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10 Cards in this Set
- Front
- Back
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What is Saltatory Conduction? |
a.k.a. 'Jumping Conduction'; the action potential jumps from one node of Ranvier to the next. |
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What is a synapse? |
A very small gap between one neuron and the next. |
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What are neurotransmitters? Examples? |
Substances that diffuse across the synapse and attach to receptors on the membrane of the next neuron. eg. acetylcholine, noradrenaline, histamine, dopamine |
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Refractory Period |
The brief time after the action potential in which that part of the nerve fibre cannot be stimulated to respond again. |
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Stages of Action Potential |
1. Slow depolarisation of the membrane brings the potential to the threshold 2. Sodium channels in the membrane open; sodium ions flood into the cell; membrane becomes depolarised; membrane voltage rises. 3. Sodium channels close and membrane becomes repolarised. 4. Membrane returns to resting state. |
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Resting membrane potential |
-70mV |
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Where are K+ ions and Na+ ions found? |
K+: Intracellular fluid (higher concentration) Na+: Extracellular fluid (higher concentration) |
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Speed of Nerve impulse - Unmyelinated |
2m/s |
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Speed of Nerve impulse - Myelinated |
18m/s to 140m/s |
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Resting potential maintenance |
sodium gates are closed. membrane 50x more permeable to K+ causing them to leak out. Outside membrane now has an abundance of + charges compared to inside. The inside is - compared to outside - helped by proteins. sodium potassium pump pulls 2K+ ions for 3Na+ ions sent out. This further creates a charge difference. |
