MUSCLES & MOVEMENT Section 9.4

Three Types of Muscle Cardiac, Smooth, Skeletal

1. Cardiac Muscle ONLY found in the heart Contracts and relaxes involuntarily (heart beat) Controlled by nerves of the autonomic nervous system

2. Smooth Muscle Found in the lining of organs Lining of the stomach, the esophagus, uterus Walls of blood vessels Involuntary movement

Skeletal Muscle Attached to the bones of the skeleton via tendons Tendons – connective tissue that joins the muscle to the bone. Under conscious (voluntary) control

Muscle Movement Muscles shorten when they contract and lengthen when they relax Many skeletal muscles are arranged in pairs that work against each other to make a joint move. These are called ANTAGONISTIC MUSCLES

Biceps & Triceps When the biceps contracts and the triceps relaxes, the bones forming the elbow joint are brought closer together (bending your arm) When the biceps relaxes and the triceps contract, the two bones are moved apart (straightening your arm)

Actin and Myosine

Sliding Filament Theory

The Sliding Filament Theory – Student Task Read about “The Sliding Filament Theory” on page 301. Why is it called a “theory”? Discuss the interaction between myosin and actin during muscle movement. Discuss ATP and its connection to rigor mortis Muscle Contraction

Lesson Assignment Read about Muscle Fatigue – Page 301 Read about Motor System Injuries – Page 303 Review content on Page 298 – Page 300 Page 304 = #3, #5, #6