1. Muscles that attach to bones and the connective tissue that attaches them make up the muscular system.Muscles that attach to bones and the connective tissue that attaches them make up the muscular system.

2. Types of Muscle Smooth MuscleSmooth Muscle –Found in the digestive tract and the blood vessels Cardiac muscleCardiac muscle –Special type of muscle found only in your heart Skeletal musclesSkeletal muscles –Attached to your bones for movement, and they help protect your inner organs

3. Skeletal Muscle

4. Cardiac Muscle

5. Smooth Muscle

6. Muscle action can be voluntary or involuntaryMuscle action can be voluntary or involuntary Muscle action that is under your control is voluntaryMuscle action that is under your control is voluntary Muscle action that is not under your control is involuntaryMuscle action that is not under your control is involuntary Smooth muscle and cardiac muscle are involuntarySmooth muscle and cardiac muscle are involuntary Skeletal muscles can be both voluntary and involuntarySkeletal muscles can be both voluntary and involuntary –You can blink your eyes any time you want to, but your eyes will also blink automatically if you do not think about it.

7. When you want to make a movement, you cause electrical signals to travel from the brain to the skeletal muscle cells.When you want to make a movement, you cause electrical signals to travel from the brain to the skeletal muscle cells. The muscle cells respond to these signals by contracting or getting shorter.The muscle cells respond to these signals by contracting or getting shorter. It takes an average of 13 muscles to smile and an average of 43 muscles to frown

8. Strands of tough connective tissue called tendons connect your skeletal muscles to your bonesStrands of tough connective tissue called tendons connect your skeletal muscles to your bones

9. Many basic movements are the result of muscle pairs that cause bending and straightening.Many basic movements are the result of muscle pairs that cause bending and straightening. If a muscle bends part of your body, then that muscle is called a flexorIf a muscle bends part of your body, then that muscle is called a flexor If the muscle straightens part of your body, then it is called an extensorIf the muscle straightens part of your body, then it is called an extensor

10. Skeletal muscles, such as the biceps and triceps muscles, work in pairs.Skeletal muscles, such as the biceps and triceps muscles, work in pairs. When the biceps muscle contracts, the elbow bends.When the biceps muscle contracts, the elbow bends. When the triceps muscle contracts, the elbow straightensWhen the triceps muscle contracts, the elbow straightens

11. When muscles are not exercised, they become smaller and weakerWhen muscles are not exercised, they become smaller and weaker When muscles are exercised, they contract allowing blood vessels in that muscle to get squeezed. This helps push blood along, increasing blood flow without demanding more work from the heart.When muscles are exercised, they contract allowing blood vessels in that muscle to get squeezed. This helps push blood along, increasing blood flow without demanding more work from the heart.

12. Resistance Exercises To develop the size and strength of your skeletal muscles, resistance exercises are the most effective form of exercise.To develop the size and strength of your skeletal muscles, resistance exercises are the most effective form of exercise. Resistance exercises require muscles to overcome the resistance of another object.Resistance exercises require muscles to overcome the resistance of another object.

13. Aerobic Exercise Aerobic Exercise increases the size and strength of your skeletal muscles somewhat, but mostly it strengthens the heart while increasing the endurance of your skeletal muscles.Aerobic Exercise increases the size and strength of your skeletal muscles somewhat, but mostly it strengthens the heart while increasing the endurance of your skeletal muscles.

14. A muscle strain, commonly called a pulled muscle, is the overstretching or even tearing of a muscle. Muscle strain often occurs because the muscle has not been properly conditioned for the workA muscle strain, commonly called a pulled muscle, is the overstretching or even tearing of a muscle. Muscle strain often occurs because the muscle has not been properly conditioned for the work A damaged tendon can become hot or inflamed as your body tries to repair it. This painful condition is called tendinitis, and an extended period of rest is often required for the tendon to heal.A damaged tendon can become hot or inflamed as your body tries to repair it. This painful condition is called tendinitis, and an extended period of rest is often required for the tendon to heal.

15. Dangers of Anabolic Steroids Some people try to make their muscles larger and stronger by taking hormones called anabolic steroids.Some people try to make their muscles larger and stronger by taking hormones called anabolic steroids. Anabolic steroids are powerful chemicals that resemble testosterone, a male sex hormone.Anabolic steroids are powerful chemicals that resemble testosterone, a male sex hormone. The use of anabolic steroids threatens the heart, liver, and kidneys, and it can cause high blood pressureThe use of anabolic steroids threatens the heart, liver, and kidneys, and it can cause high blood pressure