The Muscular System

Muscles Facts• Are there more muscles or bones?– Muscles (around 640)

• Each lb of muscle burns 75-100 calories a day just by being

Muscles Facts (cont.)

• Approximately 40% of your body weight is muscle

• Largest muscle = gluteus maximus

Muscles Facts (cont.)

• Smiling uses 17 muscles

• Frowning uses 43 muscles

Muscle Basics

• Muscles are made of bundles of protein fibers

Types of Muscle1. Skeletal muscle• attached to bones of skeleton

• Voluntary(we control them)

most of the meat we eat is this tissue

Types of Muscle (cont)

2. Cardiac muscle• found only in heart• not connected to bone

• involuntary (we don’t control)

Types of Muscle (cont.)

3. Smooth muscle• found in organs & blood vessels

• not connected to bone• involuntary

Muscular System Problems

• Strain: tearing of fibers

• Cramp: not enough oxygen, overuse

• Muscular Dystrophy: nerve messages to muscles are blocked

Steroids• Increase rate of muscle growth

• Stop bone growth• Side Effects: Heart attack, shriveled testes, etc.

Exercise & Muscles• When muscles are not used the cells become smaller & weaker

• Two main types of exercise: aerobic & anaerobic

Aerobic Exercise• Oxygen used rapidly by muscles

Uses slow twitch muscle• Glucose broken down• Ex: swimming & jogging

Anaerobic Exercise• High intensity Uses fast twitch muscle• Glucose converted to lactic acid (muscle burn)

• Ex: sprinting & weight lifting