Chapter 6

Section 6.1

She was born with a genetic defect which has left her looking like the Incredible Hulk of Hounds. While her head, heart, lungs and legs are the size of those of a normal whippet, her gene defect means she is "double muscled".

 Muscles are responsible for all types of body movement – they contract or shorten and are considered to be the machinery of the body  There are three (3) basic muscle types found in the body: smooth, cardiac, and skeletal.  Smooth muscle- located in walls of hollow, internal organs  Cardiac muscle- located in the heart  Skeletal muscle- attach to the bones, responsible for body movement

1. Muscle cells (fibers) are elongated 2. Contraction of these fibers is due to the movements of microfilaments 3. Terminology: myo - means muscle sarco - means flesh

1. Has no striations 2. Spindle shaped with a single nucleus 3. Involuntary 4. Found in the internal organs 5. Cells are arranged in parallel lines, forming sheets 6. Smooth muscle is slower to contract than skeletal muscle but can sustain prolonged contractions and does not fatigue easily

1. Single nucleated, striated, branched cells 2. Fibers contain intercalated disks- permit contractions to spread quickly throughout the heart. 3. Fibers relax completely between contractions preventing fatigue 4. Contractions are rhythmical 5. Involuntary

1. Fibers are tubular, multinucleated (more than 1 nucleus), and striated 2. Voluntary 3. Cells are covered and bundled together by connective tissue allowing them to produce great force but they fatigue easily 4. Muscles attach by tendons to bones

1. Endomysium – connective tissue around single muscle fiber 2. Perimysium – connective tissue around a fascicle, which is a bundle of fibers

3. Epimysium – covers the entire skeletal muscle 4. Fascia – on the outside of the epimysium

5. Epimysium blends into a connective tissue attachment: tendon : cord-like structure aponeuroses : sheet-like structure 6. Muscle attaches to bones, cartilage, and connective tissue coverings (periosteum)

1. Support- opposes the force of gravity and allows the body to remain upright 2. Movement 3. Helps maintain a constant body temperature (generate heat) 4. Assists movement in cardiovascular and lymphatic systems- pressure caused by your muscles keeps blood and lymph moving 5. Protect internal organs and stabilize joints