TABLE OF CONTENTS1. Overview of Skeletal System
2. Bone Growth
3. Types of Muscles
This unit is composed of the skeletal and muscular systems. Above is my table of contents which I will provide in more detail below. The first review is the Skeletal System, which is made up of bones clicking and moving together to allow us to perform the activities we are doing. In my A & P class last semester, we looked at different organs on the Cadaver, which was my first experience. It is absolutely amazing to see the skeletal shape of the body with the organs in place. Inside each of us is a skeleton! Around the bones lie muscles that help with movement and protection against other organs. Muscles have a detailed job which I will do my best to explain, the picture I provide is helpful to follow along with. Both of these systems go hand-in-hand to provide our body with the proper movement, support, and functioning it needs to maintain homeostasis.
OVERVIEW OF SKELETAL SYSTEM: The book lists 5 functions of the skeleton: "supports the body, protects soft body parts, produces blood cells, stores minerals and fat, and permits flexible body movement" (Mader 208). These functions basically keep us alive and functioning. Each of our skeleton shapes began development while we were still an embryo, at about 6 weeks. "The bones that make up your skeleton are all very much alive, growing and changing all the
time" (kids health article). Next I will discuss the different materials that make up the long bone, shown on the picture to the right. A long bone has an outer fibrous tissue known as the periosteum. The vessels on this tissue, break open the tissue and enter the bone. Next layer is the compact bone, if looking at a skeleton this is the note able tissue you see. Spongy bone is known for giving strength and the little spaces are composed of red bone marrow. One of the functions I mentioned was producing blood cells, this tissue does just that. Most babies bones are made up of a soft and flexible layer called cartilage, and as the baby grows the cartilage is replaced by bone. Athletes typically either pull/strain a ligament(bone to bone) or tendon(muscle to bone), made from the fibrous connective tissue. Fibrous joints connect without any movement. Another joint is Cartilaginous, which is attached by cartilage (spine or ribs). The last joint is Synovial, which helps prote
ct the bones and allows it to move freely; since the synovial fluid acts as a barrier. The picture to the right shows a 'ball-and-socket' joint. I used to work on the Orthopedic/Med-Surg floor at Scottsdale Health care, and saw many fractured/broken hips. These individuals needed the physical therapy to learn the healing procedure and hip precautions, to prevent hip dislocation. the synovial joint movements discussed in this section are: Flexion-Extension, Adduction(moving arm/leg toward midline)-Abduction(moving arm/leg away from the mid line), Rotation-Circumduction, and Inversion(moving sole in)-Eversion(moving sole out). As discussed above, the skeletal system has many parts to hold up a strong framework.BONE, GROWTH: The 3 different cell types of bones are: 1. Osteoblasts "bone-forming cells, promote the deposition of calcium salts into the matrix" 2. Osteocytes: "maintain the structure of bone" and 3. Osteoclasts: "break down the bone ad assist in depositing calcium and phosphate in the blood" (Mader 210). I stated earlier that during fetal development bones are begining to form, this formation is known as ossification. The book describes many different types of bones, but I will focus more on movement and structure. At this point in our lives we already know the importance of Calcium in our diets. To help keep our bones strong, and brittle-free. The book states the importance of Vitamin D, in that it helps absorb calcium. PTH keeps the bone recycling, rising the level of blood calcium. By the age of 25 an individuals bones have stopped growing. An average adults has "206" bones in their skeleton form (kids health article). Keeping our bones healthy and strong will hopefully lead to a less chance of developing bone diseases such as, Osteoporosis.
TYPES OF MUSCLES. "Humans have 3 types of muscle tissue: smooth, ca
rdiac and skeletal" (Mader 228). The picture to the right shows what each muscle tissue looks like. Smooth muscle is known to be involuntary. Examples of where this type is found is the esophagus, stomach, bladder, intestines, and bronchi. Cardiac muscle is also involuntary and this is only find surrounding the heart. Lastly, the Skeletal muscle is voluntary, moves on our commands: arms, shoulder, k
nee. Its functions are support, movement, regulating temperature, and works to keep blood flowing. "Muscle is mainly composed of muscle cells" (wikipedia). These muscle cells are also known as muscle fibers. Inside each of these fibers are numerous little myofibrils, the "contractile portion of the muscle fibers" (Mader 232). The picture to the right is a muscle fiber(#3) and inside are the myofibrils(#4). If you were to pull out one of the myofibrils(long cylinder shape) and look at it under a microscope, you would find many sarcomeres. The membrane of a muscle fiber is known as a sarcolemma, the cytoplasm is sarcoplasm, and the ER is sarcoplasmic reticulum. By following along with the picture below will help explain the following structures. Within the sacromere are two protein filaments: myosin(thick- green structure) and actin(thin-orange coiled structure). Myosin is the big producer in the break down of ATP to occur. The two protein filaments go through a zig-zag sliding process in order for ATP to supply the necessary energy. In order for a muscle fiber to contract, the axons of motor neurons need to be in the nerves. The green flaps on the myosin filament is the axon terminal which are filled with synaptic vesicles containi
ng acetylcholine-ACh(the axon terminal if flipped around resembles a shower head- the synaptic vesicles would be where the water squirts out). The gap from the axon terminal and the sarcolemma is known as the neuromuscular junction. When an impulse travels down the muscle fiber and reaches the axon terminal, it releases the ACh which binds to the sarcolemma. Calcium is also released from the sarcoplasmic reticulum, which aids in muscle contraction. The next two proteins to discuss are part of the actin filament(orange coiled structure): Tropomyosin(pink thread wrapped around the actin) and Troponin(blue clumps scattered across the actin). Once Calcium is released, myosin and actin are capable of binding. Muscle Contraction: This is also known as a muscle twitch, it occurs when a muscle fibers lengthens or shortens. The book describes 3 different stages: latent, contraction, and relaxation periods. A motor unit is known as nerve and muscle fibers. I briefly described the process of the release of Calcium ions above and it relates again to the muscle contractions. When calcium exits the sarcoplasmic reticulum it contracts, and when calcium enters the fiber it relaxes. Interesting fact the book states is that a muscle has 4 energy sources: muscle triglycerides, plasma fatty acids, blood glucose, and muscle glycogen. "ATP is the immediate source of energy for muscle contractions" (wikipedia). The 3 ways the a muscle fiber collects the energy is through creatine phosphate, fermentation, and cellular respiration. To me these are a bit difficult to try and describe, so I will leave this information as mentioned above. We all get the annoying muscle spasms, for instance while swimming laps, cramps while jogging, the occasional eye twitching, or a sprained ankle. These are a few of the common muscle disorders we probably all experienced. Each movement between our muscles and bones is important for proper functioning as well as maintaining homeostasis.
In conclusion this review was a brief summary of the important structures of the skeletal system and the muscular system. Both systems work together to help our bodies move on command. The framework of a skeletal system has important functions for: support, protection, produce blood cells, store minerals and fats, and allow for movement. The 3 joints I discussed were fibrous, cartilaginous, and synovial. I also briefly touched on the importance of Calcium in our diet, to keep a strong and healthy bone structure. Muscle fibers work hard at making sure the body is able to perform muscle contractions by allowing the nerve impulses to travel its course. ATP is an important source of energy that is released, allowing the muscle to contract. I know I always say how amazing our body is, but I truly find it to be. Inside our body there is a strong skeletal structure with muscle surrounding to help with movement and protects all of our organs. Some movements are voluntary while others are not, regardless our strong body will fight to help maintain homeostasis.
WORKS CITED:
http://en.wikipedia.org/wiki/skeletal_system muscle and muscle fibers
picture of skeleton, muscle tissues, muscle fiber, and quotes
picture of mysoin and actin
quotes
picture of hip 'ball-and-socket
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