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Types of muscle tissue.
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(review) The three types of muscle tissue are:
Skeletal Cardiac Smooth |
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Muscle fibers
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(terminology) Skeletal and smooth muscle cells (but not cardiac muscle cells) are elongated, and for this reason, are called muscle fibers.
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Prefixes myo or mys
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(terminology) Whenever you see the prefixes myo or mys (both are word roots meaning "muscle")
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Sarco
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(terminology) Sarco (flesh), the rederence is to muscle.
(e.g. The plasma membrane of muscle cells is called the sarcolemma, literally, "muscle" (sarco) "husk" (lemma), and muscle cell cytoplasm is called sarcoplasm. Okay! Let's get to it! :) |
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Skeletal muscle tissue
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Is packaged into the skeletal muscles, organs that attach to and cover the bony skeleton. skeletal muscle fibers are the longest muscle cells and have obvious stripes called striations.
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Voluntary muscle
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Although it is often activated by reflexes, skeletal muscle is called voluntary muscle because it is the only type subject to conscious control. When you think of skeletal muscle tissue, the key words to keep in mind are skeletal, striated, and voluntary.
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Cardiac muscle tissue
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Occurs only in the heart (the body's blood pump), where it constitutes the bulk of the heart walls. Like skeletal muscle cells, cardiac muscle cells are striated, but cardiac muscle is not voluntary. Key words to remember for cardiac muscle are cardiac, striated, and involuntary.
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Smooth muscle tissue
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Is found in the walls of hollow visceral organs, such as the stomach, urinary bladder, and respiratory passages. Its role is to force fluids and other substances through internal body channels. Smooth muscle cells like skeletal muscle cells are elongated "fibers," but smooth muscle has no striations. Like cardiac muscle, it is not subject to voluntary control. We can describe smooth muscle tissue as visceral, nonstriated, and involuntary.
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Special Characteristics of Muscle Tissue
Excitability |
Excitability, also termed responsiveness or irritability, is the ability to reviece and respond to a stimulus, that is, any change in the environment either inside or outside the body. In the case of muscle, the stimulus is usually a chemical - for example, a neurotransmitter released by a nerve cell, or a local change in pH. The response (sometimes separated out as an additional characteristic called conductivity), is generation of an electrical impulse that passes along the plasma membrane of the muscle cell and causes the cell to contract.
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Special Characteristics of Muscle Tissue
Contractility |
Contractility is the ability to shorten forcibly when adequately stimulated. This ability sets muscle apart from all other tissue types.
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Special Characteristics of Muscle Tissue
Extensibility |
Extensibility is the ability to be stretched or extended. Muscle cells shorten when contracting, but they can be stretched, even beyond their resting length, when relaxed.
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Special Characteristics of Muscle Tissue
Elasticity |
Elasticity is the ability of a muscle cell to recoil and resume its resting length after being stretched.
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Muscle functions
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Muscle performs at least four important functions for the body. It produces movement, maintains posture, stabilizes joints, generates heat, and more.
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Producing Movement
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Just about all movements of the human body and its parts result from muscle contraction. Skeletal muscles are responsible for all locomotion and manipulation. They enable you to respond quickly to changes in the external environment - for example, to jump out of the way of a car, to direct your eyeballs, and to smile or frown.
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Maintaining Posture and Body Position
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We are rarely aware of the workings of the skeletal muscles that maintain body posture. Yet these muscles function almost continuously, making one tiny adjustment after another to counteract the never-ending downward pull of gravity.
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