The Muscular System
Types of Muscle tissue There are 3 types of muscle tissue Skeletal Smooth Cardiac
Skeletal Muscle Usually attached to bones Are involved with voluntary movement Can be large and very long
Smooth Muscle Involuntary control Found in walls of hollow structures Stomach, blood vessels, and intestines Help move food through your digestive system and controls blood flow through your circulatory system.
Cardiac Muscle Your heart!! Shares characteristics of both skeletal and smooth muscle cells
Muscle Contraction Skeletal muscle fibers are made up of smaller structures called myofibrils, which are made up of: Myosin the protein in the thick filament Actin the protein in the thin filament
A muscle contracts when the thin filament (actin) moves over the thick filament (myosin)
Control of the Muscle Contraction Motor neurons connect the CNS to the skeletal muscle cells The neuromuscular junction is the point of contact between the motor neuron and a skeletal muscle cell To cause the muscle to contract, acetylcholine (a neurotransmitter) is released
The acetylcholine causes the release of Ca ions which trigger the actin and myosin filaments to interact and contract To stop the contraction the acetylcholine needs to stopped being released and destroyed by an enzyme
How Muscles and Bones Interact Skeletal muscles contract and pull on your bones to produce a movement Tendons are connective tissue that attach muscle to bones Joints act as the fulcrum Muscles work in opposing pairs, when one muscle contracts the other relaxes
Opposing muscle pairs
Exercise and Health Regular exercise is important in maintaining muscular strength and flexibility Exercised muscles will increase in size and strength, help with coordination, efficiency, and flexibility Unused muscles become weak and decrease in size