PHGY 215 Final Exam Questions With
100% Correct Answers 2026-2027
Updated.
The muscle tissue represents the greatest - Answer The greatest tissue mass in the body at
around half of the body’s total weight.
The majority of muscles tissue is - Answer The majority is skeletal muscle (represents 40% of
bw in men and 32% in women)
skeletal muscle - Answer striated and voluntary
straited - Answer striped
Level of skeletal muscle organization - Answer The muscle > muscle fibre > myofibrils >
sacromere
muscle - Answer tissue composed of fibers that can contract, causing movement of an organ
or part of the body
Muscle fibre - Answer a single muscle cell. They are much longer than normal cells and are
multinucleate.
Myofibrils - Answer protein structures that make up muscle fibers
A band - Answer dark area; extends length of the thick filaments
I band of sarcomere - Answer the light band between the ends of thick filaments
H zone - Answer The region at the center of an A band of a sarcomere that is made up of
myosin only. The H zone gets shorter (and may disappear) during muscle contraction.
Slightly lighter portion of A band
M line of sarcomere - Answer mid-line of sarcomere
Made of proteins that hold thick filaments together
,Z line - Answer A dark thin protein band to which actin filaments are attached in a striated
muscle fiber, marking the boundaries between adjacent sarcomeres.
Sacromere - Answer Basic contracting unit of muscle cell consits of actin and myosin filaments
between z-lines in a muscle cell
Muscle cross bridge - Answer Connection formed when mobile myosin heads bind to actin
molecules in muscles
Thick filaments (myosin) - Answer Myosin myofilament with heads that bind to actin by
reaching up and ratcheting forward
About 300/filament
Myosin - Answer The contractile protein that makes up the thick filaments of muscle fibers
Dimer of two subunits that looks like a golf club in that it has a long shaft with a globular head
Thin filaments (actin) - Answer Made up of proteins actin, tropomyosin, troponin. The main
structural component is two actin filaments
Actin - Answer A globular protein that links into chains, two of which twist helically about each
other, forming microfilaments in muscle and other contractile elements in cells.
Tropomyosin - Answer Thin double helix protein that lies end to end along the actin helix
structure. Regulatory protein that covers the actin binding sites preventing interaction of actin
and myosin
Troponin - Answer Regulatory protein complex made up of 3 polypeptides. 1 binds
tropomyosin, 1 binds actin, 1 binds Ca 2+
muscle contraction - Answer The activation of tension generating sites within muscle fibres
when a muscle contracts it shortens
sliding filament mechanism - Answer Thin filaments slide over thick filaments, by the z discs
pulling together. The I band and H zone shorten, and the A band remains the same length
concentric contraction - Answer muscle shortens
power stroke - Answer action of myosin pulling actin inward (toward the M line)
, cross bridge cycle - Answer sequence of events between binding of a cross-bridge to actin, its
release, and reattachment during muscle contraction
1) binding 2) power stroke 3) detachment 4) binding
sacroplasmic reticulum - Answer specialized smooth endoplasmic reticulum, releases calcium
on demand when the muscle fiber is stimulated to contract
Runs parallel to the fibres. The lateral sacs of the SR are in close proximity to the T-tubules.
Storage sites for Ca +2
T tubules - Answer invaginations of the sarcolemma. At the junction of A & I bands, t-tubules
dip into the fibre and run perpendicular to the fibres
Acetylcholinesterase (AChE) - Answer the enzyme that breaks down acetylcholine in the
synaptic cleft
action potential - Answer Action potential is generated in response to binding of Ach and
subsequent end-plate potential is propagated across surface membrane and down t-tubules of
muscle cell. Action potential in t-tubule triggers calcium release from sacroplasmic reticulum
muscle twitch - Answer a single momentary muscle contraction, and is the response to a
single stimulus.
Basic unit of muscle contraction
motor unit recruitment - Answer recruitment of more muscle fibers through motor unit
activation
When the motor neuron is activated it causes all of its muscle fibres to contract.
fatigue - Answer The inability to maintain contraction
How to prevent fatigue? - Answer Body can selectively rotate the activation of motor units so
that some can rest while others take over. This way activation can be maintained for much
longer.
frequency of stimulation - Answer Muscle potential recovers quickly and can actually undergo
another action potential
100% Correct Answers 2026-2027
Updated.
The muscle tissue represents the greatest - Answer The greatest tissue mass in the body at
around half of the body’s total weight.
The majority of muscles tissue is - Answer The majority is skeletal muscle (represents 40% of
bw in men and 32% in women)
skeletal muscle - Answer striated and voluntary
straited - Answer striped
Level of skeletal muscle organization - Answer The muscle > muscle fibre > myofibrils >
sacromere
muscle - Answer tissue composed of fibers that can contract, causing movement of an organ
or part of the body
Muscle fibre - Answer a single muscle cell. They are much longer than normal cells and are
multinucleate.
Myofibrils - Answer protein structures that make up muscle fibers
A band - Answer dark area; extends length of the thick filaments
I band of sarcomere - Answer the light band between the ends of thick filaments
H zone - Answer The region at the center of an A band of a sarcomere that is made up of
myosin only. The H zone gets shorter (and may disappear) during muscle contraction.
Slightly lighter portion of A band
M line of sarcomere - Answer mid-line of sarcomere
Made of proteins that hold thick filaments together
,Z line - Answer A dark thin protein band to which actin filaments are attached in a striated
muscle fiber, marking the boundaries between adjacent sarcomeres.
Sacromere - Answer Basic contracting unit of muscle cell consits of actin and myosin filaments
between z-lines in a muscle cell
Muscle cross bridge - Answer Connection formed when mobile myosin heads bind to actin
molecules in muscles
Thick filaments (myosin) - Answer Myosin myofilament with heads that bind to actin by
reaching up and ratcheting forward
About 300/filament
Myosin - Answer The contractile protein that makes up the thick filaments of muscle fibers
Dimer of two subunits that looks like a golf club in that it has a long shaft with a globular head
Thin filaments (actin) - Answer Made up of proteins actin, tropomyosin, troponin. The main
structural component is two actin filaments
Actin - Answer A globular protein that links into chains, two of which twist helically about each
other, forming microfilaments in muscle and other contractile elements in cells.
Tropomyosin - Answer Thin double helix protein that lies end to end along the actin helix
structure. Regulatory protein that covers the actin binding sites preventing interaction of actin
and myosin
Troponin - Answer Regulatory protein complex made up of 3 polypeptides. 1 binds
tropomyosin, 1 binds actin, 1 binds Ca 2+
muscle contraction - Answer The activation of tension generating sites within muscle fibres
when a muscle contracts it shortens
sliding filament mechanism - Answer Thin filaments slide over thick filaments, by the z discs
pulling together. The I band and H zone shorten, and the A band remains the same length
concentric contraction - Answer muscle shortens
power stroke - Answer action of myosin pulling actin inward (toward the M line)
, cross bridge cycle - Answer sequence of events between binding of a cross-bridge to actin, its
release, and reattachment during muscle contraction
1) binding 2) power stroke 3) detachment 4) binding
sacroplasmic reticulum - Answer specialized smooth endoplasmic reticulum, releases calcium
on demand when the muscle fiber is stimulated to contract
Runs parallel to the fibres. The lateral sacs of the SR are in close proximity to the T-tubules.
Storage sites for Ca +2
T tubules - Answer invaginations of the sarcolemma. At the junction of A & I bands, t-tubules
dip into the fibre and run perpendicular to the fibres
Acetylcholinesterase (AChE) - Answer the enzyme that breaks down acetylcholine in the
synaptic cleft
action potential - Answer Action potential is generated in response to binding of Ach and
subsequent end-plate potential is propagated across surface membrane and down t-tubules of
muscle cell. Action potential in t-tubule triggers calcium release from sacroplasmic reticulum
muscle twitch - Answer a single momentary muscle contraction, and is the response to a
single stimulus.
Basic unit of muscle contraction
motor unit recruitment - Answer recruitment of more muscle fibers through motor unit
activation
When the motor neuron is activated it causes all of its muscle fibres to contract.
fatigue - Answer The inability to maintain contraction
How to prevent fatigue? - Answer Body can selectively rotate the activation of motor units so
that some can rest while others take over. This way activation can be maintained for much
longer.
frequency of stimulation - Answer Muscle potential recovers quickly and can actually undergo
another action potential
