Muscle+System+hw+CH

=__**Muscular System**__= =__**SCI Human Biology - 2**__= =__**Assigned: 2/22 Due: 2/25**__= =__**Muscular System**__=
 * (1) What are the three types of muscles in the human body? (Describe and include pictures)**
 * 1) Smooth Muscle: spindle-shaped cells, each a uninucleated (a single nucleus)[[image:351Blabeled_copy.jpg width="195" height="150"]]
 * 2) Cardiac Muscle: forms the heart wall. [[image:muscle12.jpg width="247" height="167"]]
 * 3) Skeletal Muscle: fibers are tubular, multinucleated, and striated. They make up all the muscles attached to the skeleton.[[image:046.jpg width="239" height="159"]]


 * (2) List and discuss the functions of muscles.**
 * Support the body
 * Move bones in body
 * Maintain constant body temperature
 * Stabilize joints
 * Protect internal organs

When the tricep is raised, the forearm extends. However, when the bicep is raised, the forearm contracts.
 * (3) Give an example that illustrates how muscles work in antagonistic pairs.**


 * (4) Describe the microscopic anatomy of muscle fiber and explain the sliding filament model of muscle contraction. (long answer)**
 * Muscle fibers contain myofibrils, and myofibrils contain actin and myosin filaments. Muscle contraction occurs when sarcomeres shorten and actin filaments slide past myosin filaments.


 * (5) Describe the structure and function of the neuromuscular junction.**
 * Nerve impulses travel down motor neurons and stimulate muscle fibers at neuromuscular junctions.




 * (6) Describe the events as myosin pulls actin toward the center of the sarcomere.**
 * Threads of tropomyosin wind off an actin filament, and troponin occurs at intervals along the threads. Then the Myosin can now bind to the actin.


 * (7) Contrast a muscle twitch with summation and tetanus.**
 * A twitch is when a motor unit is stimulated by infrequent electrical impulses
 * Only one twitch occurs and lasts for only a fraction of a second
 * (8) What is muscle tone, and how is it maintained?**
 * When some motor units are always contracted but not enough to cause movement, the muscle is firm and solid. It is maintained by exercise.