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If one were examine any type of muscle cell at the molecular level, what one would find is some kind of structured array of very thin (nano-scale) chains of protein called myofilaments.
These are the smallest contractile elements in muscle tissue. There are two kinds of myofilaments: the thin actin filaments (~7 nm diameter), and the thicker myosin filaments (~16 nm diameter).
In the case of skeletal and cardiac muscle these filaments alternate many times in parallel to the axis of muscle contraction.
During muscle shortening, the job of myosin is to latch on to points along the actin filaments and pull them closer toward each other. During relaxation and muscle lengthening the gap between adjacent actin filaments increases.
The muscle cells that are responsible for contracting sphinctors, blood vessels, bronchioli, the iris, and providing gut motility are a bit different. These are called smooth muscle cells. Instead of having a regular array of filaments parallel to axis of force-generation, they are arranged irregularly in a sort of criss-cross fashion that 'squishes' the cell as it contracts.
What else can I help you with?
Are there more thick filaments than thin filaments in smooth muscle?
There more thin filaments than thick filaments in smooth muscle. The ratio is of the thin to thick filaments in the smooth muscle is approximately 15:1.
What are the 3 types of filaments within a muscle and what protein makes up each filament?
The three types of filaments within a muscle are thin filaments, thick filaments, and elastic filaments. Thin filaments are primarily composed of the protein actin, while thick filaments are made up of myosin. Elastic filaments, which help maintain the structure and elasticity of the muscle, are primarily composed of the protein titin. These filaments work together to facilitate muscle contraction and relaxation.
DO actin and myosin come from muscle fiber?
Yes, actin and myosin are protein filaments found within muscle fibers. Actin is responsible for thin filaments and myosin for thick filaments in muscle contraction.
What is composed of myosin?
Myosin is a protein found in muscle cells that plays a key role in muscle contraction. It consists of long molecules called myosin filaments, which interact with actin filaments to generate the force needed for muscle movement.
The filaments are arranged along the muscle fiber in units called?
Actin filaments
What muscle cell filaments come closer together when the sarcomere shortens?
thin filaments
Myosin cross bridges attach to active sites of?
actin filaments in muscle cells during muscle contraction.
What muscle shapes the muscle?
thick and thin bands (lines) of filaments.
What chemical triggers sliding of muscle filaments?
The chemical that triggers the sliding of muscle filaments is calcium ions. When muscle cells receive a signal to contract, calcium ions are released into the muscle cell, binding to specific proteins and initiating the sliding mechanism between actin and myosin filaments in the muscle cells.
What is the significance of the i band in muscle physiology?
The i band in muscle physiology is important because it contains the thin filaments made of actin. These filaments play a crucial role in muscle contraction by interacting with the thick filaments made of myosin. The i band shortens during muscle contraction, allowing the muscle to generate force and movement.
What are the roles of thick and thin filaments in muscle contraction?
The thin filaments are actin, and the thick filaments are myosin. The filaments run parrel to one another along the length of the sarcomere.The dark bands that occur in the middle of the sarcomere are regions where the thick filaments and thin filaments overlap.
Units of actin and myosin are arranged end to end in order to?
form the structural units responsible for muscle contraction, known as sarcomeres. Actin filaments provide the thin filaments, while myosin filaments provide the thick filaments. When the myosin heads interact with actin during muscle contraction, the sarcomere shortens, leading to muscle contraction.
