) and it builds |
| Spatial summation | potentials originating in differing parts of the cell build on one another |
| plasticity | changeability, amenability |
| Facilitation | an increase in the second post-synaptic response (PSP) after closely spaced stimuli due to prolonged calcium levels in the pre-synaptic cell |
| Postsynpatic depression | due to an absence of neurotransmitter vesicles in the presynaptic cell |
| Potentiation | tetanic stimulus/tetany and post-tetanic response |
| Tetanic stimulus/tetany | rapid stimuli that cause tatanic responses/hyper-responses that are together |
| Post-tetanic potentiation | the increased EPSP following a distance of time after tetany |
| Habituation | when a response to a repeated stimulus decreases (ex. gill contraction and siphon in Aplysia) |
| sensitization | generalization of one stimulus to another stimulus |
| Why sensitization (short term) happens | 1. Interneuron releases serotonin. 2. Serotonin binds to receptors on sensory terminal. 3. Internal signal transduction pathway. 4. Presynaptic K+ channels get phosphorylated and it closes them |
| Long term sensitization | Action of CREB |
| sensory information processing | 1. Environmental stimulus (light, sound, touch, pressure, heat, pain, etc). 2. Sensory transduction changes signal from one energy to electrical. 3. Intensity coding. 4. Sensory analysis. 5. Sensorimotor integration. (6) Motor output |
| Afferent | towards the CNS (sensory) |
| Efferent | away from the CNS (motor) |
| Sensory system | 1. Peripheral receptors. 2. Sensory neurons. 3. Dorsal root ganglia. 4. Spinal cord. 5. [Brainstem]. 6. Thalamus. 7. Cerebral cortex. |
| Grey matter | where cell bodies are located |
| white matter | where neurons/axons are located |
| How to determine stimulus intensity | Stimulus intensity is either positively or negatively correlated to the frequency |
| Stimulation function | stimulation generates a receptor potential--channels are opened--excitation occurs and depolarization of sensory cell--can become an action potential--mechanical to electrical/chemical |
| sensation | the ability to transduce, encode, and perceive information generated by internal and external stimuli |
| mechanoreceptors | afferent fibers encapsulated by special receptor cells- generally with lower threshold and a higher sensitivity to stimulation |
| free nerve endings | afferent fibers that lack specialized receptor cells |
| Afferents differ in: | axon diameter, temporal dynamics, and receptive fields |
| two-point discrimination | the minimum inter-stimulus distance required to perceive two distinct stimuli |
| Rapidly adapting | response lessons or stops after repeated stimulation - useful for perceiving changes in stimulus |
| slowly adapting | useful for providing spatial attributes of the stimulus such as size and shape |
| Nociceptors | pain receptors--unmyelinated or slow |
| Parallel pathways | differing somatic responses to the same stimuli |
| Haptics | active touching--involves complex spatiotemporal pattern interpretation |
| Stereognosis | being able to identify an object based on manipulation |
| Merkel cell afferents | slow adapting fibers, 25% of afferents in hand, create ridges that form fingerprints, adept at points edges and curvature, differentiate ~0.5mm |
| Meissnerr afferents | rapid, even more dense ~40%. Adept at grip and vibrations. |
| Pacinian corpuscles | rapid, 10-15%, 10 nm perception displacement, huge range, detect movements using tools |
| Ruffini | slowly adapting fibers, 20%, recognize finger stretches |
| Proprioception | sense of self in space. |
| muscle spindles | 4-8 special intra-fusal muscle fibers found in connective tissue--recognize changes in muscle length |
| Golgi tendon organs | composed of extrafusal muscle fibers, detect tension in muscles |
| joint receptors | similar to skin receptors, not used for proprioception, but used for positioning of fingers |
| Dorsal column | the area of white matter in the spinal cord that takes in a majority of the sensory information |
| Lateral inhibition | the capacity of an excited neuron to reduce the activity of its neighbor |
| thermoreceptors | detect changes in temperature (specifically, heat and lack of heat) |
Created by:
berge
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