Muscular system

Muscular system is the system of Human Body that provides motor power for all movements of body parts. Muscular system is composed of special tissue called muscular tissue.

Muscles have the ability to contract actvely to provide the force for movements of body parts.

It is an important system of human body because without it, life will completely stop.

Muscles produce not only those movements that are under the control of our will and that we can see and feel, but also those movements that are responsible for activities like breathing, digestion of food, pumping of blood etc.

The muscular system is the biological system of humans that produces movement.

The muscular system, in vertebrates, is controlled through the nervous system, although some muscles, like cardiac muscle, can be completely autonomous.

Muscle is contractile tissue and is derived from the mesodermal layer of embryonic germ cells.

Its function is to produce force and cause motion,either locomotion or movement within internal organs.

Much of muscle contraction occurs without conscious thought and is necessary for survival, like the contraction of the heart or peristalsis, which pushes food through the digestive system.

Voluntary muscle contraction is used to move the body and can be finely controlled, such as movements of the finger or gross movements that of the biceps and triceps.

The muscular system is made up of over 600 muscles, nearly all of them attached directly to the skeletal system at least twice. Myology, the study of muscles, determined that each muscle creates its own individual organs.

The muscular system contributes to approximately 40% of the body’s overall weight in an average sized individual.

The muscular system is comprised of more than just the muscles, it is also comprised of connective tissue and nervous tissue.

The muscular system is responsible for the body’s ability to move. Each muscle is dedicated to its own movement, one muscle for the movement of a finger, one muscle for the movement of the eyelid, and one muscle for the movement of tongue, However,a group of muscles might be responsible for a single body part, such as one muscle may move thelegforward but a different muscle moves the leg back.

While each individual muscle has its own dedicated job, it takes the cooperation ofmuscles to move an entire bodypart.

Muscle movement occurs when enough muscular impulses direct the muscle to create movement.

Muscles have a continuous although unnoticeable current of impulses running through them, although the impulses are far from significant enough to bring about movement.

The impulses which direct movement must reach a critical mass for muscles to respond appropriately and create movement within the body. Muscle cells only respond to these impulses.

Parts of the muscular system

While most people associate muscles with strength, they do more than assist in lifting heavy objects. The 650 muscles in the body not only support movement controlling walking, talking, sitting, standing, eating and other daily functions that people consciously perform but also help to maintain posture and circulate blood and other substances throughout the body, among other functions.

Muscles are often associated with activities of the legs, arms and other appendages, but musclesalso produce more subtle movements, such as facial expressions, eye movements and respiration, according to theNational Institutesof Health(NIH).

Skeletal muscle:

Skeletal muscles, like otherstriated muscles, are composed of myocytes, or muscle fibers, which are in turn composed ofmyofibrils, which are composed of sarcomeres, the basic building block of striated muscle tissue. Upon stimulation by anaction potential, skeletal muscles perform a coordinated contraction by shortening each sarcomere.

The best proposed model for understanding contraction is thesliding filament model of muscle contraction.

Within the sarcomere,actin and myosin fibers overlap in a contractile motion towards each other.

Myosin filaments have club-shaped heads that project toward the actin filaments.

Larger structures along the myosin filament called myosin heads are used to provide attachment points on binding sites for the actin filaments.

The myosin heads move in a coordinated style; they swivel toward the center ofthe sarcomere, detach and then reattach to the nearest active site of the actin filament.

This is called a ratchet type drive system.This process consumes large amounts ofadenosine triphosphate(ATP), the energy source of the cell.

ATP binds to the cross bridges between myosin heads and actin filaments. The release of energy powers the swiveling of the myosin head.

When ATP is used, it becomesadenosine diphosphate(ADP), and since muscles store little ATP, they must continuously replace the discharged ADP with ATP.

Muscle tissue also contains a stored supply of a fast acting recharge chemical,creatine phosphate, which when necessary can assist with the rapid regeneration of ADP into ATP.

Calcium ionsare required for each cycle of the sarcomere. Calcium is released from thesarcoplasmic reticuluminto thesarcomerewhen a muscle is stimulated to contract. This calcium uncovers the actin binding sites.

When the muscle no longer needs to contract, the calcium ions are pumped from the sarcomere and back into storage in thesarcoplasmic reticulum.

There are approximately 639 skeletal muscles inthe human body.

Smooth muscles:

Smooth muscles form the soft body organs like stomach, intestine, blood vessels etc.

They are not under the will of human beings and are responsible for unconscious body activities like digestion of food.

They are called smooth muscles because when seen under the microscope, they do not have any striation in contrast to theother two types of muscles.

Cardiac muscles: 

Cardiac muscles are exclusively found in human heart and no where else. They are extremely strong and powerful muscles.

They are not under the control of human will and areinvoluntary. The pumping of blood by human heart is because of the force provided by the contraction of cardiac muscles.

Functions of the muscular system

 

1. Mobility:

Mobility is your muscular system’s simplest and most crucial function. Your skeletal musclesare largely responsible for the movements and motions you make. Skeletal muscles are attached to your bones.

They’re controlled, in part, bythe central nervous system. You use your skeletal muscles whenyou bend, twist, stretch, run, and perform other movements.

Fast-twitch skeletal muscles cause short bursts of speed and strength, while slow-twitch muscles function better for longer movement.

2. Circulation:
The involuntary cardiac and smooth muscles help your heart beat and bloodflow through your body.

The cardiac muscle, known as the myocardium, is foundin the walls of heart.

The cardiac muscle is controlled by the autonomic nervous system, which is responsible for most bodily functions.

Did you know?

Your heart is considered to be the body’s hardest-working muscle.This muscle produceselectrical impulses, which help pump blood and cause yourheart to beat. It’s striated, like skeletalmuscles, and has one central nucleus, like a smooth muscle. Your blood vessels are made up of smooth muscles, and are also controlled by the autonomic nervous system.

Respiration:

Your diaphragm is the main muscle at work during quiet breathing. More labored breathing, like what you experience during exercise, may require accessory muscles to assist the diaphragm.

These may include the abdominal, neck, and back muscles.

Digestion:

Digestion is controlled by smooth muscles found in your gastrointestinal tract.

This comprises the:

• mouth
• esophagus
• stomach small
• large intestines
•  rectum
•  anus.

The digestive system also includes the liver, pancreas, and gallbladder.Your smooth muscles contract and relax asfood passes through your body during digestion.

These muscles also help push food out of your body, whether through defecation or vomiting when you’re sick.

Urination:

Smooth and skeletal muscles make up the urinary system.

The urinary system includes your:

 

• kidneys
• bladder
• ureter
• urethra
• penis or vaginaprostate

The dome of your bladder is made of smooth muscles. You’re able to release urine when those muscles tighten up. When they relax, you’re able to hold in your urine.

But all of the muscles in yoururinary system work together so you can urinate.

Child birth: Smooth muscles are also found in the uterus. During pregnancy, these muscles grow and stretch to compensate for the baby’s development.

When a woman is ready to go into labor, the smooth muscles of the uterus contract and relax to help push the baby through the vagina.

Vision: Your eye socket is made up of six skeletal muscles that help you move your eyes. Theinternal muscles of your eyes, though, are made up of smooth muscles. These muscles work together to help you see the world around you. If these muscles ever become damaged, your vision can become impaired.

Stability: The skeletal muscles in your core help with stability and protecting your spine. Your abdominal muscles, back muscles, and pelvic muscles make up your core muscle group. This core muscle group is also known as the trunk. The stronger your core, the better you’re able to stabilizeyour body. The muscles in your legs also help steady you.

Summary

The muscular system is an intricate and complex network of muscles that are vital to the human body.

Muscles play a part in everything you do, from chewing to dancing to sleeping. They control our heartbeat and breathing, help our digestion, and allow us to move in the world.Muscles, like the rest of your body, thrive on exercise and healthy eating.

But too much exercise can lead to sore muscles from overuse. Muscle pain can also be a sign that something more serious or chronicis affecting your body.

It’s important to take care of your muscles so they remain healthy and strong.

If you have a muscular condition such as muscular dystrophy, speak with your doctor about ways to maintain muscle health and manage your condition.