The human muscular system comprises more than 600 muscles, which act in groups. Muscles are contractile organs or tissues that facilitate all types of movements involving the body parts (legs, arms, appendages, etc.), and even subtle movements (smiling, frowning, etc.).
Muscles are distinguished as either involuntary or voluntary. Involuntary muscles function within the body automatically, without you being able to control them. Voluntary muscles are the ones that are under your control. Besides facilitating movement, muscles also play a vital role in pumping blood, maintaining posture and stability, digestion, etc.
Muscles are made up of a type of elastic tissue, and each muscle comprises thousands of tiny fibers. Each fiber is composed of long thin cells that are packed in bundles, which in turn are wrapped in perimysium. Myosin and actin are proteins that are present in the fibers.
There are three kinds of muscles in the human muscular system: the skeletal muscle; the cardiac muscle; and the smooth muscle. Besides these, the facial muscles and the tongue are of a unique kind.
Types of Muscles
Generally, these are attached to the ends of bones, stretching all across the joint and then attached to another bone.
Tendons, which are cords or bands of inelastic tissue, attach these muscles to the bones. Skeletal muscles are of different shapes and sizes, which enable them to perform a variety of tasks. The gluteus maximus, or the muscle that occurs in the buttocks, is the largest skeletal muscle.
Some of the other major skeletal muscles include the deltoid muscle in the shoulders, the biceps and triceps in the arm, the pectoralis in the chest, the rectus abdominus in the abdomen, and the quadriceps and hamstring muscles in the legs.
Movements that we perform involve these muscles. For example, you cannot pick up an object with your hand unless you want your hand to do so. These muscles are sometimes referred to as striated muscles, because the dark and light fibrous material make them seem striped. Along with bones, these muscles form the musculoskeletal system of the human body.
These muscles are thick and contract in order to pump out the blood and then relax in order to allow more blood in. The cardiac muscle is an involuntary muscle, which means that it is not under our control. Special type of cells in the cardiac muscle, called the pacemaker, help in controlling the heartbeat.
These are the involuntary muscles of the human muscular system. These generally occur in layers or sheets, with one muscle layer behind another. These muscles are not under our control. The brain and the body control these muscles in performing their functions without any conscious volition from your part.
These don't have the striped or banded appearance of the skeletal muscles, which is why these are called smooth muscles. These are found inside organs such as the stomach, intestines, bladder, uterus, and blood vessels. These muscles play a vital role in digestion.
For instance, peristalsis (wavelike muscle contractions of the alimentary tract) moves the food along the digestive tract. Smooth muscles also occur in the eyes, which help to keep the eyes focused. According to scientists, the eyes can move over 100,000 times in a day, making them the busiest muscles.
On a concluding note, muscles are essential for the healthy functioning of the human body. If any of these muscles get damaged due to medical conditions, it can have an adverse impact on the quality of life of an individual.