Muscular System 2018, Study notes of Biology

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Muscular System

Muscular System

Have you ever tried to sit still, without moving any muscles at all, for one minute? It’s impossible! Somewhere in your body, muscles are always working.

You use muscles when you eat and breathe. Muscles,

along with your skeleton, hold you upright and let

you move. If all of your muscles rested at once, you

would collapse. The muscular system is made up of

the muscles that let you move.

Kinds of Muscle

Your body has three types of muscle tissue—skeletal muscle, smooth muscle, and cardiac muscle. Some of these muscle tissues are involuntary, and some are voluntary. Below you can see a magnified view of each type of muscle in the body. Both skeletal and smooth muscles are found in many places in the body. Cardiac muscle is found only in the heart. Each muscle type performs specific functions in the body.

Skeletal Muscle

Skeletal muscles are attached to the bones of your skeleton, skin and fascia and provide the force that moves your bones. At each end of a skeletal muscle is a tendon. A tendon is a strong connective tissue that attaches muscle to bone. Skeletal muscle cells appear banded, or striated with light and dark tissue. For this reason, skeletal muscle is sometimes called striated (STRY ay tid) muscle.

Smooth Muscle

The inside of many hollow internal organs, such as the stomach, blood vessels, intestines, and urinary bladder contain smooth muscles. Smooth muscles even help your eyes focus. Smooth muscles are involuntary muscles. They work automatically to control certain movements inside your body, such as those involved in digestion. Unlike skeletal muscles, smooth muscle cells are not striated. Smooth muscles behave differently than skeletal muscles, too. Smooth muscles react more slowly and tire more slowly.

Smooth Muscle

For example, as the smooth muscles of your stomach contract, they produce a churning action. The churning mixes the food with chemicals, and helps to digest the food. The muscle of the arteries contracts and relaxes to regulate the blood pressure and the flow of blood.

Muscular System

Functions of the

Muscular System

1. Stabilize joints with their

TENDONS

2. Produce movement (including

standing upright)

3. Produce heat to maintain body

temperature

Muscle at Work

First, the biceps muscle on the front of the upper arm contracts to bend the elbow, lifting the forearm and hand. As the biceps contracts, the triceps on the back of the upper arm relaxes and returns to its original length. Then, to straighten the elbow, the triceps muscle contracts. As the triceps contracts to extend the arm, the biceps relaxes and returns to its original length. Another example of muscles that work in pairs are those in your thigh that bend and straighten the knee joint.

Use It or Lose It

What happens when someone wears a cast for a broken arm? Skeletal muscles around the broken bone become smaller and weaker. The muscles weaken because they are not exercised. Exercised muscles are stronger and larger. Strong muscles can help other organs, too. For example, contracting muscles squeeze blood vessels. This action increases blood flow without needing more work from the heart.

Muscle Injuries

However, despite taking proper precautions, muscles can become injured. A muscle strain , or pulled muscle, can occur when muscles are overworked or overstretched. Tendons can also be overstretched or partially torn., this is called tendonitis. (Rest is needed for it to heal)

Muscle Injuries

After a long period of exercise, a skeletal muscle can cramp. When a muscle cramps , the entire muscle contracts strongly and stays contracted. If you injure a muscle or tendon, it is important to follow medical instructions and to rest the injured area so it can heal.

Did you know!!!!!

There are over 650 muscles, which make up about 40% of the body's weight. The diaphragm is a muscle which makes us breathe. When it contracts and pulls down, air fills your lungs. When it relaxes and lifts up, air is pushed out of your lungs.

Picture from http://kidshealth.org/PageManager.jsp?lic=1&article_set=54399&cat_id= Brachioradialis Rectus Abdominus Sartorius Gastrocnemius Pectorals Deltoids Triceps Biceps External Obliques Quadriceps