A&p ch 9 Flashcards


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1

2) Which muscle cells have the greatest ability to regenerate?

A) skeletal
B) cardiac
C) smooth
D) no muscle can regenerate
Answer: C

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2

9) Calcium ions bind to the ________ molecule in skeletal muscle cells.

A) actin
B) tropomyosin
C) troponin
D) myosin
Answer: C

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3

10) Myoglobin ________.

A) breaks down glycogen

B) is a protein involved in the direct phosphorylation of ADP

C) stores oxygen in muscle cells

D) produces the end plate potential
Answer: C

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4

11) An elaborate network of membranes in skeletal muscle cells that functions in calcium storage
is the ________.

A) sarcoplasmic reticulum
B) mitochondria
C) intermediate filament network
D) myofibrillar network
Answer: A

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5

12) A sarcomere is ________.

A) the nonfunctional unit of skeletal muscle

B) the area between two Z discs

C) the area between two intercalated discs

D) the wavy lines on the cell seen in the microscope
Answer: B

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6

13) 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.

A) contraction
B) relaxation
C) latent
D) refractory
Answer: C

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7

14) Creatine phosphate functions in the muscle cell by ________.

A) forming a temporary chemical compound with myosin

B) forming a chemical compound with actin

C) inducing a conformational change in the myofilaments

D) storing energy that will be transferred to ADP to resynthesize ATP
Answer: D

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8

18) Which of the following are composed of myosin?

A) thick filaments
B) thin filaments
C) all myofilaments
D) Z discs
Answer: A

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9

19) During muscle contraction, myosin cross bridges attach to which active sites?

A) myosin filaments
B) actin filaments
C) Z discs
D) thick filaments
Answer: B

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10

20) Which of the following surrounds the individual muscle cell?

A) perimysium
B) endomysium
C) epimysium
D) fascicle
Answer: B

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11

22) Rigor mortis occurs because ________.

A) the cells are dead

B) sodium ions leak out of the muscle

C) no ATP is available to release attached actin and myosin molecules

D) proteins are beginning to break down, thus preventing a flow of calcium ions
Answer: C

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12

25) The oxygen-binding protein found in muscle cells is ________.

A) hemoglobin
B) ATP
C) myoglobin
D) immunoglobin
Answer: C

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13

26) The contractile units of skeletal muscles are ________.

A) microtubules
B) mitochondria
C) T tubules
D) myofibrils
Answer: D

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14

28) One functional unit of a skeletal muscle is ________.

A) a sarcomere
B) a myofilament
C) a myofibril
D) the sarcoplasmic reticulum
Answer: A

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15

33) 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 ________.

A) a strong base
B) stearic acid
C) hydrochloric acid
D) lactic acid
Answer: D

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16

34) When a muscle is unable to respond to stimuli temporarily, it is in which of the following
periods?

A) relaxation period
B) refractory period
C) latent period
D) fatigue period
Answer: B

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17

35) In an isotonic contraction, the muscle ________.

A) changes in length and moves the ╩║load╩║

B) does not change in length but increases tension

C) never converts pyruvate to lactate

D) rapidly resynthesizes creatine phosphate and ATP
Answer: A

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18

36) The muscle cell membrane is called the ________.

A) endomysium
B) sarcolemma
C) perimysium
D) epimysium
Answer: B

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19

38) The mechanism of contraction in smooth muscle is different from skeletal muscle in that
________.

A) actin and myosin interact by the sliding filament mechanism

B) the trigger for contraction is a rise in intracellular calcium

C) the site of calcium regulation differs

D) ATP energizes the sliding process
Answer: C

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20

41) Which of the following is true about smooth muscle contraction?

A) Certain smooth muscle cells can actually divide to increase their numbers.

B) Smooth muscle, in contrast to skeletal muscle, cannot synthesize or secrete any
connective tissue elements.

C) Smooth muscle cannot stretch as much as skeletal muscle.

D) Smooth muscle has well-developed T tubules at the site of invagination.
Answer: A

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21

42) Smooth muscle is characterized by all of the following except ________.

A) it appears to lack troponin

B) there are more thick filaments than thin filaments

C) there are no sarcomeres

D) there are noncontractile intermediate filaments that attach to dense bodies within the cell
Answer: B

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22

46) An anaerobic metabolic pathway that results in the production of two net ATPs per glucose
plus two pyruvic acid molecules is ________.

A) the citric acid cycle
B) glycolysis
C) hydrolysis
D) the electron transport chain
Answer: B

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23

49) After nervous stimulation stops, ACh in the synaptic cleft is prevented from continuing
stimulation of contraction by ________.

A) calcium ions returning to the terminal cisternae

B) the tropomyosin blocking the myosin once full contraction is achieved

C) acetylcholinesterase destroying the ACh

D) the action potential stopped going down the overloaded T tubules
Answer: C

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