A&P chapter 10

How would severing the tendon attached to a muscle affect the muscle's ability to move a body part?

The tendon attaches skeletal muscle to the bone. If the tendon were severed the muscle would be unable to move the bone.

Myofibrils

Branches of the T tubules encircle each myofibril. Shortening of the myofibrils is responsible for skeletal muscle fiber contractions. The action potential travels over the sarcolemma, through the T tubules to the myofibrils causeing them to shorten. This make the muscle contract. Myofibrils consist of bundles of myofilaments (protein filaments). Two types: 1. Thin filaments: primarily actin 2. Thick filaments: primarily myosin Myofibrils also contain titin (elastic myofilaments assoiciated with the thick filaments).

Transverse Tublues (T tubules)

narrow tubes whose surfaces are continuous with the sarcolemma and extend deep into the sarcoplasm. (conducts electrical impulses that have traveled through the sarcolemma)

Skeletal Muscle

6 Major Functions: 1. produce skeletal movement 2. maitain posture 3. support soft tissues 4. guard body entrances and exits 5. maintain body temperature 6. store nutrients contains: muscle tissue, connective tissue, blood vessels, and nerves

Sarcoplasmic Reticulum

A membrane complex that forms a tubular network around each individual myofibril. T tubules are tightly bound to the membranes of the SR wherever a t tubule cirles a myofibril. On either side of the T tubules the SR fuse to for a terminal sisternae. The combo of the two terminal cisternae and the T tubule for a triad.

The A band

1. M line: center of the A band 2. H band: a resting sarcomere, lighter region on either side of the M line. Contains no thin filaments. 3. The zone of overlap: is a dark region where thin filaments are located between thick filaments.

Features of a skeletal muscle fiber

1. Size: skeletal muscle fibers are very large 2. multinucleate: During developement, myoblasts fuse to form multinucleate skeletal muscle fibers. Each nucleas on the fiber was a myoblast. Those that do not fuse form the myosatelite cells.

Describe the Three connective tissue layers associated with skeletal muscle tissue.

1. epimysium: a denase layer of collagen fibers that surrounds the entire muscle(sepperate muscle from nearby tissues and organs). Connects to the deep fascia. Avascular 2. perimysium: divides the skeletal muscle into aseries of compartments. Each compartment contains a bundle of compartment called a fascicle. Contains: collagen, elastic fibers, elastic fibers, blood vessels, and nerves that supply the muscle fibers within the fascicles. 3. endomysium: surrounds the individual skeletal muscle cells, called muscle fibers, and loosely intercnnects adjacent muscle fibers. Flexible and elastic tissue layer: contains capillary networks, myosatelite cells ( stem cells for repair), and nerve fibers.

Identify the three types of muscle tissue

1. skeletal muscle 2. cardiac muscle 3. smooth muscle

A sarcomere contains:

1. thick filaments 2. thin filaments 3. proteins that stabilize the postitions of the thick and thin filaments 4. proteins that regulate the interactions between thick and thin filaments. Each sarcomere has dar bands called A band and light bands called I bands as well as an M line (middle).

The I band

Extends from the A band of the sarcomere to the A band of the next sarcomere.

Sarcomeres

Myofibrils are organized into repeating functional units called sacomeres. Sarcomeres are the smallestfunctional unitsof the muscle fiber. Interactions between the thick and thin filamentswithin the sarcomeres are responsible for muscle contraction.

Tendon

The collagen fibers of the epimysioum, perimysium, and endomysium at the ends of the muscle come together to form a tendon which attaches skeletal muscle to bone (usually).

Aponeurosis

The college fibers of the epimysium, perimysium, and endomysium at the ends of a muscle can come together to for a sheet or aponeurosis, which usually attaches skeletal muscle to bone.

Action Potentials

The electrical impulses that travel through the sarcolemma and T tubules that cause the muscle to contract.

Sarcolemma

The plasma membrane of a muscle fiber. It surround the sarcoplasm. (conducts electrical impulses)