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Behavioral Neuro
Ch 2
| Term | Functions |
|---|---|
| Astrocytes | Physical support for neurons (act as nerve glue) |
| Astrocytes | Regulate neuron firing |
| Astrocytes | Clean up debris |
| Astrocytes | Control Fluid composition |
| Astrocytes | Phagocytosis |
| Astrocytes | Provide nourishment |
| Oligodendrocytes | Physical support |
| Oligodendrocytes | Produce myelin for CNS |
| Schwan cells | Myelinate cells in the PNS |
| Microglia | Represent the immune system in the brain |
| Radial glia | |
| Blood Brain Barrier | Semi-permeable barrier between the CNS and circulatory system. |
| Blood Brain Barrier | Helps to regulate flow of nutrient rich fluid into the brain. |
| inhibitory neuron | decreases the activity of a motor neuron |
| membrane potential | an difference in charge across the membrane (+ or -) |
| resting potential | membrane potential remainss at approximately -70 V |
| hyperpolarized | when the inside of the axon becomes more negative relative to the outside |
| depolarized | axon becomes more positive |
| threshold of exitation | set point for depolarization to trigger the main electrical event |
| action potential | main electrical event in an axon |
| electrical charge | balance between two opposing forces: diffusion and electrostatic pressure |
| diffusion | process whereby molecules distribute themselves evenly throughout the medium in which they are disolved |
| electrolytes | when some substances are dissolved in water they split into two parts, each with opposing electrical charge |
| ions | charged particles that electrolytes decompose into |
| ions | Cations(+) and anions(-) |
| electrostatic pressure | force exerted by the attraction or repulsion of ions |
| ions in extracellular and intracellular fluid | (A-) organic anions (Cl-) chloride ions (Na+) sodium ions (K+) potassium ions |
| extracellular fluid ion | (Cl-) chloride ions (Na+) sodium ions (A-) organic ions |
| intracellular fluid | (K+) potassium |
| what charge attracts (Na+) sodium ions into the cell | the negative charge inside does not prevent positively charged particles from entering the cell |
| Sodium-potassium pump | Large number of protein molecules embedded in the membrane, driven by energy provided by molecules of ATP produced by the mitochondria. Continuously pushes Na+ out of the axon. |
| ATP molecules | sodium-potassium transporters. Pushing three sodium ions out for every two potassium ions they push in. |
| Sodium-potassium pump | uses up to 40% of a neuron's metabolic resources |
| ion channels | contain passages (pores) that can open or close. This is allowed by a protein molecule which provides an opening that permits ions to enter or leave cells |
| voltage-dependent ion channels | Only opened by changes in the membrane potential. Must reach action potential or threshold of excitation before the sodium can rush in propelled by the forces of diffusion and electrostatic pressure. |
| voltage-dependent potassium channels | require a greater level of depolarization before they open and they begin to open later than sodium channels. Because inside is + charged K+ is driven out of the cell by diffusion and by electrostatic pressure. |
| Steps for action potential | 1. threshold of exitation is reached and depolarization occurs where sodium is allowed through membrane. |
| Steps for action potential | 2. Potassium channels open after sodium and require a greater level of depolarization. |
| Steps for action potential | 3. sodium channels become refractory and will not open again until the membrane once more reaches resting potential. |
| Steps for action potential | 4. voltage dependent potassium channels open and and it moves potassium out moving membrane toward resting potential |
| Steps for action potential | 5. sodium channels reset so that another depolarization can happen again |
| Steps for action potential | 6. Membrane actually overshoots its resting value (-70 m V) and only gradually returns to normal as the potassium channels finally close. |
| Conduction of the action potential | the movement of the message down the axon |
| all-or-none law | the law states that an action potential either occurs or does not occur, and , once triggered, it is transmitted down the axon to its end. |
| Action potential | Always remains the same size. Does not grow or diminish. |
| rate law | principle that variations in the intensity of the stimulus or other information being transmitted in an axon are represented by variations in the rate at which the axon fires. The rate of fire changes not the intensity of a single fire. |
| nodes of Ranvier | naked axon segments (non-myelinated) |
| decremental conduction | The disturbance gets smaller as it passes down the axon, but it is still large enough to trigger a new actions potential at the next node. |
| saltatory conduction | transmission of message, hopping from node to node |
| advantages of saltatory conduction | economic-Myelinated axons expend less energy to maintain their sodium balance. speed- myelinated axons transmit faster due to conduction action potential. |
| Blood Brain Barrier/ area postrema | BBB is weaker to permit neurons in the area to detect toxic substances |
Created by:
Dalea
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