Chapter 10 Anatomy

Identify the three types of skeletal muscle fibers

The three types of skeletal muscle fibers are (1) fast fibers (also called white muscle fibers, fast-twitch glycolytic fibers, Type II-B fibers, and fast fatigue fibers); (2) slow fibers (also called red muscle fibers, slow-twitch oxidative fibers, Type I fibers, and slow oxidative fibers); and (3) intermediate fibers (also called fast-twitch oxidative fibers, Type II-A fibers, and fast resistant fibers).

Identify the structural characteristics of smooth muscle tissue

Lack sarcomeres and is not nonstriated Thin filaments are anchored to dense bodies

Describe muscle fatigue

Muscle fatigue is a muscle's reduced ability to contract due to low pH (hydrogen ion buildup), low ATP levels, or other problems.

How do muscle fibers continuously synthesize ATP?

Muscle fibers synthesize ATP continuously by utilizing creatine phosphate (CP) and metabolizing glycogen and fatty acids. Most cells generate ATP only through aerobic metabolism in the mitochondria and through glycolysis in the cytosol.

Define oxygen debt

Oxygen debt is the amount of oxygen required to restore normal, pre-exertion conditions in muscle tissue.

Predict what would happen to a muscle if the motor end plate lacked acetylcholinesterase.

The motor end plate would be continuously stimulated by ACh, locking the muscle in place.

Can a skeletal muscle contract without shortening?

Yes, a skeletal muscle can contract without shortening. The muscle can shorten (isotonic, concentric), elongate (isotonic, eccentric), or remain the same length (isometric), depending on the relationship between the load (resistance) and the tension produced by actin-myosin interactions.

Where would you expect to find the greatest concentration of ca2+ in a resting skeletal muscle fiber?

sarcoplasmic reticulum

What would happen to a resting skeletal muscle if the sarcolemma suddenly became very permeable to calcium ions?

this would start the interactions between the thick and thin filaments and begin to contract the muscle.

Why would a sprinter experience muscle fatigue before a marathon runner would?

A sprinter requires large amount of energy for a short burst of activity. To supply this energy, the sprinter's muscles rely on anaerobic metabolism, it is less efficient in producing energy than aerobic metabolism, and the process also produces acidic wastes; this combination contributes to muscle fatigue.Marathon runners derive most of their energy from aerobic metabolism, which is more efficient and produces fewer wastes than anaerobic metabolism does.

Which activity would be more likely to create an oxygen debt: swimming laps or lifting weights?

Activities that require short periods of strenuous activity produce the greater oxygen debt, because such activities rely heavily on energy production by anaerobic metabolism. B/c lifting weights is more strenuous over the short term than swimming laps, which is aerobic activity, lifting weights would produce a greater oxygen debt.

Why do skeletal muscle fibers appear striated when viewed through a light microscope?

Because they are build of hundred of thousands of cylindrical structures

Which type of muscle tissue is least affected by changes in extracellular ca2+ concentration during contraction?

By changes in extracellular Ca2+ concentrations.-Most of calcium ions comes from SR-Most calcium ions that trigger a contraction in cardiac and smooth muscles come from the extracellular fluid (Skeletal muscle)

What feature of cardiac muscle tissue allows the heart to act as a functional syncytium?

Cardiac muscle cells are joined together by gap junctions, which allow ions and small molecules to flow directly between cells. As a result, action potential generated in one cell spread rapidly to adjacent cells. Thus, all the cells contract simultaneously, as if they were a single unit.

Compare and contrast skeletal muscle tissue and cardiac muscle tissue.

Compared, cardiac muscle (1) relatively small cells, (2) has cells with a centrally locked nucleus, (3) has T-tubules that are short & broad and do not form triads, (4)has an SR that lacks terminal cisternae & as tubules that contract the plasma membrane as well as T tubules, (5) has cells that nearly totally dependent on aerobic metabolism as a energy source, (6) contains intercalated discs that assist in stabilizing tissue structure and spreading action potentials

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

Epimysium: a dense layer of collage fibers that surround the entire muscle. (Separates muscle from nearby tissues and organs) Perimysium: divides the skeletal muscle into a series of compartments Endomysium: surrounds the individual skeletal muscle cells, called muscle fibers

Identify the common properties shared by muscle tissues.

Excitability: responsiveness or irritability, is the ability to receive and respond to a stimulus. Contractibility: the ability of a muscle cell to shorten it is stimulated Extensibility: is stretching movement of a muscle Elasticity: is the ability of a muscle to recoil

Which types of muscle fibers would you expect to predominate in the lef msucles of someone who excels at endurance acitvities, such as cycling or long-distance running?

Individuals who excel at endurance activities have a higher than normal percentage of slow fibers. Slow fibers are physiologically better adapted to this type of activity than fast fibers, which are less vascular and fatigue faster.

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

Muscles wouldn't be able to contract

Identify the primary functions of skeletal muscle.

Producing movement, maintaining posture and body position, supporting soft tissues, guarding body entrances and exits, maintaining body temperature, storing nutrients

Describe the components of a sarcomere.

Sarcomeres, the smallest contractile units of a striated muscle cell, are segments of myofibrils. Each sarcomere has a dark A band and light I bands. The A band contains the M line, the H band, and the zone of overlap. Each I band contains thin filaments, but not thick filaments. Z lines bisect the I bands and mark the boundaries between adjacent sarcomeres.

Describe the neuromuscular junction.

Site where the nerve fiber communicates with the muscle fiber

Describe the general age-related effects on skeletal muscle tissue

Skeletal muscle fibers become smaller in diameter, skeletal muscles become less elastic, tolerance for exercise decreases, the ability to recover from muscular injuries decreases

Identify the three types of muscle tissue and cite their major functions.

Skeletal muscle tissue moves the body by pulling our bones making us move. Cardiac muscle tissue pumps blood through the cardiovascular system. Smooth muscle tissue pushes fluid and solids along the digestive tract and other internal organs, and regulates the diameters of small arteries and respiratory bronchioles.

Why can smooth muscle contract over a wider range of resting lengths than skeletal muscle?

The loose organization of actin and myosin filaments in smooth muscle allows smooth muscle ton contract over a wider range of resting lengths.

Why does a muscle that has been overstretched produce less tension?

a muscles ability to contract depends on the formation of cross-bridges between myosin and actin. in a muscle that is overstretched, the myofilaments would overlap very little, so very few cross-bridges would form, making the contraction weak

How would a drug that blocks acetylcholine release affect muscle contraction?

interfere with cross-bridge formation and prevent muscle contraction