Types, Function, and Components Chapter 9 Section 9.4 -1 Muscular System Types, Function, and Components Chapter 9 Section 9.4 -1

Three Types of Muscle

Cardiac Muscle Found only in the heart. Contraction is INVOLUNTARY – happens automatically. Controlled by autonomic nervous system

Smooth Muscle Found in the lining of many organs. stomach esophagus uterus, etc. Contraction is INVOLUNTARY. Responsible for moving food through the digestive system and for the delivery of a baby.

Skeletal Muscle Muscle that is attached to bones of skeleton and allows movement. Contraction is VOLUNTARY - we have the ability to control their movement.

Functions of Skeletal Muscles Support body Opposes force of gravity Makes bones move Contraction allows movement of limbs Maintains a constant body temperature Contraction causes ATP to break down, releasing heat to body to warm us up Helps protect the internal organs and stabilize the joints

Arrangement of Skeletal Muscles Skeletal muscles are arranged in pairs. The pairs work against each other to make a joint move. Because they work against each other they are called antagonistic muscles.

Antagonistic Muscles For the action of ONE muscle, there is ANOTHER muscle that has the OPPOSITE action. One contracts as the other muscles relaxes. Ex) Biceps and Triceps - When bicep contracts and tricep relaxes, bones forming elbow joint are brought closer together

Flexor vs. Extensor Muscles Flexor – the muscle that must contract to bend a joint (biceps). Extensor – the muscle that must contract to straighten a joint (triceps).

Skeletal Muscle Organization sarcolemma myofibril

Skeletal Muscle Organization Bundles of Muscle Fibre Sarcolemma Muscle Fibres Myofibrils Myofilaments

Skeletal Muscle Organization Skeletal muscle is composed of several bundles of cells called muscle fibres. The fibres are enclosed within a membrane called the sarcolemma that regulates the movement of material in and out of the muscle. Within the muscle fibres are myofibrils. And within the myofibrils are tiny myofilaments bundled together.

Skeletal Muscle Organization 2 Different types of Myofilaments 1. Thick Filaments Made of bundles of protein called MYOSIN. 2. Thin Filaments Made of bundles of protein called ACTIN. They overlap to produce a striped appearance.

Skeletal Muscle Organization Blood vessels and nerves run in between muscle fiber bundles. They supply muscle fibers with what they need to contract (nutrients, oxygen). Nerves trigger muscle contractions.

Muscle Fatigue Muscles begin to fatigue when the energy demand exceeds the amount of ATP that can be produced from aerobic cellular respiration. When oxygen is limited anaerobic cellular respiration will kick in and produce lactic acid. The lactic acid builds up in the muscles causing cramps.

Fighting Muscle Fatigue A compound called creatine phosphate helps to reduce muscle fatigue by regenerating ATP supplies. The creatine phosphate lends a phosphate to ADP to produce more ATP, helping to prevent muscle fatigue.

Introductory Video http://videos.howstuffworks.com/hsw/8680-our-flexible-frame-types-of-muscle-video.htm