Basic muscle contraction

Muscles shorten or contract to move the skeleton. The origin of the muscle is where it begins and the insertion is where it attaches. The insertion moves toward the origin during contraction. A muscle has a connective tissue covering called the epimysium. A little deeper are bundles of muscle fiber called fasciculi which are covered by perimysium. Each individual muscle fiber has a covering called the endomysium.


Muscle fibers ability to contract is due to the sliding filament theory. The smallest functional contractile unit of a muscle fiber is called a sarcomere. Sarcomeres contain myofibrils which are composed of the filaments actin and myosin. Actin is the thin filament and myosin is the thick filament. A nerve fires which depolarizes the muscle fiber. The sarcomere has a significant influx of calcium which move the troponin-tropomyosin complex away from the actin binding site. The myosin filament binds the actin binding site giving the myosin head ATPase ability. The breaking of this high-energy phosphate bond provides energy for the sarcomeres to shorten and muscle to contract. As the sarcomere shortens, portions of it are only the actin filament which is the lightest. There is myosin alone which is darker. The portion of sarcomere with overlapping of actin and myosin are the darkest. This different color banding pattern is called a muscle being striated.

Comments

Post a Comment

Popular posts from this blog

Foods for mental health

The foods we consume can have a  profoun d   impact  on  mental health. A diet can be created that benefits brain development, cognitive function, and slowing the aging process to decrease the risk of conditions like Alzheimer's disease or dementia. The remainder of this document will discuss foods that  will   have  a positive effect on mental processes, diseases, and health.   This is a review of some foods that have  a  positive  effect on mental health and cognitive processes. Popeye may have been much smarter than most of us realize. Spinach is believed to slow cognitive decrements associated with the aging process and risk of developing Alzheimer's disease. Eggs are considered a super food. The egg white is rich in protein and the yolk contains choline which is a  water - soluble  nutrient that improves memory, focus,  and  cognitive  performance. Red meat is very often higher in saturated fat than  other  protein sources. Although this is true, red meat is an e
Read more

Diets

The word diet is where some problems begin. Normal metabolisms can make healthy nutrition programs reasonably easy to calculate. One problem with the word diet is that it insinuates that the client will be deprived of calories or nutrients. Although changes must be made, individuals have converted meals   from two to four per day and never felt severely deprived, shaky, sick, or like they have the flu while reaching body fat or weight goals. Another problem with the word diet is that ninety percent of known diet programs are not particularly successful after a one-year time frame. Nine out of eleven top listed diets are not proven successful after one year according to market research. The reason for this is generally because of severe deprivation of calories or specific macronutrients that may benefit metabolism very short term, but not long term and may detrimental. The keys to healthy nutrition programs are appropriate daily caloric intake, percentages of macronutrients, and   foo
Read more

TPN questions 2

What makes this program better than the rest? Everyone can reach a goal weight or body fat and maintain it.  TPN is tailored.   The categories designed make programs tailored to very specific needs of the client. TPN is precise.   It allows the clients to achieve a very targeted body weight or fat percentage. Many programs are far from tailored and far from healthy.  Many systems are nothing more than a lesson in portion control. A retired former professional football player should not be selecting from the same meals and eating the same number as his female counterpart.  He lost 32 pounds, but still looks quite round.  Did he lose muscle or fat? I know these two people should not be using the same caloric breakdown.  "The meals show up at the door and I eat them “Sounds awful.  Who wants to eat like that?    TPN provides numerous meal plans. We believe in eating fresh, less processed food as possible. We wish to empower people to a lifetime of nutrition management.  The goal
Read more