Cardiac muscle is located in the heart, hence the meaning of the word ‘cardiac’ -relating to the heart. Its cells (myocardiocyte muscle cells) are joined from one end to the other. Each cell has a single nucleus. Unlike skeletal muscles, cardiac muscle is controlled involuntarily.
Smooth muscle is called so because under a microscope there are no visible lines (striations), as opposed to striated muscle. Smooth muscle tissue is found in the walls of hollow, internal structures such as blood vessels and the bladder. Like cardiac muscle, smooth muscle fibers are mostly involuntary, which is to say they contract and relax automatically. Smooth muscle tissue, like skeletal and cardiac muscle tissue, can hypertorphy - the increase in size, or volume, of organic tissue as a result of structural / internal growth.
Skeletal muscle tissue is, as the name suggests, attached to bones. It is striated, (not smooth) and can contract or relax voluntarily. Each muscle is comprised of single fibers embedded in a matrix of collagen - fibrous protein that connects and provides support to body tissue(s). At either end of the muscle belly, this matrix becomes the tendon that connects a muscle to a bone. There are currently three classifications (types) of muscle fibers:
Type I Fibers (slow oxidative fibers)
Also called slow twitch muscles. Type I fibers are red, and split Adenosine Triphosphate at a slow rate, meaning they have the ability to ‘refuel’ during aerobic activities. Type I fibers contain large amounts of myoglobin and have many mitochondria. They are resistant to fatigue.
Type II A Fibers (fast oxidative fibers)
Also called fast twitch muscles, Type II A fibers are red, and have a very high capacity for generating ATP. Type II A muscle fibers have a fast contraction velocity, and can utilize aerobic or anaerobic metabolism as a means of generating energy.
Type II B Fibers (fast glycolytic fibers)
Type II B Fibers are also called fast twitch, but these fibers are white, and have little capacity for endurance as they fatigue easily. These fibers are found in large numbers in the muscles of the arms and legs. Type II B fibers are the most ‘explosive’ muscle fibers in the human body. They contain high levels of creatine phosphate and glycogen, making them very powerful. Type II B fibers contain low content of myoglobin, relatively few mitochondria, and few blood capillaries.
Develop slow twitch muscle fibers by training aerobically (e.g. swimming, distance running)
Develop fast twitch muscle fibers by conducting plyometrics or sports specific training exercises.
Jillian Michaels, Shape Magazine
I apologize for my absence! I haven’t cooked my own meal these past days, but today I wen out to grab a few things 😀 my good old buddy lettuce, spinach 💚 cherry tomatoes, corn and two melons I’ve never tried before 😁 can’t wait to cut them open #food #myfood #healthy