A significant portion of human body weight is muscle. The skeletal, cardiac, and smooth muscle tissues of the body are distinct categories of muscle tissue.
There are several kinds of muscle tissues in the human body, each designed for a particular purpose. Skeletal muscles move bones and different structures in the body. The heart pumps blood with cardiac muscles. Organs such as the stomach and bladder have smooth muscle tissue that change shape to move with physical processes.
Skeletal muscles are voluntary muscles that control body movements. Smooth muscles are involuntary muscles that perform functions like blood pressure regulation, digestion, and peristalsis. Cardiac muscles are involuntary muscles that regulate heart rate and rhythm. Glands are organs that secrete hormones and other chemicals into the bloodstream.
Smooth Muscle
There are no striated fibres in smooth muscles, which are involuntary. Smooth muscle is divided into two subgroups: the multiunit smooth muscle and the single-unit smooth muscle.
A syncytium is a group or sheet of cells that contract as a whole (for example, a mass of cytoplasm that is not divided into cells).
- Similarly, to motor unit enlistment in skeletal muscle, cells lined by multiunit smooth muscle tissues are able to control fine movements and steady reactions.
- Blood vessels contain smooth muscle (that is, smooth muscle explicitly known as vascular smooth muscle); for example, in the tunica media layer of big (aorta) and little passageways, arterioles, and veins.
- Lymphatic vessels, the urinary bladder, uterus (the uterine smooth muscle), male and female regenerative lots, gastrointestinal muscles, respiratory muscles, arrector pili of the skin, ciliary muscles, and the eye iris contain smooth muscle as well.
- The design and capacity of smooth muscle cells in various organs is essentially similar, but the process of instigating upgrades varies considerably to make distinct impacts on the body at particular times.
- Mesangial cells, which are smooth muscle-like cells, are located within the glomeruli of the kidneys.
Anatomy of Smooth Muscles
The cells that make up the walls of our blood vessels, intestines, and other organs are called smooth muscle cells (SMCs). SMCs are different from the skeletal muscle cells that make up our muscles because they don’t attach to bone or cartilage.
- SMCs are found in tissues throughout the body where they contract (tighten) to change the shape of the organ or help move food and other material through the tissue.
- Smooth muscle cells are found in the walls of blood vessels, the digestive tract, the bladder and other organs.
- These cells are responsible for involuntary muscle contractions.
- The tunica media is the middle layer of the three tunics that make up the wall of an artery.
- The tunica media consists of numerous layers of longitudinal and circular smooth muscle cells, with a small amount of connective tissue between them.
- The arrangement of these cells allows the tunica media to contract, which affects the calibre (width) of the artery.
Cardiac Muscle
The cardiac muscle has striated muscle cells, which means that bands of protein run through them. These bands give the cardiac muscle its characteristic striped look. The cardiac muscle cells can also contract independently as well as in unison, making them unique.
- Cardiomyocytes can contract both independently (i.e., without any assistance from other cells) and in coordination with other cells. As a result, the heart beats rhythmically and pumps blood throughout the body.
- Involuntary cardiac muscles have striated fibres that are found in the heart’s wall and histological foundations, specifically its myocardium.
- Cardiomyocytes (also called myocardiocytes or cardiomyocytes) have a single core, despite populations with two or four cores existing.
- The myocardium is a muscular layer in the heart positioned between the internal endocardium and the external epicardium layer.
- Cardiac muscle cells engage in facilitated withdrawals in the heart that push blood from the atria and ventricles into the left and right bodies as well as lungs. The systole of the heart is determined by this complicated system.
- Contrary to most other tissues in the body, cardiac muscle cells depend on a blood and electricity supply to convey oxygen and supplements, and to eliminate waste products, such as carbon dioxide. The coronary vessels facilitate this function.
Skeletal Muscle
Approximately 40% of the body’s muscle mass consists of skeletal muscles, which are attached to the bones by tendons. These muscles have two types: striated and smooth. The arm, leg, and torso striated muscles can be voluntarily contracted because they are under conscious control.
- The smooth muscles found within internal organs cannot be controlled by the conscious mind. The skeleton contains striated muscle tissue that enables voluntary movement.
- The muscles are attached to the bones and can be controlled consciously. It is made up of a large number of long, thin cells known as muscle fibres. These fibres are arranged into bundles known as fascicles.
- Skeletal muscles are shaped and sized depending on how many fascicles they have. A skeletal muscle’s striae are caused by sarcomeres, which are protein filaments that overlap like beads on a string. It is these filaments that contract the muscle.
- The spinal cord supplies nerves to the skeleton’s muscles.
- A neurotransmitter called acetylcholine is released from these nerves and binds to muscle cell receptors to cause contraction. These receptors are also able to be activated by the neurotransmitter glutamate.
Anatomy Of Smooth Muscle
Movement is controlled by the skeletal muscles. To move, they contract and relax along bundles of muscle fibres. Skeletal muscle fibres are classified as slow-twitch (ST), fast-twitch (FT) and intermediate-twitch (IT).
- This type of fibre has a low contraction speed but an extremely high endurance. Unlike fast-twitch fibres, slow-twitch fibres are low energy producers. Moderate contractility and endurance are found in intermediate twitch fibres.
- The muscles are attached to the bones by tendons. Tendons and muscles together as well. Tendons transfer force between muscles and bones. A synovial sheath covers them, and they are composed of dense connective tissue. A lubricating fluid is secreted by the synovium to help the tendon slide over the bone.
Conclusion
It is the body’s contractile tissues that make muscles. All voluntary movement is controlled by these muscles, which are connected to the bones by tendons. Skeletal, cardiac, and smooth muscle tissue makes up the three types of muscle tissue.