MUSCLES

1. MUSCLES THE TYPES OF MUSCLES

2. Types of Muscles In the animal kingdom there are three types of muscle tissue: 1. Skeletal 2. Cardiac 3. Smooth These muscle tissue are responsible for movement and are contractile tissue.

4. SMOOTH MUSCLES FOUND IN THE HOLLOW PARTS OF THE BODY � like the stomach, intestines, blood vessels and your bladder!

6. Smooth muscles are arranged in layers with the fibers in each layer running in different directions. A smooth muscle is INVOLUNTARY!

7. You cannot consciously control these muscles. These muscles are under the control of the AUTONOMIC NERVOUS SYSTEM.

8. Smooth muscles have no STRIATIONS They contain less MYOSIN (we will learn what this is later) The muscle contractions are slow � but the range is greater

9. SKELETAL MUSCLES

11. Skeletal Muscles Move and support the skeleton Make up 50% of your body weight There are 640 individually named skeletal muscles These muscles link two bones across its connecting joint When these muscles contract or shorten, your bones move.

12. These muscles are arranged in layers over bones. Those nearest to the skin are called SUPERFICIAL MUSCLES. Those closest to the inside of the body are called DEEP MUSCLES. Skeletal muscles are VOLUNTARY MUSCLES.

13. We MAKE these muscles move! We consciously control these muscles. A muscles name usually describes its shape, location, or job. Some of these are: FRONTALIS �forehead DELTOID � moves shoulder and upper arm BICEPS � bends the arm

14. RECTUS ABDOMINIS � stomach muscles SARTORIUS � bends and turns the legs Muscles need oxygen and food for energy from your blood in order to work properly. If they work hard but do not get enough food for energy then they may go into a spasm and you feel the pain of a cramp!

16. Skeletal Muscle Structure These muscles are long fiber-like structures They contain nuclei and are subdivided into smaller structures called myofibrils. Myofibrils have 2 kinds of myofilaments. The thin ones are made of the protein ACTIN and the thick ones are made of the protein MYOSIN

17. Organization of Skeletal Muscles Filaments are organized into structures called SARCROMERES. Sarcromeres are constructed like this: �Z� lines are at the borders of the Sarcomeres. They line up next to the myofibrils. �I� bands are regions where thick and thin filaments overlap and are the same length as thick filaments.

18. �A� bands are regions where thick and thin filaments overlap and correspond to the length of the thick filaments. �H� zones are areas in the center of the �A� bands which contain only thick filaments.

21. OK! What makes these muscles move? Muscle contractions reduce the length of each sarcomere. It�s called the SLIDING FILAMENT THEORY.

22. Sliding Filament Theory Thin filaments move across the thick filaments to pull the �Z� lines together and shorten the sarcomere. The myofilaments do not contract.

23. Skeletal muscles contract when stimulated by motor neurons. Motor neurons usually deliver their stimuli rapidly. A motor unit consist of a single motor neuron

24. A motor neuron consist of a single motor neuron and all the muscle fibers it controls. As more motor neurons are recruited by the brain, tension in the muscle progressively increases. Slow fibers have longer lasting twitches. Fast fibers have short duration twitches and are found in fast muscles for rapid, powerful contractions.

25. CARDIAC MUSCLES

26. Have a heart! CARDIAC MUSCLE cells are striped (striated) like skeletal muscle cells. CARDIAC MUSCLE contract automatically to squeeze the wall of the heart inward.

27. The heart beat non-stop about 100,000 times a day. It does this because of the cardiac muscles. Most of your heart is made of cardiac muscles. It never gets tired, never stops working�.UNTIL YOU DIE!

28. Muscle cells in the heart are branched and the junctions between the cells contain intercalcated dics that electrically connect all heart muscle cells � allowing for a coordinated action. Cells can also generate their own potential.