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29 Cards in this Set
- Front
- Back
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Action Potential
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Fired from the axon, propagated from axon hillock and down axon either along the whole membrane or at each node of Ranvier. The more frequent the action potential, the stronger/more intense the movement is.
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Potential
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Difference in + and – ions on either side of the membrane. Resting membrane potential is aprox – 70mV (reflects the charge inside the cell.)
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Threshold
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The point of no return: -55 mV. If the graded potentials bring the negativity down to -55 mV, then an action potential is fired and there’s no stopping it (in a regular circumstance).
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Action Potential Generation
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1) Resting Membrane is VERY negative. K+ and Na+ channels are closed. Imbalances are maintained by the ATPase pump. 3 Na+ are pumped out for every 2 K+ pumped in.
2)Threshold is reached if enough graded potentials allow enough Na+ in to bring the internal charge up to 55-. 3) All Na+ channels open and Na+ shoots in. Membrane potential shoots up to 30+ mV 4) Repolarization – Sodium channels close and potassium leaves the cell. 5) Hyperpolarization – Slowly, the K+ channels shut. The dip in charge (to lower than -55) results in a pause before another action potential can be fired. 6) Charge goes back up to -55, the resting state. In resting state the nerve is polarized. |
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Synaptic Transmission
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Synaptic Transmission
1) AP reaches axonal terminal 2) AP opens the Ca2+ channels and Ca2+ rushes in. 3) Ca2+ triggers the exocytosis of synaptic vesicles. 4) Neuron transmitters diffuse out across synaptic cleft and bind to receptors of postsynaptic membrane. 5) NT bind to receptors, causing a graded potential on post synaptic membrane. A graded potential leads to sodium being let in. If enough Na+ is let in, then an AP is fired. 6) After graded potential, the NT degrade and are reuptaken by the axon terminal. |
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2 Types of Graded Potentials...
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Na+ : Acts as an excitatory postsynaptic potential (EPSP), raises the likelihood that an AP will be fired.
K+: Acts as an inhibitory postsynaptic potential (IPSP), when K+ channels are opened, it lowers the likelihood that an AP will be fired by lowering the charge further. |
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Types of Neurotransmitters
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Types of Neurotransmitters:
- Dopamine: The “feel good/reward” NT. Fine-tunes motor movements. - Glutamate: Learning and memory. Involved in OCD and addiction. - Serotonin: Mood drug/regulation. Deficiency results in depression. Anti-depressants block reuptake. - GABA: Primary inhibitory NT, alcohol and Valium releases GABA. - Acetylcholine: In the brain, but also released onto skeletal muscles. Mediator of parasympathetic functions. - Norepinephrine: Feel good NT. Mediate of sympathetic actions |
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Graded Potential
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Occurs in the dendrites, short lived. Either increases or decreases the likelihood of an AP being fired.
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Absolute Refractory Period
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No stimulus can generate an AP
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Relative refractory Period
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A VERY strong stimulus can generate an AP
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Electrochemical Gradient
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A concentrations of ions on one side
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Drug tolerance
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If the axon terminal is over stimulated buy a drug, then the post-synaptic receptors down regulate in response.
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Cauda Equina
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The end of the spinal cord, a few trailing neurons come out the end.
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Spinal bifida
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If the vertebral discs are not completely closed.
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Phrenic Nerve
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Nerve from the cervical region that controls the diaphragm.
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Sciatic Nerve
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Nerve from the sacral region. Runs down leg.
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Vertebral Arch
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Consistent bone that surrounds the spinal cord minus the body
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Transverse Process
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The two sideways-branching out-juts on the vertebrae. There is one on each side of the Spinous Process
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Pedicle
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Part of vertebral arch.
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Lamina
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The flat disc part of the vertebral disc.
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Lumbar Puncture
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Done between L4 and L5.
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Intervetebral discs
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Discs cushion between vertebrae. Made from fibrocartilage.
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Dorsal Ramus
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Nerve branches out to serve sensory and motor functions for back and skin
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Ventral Ramus
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Nerve that branches out to serve sensory and motor functions of internal organs, ventral skin, and limbs. Forms complex nerve plexuses in cervical, brachial, lumbar, and sacral regions.
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Reflexes
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doesn’t require CNS processing and only involves 2-3 neurons.
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White Matter
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Bringing sensory input to brain.
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Number of Spinal Nerves
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31 pairs/ person.
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Dorsal Horn
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Location of CNS cell bodies for sensory neurons
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Ventral Horn
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Location of CNS bodies for motor neurons.
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