PHYL 1001 - FINAL EXAM 2025
QUESTIONS AND ANSWERS
What is type of movement is controlled by skeletal muscle? - ANS Voluntary Movement
What is controlled by smooth muscle? - ANS Involuntary movements of the internal organs
What is controlled by cardiac muscle? - ANS Responsible for heart contractions
What muscle types are striated? - ANS Both skeletal and cardiac
What muscle types are not striated? - ANS Smooth muscle
What are two names for muscle cells? - ANS Muscle fibers and myofiber
What is a skeletal muscle composed of? - ANS Several muscle fibers, nerves, blood vessels,
and connective tissue
What is a muscle fascicle? - ANS bundle of muscle fibers
What structure causes the striated appearance of skeletal muscles? - ANS Sarcomeres
What function is achieved by sarcomeres? - ANS Muscle contraction
1 Copyright ©2025 FYNDLAY ALL RIGHTS RESERVED.
,Scarcolemma - ANS plasma membrane of a muscle fiber
Sacroplasm - ANS cytoplasm of a muscle cell
sarcoplasmic reticulum - ANS Organelle of the muscle fiber that stores calcium.
Do skeletal muscles contain mitochondria? In what quantities? - ANS Yes, it contains many
mitochondria
What are the two myofilaments? - ANS actin (thin) and myosin (thick)
How does muscle contraction influence Z disc location? - ANS Muscle contraction brings z
discs closer together
What is the role of titin? - ANS stability of z discs/M-line and elasticity
What is the M line? - ANS supporting proteins that hold the thick filaments together in the H
zone
What two things bind myosin? - ANS ATP and actin
What two proteins are associated with actin? - ANS troponin and tropomyosin
What is the role of tropomyosin in skeletal muscles? - ANS covers actin preventing myosin
binding and therefore muscle contraction at rest
What is the role of troponin? - ANS Binds to calcium to expose active sites on thin filaments
2 Copyright ©2025 FYNDLAY ALL RIGHTS RESERVED.
,What three things does troponin bind to allow muscle contraction? - ANS It must bind
calcium, actin, and tropomyosin. This causes a conformational change in troponin which
exposes actin binding sites for myosin.
What type of neuron activates a muscle fiber? - ANS Motor neuron
Where does the synapse between motor neuron and muscle fiber (myofiber) occur? -
ANS Neuromuscular Junction
What neurotransmitter is released at the neuromuscular junction? - ANS Acetylcholine
What type of receptors do muscle fibers have? Why? - ANS Nicotinic. Muscle impulses must
be delivered quickly so a GPCR receptor will not be used. Ion channels are preferable.
Describe the features of a motor neuron that allows fast signal transduction. - ANS Large
diameter, heavily myelinated axona
What does ACh depolarize in the neuromuscular Junction? - ANS myofiber/muscle cell
What ion triggers ACh release from the motor neuron? - ANS Calcium
What does ACh bind on muscle cell? - ANS ACh binds nicotinic ion channels on motor end
plate
Briefly describe what happens when ACh is released in the NMJ. - ANS ACH binds nicotinic
ion receptors which allows Na+ flow into cell and K+ out of cell. End plate potential (graded)
potential must be reached to trigger action potential.
3 Copyright ©2025 FYNDLAY ALL RIGHTS RESERVED.
, What type of potential is the end plate potential? - ANS Graded
What needs to be achieved to trigger action potential in muscle cells? - ANS End plate
potential must be reached
How does the depolarization signal stop in the NMJ? - ANS 1. ACH esterase
2. Reuptake into presynaptic axon
3. Uptake into glial cells
What is curare? - ANS an antagonist of acetylcholine that blocks acetylcholine's receptors in
NMJ resulting in muscle paralysis (native american arrow poison)
Describe the structural advantages of T-tubules - ANS dips in cell membrane allow end plate
potential (sarcolemma) to be reached close to sarcoplasmic reticulum
Why does every end plate potential result in an action potential? - ANS Nicotinic
receptors/ion channels are very close to endplate resulting in a strong stimulus (as opposed to
traveling distance in regular neuron)
What does the initial depolarization via NA ion channels cause? - ANS The opening of voltage
gated NA channels along the muscle fiber to propagate action potential
Why does the muscular action potential need to be propagated? - ANS Excitability-
contraction coupling: many contractions are required contract muscle and increase muscle
tension.
Why do muscles become shorter when they contract? - ANS The sarcomeres shorten
What does an action potential do to DHPR? - ANS Causes conformational change to DHPR
4 Copyright ©2025 FYNDLAY ALL RIGHTS RESERVED.
QUESTIONS AND ANSWERS
What is type of movement is controlled by skeletal muscle? - ANS Voluntary Movement
What is controlled by smooth muscle? - ANS Involuntary movements of the internal organs
What is controlled by cardiac muscle? - ANS Responsible for heart contractions
What muscle types are striated? - ANS Both skeletal and cardiac
What muscle types are not striated? - ANS Smooth muscle
What are two names for muscle cells? - ANS Muscle fibers and myofiber
What is a skeletal muscle composed of? - ANS Several muscle fibers, nerves, blood vessels,
and connective tissue
What is a muscle fascicle? - ANS bundle of muscle fibers
What structure causes the striated appearance of skeletal muscles? - ANS Sarcomeres
What function is achieved by sarcomeres? - ANS Muscle contraction
1 Copyright ©2025 FYNDLAY ALL RIGHTS RESERVED.
,Scarcolemma - ANS plasma membrane of a muscle fiber
Sacroplasm - ANS cytoplasm of a muscle cell
sarcoplasmic reticulum - ANS Organelle of the muscle fiber that stores calcium.
Do skeletal muscles contain mitochondria? In what quantities? - ANS Yes, it contains many
mitochondria
What are the two myofilaments? - ANS actin (thin) and myosin (thick)
How does muscle contraction influence Z disc location? - ANS Muscle contraction brings z
discs closer together
What is the role of titin? - ANS stability of z discs/M-line and elasticity
What is the M line? - ANS supporting proteins that hold the thick filaments together in the H
zone
What two things bind myosin? - ANS ATP and actin
What two proteins are associated with actin? - ANS troponin and tropomyosin
What is the role of tropomyosin in skeletal muscles? - ANS covers actin preventing myosin
binding and therefore muscle contraction at rest
What is the role of troponin? - ANS Binds to calcium to expose active sites on thin filaments
2 Copyright ©2025 FYNDLAY ALL RIGHTS RESERVED.
,What three things does troponin bind to allow muscle contraction? - ANS It must bind
calcium, actin, and tropomyosin. This causes a conformational change in troponin which
exposes actin binding sites for myosin.
What type of neuron activates a muscle fiber? - ANS Motor neuron
Where does the synapse between motor neuron and muscle fiber (myofiber) occur? -
ANS Neuromuscular Junction
What neurotransmitter is released at the neuromuscular junction? - ANS Acetylcholine
What type of receptors do muscle fibers have? Why? - ANS Nicotinic. Muscle impulses must
be delivered quickly so a GPCR receptor will not be used. Ion channels are preferable.
Describe the features of a motor neuron that allows fast signal transduction. - ANS Large
diameter, heavily myelinated axona
What does ACh depolarize in the neuromuscular Junction? - ANS myofiber/muscle cell
What ion triggers ACh release from the motor neuron? - ANS Calcium
What does ACh bind on muscle cell? - ANS ACh binds nicotinic ion channels on motor end
plate
Briefly describe what happens when ACh is released in the NMJ. - ANS ACH binds nicotinic
ion receptors which allows Na+ flow into cell and K+ out of cell. End plate potential (graded)
potential must be reached to trigger action potential.
3 Copyright ©2025 FYNDLAY ALL RIGHTS RESERVED.
, What type of potential is the end plate potential? - ANS Graded
What needs to be achieved to trigger action potential in muscle cells? - ANS End plate
potential must be reached
How does the depolarization signal stop in the NMJ? - ANS 1. ACH esterase
2. Reuptake into presynaptic axon
3. Uptake into glial cells
What is curare? - ANS an antagonist of acetylcholine that blocks acetylcholine's receptors in
NMJ resulting in muscle paralysis (native american arrow poison)
Describe the structural advantages of T-tubules - ANS dips in cell membrane allow end plate
potential (sarcolemma) to be reached close to sarcoplasmic reticulum
Why does every end plate potential result in an action potential? - ANS Nicotinic
receptors/ion channels are very close to endplate resulting in a strong stimulus (as opposed to
traveling distance in regular neuron)
What does the initial depolarization via NA ion channels cause? - ANS The opening of voltage
gated NA channels along the muscle fiber to propagate action potential
Why does the muscular action potential need to be propagated? - ANS Excitability-
contraction coupling: many contractions are required contract muscle and increase muscle
tension.
Why do muscles become shorter when they contract? - ANS The sarcomeres shorten
What does an action potential do to DHPR? - ANS Causes conformational change to DHPR
4 Copyright ©2025 FYNDLAY ALL RIGHTS RESERVED.
