We hypothesized that the Nernst-derived equilibrium potential of potassium cannot sufficiently predict the membrane potential. In the experiment however our hypothesis was incorrect, we found no significant between the Nernst-derived equilibrium potential of potassium and the observed membrane voltage within crayfish tail muscle at extracellular potassium concentrations of 10mM, 20mM and 40mM. What this finding tells us is that our manipulation of altering the extracellular potassium concentration cannot be said to have changed the observed membrane voltage. We might begin to reason why the Nernst-derived equilibrium potential for potassium did not predict the membrane voltage at other potassium concentrations by referring to
Figure 2. In Figure 2. we can
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Referring to Figure 2., also notice that the average observed membrane voltage in the DEM muscle group at 80mM and 100mM seems to even lower than the observed membrane voltage across all muscle groups (Class AVG Vm). Referring to Figure 16. in (Baierlein et al. 2011), it is clear that the DEM muscle group is quite larger than its DEL1 or DEL2 counterparts. Perhaps if we assume that cells that make up the DEM fibers are larger (with a smaller Surface Area to
Volume ratio) than those that make up DEL1 and DEL2, we may be able to reason that diffusion is less effective in large DEM muscle cells. Thus, the affect of this membrane leakiness may be stunted in DEM.
(Continue driving forces at elevated extracellular K+, GHK model, Ek (K+ closer to the resting membrane voltage than perhaps other ions -> Ek for other ions using Nernst at values given at 5.4mM) ?
(Katz shows major hyperpolarization with no extracellular potassium concentration and depolarization with increasing extracellular potassium concentrations) (they think of
[8.3] In what ways do you think your results would have been different if you had sampled at a different height on the rock?
Last segment in data collection was to analyze the effects of direct electrical stimulation. The hook electrode was disconnected and two electrode needles were inserted about five mm from each end of the gastrocnemius muscle. Starting at the maximum voltage from the first experiment, voltage was slowly increased until a twitch appeared. Then voltage was set ten times the maximum voltage from the first experiment. For both experiments, data were collected for thirty
...e progression. In DMD the muscle fibres are continuously damaged when the muscles contract. This causes inflammation which further damages the muscles leading to muscle wasting and the accumulation of scar tissue (‘fibrosis’). Drugs are being researched that could improve the ability of the body to repair damaged muscle, suppress inflammation and inhibit scar tissue formation.
Muscle fibers are cylindrical. They have a diameter around ten to one hundred micrometers and are generally a few centimeters long. Within each muscle cells, contains basal lamina of collagen and glycoproteins. Each fiber contains a structure called excitation-contraction coupling, which is used to make sure the each contractile stimulus is quickly and equally communicated throughout the muscle fiber.
...otassium is decreased and the intracellular concentration increases. The permeability of the apical membrane increases and potassium crosses through the potassium channels with ease. Potassium excretion is increased and plasma concentration of potassium is decreased. [5]
James’s biopsy of his right gastrocnemius muscle would have shown a degeneration of the muscle or skeletal fibers due to the lack of dystrophyn. Another microscopic change that would be noticed is the accumulation of white blood cells. White blood cells have a very specific function which is to clear the damaged muscle fibers from the debris. Clearly, due to some of the muscle fibers being damaged other healthy fibers that have not been damaged appear denser. By having damaged muscle fibers, all the work rest upon the healthy fibers making them contract to the fullest due to the fact that the myosin and acting would have to overlap even more to make the muscle work.
VanPutte, C., Regan, J., & Russo, A. (2014). Seeley's anatomy & physiology(10th ed.). NEW YORK, NY: MCGRAW-HILL.
Simon, E. J., Reece, J. B., Dickey, J. L. (02/2012). Campbell Essential Biology with Physiology, 4th Edition [VitalSource Bookshelf version 6.2]. Retrieved from http://online.vitalsource.com/books/9781256902089
The procedure for this lab was separated into two sections, one pertaining to the muscle activities and other for nerve activities. In the muscle section, data was acquired through the use of iWorx TA unit in conjunction with LabScribe 3 software. The iWorx TA unit was also connected to stimulating electrodes and a pressure ball. Sticky pads were placed on the forearm and readjusted until optimal motor point was located. A specific software setting and the correct procedure to locate the point can be found on the Muscle lab manual (*-*-*-). The ball must be grasped in a relaxed state with minimal pressure. The pressure on the ball resulting from the contraction is recorded in Volt (V). For each part the provided parameters were set in the software.
Ross, A. C. (2005). Physiology. In B. Caballero, L. Allen, & A. Prentice (Eds.), Encyclopedia of
There are quantitative differences in the skeletal muscle action potentials and its duration potentials that is up to five times longer than the duration of myelinated nerve fibers. Significantly lower than the velocity of conduction in the nerve fibers that innervate muscle fibers is the velocity of conduction in skeletal muscle fibers. The stretching of the tendon attached to the muscle activates specialized receptors in the muscle that send signals to motorneurons through one synapse. The impulse from the motorneuron causes the muscle fibers to depolarize and
The many nuclei of skeletal muscle fiber are located underneath the sarcolemma, which is the fiber’s plasma membrane. Thousands of invaginations of the sarcolemma, which are called T Tubules, Tunnel from the surface to the center of the muscle fiber. These T Tubules are open to the outside of the fiber and are filled with extra-cellular fluid. Muscle action potentials propagate along the sarcolemma and through the T tubules and quickly spread through the muscle fiber. This process ensures that all parts of the muscle fiber become excited by an action potential virtually simultaneously.
surface region to volume proportion builds the surface range, which permits a more prominent association with the
Anatomically and functionally, muscle fiber can be divided into three types: skeletal, smooth and cardiac. Below we summarize in a table the different characteristics of each type of muscle fibe...
Muscle tissues grow by means of physical activity in the same way they are able to become more well-defined (with regards to physical