Types of Muscle Tissue• There are three different types of muscle

tissue– Skeletal– Smooth– Cardiac

Skeletal Muscles• Usually attached to bones

• They are responsible for voluntary movements, such as: Typing on a computer, dancing, or winking an eye.

• Most skeletal muscles are controlled by the central nervous system.

• Complete skeletal muscles consist of muscle fibers, connective tissues, blood vessels, and nerves.

The tissue most commonly thought of as muscle is skeletal muscle. Skeletal muscles cover your skeleton, giving your body its shape. They are attached to your skeleton by strong, springy tendons or are directly connected to rough patches of bone. Skeletal muscles are under voluntary control, which means you consciously control what they do.

Smooth Muscle• Usually not under voluntary control

• Found in the walls of a hollow structure such as the stomach, blood vessels, and intestines.

• Moves food through the body, controls the way our blood flows, and decreases the size of pupils in our eyes.

• Can function without nervous stimulation

Smooth muscle is found in the walls of hollow organs like your intestines and stomach. They work automatically without you being aware of them. Smooth muscles are involved in many 'housekeeping' functions of the body. One functions is that your intestines contract to push food through your body.

Cardiac Muscles• Is only found in one place in the body, the heart

• Striated like the skeletal muscles, but the cells are smaller

• they usually have one nucleus, but they may have two

• Doesn’t need to be under the direct control of the central nervous system

Your heart is made of cardiac muscle. This type of muscle only exists in your heart. Unlike other types of muscle, cardiac muscle never gets tired. It works automatically and constantly without ever pausing to rest. Cardiac muscle contracts to squeeze blood out of your heart, and relaxes to fill your heart with blood.

Muscle Contraction• Muscle fibers in skeletal muscles are composed of smaller

structures called Myofibrils. Each Myofibrils is made up of even smaller structures called Filaments.

• The thick filament contain a protein called Myosin.

• The thin filament are made up mainly of a protein called Actin.

• The tiny myosin and actin filament are the force producing engines that cause a muscle to contract.

• A muscle contracts when the thin filaments in the muscle fiber slide over the thick filament, this is called sliding filament model of muscle contraction.

Control of Muscle Contraction• Neuromuscular Junction- the point of contract

between a motor neuron and a skeletal muscle cell.

• Each muscle contains hundreds of cells– This is the difference between a strong contraction and a

weak contraction.

• When you lift something light, such as a sheet of paper, your brain stimulates only a few cells in each arm muscles to contract, but if you use maximum effort, like a rock climber you use almost all of your muscle cells in your arms.

How Muscles and Bones Interact• Skeletal muscles are joined to bones by tough

connective tissues called tendons.

• Tendons are attached in a way that they pull on the bones and make them work like levers

• Most skeletal muscles work in opposing pairs. When one muscle contracts, the other relaxes.

– Biceps contracting- bends, or flexes the elbows joint.

– Triceps contracting- opens, or extends the elbows joint

Exercise and Health• Skeletal muscles are normally in a partial contraction called resting muscle tone.

• Muscle tone- responsible for keeping the back and legs straight and the head upright, even when you are relaxed.

• Regular exercise is important in maintaining muscular strength and flexibility.

• Muscles that are exercised regularly– Stay firm and increase in size and strength by adding actin and myosin filaments

• Aerobic exercises– Running and swimming – Aerobic exercise helps your heart and lungs become more efficient

• Resistance exercises– Weight lifting– Helps maintain coordination and flexibility