Our muscles allow us to do amazing things maintain our posture or produce heat even blink. When You flex or (contract) your muscles you ar shorting them to enable a sort of pulling force. Now the Muscle Tissue Characteristics They are made up of contractible fibers. Red V White Muscle fibers, Red is the slow-moving fibers They have a Greater Number or amount Of Mitochondria They contain high concentration of myoglobin. They also move at a slow rate but do not fatigue thanks to sustained contraction. Postural muscles which are opposed to gravity. White muscle fibers contain little myoglobin/Mitochon They move fast and rapidly and undergo something called anaerobic respiration.Now we move to the cell itself we call it sarco mmila this cell like many others maintain a membrane potential so that impulses of the muscle can travel through it. Now Vasoconstriction Constriction and dilation of a blood vessel´s walls are the main things that results in smooth muscle contractions. Peristalsis are a wave like Motions that along the digestive tracts that the smooth muscle can produce. Now we go to skeletal muscle fibers every single one of these are a cell. Muscle fiber cells are cylinder shaped cells with a huge amount of nuclei inside of these cells are (Dark a bands,Light i bands,many Nuclei,Myofibril,Mitochondria and Saracomma. The Myofibrils contain thick filaments and thin filaments.Ultrastructure of thick Filaments: the thick filaments have something called tails and heads. The tails twist and the heads are just a are just round structures that go throughout the entire twist. The Ultrastructure of thin filaments include Troponin complex,tropomyosin and actin. The skeletal muscles are made up of a bunch of discs and bands. There’s a pattern it goes Z-disk H-zone Z-disk and That is only on one side the other is I-Band A-Band I-Band. When you flex or tighten your muscles they compress down and leave you to fell a harder surface then when you are just sitting down. Our muscles are very complicated they have mixtures that are Ca2atoms diffuse from the sarcoplasmic reticulum into a sarcoplasm bind to a bunch troponin molecules. Or things like a transverse tubule or a (t tube) that is well developed in skeletal and cardiac to transport calcium. Or just something as simple as a muscle spasm you could have it in the skeletal or smooth sections I thought that it was just your whole muscle that did that. We as a human race still have things to find so think when you get a cramp or a little twitch it’s not as easy of a thing that you would think. It’s a huge puzzle of things that are intertwined and smushed together.