NPB 101 Midterm 2 Questions and
Answers Graded A+
Muscle - Correct answer-•Comprises largest group of tissues in body
•Produce force; different control mechanisms
•Similar contractile mechanisms; different morphologies
•Classified in two different ways
•Striated or unstriated
•Voluntary or involuntary
Skeletal muscle - Correct answer-Three types of muscle•Skeletal muscle (40-50%
of body mass)•Make up muscular system - voluntary
Smooth muscle - Correct answer-(5-10% of body mass)
•Appears throughout the body systems as components of hollow organs and tubes -
involuntary; ANS control
Cardiac muscle - Correct answer-•Found only in the heart
Controlled muscle contraction - Correct answer-Allows:
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,•Purposeful movement of the whole body or parts of the body
•Manipulation of external objects
•Propulsion of contents through various hollow internal organs
•Emptying of contents of certain organs to external environment.
Structure of Skeletal Muscle - Correct answer-•Muscle consists a number of
muscle fibers lying parallel to one another and held together by connective tissue
•Single skeletal muscle cell is known as a muscle fiber
•Multinucleated
•Large, elongated, and cylindrically shaped
•Fibers usually extend entire length of muscle
Myofibrils - Correct answer-•Contractile elements of muscle fiber
•Regular arrangement of thick and thin filaments
•Thick filaments - myosin (protein)
•Thin filaments - actin (protein)
Sarcomere - Correct answer-•Functional unit of skeletal muscle
•Found between two Z lines (connects thin filaments of two adjoining sarcomeres)
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,Myosin - Correct answer-•Component of thick filament
•Protein molecule consisting of two identical subunits shaped somewhat like a golf
club
•Tail ends are intertwined around each other
•Globular heads project out at one end
•Tails oriented toward center of filament and globular heads protrude outward at
regular intervals
•Heads form cross bridges between thick and thin filaments
•Cross bridge has two important sites critical to contractile process
•An actin-binding site
•A myosin ATPase (ATP-splitting) site
Actin - Correct answer-•Primary structural component of thin filaments
•Spherical in shape
•Thin filament also has two other proteins
•Tropomyosin and troponin
•Each actin molecule has special binding site for attachment with myosin cross
bridge
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, •Binding results in contraction of muscle fiber
Actin and myosin - Correct answer-•often called contractile proteins.
•Neither actually contracts.
•not unique to muscle cells,
•more abundant and more highly organized in muscle cells.
Tropomyosin and Troponin - Correct answer-•Often called regulatory muscle
proteins
Tropomyosin - Correct answer-•Thread-like molecules that lie end to end alongside
groove of actin spiral
•In this position, covers actin sites blocking interaction that leads to muscle
contraction
Troponin - Correct answer-•Made of three polypeptide units
•One binds to tropomyosin
•One binds to actin
•One can bind with Ca2+
Sliding Filament Mechanism - Correct answer-•Increase in Ca2+ starts filament
sliding
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Answers Graded A+
Muscle - Correct answer-•Comprises largest group of tissues in body
•Produce force; different control mechanisms
•Similar contractile mechanisms; different morphologies
•Classified in two different ways
•Striated or unstriated
•Voluntary or involuntary
Skeletal muscle - Correct answer-Three types of muscle•Skeletal muscle (40-50%
of body mass)•Make up muscular system - voluntary
Smooth muscle - Correct answer-(5-10% of body mass)
•Appears throughout the body systems as components of hollow organs and tubes -
involuntary; ANS control
Cardiac muscle - Correct answer-•Found only in the heart
Controlled muscle contraction - Correct answer-Allows:
©COPYRIGHT 2025, ALL RIGHTS RESERVED 1
,•Purposeful movement of the whole body or parts of the body
•Manipulation of external objects
•Propulsion of contents through various hollow internal organs
•Emptying of contents of certain organs to external environment.
Structure of Skeletal Muscle - Correct answer-•Muscle consists a number of
muscle fibers lying parallel to one another and held together by connective tissue
•Single skeletal muscle cell is known as a muscle fiber
•Multinucleated
•Large, elongated, and cylindrically shaped
•Fibers usually extend entire length of muscle
Myofibrils - Correct answer-•Contractile elements of muscle fiber
•Regular arrangement of thick and thin filaments
•Thick filaments - myosin (protein)
•Thin filaments - actin (protein)
Sarcomere - Correct answer-•Functional unit of skeletal muscle
•Found between two Z lines (connects thin filaments of two adjoining sarcomeres)
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,Myosin - Correct answer-•Component of thick filament
•Protein molecule consisting of two identical subunits shaped somewhat like a golf
club
•Tail ends are intertwined around each other
•Globular heads project out at one end
•Tails oriented toward center of filament and globular heads protrude outward at
regular intervals
•Heads form cross bridges between thick and thin filaments
•Cross bridge has two important sites critical to contractile process
•An actin-binding site
•A myosin ATPase (ATP-splitting) site
Actin - Correct answer-•Primary structural component of thin filaments
•Spherical in shape
•Thin filament also has two other proteins
•Tropomyosin and troponin
•Each actin molecule has special binding site for attachment with myosin cross
bridge
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, •Binding results in contraction of muscle fiber
Actin and myosin - Correct answer-•often called contractile proteins.
•Neither actually contracts.
•not unique to muscle cells,
•more abundant and more highly organized in muscle cells.
Tropomyosin and Troponin - Correct answer-•Often called regulatory muscle
proteins
Tropomyosin - Correct answer-•Thread-like molecules that lie end to end alongside
groove of actin spiral
•In this position, covers actin sites blocking interaction that leads to muscle
contraction
Troponin - Correct answer-•Made of three polypeptide units
•One binds to tropomyosin
•One binds to actin
•One can bind with Ca2+
Sliding Filament Mechanism - Correct answer-•Increase in Ca2+ starts filament
sliding
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