ASU BIO 201 EXAM 3 PRACTICE QUESTIONS AND CORRECT ANSWERS
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Module
BIO 201
Institution
BIO 201
3 kinds of muscle tissue skeletal, cardiac, smooth
Major purpose of muscle converting chemical energy in atp --> mechanical energy of motion
Muscle functions -movement of: whole body, body parts, organ contents -stability: maintain posture and prevent mvmt. -communication: speech, facial expre...
ASU BIO 201 EXAM 3 PRACTICE
QUESTIONS AND CORRECT ANSWERS
3 kinds of muscle tissue ✅skeletal, cardiac, smooth
Major purpose of muscle ✅converting chemical energy in atp --> mechanical energy of
motion
Muscle functions ✅-movement of: whole body, body parts, organ contents
-stability: maintain posture and prevent mvmt.
-communication: speech, facial expressions and writing
-control of openings and passageways: sphincters
-body heat production
Characterizations of connective tissues of a muscle ✅fascia, epimysium, perimysium,
endomysium
Ct elements and how they merge with other tissues ✅tendons = attachments between
muscle and bone, dense-regular ct made of collagen fibers, epimysium surrounding
entire muscle is continuous with collagen fibers of tendons
Role of collagen in connective tissues ✅stretches slightly under tension and recoils
when released
-resists excessive stretching and protects muscle from injury
-returns muscle to resting length
-contribute to power output and muscle efficiency
Ways in which muscle attach to bone ✅indirect: tendons attach muscle to bone
Direct: fleshy attachment to bone
Some skeletal muscles do not insert on bone, but in dermis of the skin
How tendons attach muscle to bone ✅collagen fibers fibers of endo-, peri-, and
epimysium continue into the tendon, the tendon merges into the periosteum of bone
-aponeurosis: tendon is a broad, flat sheet
Origin and insertion definition ✅origin: bony attachment at stationary end of muscle
Insertion: bony attachment to mobile end of muscle
,Functional groups of muscles with example ✅for elbow flexion
Prime mover (agonist): brachialis
Synergist: biceps brachii
Antagonist: triceps brachii
Fixator: rhomboideus
Intrinsic vs extrinsic muscles ✅intrinsic: contained within a region (both origin and
insertion there)
Extrinsic: act on a designated regions, but has origins elsewhere
Characteristics of muscle ✅responsiveness (excitability): to chemical signals, stretch
and electrical changes across plasma membrane
Conductivity: local electrical change triggers a wave of excitation that travels along the
muscle fiber
Contractility: shortens when stimulated
Extensibility: capable of being stretched between contractions
Elasticity: returns to its original resting length after being stretched
Properties of skeletal muscle ✅voluntary, straitaed muscle attached to one or more
bones
Myofiber ✅muscle cell/muscle fiber, composed of myofibrils
Myofibrils ✅long protein bundles that occupy the main portion of the interior of a
muscle fiber, composed of myofilaments
Myofilament ✅protein microfilament responsible for muscle cell contraction, composed
of myosin or actin proteins
Functions of each part of a muscle fiber ✅sarcolemma: plasma membrane of a muscle
fiber
Sarcoplasm: cytoplasm of a muscle fiber
Mitochondria: packed in spaces between myofibrils
Sarcoplasmic reticulum (sr): smooth er that forms a network around each myofibril-
calcium reservoir
Terminal cisternae: dilated end-sacs of sr which cross muscle fiber from one side to the
other
T tubules: tubular infoldings of the sarcolemma which penetrate through the cell and
emerge on the other side
Triad: a t tubule and 2 terminal cisterns
Internal proteins: long protein bundles that occupy the main portion of the sarcoplasm
Multiple nuclei: flattened nuclei pressed against the inside of the sarcolemma
, Glycogen and myoglobin functions ✅glycogen: stored in abundance to provide energy
with heightened exercise
Myoglobin: red pigment that stores oxygen needed for muscle activity
Process of muscle growth and repair ✅repair by fibrosis rather than regeneration of
functional muscle
3 kinds of myofilaments found in a myofibril ✅thick filaments: myosin proteins
Thin filaments: primarily actin proteins
Elastic filaments: titin (connectin) proteins
Thick myofilaments ✅made of several hundred myosin molecules
-shaped like a golf club (2 chains make shaft-like tail, double globular head)
-heads directed outward in a helical array around the bundle
Thin myofilaments ✅fibrous (f) actin: 2 intertwined strands, string of globular (g) actin
subunits each with an active site that can bind to head of myosin molecule
-tropomyosin: each blocking 6 or 7 active sites on g actin subunits
-troponin complex: small, calcium-binding protein on each tropomyosin molecule
Elastic myofilaments ✅titin (connection): huge springy protein
-flank each thick filament and anchor it to the z disc
-help the cell recoil to its resting length (elasticity)
-keeps thick and thin filaments aligned: helps stabilize the thick filament, center it
between thin filaments
-prevents overstretching
Regulatory and contractile proteins of myofilaments ✅regulatory: tropomyosin and
troponin, like a switch that starts and stops contraction
-contraction activated by release of ca into sarcoplasm and its binding to troponin
-troponin changes shape and moves tropomyosin off the active sites on actin
Contractile: myosin and actin, do the work of contracting the muscle
Functions of accessory proteins ✅-anchor the myofilaments
-regulate length of myofilaments
-alignment of myofilaments for optimal effectiveness
Dystrophin = most clinically important
-links actin in outermost myofilaments to transmembrane proteins and eventually to
fibrous endomysium surrounding the entire muscle cell
-transfers forces of muscle contraction to connective tissue around myofiber
How defects in dystrophin result in muscular dystrophy ✅genetic defects in dystrophin
produce this disabling disease
-normal allele makes dystrophin, the absence leads to torn cell membranes ->
degeneration of skeletal muscles and are replaced with scar and adipose tissue
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