Anatomy 101: Chapter 10

During which period of a twitch contraction does the muscle action potential move along the sarcolemma of the muscle cell and trigger calcium release into the sarcoplasm? a) latent period b) contraction period c) relaxation period d) absolute refractory period e) relative refractory period

a) latent period

10) The contractile organelles of a skeletal muscle fiber are thread-like structures called a) myofibrils. b) myoglobin. c) mitochondria. d) Z discs. e) M lines.

a) myofibrils.

The site where a somatic motor neuron releases acetylcholine to stimulate a skeletal muscle fiber is called the a) neuromuscular junction b) synaptic end bulbs c) motor end plate d) myofibril e) sarcolemma

a) neuromuscular junction

Which of the following is referred to as the period of lost excitability in skeletal muscle fibers? a) refractory period b) contraction period c) latent period d) relaxation period e) wave summation

a) refractory period

Muscular tissue has several important properties, such as electrical excitability. Another property of muscular tissue is that it is able to stretch, and return to its original size and shape. Which property of muscular tissue is this? a) Conductivity b) Elasticity c) Extensibility d) Plasticity e) None of these are correct.

b) Elasticity

Native people of the Amazon basin in South America use curare, a poison, on arrows and blow darts, to paralyze and bring down small game. Which part of the sequence of events at the neuromuscular junction does curare specifically disrupt? a) release of acetylcholine (ACh) b) activation of ACh receptors c) production of a muscle action potential d) activation of acetylcholinesterase e) release of calcium from the terminal cisterns

b) activation of ACh receptors

Smooth muscle tone is maintained by the prolonged presence of _____ in the muscle cell's cytosol? a) ATP b) calcium ions c) phosphate ions d) myoglobin e) None of these choices.

b) calcium ions

When oxygen is plentiful inside a skeletal muscle cell, what happens to the pyruvic acid that is formed during glycolysis? a) it is converted into lactic acid b) it diffuses into mitochondria to be broken down to generate ATP c) it diffuses out of the cell and into the bloodstream d) it is used to convert creatine into creatine phosphate e) it is converted into glycogen

b) it diffuses into mitochondria to be broken down to generate ATP

Which of the following describe the regeneration capacity of cardiac muscle cells? a) limited, via satellite cells b) limited, under certain conditions c) considerable (compared with other muscle cells, but limited compared with epithelium), via pericytes d) all of these are correct e) none of these are correct

b) limited, under certain conditions

Which of the following consists of a somatic motor neuron and all the skeletal muscle fibers it stimulates? a) sarcomere b) motor unit c) neuromuscular junction d) muscle unit e) multi-unit smooth muscle

b) motor unit

Which of the following functions as a motor protein in all three types of muscle tissue? a) actin b) myosin c) troponin d) titin e) tropomyosin

b) myosin

What regulatory proteins can be found in the thin filaments of skeletal muscle fibers? a) troponin and titin b) tropomyosin and troponin c) myosin and titin d) titin and tropomyosin e) tropomyosin and myosin

b) tropomyosin and troponin

During muscle contraction by the sliding filament mechanism, thin filaments are pulled towards the a) Z disc. b) H zone. c) M line. d) A band. e) I band.

c) M line.

Which property of muscle gives it the ability to stretch without damage? a) electrical excitability b) contractility c) extensibility d) elasticity e) thermogenesis

c) extensibility

What type of skeletal muscle fiber would an Olympic quality weight lifter specifically be developing during training, to enhance his or her weight lifting power? a) slow oxidative fibers b)fast oxidative-glycolytic fibers c) fast glycolytic fibers d) all of these choices e) none of these choices

c) fast glycolytic fibers

Leg muscles are predominantly composed of which type of muscle fiber? a) slow oxidative b) fast glycolytic c) fast oxidative-glycolytic d) slow glycolytic e) fast oxidative

c) fast oxidative-glycolytic

This structure is unique to cardiac muscle cells, and allows individual cells to be firmly attached to each other (to provide mechanical strength during contraction), and also allow the action potential to spread rapidly through the cardiac muscle tissue, so that contractions are smooth and coordinated. a) desmosomes b) gap junctions c) intercalated discs d) Z discs e) sarcomeres

c) intercalated discs

Increasing the number of active motor units within a skeletal muscle is called a) wave summation. b) fused tetanus. c) motor unit recruitment. d) muscle tone. e) flaccidity.

c) motor unit recruitment.

A small amount of muscle tension and muscle definition (the appearance of muscle beneath the skin) is present even in a relaxed muscle. A person who is physically fit due to regular exercise, will have more of this characteristic of muscle tissue than someone who is not fit. What is this characteristic? a) muscle contraction b) muscle refraction c) muscle tone d) muscle refraction e) muscle recruitment

c) muscle tone

Which of the following molecules found in skeletal muscle cells binds oxygen that can later be used during aerobic metabolism to help generate ATP? a) creatine b) creatine phosphate c) myoglobin d) titin e) glycogen

c) myoglobin

Cross bridges are formed during muscle contraction when _____ on the thick filaments binds to _____ on the thin filaments. a) myosin; troponin b) actin; troponin c) myosin; actin d) actin; myosin e) actin; tropomyosin

c) myosin; actin

In a neuromuscular junction, the effect of acetylcholine (ACh) binding to receptors on the motor end plate lasts only briefly due to a) rapid uptake of the ACh into the myofiber. b) endocytosis of the ACh receptor into the myofiber. c) rapid destruction of ACh in the synaptic cleft by acetylcholinesterase. d) rapid destruction of ACh in the synaptic cleft by monoamine oxidase. e) diffusion of the ACh out of the synaptic cleft.

c) rapid destruction of ACh in the synaptic cleft by acetylcholinesterase.

Smooth muscle fibers do not have striations like skeletal and cardiac muscle cells do. This is because: a) the sarcomeres are smaller than in cardiac muscle cells and skeletal fibers, and aren't visible even when smooth muscle fibers are examined microscopically b) smooth muscle fibers contain only intermediate filaments, which aren't arranged in sarcomeres c) smooth muscle fibers contain thin and thick filaments, as well as intermediate filaments, but none of them are arranged in sarcomeres d) visceral smooth muscle fibers don't have striations, but multiunit smooth muscle cells do, but these cells are more rare, and so we rarely have a chance to view them with a microscope e) both b and d are correct

c) smooth muscle fibers contain thin and thick filaments, as well as intermediate filaments, but none of them are arranged in sarcomeres

Release of calcium from these structures triggers skeletal muscle contraction. a) myofibrils b) mitochondria c) terminal cisterns of sarcoplasmic reticulum d) T-tubules e) none of the answer choices

c) terminal cisterns of sarcoplasmic reticulum

Which of the following regions of the sarcomere contain thick filaments? a) zone of overlap b) A band c) H zone d) both A band and H zone e) All of these answer choices are correct.

e) All of these answer choices are correct.

The different types of muscle tissue differ from each other by a) microscopic anatomy. b) location. c) type of Control. d) both microscopic anatomy and location. e) All of these choices are correct.

e) All of these choices are correct.

Which of the following is a common effect of aging on skeletal muscle? a) loss of muscle mass b) decrease in maximal strength c) a slowing of muscle reflexes d) loss of flexibility e) all of these are correct

e) all of these are correct

Which type of muscle tissue is involuntary (can't be consciously controlled)? a) skeletal muscle b) smooth muscle c) cardiac muscle d) a and b only e) b and c only

e) b and c only

Which list of organs contains smooth muscle tissue? a) blood vessels, stomach, esophagus b) bladder, uterus, small intestine c) biceps brachii, triceps brachii (muscles of the arm) d) heart e) both blood vessels, stomach, esophagus and bladder, uterus, small intestine

e) both blood vessels, stomach, esophagus and bladder, uterus, small intestine

Which of the following proteins is used to reinforce the sarcolemma and to help transmit the tension generated by the sarcomeres to the tendons? a) troponin b) tropomyosin c) myosin d) actin e) dystrophin

e) dystrophin

Which of following is a common characteristic of fast glycolytic (FG) skeletal muscle fibers? a) large amount of myoglobin. b) many mitochondria. c) low concentration of creatine kinase in the sarcoplasm. d) slow myosin ATPase. e) high amount of glycogen in the sarcoplasm.

e) high amount of glycogen in the sarcoplasm.

Which of the following muscle groups would be more likely to have many small motor units (one motor neuron, and just a few muscle fibers under its control)? a) the muscles that control eye movement b) the postural muscles that control standing c) the muscles that control the many movements of the hands d) all of these choices would have many small motor units e) only a and c would have many small motor units

e) only a and c would have many small motor units

Depending on how specialized a type of muscle tissue is, the muscle fibers or cells of that tissue will have varied abilities to regenerate (healing and production of new cells). What type of muscle tissue has the greatest ability to regenerate? a) skeletal, cardiac and smooth muscle all have similar abilities to regenerate b) only skeletal and cardiac muscle cells can undergo limited regeneration c) only cardiac and smooth muscle cells can undergo regeneration d) although all muscle cells can undergo some regeneration, only skeletal muscle fibers can do it easily and frequently, especially when we regularly exercise e) smooth muscle cells have the greatest ability to regenerate

e) smooth muscle cells have the greatest ability to regenerate

Which of the following statements about creatine are correct? a) some studies have shown it boosts athletic performance when taken as a supplement b) some studies have shown no benefit to athletic performance when it is taken as a supplement c) it is harmful, and will cause kidney damage d) all of these choices are correct e) some studies have shown it boosts athletic performance when taken as a supplement and some studies have shown no benefit to athletic performance when it is taken as a supplement

e) some studies have shown it boosts athletic performance when taken as a supplement and some studies have shown no benefit to athletic performance when it is taken as a supplement

A brief contraction of all muscle fibers in a motor unit in response to a single action potential moving down the somatic motor neuron is known as a) isometric contraction. b) isotonic contraction. c) tetany. d) refractory period. e) twitch contraction.

e) twitch contraction.

In skeletal muscles, the combined amounts of creatine phosphate and ATP provide enough energy for the muscle to contract maximally for approximately a) 15 seconds. b) 15 minutes. c) 1.5 minutes. d) 5 seconds. e) one minute.

a) 15 seconds.

Which of the following types of muscle tissue contract when excited by their own autorhythmic muscle fibers? a) cardiac muscle b) slow twitch oxidative skeletal muscle c) multi-unit smooth muscle d) fast twitch glycolytic skeletal muscle e) All of these choices are correct.

a) cardiac muscle

Which of the following would not be a contributing factor to muscle fatigue? a) release of excessive amounts of acetylcholine at the neuromuscular junction b) a feeling that you want to quit, that the activity is too difficult (central fatigue) c) depletion of adequate supplies of oxygen and ATP d) a buildup of lactic acid e) all of these contribute to muscle fatigue

a) release of excessive amounts of acetylcholine at the neuromuscular junction

This is the least powerful type of skeletal muscle fiber. a) slow oxidative fiber b) fast oxidative fiber c) fast glycolytic fiber d) slow glycolytic fiber e) None of these choices.

a) slow oxidative fiber

If you are an endurance athlete, you especially rely on which type of skeletal muscle fiber to perform your sport? a) slow oxidative fibers b) fast oxidative-glycolytic fibers c) fast glycolytic fibers d) all of these choices are correct. e) none of these choices are correct.

a) slow oxidative fibers

Why does skeletal muscle require more ATP than many other tissues in the body? 1 both contraction and relaxation require ATP to occur 2 the sarcoplasmic reticulum uses ATP to "pump" calcium ions back into the terminal cisterns after contraction 3 ATP is needed to convert creatine into creatine phosphate needed to provide energy at the beginning of muscle contraction a) 1 only b) 2 only c) 3 only d) 1,2 &3 e) Only 1 and 3

d) 1,2 &3

Which of the following are commonly used to produce ATP during skeletal muscle contraction? a) creatine phosphate b) anaerobic cellular respiration c) aerobic cellular respiration d) All of these choices are correct. e) None of these choices are correct.

d) All of these choices are correct.

Which of the following regions of a sarcomere contain thin filaments? a) I band b) A band c) H zone d) Both I band and A band. e) All of these answer choices are correct

d) Both I band and A band.

Which of the following statements does NOT accurately describe aerobic cellular respiration in skeletal muscles? a) Pyruvic acid generated by glycolysis enters the mitochondria. b) O2 is essential. c) CO2 is produced as a waste product. d) Lactic acid is continually produced. e) Can be used to generate ATP from fats, proteins or carbohydrates.

d) Lactic acid is continually produced.

What type of tendon is formed when the connective tissue elements of a skeletal muscle extend as a broad flat layer? a) perimysium b) deep fascia c) fascicle d) aponeurosis e) endomysium

d) aponeurosis

Which of the following correctly lists the sequence of structures that action potentials must move through to excite skeletal muscle contraction? a) sarcolemma, axon of neuron, T tubules b) T tubules, sarcolemma, myofilament c) muscle fiber, axon of neuron, myofibrils d) axon of neuron, sarcolemma, T tubules e) myofibrils, myofilaments, mitochondria

d) axon of neuron, sarcolemma, T tubules

This is the outermost layer of connective tissue surrounding a skeletal muscle. a) tendon b) ligament c) endomysium d) epimysium e) perimysium

d) epimysium

Which of the regions of a sarcomere contain titin? a) the A band only b) the H zone only c) the zone of overlap only d) from M line to Z disc e) the I band only

d) from M line to Z disc

Which of the following microscopic structures is only found in the cardiac muscle tissue? a) myosin b) tropomyosin c) sarcomeres d) intercalated discs e) striations

d) intercalated discs

Which of the following is not a function of skeletal muscle tissue? a) moving your eyes from left to right as you read this question b) holding your head up c) shivering to generate body heat when you've become chilled d) moving food through the small intestine e) stabilizing joints and helping to maintain body positions

d) moving food through the small intestine

Skeletal muscle is covered, surrounded and protected by various layers of connective tissue. Which layer of connective tissue would surround a bundle of muscle fibers (muscle cells)? a) epimysium b) hypodermis c) fascia d) perimysium e) endomysium

d) perimysium

) The contractile organelle of skeletal muscle fibers is a) the endoplasmic reticulum b) the myofilament c) the T tubule d) the myofibril e) the sarcomere

d) the myofibril