Flashcards
Action Potentials
Flashcards do conjunto (26)
- 1Action potentials are produced whenthe membrane depolarises in excitable cells.
- 2Positive feedback is switched off when the membrane voltage reaches what level?+30mv
- 3Only when the stimulus strength is at a certain level is an action potential generated. This level is called the?Threshold.
- 4The threshold voltage is-55mv.
- 5Once APs are generated they are always of the same size, even though the stimulus strength might increase. This is...The all or none law of action potentials.
- 6Action potentials can code?information
- 7Information is coded by sequences or trains of APs. Information can be coded in the ....frequency of APs
the duration of the AP train - 8Only when two stimuli are separated by a sufficient time interval will a.....AP be generated after the first.second
- 9The time interval is about10 milliseconds.
- 10This period is known as theRefractory period.
- 11Action potentials move from one end of the nerve axon to the other. This is called....Propagation
- 12In some nerves the axon is surrounded by a sheath of fatty material called...Myelin
- 13Myelin is produced bySchwann cells
- 14Myelin acts as anelectrical insulator.
- 15The myelin sheath is interrupted by gaps called the ....nodes of ranvier.
- 16Action potentials are therefore ONLY generated at the ......in a myelinated nerve.nodes of ranvier
- 17Aps appear to jump from one node to the next. This is known asSaltatory conduction.
- 18The larger the diameter of the nerve axon....the faster the conduction velocity.
- 19The fastest nerves arelarge diameter, myelinated nerves. Up to 100m/sec.
- 20The slowest nerves aresmall diameter, non-myelinated nerves.0.5-2m/sec
- 21What happens when the AP reaches the axon terminals?AP depolarises the terminal region.
Causes small vesicles in the terminal to fuse with the terminal membrane.
These vesicles contain neurotransmitters. - 22Examples of neurotransmitters?Noradrenaline.
acetylcholine.
dopamine
histamine
5-hydroxytryptamine - 23A nerve junction is called asynapse.
- 24A muscle junction is called aneuromuscular junction.
- 25Absolute refractory periodCannot generate an AP no matter how big the stimulus is.
- 26Relative refractory periodAP can be generated but only if a bigger stimulus is used.
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- University Pod Year 1 FlashCards sobre Action Potentials, criado por Morgan Morgan em 01-01-2014.
- Criado por
- Morgan Morgan
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