Muscular System

Muscular System

• Did you know you have more than 600 muscles in your body? They do everything from pumping blood throughout your body to helping you lift your heavy backpack. You control some of your muscles, while others — like your heart — do their jobs without you thinking about them at all

Function of the Muscular System

• Enables body and its parts to move. – Movement caused by ability of muscle

cells to shorten (contract).– Muscle cells shorten by converting

chemical energy to mechanical energy.– There are two types of muscle:

• Involuntary muscle: Muscles that you do not control consciously. Examples?

• Voluntary muscle: Muscles that you control consciously. Examples?

Types of Muscle Tissue

• Types of muscle tissue:– Skeletal Muscle• Voluntary muscle• Provide the force that

moves bones• Sometimes called

striated because of their striped appearance

• React quickly and tire quickly

• Attached to bones through tendons

Questions

• Are your skeletal muscles at work even when you are not moving? Explain

• What would happen if the tendons in your index finger were cut?

Types of Muscle Tissue

– Cardiac Muscle• Is only found in he

heart.• It is striated, but

involuntary.• Does not get tired.• It contracts

repeatedly using information from the brain

• The repeated contractions are called heartbeat.

Types of Muscle Tissue– Smooth Muscle

• Contractions are involuntary

• They work automatically to control movement inside your body.

• React slowly and tire slowly.

• Found in the blood vessels, esophagus, stomach, bladder, intestines, etc.

Questions

• How do voluntary and involuntary muscles differ?

• What is the role of smooth muscles in digestion?

• What would happen if your digestive system was composed of skeletal muscle?

Muscles at work

• Skeletal muscles can only move bones when the contract, so they have to work in pairs.

• While one muscle contracts, the other muscle in the pair relaxes to its original length.

• This is called movement in coordinating pairs.

When exercising to build muscular strength, why I it important to exercise both muscles in a muscle pair equally?

• Which two muscles are working in coordinated pairs to lift the dumbbell?

• When the dumbbell is up, which muscle is contracted?; Which is extended?

• When the dumbbell is down, which muscle is contacted?; Which muscle is extended?

Functions of skeletal muscle– Movement: Muscles produce movement

through contractions

– Posture: Few muscles are contracted; no movement

– Heat Production: Contraction of muscle fibers produces most of the heat required to maintain normal body temperature (this is why you shiver).

Muscular strength and flexibility

• Exercise improves muscle tone and posture, resulting in increased heart and lung function and reduces fatigue.

• To avoid injury, warm up thoroughly. This increases blood flow to the muscle. After warm-up, STRETCH. This increases flexibility and prepares your muscles for the more vigorous exercise ahead.