According to PearsonHigherEd.com, the sarcomere is the basic unit of contraction within a bundle of muscle fibers. Individual sarcomeres contain clearly defined bands of filaments which have a special terminology.
Each sarcomere is surrounded by Z lines which denote the boundary from one sarcomere to the next. I bands are that portion of the sarcomere which contain thin filaments. H bands contain thick filaments, and A bands contain a mix of thick and thin. BiologyGuide.net states that these differences in thickness produce the characteristic striations of skeletal muscle.
BiologyGuide.net also states that the differences in thickness represent differences in what the filaments are made of. I bands contain filaments made up of actin alone, while H bands contain myosin filaments alone; A bands contain lengths of myosin.
The University of Washington describes how the filaments are typically arranged within a sarcomere; thin filaments extend from the Z lines to the center of the sarcomere, with thick filaments in the middle. The thick filaments never get as far as the Z lines, but they overlap the thin filaments that do. The two kinds of filament slide in respect to one another, causing the Z lines to be pulled toward one another, creating a muscle contraction.Learn More
The bicep and tricep muscles are located in the upper arm between the shoulder and elbow joint. The triceps are the posterior arm muscles, supplied by the radial nerve. The biceps, along with the brachialis and coracobrachialis, are the anterior arm muscles, and are supplied by the musculocutaneous nerve.Full Answer >
According to the National Museum of Health and Medicine, muscles attach to stationary bone by ligaments, which are attached to a point on the bone called the origin. Ligaments are composed of cartilaginous tissue, which is fibrous and tough.Full Answer >
Sarcoplasm is present in certain muscle fibres that have a large number of mitrochondria, which can be thought of as energy-producing units in a cell. The mitochondria produce large quantities of the chemical adenosine triphosphate, commonly referred to as ATP.Full Answer >
Knee cartilage absorbs the shock of bones moving against each other as a person walks, runs, jumps or otherwise moves the bones in the knee area. Cartilage covers the ends of the bones in the knee joint and has a rubbery texture. Damage to cartilage results in pain that occurs with knee movement.Full Answer >