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Health Science Education 1 Angie Pruitt, MSN, RN, CNS. THE MUSCULAR SYSTEM PART 2. Involuntary Movement and Lack Striations. SMOOTH MUSCLE. Smooth Muscle. Involuntary or unconscious control Contraction essentially the same as skeletal The cells have important differences.
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Health Science Education 1 Angie Pruitt, MSN, RN, CNS THE MUSCULAR SYSTEMPART 2
Involuntary Movement and Lack Striations SMOOTH MUSCLE
Smooth Muscle • Involuntary or unconscious control • Contraction essentially the same as skeletal • The cells have important differences.
Smooth Muscle • Elongatedwith tapering ends. (remember skeletal muscle was elongated with round ends) • Contains filaments of Actin and Myosin, organized differently, more random • NOTSTRIATEDbecause Actin and Myosin are arranged differently.
Smooth Muscle • Multiunit smooth muscle: • In irises of the eyes • Walls of the blood vessels. • Visceral smooth muscle: • more common type of smooth muscle • in the walls of hollow organs • stomach, intestines, urinary bladder, and uterus. http://www.youtube.com/watch?v=Ln09qihUi3g&feature=related
Smooth muscle fibers • One fiber is stimulated, the impulse moves over its surface exciting adjacent fibers • Visceral smooth muscles • Rhythmicity-a pattern of repeated contractions. Remember Peristalsis?? http://www.youtube.com/watch?v=o18UycWRsaA&feature=related
Smooth muscle like skeletal muscle contracts by reactions of Actin and Myosin.
2 neurotransmitters in smooth muscle: • Acetylcholine • Norepinephrine. • Stimulates contractions in some smooth muscles and inhibits contractions in others. • Hormones also affect smooth muscle.
Slower to contract and relax • Maintains a forceful contraction longer. • Change length without changing tautness • The stomach and intestinal walls stretch as the organs fill.
Moving on to Cardiac Muscle • This is called progress!
Cardiac Muscle • Only in the heart • Striated cells joined end to end, forming fibers. • Intercalated disks allow muscle impulses to pass freely so they travel rapidly from cell to cell.
Cardiac Muscle • Cardiac muscle is self exciting and rhythmic. A pattern of contraction and relaxation repeats again and again and causes the rhythmic contractions of the heart. • Cardiac muscle is involuntary.
Skeletal Muscle Actions • As stated previously, skeletal muscles provide a variety of body movements. • Each muscles movement depends on the kind of joint it is associated with and the way the muscle attaches on either side of that joint.
Origin and Insertion • Bones form moveable joints and function as levers. • End of a skeletal muscle fastens to a relatively immovable or fixed part at such a joint, • Other end connects to a moveable part of the other side of the joint. • The immoveable part is the origin • The movable end is its insertion
When a muscle contracts, its insertion is pulled toward its origin • Some muscles have more than one origin or insertion. • Example: the biceps has 2 origins. The word biceps means 2 heads. The head of a muscle is the part nearest its origin. • Attaches at 2 spots on the scapula
Individual muscles Muscles are named according to any of the following criteria: size,shape, location, action, number of attachments, or direction of its fibers.
Immovable Moveable