Dominic Stone
There are two types of striated muscle: skeletal muscle and cardiac muscle. Striated muscle tissue features repeating functional units called sarcomeres, which are visible under a microscope and give the tissue its striated appearance. Skeletal muscle is the most common type of muscle in the body, making up between 30% and 40% of total body mass. Cardiac muscle, on the other hand, is about 100 times smaller than skeletal muscle. Both types of striated muscle contain T-tubules, which enable the synchronous release of calcium ions from the sarcoplasmic reticulum.
| Characteristics | Values |
|---|---|
| Number of muscles that are striated | 2 |
| Types of striated muscle | Skeletal muscle, cardiac muscle |
| Muscle tissue appearance | Striped |
| Muscle tissue composition | Repeating functional units called sarcomeres |
| Muscle tissue functions | Create force and contract |
| Skeletal muscle composition | Multinucleated contractile muscle fibres (myocytes) |
| Skeletal muscle functions | Producing movement, maintaining posture and position, maintaining body temperature, storing nutrients, stabilising joints |
| Skeletal muscle mass | 30% to 40% of total body mass |
| Skeletal muscle regeneration | Better than cardiac muscle due to satellite cells |
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What You'll Learn
- Skeletal muscle is striated and is the most common type of muscle in the body
- Cardiac muscle is striated and is located in the walls of the heart
- Striated muscles are required for whole-body oxygen supply, metabolic balance, and locomotion
- Skeletal muscles are attached to the skeleton and are under voluntary control
- Striated muscles have a highly ordered ultrastructure consisting of sarcomeres
Skeletal muscle is striated and is the most common type of muscle in the body
Skeletal muscle, also known as striated muscle, is the most common type of muscle in the body, making up between 30% and 40% of total body mass. They are part of the voluntary muscular system and are attached to bones by tendons. Skeletal muscles are located throughout the body, between the bones of the skeletal system. They consist of flexible muscle fibres that range from less than half an inch to just over 3 inches in diameter.
The skeletal muscle cells are much longer than other types of muscle tissue and are also known as muscle fibres. Each skeletal muscle contains multiple fascicles, or bundles of muscle fibres. The outermost connective tissue sheath surrounding the entire muscle is called the epimysium, while the innermost layer surrounding each individual muscle fibre is called the endomysium. Skeletal muscle fibres are red and white and have a striped appearance due to the arrangement of sarcomeres, the basic contractile units.
The primary function of skeletal muscle is contraction, which allows for movement. Skeletal muscles are also involved in maintaining body posture, controlling body temperature, and stabilising joints. They play a vital role in everyday activities such as breathing, eating, and moving bones. Additionally, skeletal muscles act as a storage source for amino acids and play a role in maintaining thermostasis and energy balance.
Skeletal muscles can be further categorised into slow-oxidative/Type I, fast-oxidative/Type IIa, and fast-glycolytic/Type IIb types, based on their contractile and metabolic phenotypes. They are also the site of myoblast activity during embryonic development, which forms the primary muscle fibres.
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Cardiac muscle is striated and is located in the walls of the heart
There are three types of muscle tissue in the human body: cardiac, smooth, and skeletal. Cardiac muscle, also called the myocardium, is one of the three major categories of muscles found in the human body. It is an involuntary, striated muscle that constitutes the main tissue of the wall of the heart. The cardiac muscle forms a thick middle layer between the outer layer of the heart wall (the pericardium) and the inner layer (the endocardium).
Cardiac muscle cells, also called cardiomyocytes, are the contractile myocytes of the cardiac muscle. They are surrounded by an extracellular matrix produced by supporting fibroblast cells. The cardiac muscle is responsible for the contractility of the heart and, therefore, the pumping action. The cardiac muscle must contract with enough force and blood to supply the metabolic demands of the entire body. Each cardiomyocyte needs to contract in coordination with its neighboring cells, known as a functional syncytium, to efficiently pump blood from the heart.
The cardiac muscle cells are roughly rectangular and are joined at their ends by intercalated discs to form long fibers. Each cell contains myofibrils, specialized protein contractile fibers of actin and myosin that slide past each other. These are organized into sarcomeres, the fundamental contractile units of muscle cells. The regular organization of myofibrils into sarcomeres gives cardiac muscle cells a striped or striated appearance when viewed through a microscope, similar to skeletal muscle.
The growth of individual cardiomyocytes occurs during normal heart development and in response to extensive exercise, heart disease, or heart muscle injury. A healthy adult cardiomyocyte has a cylindrical shape that is approximately 100 μm long and 10–25 μm in diameter.
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Striated muscles are required for whole-body oxygen supply, metabolic balance, and locomotion
Striated muscles, also known as skeletal muscles, are the most common type of muscles in the human body. They make up between 30% and 40% of our total body mass. Striated muscles are attached to bones by tendons, which are tough connective tissues. Examples of striated muscles include shoulder, hamstring, and abdominal muscles. These muscles are under our conscious control and are responsible for various functions, including whole-body oxygen supply, metabolic balance, and locomotion.
Striated muscles play a vital role in breathing, eating, and moving our bones, making them essential for our daily activities. They contract to enable movement, and this contraction requires a significant amount of oxygen. During exercise, the body's transition from rest to activity demands remarkable adjustments in the cardiovascular system to meet the oxygen needs of the heart, respiratory muscles, and active skeletal muscles. This involves increasing the heart rate and cardiac contractility to boost cardiac output and blood flow to the muscles.
Long-term exercise training induces adaptations in the striated muscle circulation, enhancing blood flow capacity and improving oxygen diffusion. These adaptations help increase whole-body oxygen consumption, cardiac output, and oxygen extraction from the blood. The design of the energy metabolism system in striated muscles is a subject of ongoing research, with a focus on understanding the metabolic support of muscle contraction. Maintaining energy homeostasis through mitochondrial oxidative phosphorylation is critical for sustained contractile activity.
Striated muscles also contribute to metabolic balance. The distribution of potential energy across these large muscle cells is facilitated by the ubiquitous distribution of ATPases. Recent studies suggest that the mitochondrial reticulum may provide a rapid energy distribution system by conducting the mitochondrial membrane potential to maintain metabolic homeostasis during muscle contraction. This understanding of the energy metabolism design in striated muscles has implications for various physiological conditions, including heart failure, metabolic syndrome, aging, and arrhythmias.
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Skeletal muscles are attached to the skeleton and are under voluntary control
The human body has three types of muscle tissue: skeletal, cardiac, and smooth muscle. Skeletal muscles are under voluntary control, meaning an individual can control how and when they move and work. These muscles are connected to the bones and allow for a wide range of movements and functions. For example, when reaching for a book on a shelf, you are using the skeletal muscles in your neck, arm, and shoulder.
Skeletal muscles serve many purposes, including producing movement, sustaining body posture and position, maintaining body temperature, storing nutrients, and stabilizing joints. They also play a vital role in everyday activities such as breathing and eating. These muscles consist of flexible muscle fibres that contract, allowing the muscles to move bones and perform various movements. Each muscle can contain thousands of fibres.
Skeletal muscles are composed of bundles of muscle fibres called myofibers, which contain several myofibrils. These myofibrils are made up of actin (thin filaments), myosin (thick filaments), and support proteins. The arrangement of actin and myosin gives skeletal muscle its microscopic striated appearance and creates functional units called sarcomeres. The sarcomeres are the basic contractile units containing a central myosin-rich dark anisotropic (A) band and two actin-dominated light isotropic (I) bands.
Skeletal muscles are essential for whole-body oxygen supply, metabolic balance, and locomotion. They also contribute to basal energy metabolism, serving as a storage site for essential substrates such as carbohydrates and amino acids.
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Striated muscles have a highly ordered ultrastructure consisting of sarcomeres
Skeletal and cardiac muscles are the two types of striated muscles. Striated muscles are required for whole-body oxygen supply, metabolic balance, and locomotion. They are made up of repeating functional units called sarcomeres, which are the basic contractile units of muscle fibres.
Under light microscopy, striated muscles reveal a highly ordered ultrastructure consisting of sarcomeres. These sarcomeres are composed of two main protein filaments—actin and myosin—which are the active structures responsible for muscular contraction. The sarcomere is the contractile unit of the cardiac myocyte. Its myofilaments are arranged in parallel, cross-striated bundles of thin fibres that contain actin, tropomyosin, and the troponin complex, and thick fibres that are primarily composed of myosin and its supporting proteins.
Sarcomeres are connected in series, and the long and short axes of each myocyte simultaneously shorten and thicken, respectively, during contraction. Each sarcomere is composed of a central myosin-rich dark anisotropic (A) band and two actin-dominated light isotropic (I) bands. The Z line, or Z disk, is the terminal boundary of the sarcomere, where alpha-actinin acts as an anchor for the actin filaments. The M line is the central-most line of the sarcomere, where myosin filaments are anchored together through binding sites within the myosin filament. The H band contains the M line and is the central region of the sarcomere that contains only myosin filaments. The A band is a larger portion of the sarcomere that contains the entirety of the myosin fibres and includes regions of actin and myosin overlap.
All types of striated muscle contain a branched network of membrane invaginations called T-tubules that enable synchronous calcium release throughout the entire cell volume. The T-tubules contact the sarcoplasmic reticulum (SR) between the A and I bands in skeletal muscle and at the Z-disc in cardiac muscle.
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Frequently asked questions
Striated muscles are muscles that feature repeating functional units called sarcomeres, which are basic contractile units containing a central myosin-rich dark anisotropic band and two actin-dominated light isotropic bands. They are called striated muscles because they have a striped appearance.
The two types of striated muscles are skeletal muscle and cardiac muscle.
Skeletal muscles are attached to the skeleton and are under voluntary control. They are the most common type of muscle in the body, making up between 30% and 40% of total body mass. They are used for breathing, movement, and posture maintenance.
Cardiac muscles are located in the walls of the heart and are under involuntary control. They are used to pump blood throughout the body.
Skeletal muscles are attached to the skeleton and are under voluntary control, whereas cardiac muscles are located in the heart and are under involuntary control. Skeletal muscles can regenerate better than cardiac muscles due to the presence of satellite cells.
