Sarcomere

The SR is extensive and covering all the myofibrils this allows fine control of contractions of the myofibrils due to depolarization only affecting the targeted areas since the SR release of calcium ions is the key to muscle contraction. Myofibrils are protein bundles containing actin and myosin. Actin (thin) and myosin (thick) make up a unit of skeletal muscle cell called a sarcomere, the main unit of contraction in skeletal muscle cells. The patterns of sarcomeres make up the striations or the stripe like feature of the cell. The actin and myosin in the sarcomere use what is known as the sliding filament theory as means of causing the contractions of muscle. Myosin slides along actin filaments to contract a sarcomere as the number of sarcomeres contracting increases the muscle contracts stronger and stronger vice-versa as more sarcomeres relax the muscle contraction grows weaker and weaker. A sarcomere contraction can only occur when calcium ions from the SR that are released by action potentials from nerve fibers bind to the protein troponin that is associated with tropomyosin this calcium binding…

Overview of The Myocyte The myocyte is composed of various protein filaments that comprise the contractile apparatus of the cardiac cell. Myofibrils, a collection of individual sarcomeres, enable contraction and relaxation of the myocyte. The sarcomere is the chief contractile unit of the cell. It is made up of two main proteins, myosin (thick filament) and actin (thin filament), as well as two regulatory proteins, tropomyosin and troponin. In order for the myocyte to contract and shorten it…

muscle and sarcomere length in isolated sartorius muscle of Rhinella marina Abstract: An isolated Sartorius muscle of Rhinella marina was repeatability stimulated with electrical impulses to induce isometric contraction. Contractile forces evoked were measured with a force transducer and the relationship between force and muscle length was investigated through the modulation of sample lengths from 80%-140% of the sample resting length. The data was plotted and the active force produced a…

In order for a skeletal muscle to contract, it has to first be stimulated by a nerve (Harrison, 2006). The muscles contract by a process known as the sliding filament theory. The structures involved in this process are myofibril, sarcomere, actin and myosin (Jackson,…

There are many different parts of skeletal muscles that are important to the function of the muscles. Each muscle is made up of a lot of muscle fibers. Each muscle fiber has a thin coating covering the fiber called the sarcolemma. The muscle fibers also have a cytoplasmic type substance called sarcoplasm. Sarcoplasm contains large amount of glycosomes and myoglobin. Myoglobin is a protein that stores oxygen inside the muscle fibers. The muscle fibers contain striations that are made up of…

Once the bridges are formed, the myosin pulls on the actin contracting the muscle. Cross bridge formation can only occur, however, when the binding sites on the actin are free. Calcium ions work to free up the myosin binding sites on actin. When a muscle is relaxed, a protein called tropomyosin blocks the myosin binding site. Calcium rushes into the cell and attaches to a special protein troponin when a muscle is stimulated by a nerve cell. The troponin then changes shapes and pulls the…

Biology 201 B1 Assignment #2 A four question analysis on "The myosin-interacting protein SMYD1 is essential for sarcomere organization" by Just et al. (2011) 1.) Wild-type Fla Mutant (SMYD-deficient) In the current study, the authors used a zebra fish mutant known as Flatline (fla). This mutant contains a nonsense mutation within the SMYD1 gene, consequently, these mutants show disturbed sarcomere assembly. The authors…

Myofibrils are threadlike elongated structures found in striated muscle cells that contain these contractile proteins. It is believed that each muscle fibre is made up of thousands of myofibril containing billions of myofilaments (Frontera and Ochala 2015). The building block of these myofibrils is the sarcomeres which are the basic contractile units of skeletal muscle. They are made up of actin and myosin filaments that are divided by a thin sheet of structural proteins called the Z band/ Disk.…

The article I chose was “SmartStretch™ Technology. I. Improving the tenderness of sheep topsides (m. semimembranosus) using a meat stretching device” (Meat Science 91 (2012) 142-147). The goal of this experiment was to see whether SmartStretchtm can improve hot-boned mutton tenderness. SmartStretchtm is a device developed by Meat & Livestock Australia and Meat & Wool New Zealand with the goal of preventing the muscular contraction of a boneless piece of meat by stretching it The animals used in…

Alexandra Banales X explains Y The purpose of this experiment was to measure the tension, or force, produced by interacting filaments in a muscle fiber. In order to test this, a subject had three electrode disks located on their forearm. These disks were connected to a computer monitor which traced the EMG records and the Force trace of their muscle contraction. Data was observed while the subject changed their hand movement in different ways including wrist positions such as fully flexed,…