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Muscles and Levers

Chapter 15, section 3

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Kinds of Muscle

•Skeletal muscle = muscles attached to bone

•Smooth muscle = involuntary muscles inside many internal organs (found in your digestive tract and walls of blood vessels)

•Cardiac muscle =heart muscle, involuntary

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Kinds of Muscle

• Involuntary = muscle not under your control▫Example: smooth and cardiac (digestion

and pumping your blood)

•Voluntary = muscle you control▫Example: skeletal (jumping up and down)

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Movement

•Tendons are strands of connective tissue that attach muscles to bones.

•When a muscle gets shorter or contracts, the two bones it is connected to move closer.

•Muscles often work in pairs to produce controlled motions.

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Movement

•The muscle that bends part of your body is a flexor.

•The muscle that straightens part of your body is an extensor.

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Levers in the Body•Read Page 478 and write down a

definition for the following words:•Lever

•Fulcrum

•Effort Force

•Load

•Mechanical Advantage

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Levers in the Body•Lever = rigid bar that pivots around a fixed point

•Fulcrum = fixed point

•Effort Force = force applied to the lever

•Load = force that resists the motion of the lever

•Mechanical Advantage = an increase in the amount of work that can be done with a lever.

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Match the Body Parts

•Bone is the….• LEVER!

• Joint is the…• FULCRUM!

•Muscle is the…•Effort Force!

•Now give an example of a lever system in your body, be sure to label what is the lever, fulcrum, etc.

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Three Classes of Levers

•The type of lever is determined by the location of the fulcrum, in relation to the load and the effort force.

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Class Picture Example

1st Tilting the neck

2nd Raising up on

the balls of your feet

3rd Lifting a book with your arm

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Use it or Lose it

•Exercised muscles are stronger and longer than those that are not used.

•Strong muscles can also help squeeze blood to the heart.

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Use it or Lose it

•Resistance Exercise strengthens skeletal muscles by working against a weight.

•Aerobic Exercise increases the muscle strength of the heart and increases endurance.

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Muscle Injury•Read page 481 and explain the terms

•Strain = when a muscle or tendon is over stretched or torn.▫Usually happens because of an inadequate

warm-up

•Tendonitis = an inflammation of the tendon that did not heal after a strain.

•Anabolic Steroids = drugs that make muscles stronger and damage the heart, liver, kidneys, and can stop bone growth.