MCPHS ANATOMY AND PHYSIOLOGY Exam 3
Questions and Answers 2026 | Comprehensive
Review with Detailed Rationales | Grade A+
• Functions of the muscular system: -✓✓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 -✓✓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 -✓✓Skeletal - voluntary
Smooth - controlled involuntarily by endocrine and autonomic nervous system
Cardiac - controlled involuntarily by endocrine and autonomic nervous system
• Epimysium -✓✓CT that surrounds whole muscle
• Perimysium -✓✓loose CT surrounding a group of muscle fibers; passage for blood
vessels and nerves
• Endomysium -✓✓loose CT separating individual muscle fibers within each fasicle
• Fiber anatomy -✓✓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 -✓✓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 -✓✓Not striated, small fibers
Spindle-shaped, single, central nucleus
More actin than myosin, cross-bridging occurs
Ca2+ required to initiate contraction
Wavy
• Sarcolemma -✓✓plasma membrane, surround sarcoplasm (cytoplasm)
• Transverse tubules (T tubules) -✓✓inward folds of sarcolemma; project into interior of
muscles
• Sarcoplasmic reticulum -✓✓specialized smooth ER; store calcium
• terminal cisternae -✓✓Enlarged portion od SR adjacent to T tubules
• Myofibrils -✓✓protein filament bundles; contain myofilaments that cause contraction
• Myofilament -✓✓actin and myosin
• Actin -✓✓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 -✓✓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 -✓✓basic functional unit of fiber - smallest part that can contract
Sarcomeres give striated appearance
• Neuromuscular junction -✓✓Motor neuron carry electrical signal that stimulate muscle
fiber action potentials followed by muscle contraction
NJ (or synapse) is point of contact between motor neuron and muscle fiber
• Presynaptic terminal (end of neuron) -✓✓axon terminal w/ synaptic vesicles that
contain AcH
Questions and Answers 2026 | Comprehensive
Review with Detailed Rationales | Grade A+
• Functions of the muscular system: -✓✓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 -✓✓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 -✓✓Skeletal - voluntary
Smooth - controlled involuntarily by endocrine and autonomic nervous system
Cardiac - controlled involuntarily by endocrine and autonomic nervous system
• Epimysium -✓✓CT that surrounds whole muscle
• Perimysium -✓✓loose CT surrounding a group of muscle fibers; passage for blood
vessels and nerves
• Endomysium -✓✓loose CT separating individual muscle fibers within each fasicle
• Fiber anatomy -✓✓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 -✓✓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 -✓✓Not striated, small fibers
Spindle-shaped, single, central nucleus
More actin than myosin, cross-bridging occurs
Ca2+ required to initiate contraction
Wavy
• Sarcolemma -✓✓plasma membrane, surround sarcoplasm (cytoplasm)
• Transverse tubules (T tubules) -✓✓inward folds of sarcolemma; project into interior of
muscles
• Sarcoplasmic reticulum -✓✓specialized smooth ER; store calcium
• terminal cisternae -✓✓Enlarged portion od SR adjacent to T tubules
• Myofibrils -✓✓protein filament bundles; contain myofilaments that cause contraction
• Myofilament -✓✓actin and myosin
• Actin -✓✓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 -✓✓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 -✓✓basic functional unit of fiber - smallest part that can contract
Sarcomeres give striated appearance
• Neuromuscular junction -✓✓Motor neuron carry electrical signal that stimulate muscle
fiber action potentials followed by muscle contraction
NJ (or synapse) is point of contact between motor neuron and muscle fiber
• Presynaptic terminal (end of neuron) -✓✓axon terminal w/ synaptic vesicles that
contain AcH
