MCPHS ANATOMY AND PHYSIOLOGY
EXAM 3 2025 QUESTIONS AND
ANSWERS
Functions of the muscular system: - ANS Movement of the body
Maintenance of posture
Respiration
Production of body heat
Communication
Constriction of organs and vessels
Contraction of heart
Three Es and a C: Properties of muscle tissue - ANS Contractility - ability of a muscle to
shorten with force
Excitability - capacity of a muscle to respond to a stimulus
Extensibility - muscle can stretch beyond normal resting length and be able to contract
Elasticity - ability of muscle to recoil to original resting length after stretched
3 types of muscle - ANS Skeletal - voluntary
Smooth - controlled involuntarily by endocrine and autonomic nervous system
Cardiac - controlled involuntarily by endocrine and autonomic nervous system
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, Epimysium - ANS CT that surrounds whole muscle
Perimysium - ANS loose CT surrounding a group of muscle fibers; passage for blood vessels
and nerves
Endomysium - ANS loose CT separating individual muscle fibers within each fasicle
Fiber anatomy - ANS Large, multinucleated
1-4 mm avg length
Have striated appearance
Number of fibers is relatively constant after birth
- Get larger, but not more
cardiac muscle - ANS Only in heart
Striated
Each cell has 1 nucleus
Intercalated disks and gap junctions
Autorhythmic
Action potentials of longer curation and refractory period
Ca2+ regulated contraction
smooth. muscle - ANS Not striated, small fibers
Spindle-shaped, single, central nucleus
More actin than myosin, cross-bridging occurs
Ca2+ required to initiate contraction
Wavy
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, Sarcolemma - ANS plasma membrane, surround sarcoplasm (cytoplasm)
Transverse tubules (T tubules) - ANS inward folds of sarcolemma; project into interior of
muscles
Sarcoplasmic reticulum - ANS specialized smooth ER; store calcium
terminal cisternae - ANS Enlarged portion od SR adjacent to T tubules
Myofibrils - ANS protein filament bundles; contain myofilaments that cause contraction
Myofilament - ANS actin and myosin
Actin - ANS thin
2 strands of F actin form double helix extending length of myofilament; composed of G actin
monomer that has active site, bind myosin during contraction
Tropomyosin - elongated protein along the groove of F actin double helix - BLOCK binding site G
actin
Troponin - 3 subunits: bind actin, binds tropomyosin, bind calcium ions
Troponin/tropomyosin complex regulates interaction between active sites on G actin and
myosin
myosin - ANS thick
Shaped like golf clubs, consist of heave chains wound together to form rod portion lyin parallel
to myosin microfilament and 2 myosin heads that extend laterally
Heads: can bind active sites on actin to form cross-bridge, attach to rod portion bt hinged
region that can bed during contraction, ATPase enzymes (break down ATP to release energy)
sarcomeres - ANS basic functional unit of fiber - smallest part that can contract
3|P a g e C o p y r i g h t © 2 0 2 5 T H E B R I G H T A L L R I G H T S R E S E R V E D
EXAM 3 2025 QUESTIONS AND
ANSWERS
Functions of the muscular system: - ANS Movement of the body
Maintenance of posture
Respiration
Production of body heat
Communication
Constriction of organs and vessels
Contraction of heart
Three Es and a C: Properties of muscle tissue - ANS Contractility - ability of a muscle to
shorten with force
Excitability - capacity of a muscle to respond to a stimulus
Extensibility - muscle can stretch beyond normal resting length and be able to contract
Elasticity - ability of muscle to recoil to original resting length after stretched
3 types of muscle - ANS Skeletal - voluntary
Smooth - controlled involuntarily by endocrine and autonomic nervous system
Cardiac - controlled involuntarily by endocrine and autonomic nervous system
1|P a g e C o p y r i g h t © 2 0 2 5 T H E B R I G H T A L L R I G H T S R E S E R V E D
, Epimysium - ANS CT that surrounds whole muscle
Perimysium - ANS loose CT surrounding a group of muscle fibers; passage for blood vessels
and nerves
Endomysium - ANS loose CT separating individual muscle fibers within each fasicle
Fiber anatomy - ANS Large, multinucleated
1-4 mm avg length
Have striated appearance
Number of fibers is relatively constant after birth
- Get larger, but not more
cardiac muscle - ANS Only in heart
Striated
Each cell has 1 nucleus
Intercalated disks and gap junctions
Autorhythmic
Action potentials of longer curation and refractory period
Ca2+ regulated contraction
smooth. muscle - ANS Not striated, small fibers
Spindle-shaped, single, central nucleus
More actin than myosin, cross-bridging occurs
Ca2+ required to initiate contraction
Wavy
2|P a g e C o p y r i g h t © 2 0 2 5 T H E B R I G H T A L L R I G H T S R E S E R V E D
, Sarcolemma - ANS plasma membrane, surround sarcoplasm (cytoplasm)
Transverse tubules (T tubules) - ANS inward folds of sarcolemma; project into interior of
muscles
Sarcoplasmic reticulum - ANS specialized smooth ER; store calcium
terminal cisternae - ANS Enlarged portion od SR adjacent to T tubules
Myofibrils - ANS protein filament bundles; contain myofilaments that cause contraction
Myofilament - ANS actin and myosin
Actin - ANS thin
2 strands of F actin form double helix extending length of myofilament; composed of G actin
monomer that has active site, bind myosin during contraction
Tropomyosin - elongated protein along the groove of F actin double helix - BLOCK binding site G
actin
Troponin - 3 subunits: bind actin, binds tropomyosin, bind calcium ions
Troponin/tropomyosin complex regulates interaction between active sites on G actin and
myosin
myosin - ANS thick
Shaped like golf clubs, consist of heave chains wound together to form rod portion lyin parallel
to myosin microfilament and 2 myosin heads that extend laterally
Heads: can bind active sites on actin to form cross-bridge, attach to rod portion bt hinged
region that can bed during contraction, ATPase enzymes (break down ATP to release energy)
sarcomeres - ANS basic functional unit of fiber - smallest part that can contract
3|P a g e C o p y r i g h t © 2 0 2 5 T H E B R I G H T A L L R I G H T S R E S E R V E D
