Chapter 10
What happens when the muscles contract
Myosin pulls on actin, causing the thin filament to slide inward ●Consequently, Z discs move toward each other and the sarcomere shortens ●Thanks to the structural proteins, there is a transmission of force throughout the entire muscle, resulting in whole muscle contraction
3) 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
I band
Lighter, less dense area of sarcomere that contains remainder of thin filaments but no thick filaments. A Z disc passes through center of each I band.
capacity for generating ATP and method used Slow oxidative Fast oxidative Fast glycolytic
Slow - high by aerobic respiration's Fast - intermediate, by bother aerobic respiration and anaerobic glycolysis Fast G- low by anaerobic glycolysis
Rate of ATP hydrolysis Slow oxidative Fast oxidative Fast glycolytic
Slow oxidative- slow Fast oxidative -fast Fast glycolytic-fast
17) 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
21) 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
11) 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
muscle metabolism How do muscles derive the ATP necessary to power the contraction cycle?
Creatine phosphate ●Anaerobic glycolysis ●Cellular respiration
13) 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
18) 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
1) 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
14) 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
19) 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
2) 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
2) 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
isometric contraction
Isometric - muscle contracts but does not change length. Tension increases greatly.
M line
Region in the center of h zone that proteins that hold thick filaments together at center sarcomere
Appearance of muscle Skeletal Cardiac Smooth
Skeletal - multi-nucleated & striated Cardiac- one nucleus, striated, & intercalated discs Smooth- one nucleus & no striations
types of muscular tissue Cardiac Skeletal Smooth
Skeletal muscle - mainly voluntary but some involuntary. Striated. 2.Cardiac muscle - Involuntary. Striated. 3.Smooth muscle - Located in walls of hollow internal structures, such as blood vessels, airways, and most organs. Non-striated (looks smooth).Involuntary. 3 Types of Muscular Tissue
Skeletal muscle fibers Slow oxidative Fast oxidative glycolytic Fast glycolytic
Slow oxidative -dark red=much myoglobin and blood capillaries. Lots mitochondria = ATP by aerobic respiration. Myosin hydrolyzes ATP slowly. Contraction 100-200 msec. Resistant to fatigue. ●Fast oxidative glycolytic-Like SO but intracellular glycogen is high and generate ATP by anaerobic glycolysis.Myosin heads hydrolyse ATP 3 times faster than SO ●Fast glycolytic-Large amounts glycogen. Intense anaerobic
Question type: True/False 25) To delay the onset of muscle fatigue, not all the motor units in a muscle will contract at the same time. Some will remain relaxed while others are contracting. If the contraction continues, and greater force is needed, more motor units will be recruited.
True
Question type: True/False 35) Nearly all muscles of the body develop from an early embryonic layer of cells called the mesoderm.
True
Aponeurosis
When connective tissue elements extend as a broad flat sheet = aponeurosis
A band
dark, middle part of sarcomere that extends entire length of thick filaments and includes those parts of thin filaments that overlap thick filaments
sacroplasmic reticulum
= calcium
23) 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
55) Which of the following disorders is characterized by the wasting away of muscles due to the progressive loss of myofibrils? a) muscular hypertrophy b) muscular atrophy c) fibromyalgia d) myasthenia gravis e) tremors
B
28) 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
10) 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
16) 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
28) 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
29) 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
31) 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
4) Which property of muscle gives it the ability to stretch without damage? a) electrical excitability b) contractility c) extensibility d) elasticity e) thermogenesis
C
19) 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
66) 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
67) After prolonged strenuous exercise has stopped, heavy breathing will often continue for several minutes in order to provide the oxygen needed to a) convert the lactic acid produced during exercise back into glycogen. b) resynthesize creatine phosphate. c) replace oxygen displaced from muscle myoglobin. d) All of these choices e) None of these choices
D
7) 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
Electromyograph
EMG uses tiny devices called electrodes to transmit or detect electrical signals
64) Which of the following types of abnormal contractions of skeletal muscle may be caused by holding a position for a prolonged period? a) spasm b) fasciculation c) tremor d) fibrillation e) cramp
E
65) 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
Muscle fatigue . The inability to maintain muscle force of contraction after prolonged activity
●Inadequate release of Ca2+ from SR ●Depletion of creatine phosphate, oxygen, and nutrients ●Build up of lactic acid and ADP ●Insufficient release of ACh at Neuromuscular Junction
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
18) What is rigor mortis? a) muscle rigidity that occurs approximately 3-24 hours after death, because ATP is no longer being produced b) a condition in there are no acetylcholine receptors in the motor end plate of the muscle fiber c) a condition in which motor neurons cannot release acetylcholine d) e) a condition in which muscle tears can't be repaired, due to a lack of human growth hormone (hGH) e) an injury characterized by a stretched or torn tendon or muscle
A
26) 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
30) 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
30) 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
9) 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
12) 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
24) To stimulate skeletal muscle contraction, acetylcholine must cross the _____ of the neuromuscular junction and bind to receptors on the motor endplate. a) node of Ranvier b) synaptic cleft c) sarcolemma d) synaptic end bulb e) transverse tubule
B
11) 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
20) 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
69). 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
25) 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
33) 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
4) 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
6) This is the outermost layer of connective tissue surrounding a skeletal muscle. a) tendon b) ligament c) endomysium d) epimysium e) perimysium
D
63) Which is a NOT a side-effect of anabolic steroid use by male athletes? a) sterility b) baldness c) diminished testosterone secretion d) deepening of the voice e) atrophy of testes
D
8) After the fusion of myoblasts, the muscle fiber loses its ability to do what? a) grow b) lengthen c) contract d) go through cell division. e) all of the answer choices
D
8) 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
20) 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
24) 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
29) 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
37) Most people don't notice they've lost muscle strength until around age 60 - 65. By this time, what percentage of muscle mass has the average person lost? a) 10% b) 20% c) 30% d) 40% e) 50%
E
Power point . Properties of muscle Electrical Excitability- Contractility- Extensibility- Elasticity-
Electrical Excitability - Action potentials (impluses) •Contractility - when stimulated by an action potential •Extensibility - stretch within limits. Normally smooth muscle stretches the most. Good example is the smooth muscles of the stomach when filling with food. Cardiac muscles also stretch when heart fill with blood. •Elasticity - ability to return after contraction or extension.
3 layers of tissue. Epimysium, perimysium, endomysium
Epimysium - outer, encirles entire muscle. Dense irregular connective tissue •Perimysium - surrounds groups of 10-100 or more muscle fibers and separates them into bundles called fascicles. Mostly Dense irregular connective tissue •Endomysium - penetrates the interior of each fascicle and separates individual muscle fibres from each other. Reticular fibers.
muscle tone
Even when at rest, a skeletal muscle exhibits a small amount of tension, called tone ●Due to weak, involuntary contraction of motor units
32) 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
34) 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
71) 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
35) 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
5) 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
31) Which of the following statements is correct about why a person's muscles get larger after weeks of regular exercise and strength training? a) the person has been able to change the proportion of skeletal muscle fiber types in the exercised muscles (i.e., they've added more slow oxidative fibers to their muscles) b) the person has stimulated some of their muscle fibers to reproduce—they have added additional cells to their exercised muscles c) the person has added more thin and thick filaments to their muscles d) all of these choices can happen with exercise e) none of these choices explain muscle enlargement
C
33) 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
34) 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
70) 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
73) Myasthenia Gravis is an autoimmune disorder that targets the ACh receptors at the NMJ and ultimately reduces the number of available receptors. Predict what happens if you treat the patient with a drug that inhibits the activity of acetylcholinesterase? a) prevent contraction b) weak contraction c) normal contraction d) cause spasm e) none of these choices
C
74) 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
9) 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
36) 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
68) Which of the following types of muscle tissue is capable of undergoing the stress-relaxation response when they are stretched? a) cardiac muscle fibers b) fast glycolytic fibers c) fast oxidative-glycolytic fibers d) slow oxidative fibers e) single-unit smooth muscle fibers
E
72) 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
Question type: True/False 32) Stretching is most effective at reducing injury and promoting greater flexibility if it is done over the course of many weeks, and always when the muscle is cold (before beginning to exercise).
False
isotonic contractionb
Isotonic - tension is constant while muscle length changes ●Concentric ●Eccentric
H zone
Narrow region in center of each A band that contains thick filaments but no thin filaments
Z disk
Narrow, plate shaped regions of dense material that separates one sarcomere from the next
How is muscle formed ?
Occurs during embryonic development. Once fusion has occurred muscle fibers lose ability to undergo cell division. Therefore number of skeletal muscles preset.
Why do you continue to breathe heavily for a period of time after stopping exercise?
Oxygen debt ●Replenish creatine phosphate stores ●Convert lactate into pyruvate ●Reload O2 onto myoglobin
Primary function of fibers Slow oxidative Fast oxidative Fast glycolytic
Slow oxidative-maintaining posture and aerobic Fast oxidative- walking, sprinting Fast glycolyti-rapid intense movements in a short duration
