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Neuromuscular Physiology
Published in Michael H. Stone, Timothy J. Suchomel, W. Guy Hornsby, John P. Wagle, Aaron J. Cunanan, Strength and Conditioning in Sports, 2023
Michael H. Stone, Timothy J. Suchomel, W. Guy Hornsby, John P. Wagle, Aaron J. Cunanan
Several stimuli, including extreme temperature changes and chemical, mechanical, and electrical stimuli, can cause an excitable membrane to depolarize. A wave of depolarization that occurs along the surface of excitable tissue such as muscle and nerve is termed an AP. The AP is a result of sequential alterations in the membrane potential lasting a fraction of a second. Depolarization of an excitable membrane, such as the neurolemma or sarcolemma, is followed by a rapid return to RMP values. Rapid alterations in membrane permeability for Na+ and K+ are associated with the AP. Alterations in membrane permeability for various ions can be quite rapid and these rapid movements are associated with the opening and closing of ionic gates (channels). These gates, along with electrogenic pumps such as the Na+ / K+ pump, largely control the movement of specific ions across the plasmalemma (13, 33, 108, 125, 127).
Muscle and Nerve Histology
Published in Maher Kurdi, Neuromuscular Pathology Made Easy, 2021
The sarcolemma consists of an inner plasma membrane (plasmalemma) and outer membrane (external basal lamina). The plasmalemma is an excitable membrane composed of a lipid bilayer and a variety of ion channels and proteins present on the cytoskeleton. Some of these sarcolemmal proteins are summarized in Table. 1.1 and Figure 1.3.
Generation of the Action Potential
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
In practice, Rm is not constant, as the membrane voltage rises toward threshold because of the nonlinear behavior of an excitable membrane noted earlier. Moreover, Vthr is not a constant voltage, as explained previously. As TD increases, potassium activation and sodium inactivation would have more time to exercise their effects, which increases Vthr. This would require a larger imp to generate an AP than if Vthr remained constant (Equation 3.22). The actual strength-duration relationship would then be “flatter” than is given by Equation 3.22.
Neuroscience for the mental health clinician
Published in Neuropsychological Rehabilitation, 2019
The book is aimed by and large at psychiatrists, but I think it will be helpful to any clinician interested in neuroscience, and to any neurorehabilitation clinician who feels uncomfortable by a lack of a good grounding in how the brain works. The book does not expect too much prior knowledge. The early chapters, for example on neuroanatomy, neurotransmission or genetics, start at the beginning. If you want to be reminded of some of the basic principles of the function of the nervous system then you will find it here, written in language that is plain speaking and easily understood. For example, the workings of the excitable membrane, why neurons have a potential gradient and what happens during an action potential, are clearly described in a few brief pages. And this is followed by brief descriptions of messenger systems within the cell and more detailed discussion of neurotransmitters and their receptors.