MUSCULAR SYSTEM pp. 917-920

FUNCTION Support, movement, and protection

Types of Muscle

Types Skeletal Muscle Voluntary Muscle that moves bones Over 400 skeletal muscles Long cells with several nuclei along edge Stripes called striations visible under high power

TYPES 2. Smooth Muscle Involuntary muscles that protect organs Movement of intestines, esophagus, stomach, and other organs

TYPES 2. Smooth Muscle Contract slowly and smoothly Usually one nucleus per cell in middle No striations

TYPES 3. Cardiac Muscle Involuntary muscles Contract heart and certain blood vessels

TYPES 3. Cardiac Muscle Strongest type of muscle Only one nucleus per cell Branching Cells Some striations (not as much as skeletal)

MUSCLE STRUCTURE myofibril muscle cell (fiber)fascicle muscle

Muscle Structure Two types of proteins (actin and myosin) involved

Muscle Structure actin filaments anchored to Z line Sarcomere: functional unit from Z line to Z line

MUSCLE CONTRACTION contraction: shortening of sarcomere between Z – lines

MUSCLE CONTRACTION Myosin “heads” walk along the actin (shortens sarcomere) Movement of myosin requires ATP

MUSCLE FATIGUE The inability to contract the muscle due to the lack of ATP

Body Reacts by… Increasing breathing Increasing heart rate Increasing production of ATP by breaking down fats