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Striated muscle tissue is a muscle tissue that features repeating functional units called sarcomeres. The presence of sarcomeres manifests as a series of bands visible along the muscle fibers, which is responsible for the striated appearance observed in microscopic images of this tissue. There are mainly two types of striated muscl :
Three distinct types of muscle (L to R): Smooth (non-striated) muscle in internal organs, cardiac or heart muscle, and skeletal muscle. There are three distinct types of muscle: skeletal muscle, cardiac or heart muscle, and smooth (non-striated) muscle. Muscles provide strength, balance, posture, movement, and heat for the body to keep warm. [3]
Cardiac muscle tissue is striated like skeletal muscle, containing sarcomeres in highly regular arrangements of bundles. While skeletal muscles are arranged in regular, parallel bundles, cardiac muscle connects at branching, irregular angles known as intercalated discs. Smooth muscle tissue is non-striated and involuntary.
Smooth muscle is grouped into two types: single-unit smooth muscle, also known as visceral smooth muscle, and multiunit smooth muscle. Most smooth muscle is of the single-unit type, and is found in the walls of most internal organs (viscera); and lines blood vessels (except large elastic arteries), the urinary tract , and the digestive tract .
These consist of an extensor muscle, which "opens" the joint (by increasing the angle between the two bones) and a flexor muscle, which does the opposite by decreasing the angle between two bones. However, muscles do not always work this way; sometimes agonists and antagonists contract at the same time to produce force, as per Lombard's paradox ...
The protein complex composed of actin and myosin, contractile proteins, is sometimes referred to as actomyosin.In striated skeletal and cardiac muscle, the actin and myosin filaments each have a specific and constant length in the order of a few micrometers, far less than the length of the elongated muscle cell (up to several centimeters in some skeletal muscle cells). [5]
Skeletal muscle cells are the individual contractile cells within a muscle and are more usually known as muscle fibers because of their longer threadlike appearance. [10] Broadly there are two types of muscle fiber performing in muscle contraction , either as slow twitch ( type I ) or fast twitch ( type II ).
Only skeletal and smooth muscles are part of the musculoskeletal system and only the muscles can move the body. Cardiac muscles are found in the heart and are used only to circulate blood; like the smooth muscles, these muscles are not under conscious control. Skeletal muscles are attached to bones and arranged in opposing groups around joints. [8]