Here we are again with blog post numero tres. In case you didn't catch that, this time we are talking about the muscular system...not killing anybody. Okay, so the muscular system is composed three types of muscles: skeletal, cardiac and smooth and of those categories, there are over 600 striated muscles that are connected to bones and muscles make up about 30-40% of our body weight.
Let's talk skeletal muscles first. These groups of muscles perform five primary functions: produce movement of the skeleton, maintain posture and body position, supports soft tissues, guards entrances and exits, and maintains body temperature. Skeletal muscles also contain muscle tissue (duh), connective tissues, blood vessels, and nerves. The connective tissues are separated into three layers: the Epimysium which separates muscles from surrounding tissues, the Perimysium which surrounds the muscle fiber bundles also known as fascicles, and lastly the Endomysium which surrounds individual muscle cells also known as muscle fibers.
Let's talk skeletal muscles first. These groups of muscles perform five primary functions: produce movement of the skeleton, maintain posture and body position, supports soft tissues, guards entrances and exits, and maintains body temperature. Skeletal muscles also contain muscle tissue (duh), connective tissues, blood vessels, and nerves. The connective tissues are separated into three layers: the Epimysium which separates muscles from surrounding tissues, the Perimysium which surrounds the muscle fiber bundles also known as fascicles, and lastly the Endomysium which surrounds individual muscle cells also known as muscle fibers.
Next shall we discuss the blood vessels and nerves of these lovely muscles. The nerves of skeletal muscles are completely voluntary which means that we have to put effort and thought on when and how you want them moved. this is all controlled by the nerves of the central nervous system which is the brain and spinal cord.The blood vessels are part of an extensive vascular system that is in charge of supplying our body and muscles with large amounts of oxygen and nutrients and also carries away wastes.
This wouldn't be proper blog if appearance wasn't brought up at least once throughout, so here it is. Skeletal muscle fibers have distinctive features.
This wouldn't be proper blog if appearance wasn't brought up at least once throughout, so here it is. Skeletal muscle fibers have distinctive features.
Skeletal muscle fibers are broken own into smaller and smaller portions. The sarcolemma is the cell membrane of a muscle fiber cell that surrounds the sarcoplasm which is the cytoplasm of a muscle fiber. This is where a change in transmembrane potential begins contractions. Then we have the transverse(T) tubules which have the same properties as the sarcolemma. These transmit action potential through the cell and allows the entire muscle fiber to contract simultaneously. Even more in depth, we have the myofibrils which are subdivisions within the fibers and are made up of protein filaments (myofilaments) which are responsible for muscle contraction. There are two types of myofilaments: thick, which are composed of the protein myosin, an thin filaments which are made up of the protein actin. Next we have the sarcoplasmic reticulum(SR) which is a membranous structure that surrounds each myofibril and helps transmit action potential to the myofibril. It also forms chambers( terminal cisternae) which are attached to the T tubules. This results in a triad forming made from one T tubule and two terminal cisternae. Cisternae is basically calcium concentrate and it releases calcium into sarcomeres to begin the overall muscle contraction.
This may blow your mind, but the skeletal muscle fibers breaks down EVEN MORE!! Okay, okay, try to control your excitement while I try to explain. So there are these things called sarcomeres, I may have mentioned them briefly earlier. Well any-who, these lovely things are the contractile units of the muscle and the structural units of myofibrils. Yeah, remember those thingies? Well these come together to form visible patterns within myofibrils. Then we have these muscle striations which are basically a striped (or striated) patterns within myofibrils. They are super snazzy and even alternate colors of dark, thick filaments (A bands ) and light, thin filaments (I bands). There is also a "zone of overlap" where the thick and thin filaments overlap.
The massive process boils down to a muscle contraction which is caused by interactions of thick and thin filaments. Think about this: In the time I have spent writing this simple sentence, the whole process that I just explained in this entire blog so far, my hand muscles have gone through the process millions of times. Every movement you or I make is the end result of all of these muscle pistons firing all over our body to create steady, precise and balanced movements. We spend a large portion of our life trying to get our muscles trained and there are different processes for each type of person: dancers, musicians, engineers, mechanics, pilots, etc.What is really adorable is if you think about little clumsy kids between the ages of 6 months and 2 years old. These muscle contractions happen in them too and their motions are so jerky because their pistons are still getting used to being used and activated.
CONNECTIONS!!! So to connect the muscular system to the skeletal system is basic and to the point, not to mention painfully obvious. So muscles attach to he bones with accounts for our ability to lift the massive bones in our bodies, gives us the ability to run, walk, dance, write, and pick up stuff. The muscle system is our source of ability to have basic motor skills. Without muscles, we basically can't do anything. Drinking and eating as well as digestion is all an end result of our muscles doing their job. Blinking or talking would be impossible, giving people hugs, also impossible. Laughing or smiling in general would never be possible. To think of not being able to do the things we all take for granted and do without giving it a second thought is kinda scary. So then next time you smile, remember, without muscles and bones, you wouldn't move. You'd die.
Sources:
- http://www.innerbody.com/image/musfov.html
- http://www.livescience.com/26854-muscular-system-facts-functions-diseases.html
- http://www.healthline.com/human-body-maps/muscular-system