Action potential frequency in phasic receptors with a prolonged stimulus..... action potential frequency in tonic receptors with a prolonged stimulus. greater than less than equal to
Action potential frequency in phasic receptors with a prolonged stimulus..... action potential frequency in tonic receptors with a prolonged stimulus.
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The nervous system in the human body is responsible for controlling all the body parts through transmission of nerve impulses. The specialized cells which make up the nervous system are the neurons and the glial cell. The neurons have a special ability to get excited via acting potential. In human physiology, the phenomena of action potential refers to the rapid changes in the membrane potential. In action potential, the membrane potential and thus the voltage across the cell rises and falls very rapidly. The cell to cell communication between the neurons is achieved by the action potential. The glial cells provide nutrition to nerves and are responsible for formation of myelin sheath around axons which acts as an insulator during electrical nerve signal transmission.
The neurons, based on their functions, can be classified into three categories: afferent or sensory neurons which convey information from tissues and organs into the central nervous system; efferent or motor neurons which transmit signals from the central nervous system to the effector cells; and interneurons which connect neurons within the central nervous system.
The sensory receptors are receptors which intercept the stimulus in the form of sensations such as heat, smell or vibrations. Some of these sensory receptors are neurons directly attached to the neurons and generate the nerve impulse on receiving stimuli. Whereas some of the sensory receptors send the signals to the nearby neurons upon receiving a stimulus to initiate the reflex. The sensory neuron upon receiving the signals from the sensory receptor generates the nerve signals by action potential. The action potential causes a rapid rise and fall in the neuron’s resting membrane potential therefore generating electrical signals. The generated signals are carried to the spinal cord by the neurotransmitters.
Based on the rate at which they adapt the stimulus, sensory receptors can be categorized as tonic or phasic receptors.
- Tonic receptors: These are the sensory receptors which adapt slowly to a stimulus. Since they are slow adapting receptors, they respond as long as the stimulus persists. Therefore, these receptors continue to produce action potential over the duration of stimulus. These receptors convey information about the stimulus duration.Since the action potential frequency in tonic receptors with a prolonged stimulus is continuous, these receptors are permanently active. The examples of such receptors include pain receptors and muscle spindle.
- Phasic receptors: These are the sensory receptors which adapt rapidly to a stimulus. These receptors respond quickly to the stimulus. However, the response generated diminishes very quickly and stops upon continual stimulations. As a result, action potential frequency decreases during prolonged stimulation. Such receptors convey information about intensity and rate of stimulus. The example of such receptors include the pacinian corpuscle.
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