About half of your body’s weight is muscle. In the muscular system, muscle tissue is categorized into three distinct types of muscle tissue: skeletal, cardiac, and smooth (TYPES OF MUSCLE TISSUE). Each type of muscle tissue in the human body has a unique structure and a specific role. Skeletal muscle moves bones and other structures.
Cardiac muscle contracts the heart to pump blood. The smooth muscle tissue that forms organs like the stomach and bladder changes shape to facilitate bodily functions. Here are more details about the structure and function of each type of muscle tissue in the human muscular system.
What is Muscle Tissue?
Muscle tissue is a soft tissue that composes muscles in animal bodies and gives rise to muscles’ ability to contract. This is opposed to other components or tissues in muscle such as tendons or perimysium. It is formed during embryonic development through a process known as myogenesis.
A muscle tissue varies with function and location in the body. In mammals, the three types are skeletal or striated muscle; smooth or non-striated muscle; and cardiac muscle, which is sometimes known as semi-striated. Smooth and cardiac muscle contracts involuntarily, without conscious intervention.
These muscle types may be activated both through the interaction of the central nervous system as well as by receiving innervation from peripheral plexus or endocrine (hormonal) activation. Striated or skeletal muscle only contracts voluntarily, upon the influence of the central nervous system. Reflexes are a form of nonconscious activation of skeletal muscles but nonetheless arise through activation of the central nervous system, albeit not engaging cortical structures until after the contraction has occurred.
The different muscle types vary in their response to neurotransmitters and endocrine substances such as acetylcholine, noradrenaline, adrenaline, nitric oxide and among others depending on muscle type and the exact location of the muscle.
Sub-categorization of muscle tissue is also possible, depending on among other things the content of myoglobin, mitochondria, myosin ATPase etc.
Types of Muscle Tissue in the human body:-
There are three types of muscle tissue (Skeletal, Cardiac, and Smooth Muscle)
Here is the explanation of all these muscle tissues.
muscle is under voluntary control. Similar to cardiac muscle, however, skeletal muscle is striated; its long, thin, multinucleated fibers are crossed with a regular pattern of fine red and white lines, giving the muscle a distinctive appearance. Skeletal muscle fibers are bound together by connective tissue and communicate with nerves and blood vessels.
The best-known feature of skeletal muscle is its ability to contract and cause movement. Skeletal muscles act not only to produce movement but also to stop movement, such as resisting gravity to maintain posture. Small, constant adjustments of the skeletal muscles are needed to hold a body upright or balanced in any position.
Muscles also prevent excess movement of the bones and joints, maintaining skeletal stability and preventing skeletal structure damage or deformation. Joints can become misaligned or dislocated entirely by pulling on the associated bones; muscles work to keep joints stable.
Skeletal muscles are located throughout the body at the openings of internal tracts to control the movement of various substances. These muscles allow functions, such as swallowing, urination, and defecation, to be under voluntary control. Skeletal muscles also protect internal organs (particularly abdominal and pelvic organs) by acting as an external barrier or shield to external trauma and by supporting the weight of the organs.
Skeletal muscles contribute to the maintenance of homeostasis in the body by generating heat. Muscle contraction requires energy, and when ATP is broken down, heat is produced. This heat is very noticeable during exercise, when sustained muscle movement causes body temperature to rise, and in cases of extreme cold when shivering produces random skeletal muscle contractions to generate heat.
Each skeletal muscle is an organ that consists of various integrated tissues. These tissues include skeletal muscle fibers, blood vessels, nerve fibers, and connective tissue. Each skeletal muscle has three layers of connective tissue (called “Mysia”) that enclose it and provide structure to the muscle as a whole, and also compartmentalize the muscle fibers within the muscle.
Each muscle is wrapped in a sheath of dense, irregular connective tissue called the epimysium, which allows a muscle to contract and move powerfully while maintaining its structural integrity. The epimysium also separates muscle from other tissues and organs in the area, allowing the muscle to move independently.
Smooth muscle is an involuntary non-striated muscle. It is divided into two subgroups: the single-unit (unitary) and multiunit smooth muscle. Within single-unit cells, the whole bundle or sheet contracts as a syncytium (i.e. a multinucleate mass of cytoplasm that is not separated into cells).
Multiunit smooth muscle tissues innervate individual cells; as such, they allow for fine control and gradual responses, much like motor unit recruitment in skeletal muscle.
Smooth muscle is found within the walls of blood vessels (such as smooth muscle specifically being termed vascular smooth muscle) such as in the tunica media layer of large (aorta) and small arteries, arterioles, and veins.
Smooth muscle is also found in lymphatic vessels, the urinary bladder, uterus (termed uterine smooth muscle), male and female reproductive tracts, gastrointestinal tract, respiratory tract, arrector pili of skin, the ciliary muscle, and iris of the eye.
The structure and function are basically the same in smooth muscle cells in different organs, but the inducing stimuli differ substantially, in order to perform individual effects in the body at individual times. In addition, the glomeruli of the kidneys contain smooth muscle-like cells called mesangial cells.
Smooth muscle is organized in two ways: as single-unit smooth muscle, which is much more common; and as multiunit smooth muscle. The two types have different locations in the body and have different characteristics.
Single-unit muscle has its muscle fibers joined by gap junctions so that the muscle contracts as a single unit. This type of smooth muscle is found in the walls of all visceral organs except the heart (which has cardiac muscle in its walls), and so it is commonly called visceral muscle.
Because the muscle fibers are not constrained by the organization and stretchability limits of sarcomeres, visceral smooth muscle has a stress-relaxation response. This means that as the muscle of a hollow organ is stretched when it fills, the mechanical stress of the stretching will trigger contraction, but this is immediately followed by relaxation so that the organ does not empty its contents prematurely.
This is important for hollow organs, such as the stomach or urinary bladder, which continuously expand as they fill. The smooth muscle around these organs also can maintain a muscle tone when the organ empties and shrinks, a feature that prevents “flabbiness” in the empty organ. In general, visceral smooth muscle produces slow, steady contractions that allow substances, such as food in the digestive tract, to move through the body.
Cardiac muscle is involuntary, striated muscle that is found in the walls and histological foundation of the heart, specifically the myocardium. Cardiac muscle is one of three major types of muscle, the others being skeletal and smooth muscle. These three types of muscle all form in the process of myogenesis.
The cells that constitute cardiac muscle, called cardiomyocytes or myocardiocytes, predominantly contain only one nucleus, although populations with two to four nuclei do exist. The myocardium is the muscle tissue of the heart and forms a thick middle layer between the outer epicardium layer and the inner endocardium layer.
Coordinated contractions of cardiac muscle cells in the heart propel blood out of the atria and ventricles to the blood vessels of the left/body/systemic and right/lungs/pulmonary circulatory systems. This complex mechanism illustrates the systole of the heart.
Cardiac muscle cells, unlike most other tissues in the body, rely on an available blood and electrical supply to deliver oxygen and nutrients and remove waste products such as carbon dioxide. The coronary arteries help fulfill this function.
Cardiac muscle is a striated muscle that is present only in the heart. Cardiac muscle fibers have a single nucleus, are branched, and joined to one another by intercalated discs that contain gap junctions for depolarization between cells and desmosomes to hold the fibers together when the heart contracts. The contraction in each cardiac muscle fiber is triggered by CA++ ions in a similar manner as skeletal muscle, but here the CA++ ions come from SR and through voltage-gated calcium channels in the sarcolemma. Pacemaker cells stimulate the spontaneous contraction of cardiac muscle as a functional unit, called a syncytium.
Here we provide all the information of different types of muscle above I hope you understand everything. If you have any question-related muscle you can simply ask me in the comment box as shown below.
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Source of information – Wikipedia, opentextbc.ca, visiblebody.com