Chapter 11: Muscle Tissue

All muscle types will respond to an electrical stimulus because all muscle cells are _________. excitable contractile striated involuntary isometric

Skeletal muscle is called ___________, because it is usually subject to conscious control. excitable contractile striated voluntary isometric

When a skeletal muscle lengthens, its __________ helps resist excessive stretching and subsequent injury to the muscle. thick filaments collagen actin troponin-tropomyosin complex varicosities

Extensibility refers to the ability of a muscle to stretch. True False

A dark band formed by parallel thick filaments that partly overlap the thin filaments is known as an H band. True False

Clinically, dystrophin is the most important noncontractile protein to occur in muscle fibers. True False

The sliding filament theory of muscle contraction has emerged from research only in the last 10 to 15 years. True False

Some smooth muscle is autorhythmic. True False

Which of the following marks the boundaries of a sarcomere? I bands H bands Z discs M lines A bands

Which of the following is predominately made up of myosin? G actin F actin The thin filament The thick filament The elastic filament

Which of the following contains overlapping thick and thin filaments? A band H band I band M line Z discs

Which of the following is not a purpose of the excess postexercise oxygen consumption (EPOC) in muscle? To neutralize carbon dioxide buildup To replenish the phosphagen system To oxidize lactic acid To serve elevated metabolic rate To restore resting levels of ATP and CP

Which muscle type depends solely on the sarcoplasmic reticulum as its calcium source? Skeletal muscle Smooth muscle Cardiac muscle Skeletal and smooth muscle Smooth and cardiac muscle

Which muscle(s) can contract without the need for nervous stimulation? Skeletal muscle only Smooth muscle only Cardiac muscle only Smooth and cardiac muscle Skeletal, smooth and cardiac muscle

80% of the lactic acid produced by skeletal muscle is converted to pyruvic acid by the __________. kidneys liver muscle tissue sarcoplasmic reticulum neuromuscular junction

During muscle contraction, a single myosin head consumes ATP at a rate of about __________ ATP per second. 1 3 5 7 9

Shortening a muscle while it maintains constant tension is called __________. complete tetanus incomplete tetanus an isokinetic contraction an isometric contraction an isotonic contraction

Which fibers are primarily responsible for producing lactic acid? Type I slow oxidative fibers Type IIA intermediate glycolytic fibers Type IIB fast glycolytic fibers Type I slow-twitch fibers Red fibers

Which of the following is an accurate comparison of skeletal muscle to smooth muscle? Smooth muscle contracts more slowly but relaxes more rapidly. Smooth muscle contracts more rapidly but relaxes more slowly. Smooth muscle contracts and relaxes more slowly. Smooth muscle consumes more ATP to maintain a given level of muscle tension. Smooth muscle depends on a nerve fiber to supply the calcium needed for contraction.

In order for muscle to continue contracting during anaerobic fermentation, which of the following is essential? Cholinesterase inhibitors Protease Myokinase Acetylcholinesterase Acid phosphatase

The minimum stimulus needed to cause muscle contraction is called the __________. threshold latent period twitch motor unit innervation

If one nerve stimulus arrives at a muscle fiber so soon that the fiber has only partially relaxed from the previous twitch, the most likely result will be __________. fatigue spasm incomplete tetanus complete tetanus flaccid paralysis

Which of the following is true concerning isotonic eccentric contraction? The muscle shortens but tension remains constant. The muscle lengthens but tension remains constant. The muscle tenses and shortens. The muscle tenses but length remains unchanged. The muscle lengthens and tension declines.

Which of the following has the largest mitochondria? Slow oxidative fibers Fast glycolytic fibers Cardiac muscle Smooth muscle Intermediate fibers

To stimulate muscle contraction, acetylcholine is released from the ___________ into the synaptic cleft. synaptic vesicles junctional folds sarcoplasmic reticulum sarcolemma terminal cisterna

The absence or inhibition of acetylcholinesterase at a synapse would lead to __________. flaccid paralysis tetanus atrophy numbness muscle wasting

Which statement best describes the goal of medications used to treat myasthenia gravis? To increase the number of acetylcholine receptors To decrease the number of synaptic vesicles To promote multiple motor unit summation To inhibit Ca2+ release from the sarcoplasmic reticulum To inhibit the function of cholinesterase

The process of engaging more motor units to increase the strength of a muscle contraction is called __________. wave summation recruitment temporal summation incomplete tetanus complete tetanus

Aerobic respiration produces approximately _________ more ATPs per glucose molecule than glycolysis does. 12 24 36 48 100

Athletes who train at high altitudes increase their red blood cell count, which increases their oxygen supply during exercise. Increased oxygen supply results in __________. increased glycolysis increased use of myokinase longer aerobic respiration longer anaerobic fermentation reduced ATP consumption

Cardiac muscle has very little capacity for regeneration because it lacks __________. satellite cells an endomysium sarcomeres dense bodies somatic nerve fibers

Which of the following would be caused by a contraction of smooth muscle? Goose bumps Blood leaving the left ventricle of the heart Elevating the eyebrows Blinking the eyelids Deep inspiration

The triads of a muscle fiber consist of __________. two A bands and one I band two T tubules and one terminal cisterna two terminal cisternae and one T tubule two thin myofilaments and one thick myofilament two thick myofilaments and one thin myofilament

As you are lifting a box, someone places extra weight on top of it. For your muscle to continue contracting and lifting the box, the muscle must __________. recruit more muscle fibers lower its threshold reduce its wave summation shift from isometric to isotonic contraction shift from slow-twitch to fast-twitch mode

The protein that acts as a calcium receptor in skeletal muscle is __________. F actin tropomyosin troponin titin dystrophin

Drugs called calcium channel blockers may be used to lower blood pressure by causing arteries to vasodilate. How do you suppose these drugs work? They prevent calcium from entering the sarcoplasmic reticulum of smooth muscle. They stimulate the calcium pump in smooth muscle, thus removing calcium from the calmodulin. They prevent calcium from exiting the sarcoplasmic reticulum in skeletal muscle. They prevent calcium from entering cardiac muscle, thus slowing down the heart rate. They prevent calcium from entering smooth muscle, thus allowing the muscle to relax.

Exposure to the bacterium Clostridium tetani causes continuous release of acetylcholine. What effect does this have on smooth muscle? Flaccid paralysis Spastic paralysis Lockjaw No effect Myocardial atrophy

Where is dystrophin, the protein that is defective in muscular dystrophy, normally found? Between the outermost myofilaments and the sarcolemma of a muscle fiber As a transmembrane protein of the sarcolemma In the Z discs of skeletal and cardiac muscle In the dense bodies of smooth muscle Bridging the gap between the sarcolemma and synaptic knob References Multiple ChoiceSection: 11.02

What is the purpose of motor nerve varicosities as they relate to smooth muscle? They link the thin filaments to the inside of the sarcolemma in smooth muscle. They reabsorb the decomposition products of acetylcholine after acetylcholinesterase breaks it down. They enable each cardiac myocyte to directly stimulate its neighbors. They release neurotransmitter onto smooth muscle cells. They prevent single-unit smooth muscle cells from pulling apart. References Multiple ChoiceSection: 11.07

The transfer of phosphate from CP to ADP is catalyzed by __________. myokinase creatinine cAMP creatine kinase ATP

What happens when acetylcholine stimulates its receptors in the neuromuscular junction? The release of Ca2+ from the sarcoplasmic reticulum decreases. The permeability of the sarcolemma to Na+ increases. The positive charge on the sarcolemma decreases. The threshold of the muscle fiber lowers. The inhibitory effect of acetylcholinesterase is overridden.

Which of the following best describes the resting membrane potential (RMP)? The intracellular environment is negatively charged. The intracellular environment has more positively charged sodium. The extracellular environment is negatively charged. It has a voltage of about +75 mV. It is dependent upon the absorption of potassium ions by the muscle fiber.

The sarcolemma of a resting muscle fiber is most permeable to __________. calcium potassium sodium lithium magnesium

What is the purpose of the triad? The triad stores sodium. The triad synthesizes ATP. The triad maintains the resting membrane potential. The triad removes acetylcholine from the synaptic cleft. The triad allows for Ca2+ release when a muscle fiber is excited.