Chapter 12 study guide
Terms in this set (76)
Which is the smallest structure?
Myosin Heavy Chains
Which structural protein of skeletal muscle also acts as an enzyme?
Tropomyosin is pulled away from the actin active site
What happens when calcium binds troponin?
Because of their shape, muscle cells are also known as ________.
Thick filaments are composed of ________.
Ca 2+ comes from the extracellular fluid as well as the SR
How does the process of smooth muscle contraction differ from contraction in skeletal muscle?
They are electrically linked to one another
How are cardiac muscle cells similar to smooth muscle cells?
Towards one another
A flexor is a skeletal muscle whose shortening moves attached bones
Skeletal muscle cells are usually attached to bone by
More stationary bone
The origin is the end of the skeletal muscle that attaches to the
Relaxation of the extensor
For antagonistic muscle groups to move a limb, flexor contraction occurs coincident with
Rapidly conduct action potentials to the interior of the muscle fiber
The function of transverse tubules is to
________ is composed of multiple globular molecules polymerized to form long chains or filaments.
Most of the time, the parallel thick and thin filaments of the myofibrils are connected by ________ that span the space between myosin and actin molecules.
Striated muscles are so-called because of a repeating pattern of light and dark bands. One repeating unit of the banding pattern is called a
Thin filaments only
The I band contains
The H zone contains
Stabilize the position of the contractile filaments
The function of the titin protein is to
The sarcomere and the I band will shorten.
When a skeletal muscle generates enough force during contraction to shorten,
High energy crossbridges formed
The tension generated in a skeletal muscle fiber is directly proportional to the number of
Some myosin heads are forming crossbridges as others are releasing them
When a skeletal muscle cell contracts and the muscle shortens,
Bind to troponin which moves the tropomyosin
In order for high force crossbridges to form in contracting skeletal muscle, calcium must
actin and ATP
Each myosin head has a binding site for
Detaches from actin
As ATP binds to the myosin head at the beginning of a muscle contraction cycle, the myosin head immediately
Release of ADP from the Myosin
The molecular event that occurs immediately after the power stroke is the
Rotate into a position (cocked) to bind to actin
The hydrolysis of ATP causes myosin to immediately
Decreasing intracellular calcium
Which of the following would cause the crossbridge to transition from a high force state to a low force state?
Dihyropyridine (DHP) receptor (L-type calcium channel)
The action potential traveling along the t-tubule is detected by the
Channel for both Na+ and K+
The binding of acetylcholine to its receptor at the neuromuscular junction causes the opening of a
The contraction cycle is triggered by the rise in ________ released from the sarcoplasmic reticulum (SR).
The relaxation of skeletal muscle relies on the activity of the ________, which decreases cytoplasmic calcium concentration.
The brief period of time between the beginning of the action potential in the muscle and the beginning of contraction is referred to as the
________ is the backup energy molecule that can be rapidly converted to ATP in active skeletal muscle.
During heavy exercise, the ATP requirements of active muscle are likely to be met by metabolism of
Muscle fatigue arises primarily from failure in
Depletion of glycogen stores
The cause of skeletal muscle fatigue during extended submaximal exercise is primarily a(n)
Long contraction duration and high capillary density
Which of the following is a characteristic of slow-twitch oxidative skeletal muscle fibers?
Myosin ATPase isoform
The speed with which force is developed by skeletal muscles is determined by the
Length of the sarcomeres prior to contraction
Within a single fiber, the tension developed during a twitch depends upon the
Complete tetanus involves development of maximum tension
When comparing complete tetanus with unfused (incomplete) tetanus, which is true?
One neuron and all the skeletal muscle fibers it controls
A motor unit consists of
Motor units that control skeletal muscles involved with fine motor movements (eye muscles or the hands) have ________ muscle fibers than motor units that control more gross movements (gastrocnemius muscle of the lower leg).
A week contractile stimulus activates fast-twitch motor units
Which of the following statements is NOT correct regarding the motor units and their activation?
Which fibers generate more force?
Which fibers fatigue sooner?
The nervous system avoids muscle fatigue during submaximal contraction by
Inward extensions of the muscle cell membrane
Sarcolemma and Myofibril
Highly organized bundles of contractile proteins within a skeletal muscle cell
A single muscle cell
The muscle cell membrane
A bundle of adjacent muscle cells
The structures that serve as the attachment site for the thin filaments and mark the boundaries for one sarcomere.
The letter assigned to this structure stands for the German word for middle; it is the attachment site for the thick filaments.
The band with the most overlap between thick and thin filaments, which unevenly scatters light leading to its dark appearance.
All types of muscle generate heat by shivering when we are cold
Which of the following is not a correct statement concerning the muscles in the body?
Fascicles, collagen, blood vessels
Groups of adjacent fibers bundled together into units are called ________. These bundles are surrounded by the proteins ________ and elastin as well as ________ that deliver nutrients to the muscle cells.
Dihydropyridine (DHP) voltage sensing, ryanodine (RyR)
The T-tubular membrane contains ________ receptors that are ________ and therefore respond to action potentials. This receptor is mechanically linked to ________ receptors in the adjacent sarcoplasmic reticulum.
ATP, phosphocreatine, create kinase
In order to contract and relax, muscle cells require energy in the form of ________. The immediate backup energy source is ________ that requires the enzyme ________.
Troponin C, tropomyosin
Calcium, released by the sarcoplasmic reticulum, binds to ________ to move the ________, which allows actin to form a high-force crossbridge with myosin.
The heavy chain of myosin contains two important regions: the first acts as ________ to convert energy into movement whereas the second binds to ________.
Increase, does not change
As a muscle cell undergoes an eccentric contraction, sarcomere length will ________ as the length of the A band ________.
A contraction that generates enough force to move a load is known as ________, whereas one that generates force that equals the load is known as ________.
Series elastic elements
Before the entire muscle can change length, the force generated by the muscle must stretch the
In the lever system that characterizes the interaction between bones and muscle, the bones act as the ________ whereas the joints form the ________.
In order for the bicep muscle to shorten, the force applied by the muscle must be ________ the load applied at the hand.
A slower response to a stimulus and sustained without fatigue
Compared to skeletal muscle, contraction of smooth muscle cells is
Smooth muscle cells lack which protein(s)?
Each cell functions independent of its neighbor
Which of the following is NOT a property of single-unit smooth muscles?
Myosin light chain kinase
This protein is activated by the Ca2+-calmodulin complex to phosphorylate the myosin light chain protein.
Inositol trisphosphate (IP3) receptor channel
he calcium release channel in the smooth muscle sarcoplasmic reticulum that is opened by increases in phospholipase C activity is the
A change in smooth muscle cell tension in the absence of a change in electrical potential of the cells is described as a
Like skeletal muscle, contraction of cardiac muscle is under autonomic nervous control
Which of the following is NOT a correct comparison of cardiac myocytes to other muscle cell types?
In comparison to skeletal muscle, smooth muscle cells function over a ________ range of muscle lengths and exhibit a speed of contraction that is ________ than skeletal muscle.
The gap junctions in cardiac muscle are part of specialized cell junctions that are localized to the
depleted intracellular stores of calcium
Store-operated calcium channels open in response to
Stretch activated, blood vessels
A myogenic contraction describes the opening of ________ channels in smooth muscle cells in response to a distortion of the cell membrane that is commonly observed in ________.