109 terms

chapter 9

Slow (oxidative), fatigue-resistant fibers
Depends on oxygen delivery and aerobic mechanisms
Fast (oxidative or glycolytic), fatigable fibers
Have very fast-acting myosin ATPases and depend upon anaerobic metabolism during contraction.
Slow (oxidative), fatigue-resistant fibers
Red fibers, the smallest of the fiber types.
Fast (oxidative or glycolytic), fatigable fibers
Contain abundant amounts of glycogen.
Slow (oxidative), fatigue-resistant fibers
Abundant in muscles used to maintain posture.
Slow (oxidative), fatigue-resistant fibers
A relatively high percentage are found in successful marathon runners.
Maximal stimulus
The stimulus above which no stronger contraction can be elicited, because all motor units are firing in the muscle
The phenomenon in which the contraction strength of a muscle increases, due to increased Ca2+ availability and enzyme efficiency during the warm-up.
Continued sustained smooth contraction due to rapid stimulation.
Wave summation
The situation in which contractions become stronger due to stimulation before complete relaxation occurs
Multiple motor unit summation
How a smooth increase in muscle force is produced
Z discs
A sarcomere is the distance between two ________.
I band
The ________ contains only the actin filaments.
The thicker filaments are the ________ filaments.
A band
Both actin and myosin are found in the ________.
A band
The myosin filaments are located in the ________.
Calcium ions
Serves as the actual "trigger" for muscle contraction by removing the inhibition of the troponin molecules.
A neurotransmitter released at motor end plates by the axon terminals.
Aerobic respiration
A metabolic pathway that provides for a large amount of ATP per glucose because oxygen is used. Products are water and carbon dioxide and ATP.
Calcium ions
Normally stored in the terminal cisternae of the sarcoplasmic reticulum
Creatine phosphate
Used to convert ADP to ATP by transfer of a high-energy phosphate group. A reserve high-energy compound.
Destroys ACh.
Once a motor neuron has fired, all the muscle fibers in a muscle contract
The thin filaments (actin) contain a polypeptide subunit G actin that bear active sites for myosin attachment.
The force of muscle contraction is controlled by multiple motor unit summation or recruitment.
Eccentric contractions are more forceful than concentric contractions
A motor neuron and all the muscle cells that it stimulates are referred to as a motor end plate.
Peristalsis is characteristic of smooth muscle
A contraction in which the muscle does not shorten but its tension increases is called isometric.
During isotonic contraction, the heavier the load, the faster the velocity of contraction
During isometric contraction, the energy used appears as movement
One of the important functions of skeletal muscle contraction is production of heat.
Oxygen debt refers to the oxygen required to make creatine phosphate.
Muscle contraction will always promote movement of body parts regardless of how they are attached.
Although there are no sarcomeres, smooth muscle still possesses thick and thin filaments.
Whereas skeletal muscle cells are electrically coupled, smooth muscle cells appear to be chemically coupled by gap junctions.
Single-unit smooth muscle is found in the intestines.
A resting potential is caused by a difference in the concentration of certain ions inside and outside the cell.
The effect of a neurotransmitter on the muscle cell membrane is to modify its ion permeability properties temporarily.
When a muscle fiber contracts, the I bands diminish in size, the H zones disappear, and the A bands move closer together but do not diminish in length.
The more slowly a skeletal muscle is stimulated, the greater its exerted force becomes
Contractures are a result of a total lack of ATP.
Smooth muscles relax when intracellular levels drop but may not cease contractions.
Recruitment is an option in a single-unit smooth muscle cell
muscle fibers degenerate and atrophy
With muscular dystrophy ________.
Which muscle cells have the greatest ability to regenerate?
a mixture of fiber types
Most muscles contain ________.
intense exercise of short duration
Fatigued muscle cells that recover rapidly are the products of ________.
increasing the stimulation up to the maximal stimulus
The strongest muscle contractions are normally achieved by ________.
motor units with larger, less excitable neurons
Which of the following would be recruited later in muscle stimulation when contractile strength increases?
increase in the number of muscle cells
Which of the following is not a usual result of resistance exercise?
remove the blocking action of tropomyosin
In skeletal muscle contraction, calcium apparently acts to ________.
Calcium ions bind to the ________ molecule in skeletal muscle cells.
stores oxygen in muscle cells
Myoglobin ________.
sarcoplasmic reticulum
An elaborate network of membranes in skeletal muscle cells that functions in calcium storage is the ________.
the area between two Z discs
A sarcomere is ________.
Immediately following the arrival of the stimulus at a skeletal muscle cell there is a short period called the ________ period during which the events of excitation-contraction coupling occur.
storing energy that will be transferred to ADP to resynthesize ATP
Creatine phosphate functions in the muscle cell by ________.
level in the cytoplasm drops
After nervous stimulation of the muscle cell has ceased, the calcium ________.
regulate intracellular calcium concentration
The major function of the sarcoplasmic reticulum in muscle contraction is to ________.
the arrangement of myofilaments
The striations of a skeletal muscle cell are produced, for the most part, by ________.
thick filaments
Which of the following are composed of myosin?
actin filaments
During muscle contraction, myosin cross bridges attach to which active sites?
Which of the following surrounds the individual muscle cell?
multiunit muscles
Smooth muscles that act like skeletal muscles but are controlled by autonomic nerves and hormones are ________.
no ATP is available to release attached actin and myosin molecules
Rigor mortis occurs because ________.
a change of temperature
Which of the following does not act as a stimulus to initiate a muscle contraction?
a sheetlike indirect attachment to a skeletal element
The term aponeurosis refers to ________.
The oxygen-binding protein found in muscle cells is ________.
The contractile units of skeletal muscles are ________.
The site of calcium regulation in the smooth muscle cell is ________.
a sarcomere
One functional unit of a skeletal muscle is ________.
enhance cellular communication during muscle contraction
The functional role of the T tubules is to ________.
bind to regulatory sites on troponin, changing the configuration
The role of calcium ions in muscle contraction is to ________.
The warm-up period required of athletes in order to bring their muscles to peak performance is called ________.
enhance the availability of calcium and the efficiency of enzyme systems
The main effect of the warm-up period of athletes, as the muscle contractions increase in strength, is to ________.
lactic acid
During vigorous excercise, there may be insufficient oxygen available to completely break down pyruvic acid for energy. As a result, the pyruvic acid is converted to ________.
refractory period
When a muscle is unable to respond to stimuli temporarily, it is in which of the following periods?
changes in length and moves the "load"
In an isotonic contraction, the muscle ________.
The muscle cell membrane is called the ________.
Smooth muscle contracts in a twisting way.
Smooth muscle is significantly different from striated muscle in several ways. Which of the following is true?
the site of calcium regulation differs
The mechanism of contraction in smooth muscle is different from skeletal muscle in that ________.
exhibit spontaneous action potentials
The cells of single-unit visceral muscle ________.
There is no biological basis for the difference in strength between women and men.
Which of the following statements is not true concerning developmental aspects of muscle?
Certain smooth muscle cells can actually divide to increase their numbers.
Which of the following is true about smooth muscle contraction?
there are more thick filaments than thin filaments
Smooth muscle is characterized by all of the following except ________.
Muscle tissue has all of the following properties except ________.
A band
The giant protein titin maintains the organization of the ________ assisting in muscle stretching.
Striated muscle cells are long and cylindrical with many nuclei.
Which of the following statements is true?
An anaerobic metabolic pathway that results in the production of two net ATPs per glucose plus two pyruvic acid molecules is ________.
a state of sustained partial contraction
Muscle tone is ________.
actin and myosin sliding past each other and partially overlap
The sliding filament model of contraction involves ________.
acetylcholinesterase destroying the ACh
After nervous stimulation stops, ACh in the synaptic cleft is prevented from continuing stimulation of contraction by ________.
Muscle tension remains relatively constant during isotonic contraction.
Which of the following is most accurate?
the ability to transform chemical energy into mechanical energy
The most distinguishing characteristic of muscle tissue is ________.
a long, relaxing swim
Three discrete types of muscle fibers are identified on the basis of their size, speed, and endurance. Which of the following athletic endeavors best represents the use of red fibers?
multiunit smooth muscle
Of the following muscle types, which has only one nucleus, no sarcomeres, and rare gap junctions?
no muscle tension could be generated
Hypothetically, if a muscle were stretched to the point where thick and thin filaments no longer overlapped ________.
no contraction at all by nervous mechanisms, but contraction if stimulated by an external electrode
An individual has just ingested a chemical that binds irreversibly to the ACh receptors in the sarcolemma. By itself it does not alter membrane potential, yet prevents normal neurotransmitter binding. Ignoring the effects on any other system, the consequence to skeletal muscle would be ________.
Only ________ muscle cells are alwyas multinucleated.
Claudication might more simply be called ________.
The end of the muscle that typically moves when a muscle contracts is called the ________.
In the synaptic cleft of a neuromuscular junction, an enzyme called ________ is always present.
The time in which cross bridges are active is called the period of ________.
________ (color) fibers are slow (oxidative) fibers.
Only ________ muscle cells commonly branch.
A smooth, sustained contraction is called ________.
Fatigue occurs when ATP production fails to keep pace with ATP use even though the muscle still receives stimuli.
Define physiologic muscle fatigue.
Red muscles tend to have a slow (oxidative) rate and fatigue resistance, whereas white muscle cells have a fast (oxidative) rate and fatigue easily.
Compare red and white muscles relative to their speed of action and endurance.