Physiology Of Nerve By Dr. Ehab Shokry

The Axillary nerve is a part of the peripheral nervous system (PNS). It is responsible for innervating the deltoid muscle and the teres minor muscle in the shoulder. It also provides sensory information from the shoulder joint. The Cerebrum and Cerebellum are both part of the central nervous system (CNS) and not the PNS. The Spinal cord is also part of the CNS, although it does have connections to the PNS through spinal nerves. Therefore, the correct answer is the Axillary nerve.

The correct answer is "All of the above" because the question asks for the types of junctions, and all three options listed (Synapse, MEP, Neuro-epithelial) are different types of junctions. Therefore, all of these options are correct and can be considered as types of junctions.

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The correct answer is "Polarized state." In a polarized state, there is a difference in electrical charge between the inside and outside of a cell membrane. This difference in charge is maintained by the active transport of ions across the membrane, creating an electrical potential. This polarized state is necessary for the generation of an action potential, which is a rapid change in electrical potential that allows for the transmission of signals in the nervous system.

All of the above options contribute to energy consumption at the neural level. During the action potential, energy is required for the propagation of the electrical signal along the neuron. During repolarization, energy is needed to restore the ion concentration gradients across the cell membrane. Even during the polarized state, when the neuron is at rest, energy is still consumed to maintain the ion gradients and to support various cellular processes. Therefore, all of these states require energy consumption at the neural level.

Excitable tissue contracts by electrical changes because it is made up of cells that have the ability to generate and transmit electrical impulses. These electrical changes occur when ions move across the cell membrane, causing a change in the membrane potential. This change in electrical potential triggers the contraction of the excitable tissue, allowing it to respond to stimuli.

The supernormal phase occurs when the threshold for excitation is decreased. This means that it takes less stimulation for a neuron to reach its firing threshold and generate an action potential. As a result, the neuron becomes more excitable and is able to fire more easily. This can lead to an increase in the frequency of action potentials and a prolonged period of excitability.

The Chronaxie is the time needed for the excitation of the nerve. It refers to the minimum duration of an electric stimulus required to generate an action potential in a nerve fiber. This means that it is the time needed for the nerve to reach its threshold and initiate an impulse. The contraction of the muscle and conduction of the impulse are not directly related to the Chronaxie, as they involve different processes and timeframes. Therefore, the correct answer is "Excitation of the nerve".

Alkalosis is a condition characterized by an increase in the pH levels of the blood, making it more alkaline. This disrupts the balance of electrolytes in the body, leading to various symptoms. Convulsions refer to involuntary muscle contractions and spasms, which can be a result of alkalosis. When the pH levels are too high, it can affect the normal functioning of the nervous system, leading to convulsions. Therefore, convulsions can be caused by alkalosis.

The given answer suggests that the action potential is caused by temporal summation. Temporal summation refers to the accumulation of small, sub-threshold stimuli over time, which can eventually reach the threshold required for an action potential to be generated. This process involves the integration of multiple inputs from different synapses or neurons, leading to the depolarization of the neuron's membrane and the initiation of an action potential. Therefore, the correct answer implies that temporal summation plays a crucial role in generating action potentials.

The correct answer is "Is 10 times the initial one." This suggests that the delayed amount of heat is 10 times greater than the initial amount. This could be due to various factors such as increased energy input, accumulation of heat over time, or a specific reaction that occurs after the initial heat is generated. Without further context, it is difficult to determine the exact reason for this increase in heat.

The answer "None of the above" is correct because the question is asking about the cause of the polarized state, and none of the options provided (K outflux, Na influx, Na-K pump) directly explain the cause of polarization. The polarized state is typically caused by the unequal distribution of ions across the cell membrane, with more positive ions outside the cell and more negative ions inside. This imbalance creates an electrical potential difference, resulting in the polarized state.

The slow outflux of K ions after depolarization is the cause of repolarization. During depolarization, the membrane potential becomes more positive, and this is mainly due to the influx of Na ions. After depolarization, the slow outflux of K ions helps to restore the membrane potential back to its resting state by making the inside of the cell more negative again. This process is known as repolarization and is crucial for the proper functioning of nerve cells and muscle cells. After hyperpolarization refers to a further decrease in membrane potential below the resting state, which is not directly related to the slow outflux of K ions after depolarization.