Podcast
Questions and Answers
What is the minimum stimulus strength required to produce a response after an infinite duration known as?
Which statement about the rate of rise in stimulus intensity is correct?
How does the Strength-Duration Curve illustrate the relationship between stimulus strength and duration?
What is the primary reason electrical stimuli are preferred for stimulating nerves?
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What is the necessary condition for a stimulus to effectively cause an action potential?
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What is defined as the minimum stimulus strength needed to produce a response after a duration of 1 Time Constant?
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If a stimulus is applied too slowly, what will be the likely outcome?
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Which part of the nerve-stimulation process is critical for depolarization?
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How does the rate of rise of a stimulus influence its effect on nerve fibers?
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What membrane potential indicates that the inner side of the cell membrane is less than the outer side by 90 mV?
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Study Notes
Nerve Excitability
- Nerve excitability is the ability of a living cell to respond to a stimulus.
- Nerves and muscles are the most excitable tissues in the body.
- The membrane potential in these cells reaches 90 mV, with the inside being more negative than the outside.
Stimuli
- Nerves can be stimulated by various stimuli including electrical, mechanical, chemical, and thermal.
- Electrical stimuli are preferred because they are similar to the energy conducted by nerves, controllable, measurable, and don't damage tissue.
Stimulating a Nerve with Electric Stimuli
- Two electrodes are connected to a stimulator, one positive and one negative.
- The electrodes are placed on the nerve fiber.
- Current enters the nerve at the positive electrode and leaves at the negative electrode.
- The negative electrode (cathode) is crucial as it induces depolarization in the stimulation region.
Factors Affecting Nerve Stimuli
- Amplitude: A stimulus needs a certain intensity to be effective. A stronger stimulus creates a larger signal.
- Duration: An effective stimulus must be applied for a certain duration to trigger an action potential.
- Rate of rise: A rapidly rising stimulus has a greater effect.
Strength of Stimuli
- Higher intensity stimuli produce larger responses.
Factors Affecting Effectiveness of Stimulus
- Amplitude (strength): A stimulus needs a certain intensity to generate a nerve impulse.
- Duration of application: An effective stimulus needs to be applied for a certain period.
- Rate of rise in stimulus intensity: A rapidly increased stimulus intensity reaches the threshold value quickly, triggering an action potential. A slowly increased intensity may not trigger a response because the nerve adapts.
Strength - Duration Curve
- There's a close relationship between stimulus strength and the duration required to elicit a response.
- The Strength-Duration Curve plots stimulus strength (y-axis) against stimulus duration (x-axis).
- Rheobase: The minimum stimulus strength needed to elicit a response after an infinite duration.
- Chronaxie: The minimum stimulus strength needed to elicit a response after a duration of 1 Time Constant.
- Utilization Time: The time required to achieve a given stimulus strength.
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Description
Test your knowledge on nerve excitability, the types of stimuli that affect nerve response, and the mechanisms involved in stimulating nerves with electrical signals. Explore how factors like amplitude influence nerve function and understand the roles of different electrodes in nerve stimulation.
