BIO 2350 Human Physiology Exam 2 UPDATED ACTUAL
Questions and CORRECT Answers
Where is cardiac muscle located? Cardiac muscle is found solely in the heart within the borders of the
endocardium
What are similarities and differences between cardiac Cardiac myocytes: muscle only found in the heart; involuntary muscle; single
and skeletal muscle? central nucleus; large numbers of mitochondria; aerobic metabolism;
intercalated discs; cardiac muscle can contract without stimulus from the
nervous system from it's pacemaker cells/nodes
Both: striated (actin and myosin); repeating units of sarcomere; regulatory
molecules troponin and tropomyosin; T-tubules amp sarcoplasmic reticulum for
Ca2+ storage and release
Skeletal: tectonic contractions; acetylcholine
T or F? Cardiac muscle cells are smaller than skeletal True
muscle fibers, and generally have a single nucleus.
Why is excitation-contraction coupling in the cardiac The mechanism: a small amount of extracellular Ca2+ enters the cell and binds
muscle referred to as calcium-induced calcium release? to the ryanodine receptor on Ca2+ channels in the sarcoplasmic reticulum
membrane. This triggers the release of a larger amount of Ca2+ from the
sarcoplasmic reticulum
Which of the following choices lists a correct sequence calcium ion influx through sarcolemma, calcium release into cytosol, actin and
of events following the depolarization of transverse myosin attach, thin myofilaments slide toward the middle of sarcomeres
tubules in excitation-contraction coupling in cardiac
muscle?
How does the organization of thick and thin filaments in Smooth muscle fibers are long spindle-shaped cells with no striations because
smooth muscle fiber differ from that in strained muscle their actin and myosin filaments are not arranged in sarcomeres; smooth
fibers? muscle does not contain troponin; single nucleus; under involuntary control
(autonomic nervous system)
organization of the smooth muscle cell: dense bodies (similar to Z lines) in
parallel and diagonal which allows them to contract on multiple axis
What is the difference between single-unit and multi- Single-unit: arranged in layers and respond to stimulus as a single unit because
unit smooth muscles? the cells are connected by gap junctions. This can produce wave-like
contractions called peristalsis
Multi-unit: organized into motor units that are innervated but the nervous
system. Multiunit smooth muscles contain cells that respond to stimuli
independently, ands they contain few gap junctions
T or F? Multi-unit smooth muscle is characterized by False. Multi-unit
many gap junctions between cells?
T or F? Smooth muscle does not have thick and thin False. Smooth muscle does have thick and thin filaments but no troponin
filaments.
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, T or F? In cardiac muscle cells the release of Ca2+ False. In cardiac muscle cells, the release of Ca2+ through L-type Ca2+
through L-type Ca2+ channels depolarizes the channels depolarizes the sarcoplasmic reticulum and CAUSES the release of
sarcoplasmic reticulum and inhibits the release of any Ca2+ necessary for excitation-contraction coupling
additional Ca2+ necessary for excitation- contraction
coupling?
What types of stimuli cause smooth muscle to contract? the overall amount of smooth muscle contraction depends on the relative
How do these stimuli alter the amount of smooth intensity of the various stimuli. The one thing that all these input have in
muscle contraction? common is that they all influence contractile activity by altering the
concentration of calcium in the cytosol.
Examples of inputs influencing smooth muscle contractile activity
-spontaneous electrical activity in the plasma membrane of the muscle cell
-neurotransmitter released by autonomic neurons
-hormones
-locally induced changes int he chemical composition (paracrine factors,
acidity, oxygen, osmolarity, and ion concentrations) of the extracellular fluid
surrounding the cell
-stretch
The stimuli alter the amount of smooth muscle contraction
Smooth muscle tension can be increased by increasing the amount of Ca2+ in
the cytosol
slow waves A pattern if spontaneous, period depolarization of the membrane potential
seen in smooth muscle pacemaker cells
Which of the following statements is false? Contractile activity of smooth muscle cells does not normally required Ca2+
T or F? In smooth muscle cells that can produce action False. In smooth muscle cells that can produce action potentials, cell
potentials, cell membrane depolarization usually opens membrane depolarization usually opens voltage-sensitive Ca2+ channels
voltage-sensitive sodium channels.
T or F? Smooth muscle cells may contract in the True
absences of neuronal stimulation.
Smooth muscle cells may contract in the absence of neuron all stimulation
because of pacemaker cells that spontaneously depolarize.
Describe the neural control of smooth muscle activity. Smooth: autonomic nervous system innervates it
How does it different from that of skeletal muscle? - lack of a motor end-plate regions; instead they have varicosities
- a single neuron influence several smooth muscle cells
- a single smooth muscle cell may be influenced by neurotransmitters from
more than one neuron
- hormones (catecholamines)
skeletal muscle: under voluntary control
T or F? A Ca2+ binding protein in smooth muscle is True.
called calmodulin
https://quizlet.com/543519454/bio-2350-human-physiology-exam-2-flash-cards/ 2/11
Questions and CORRECT Answers
Where is cardiac muscle located? Cardiac muscle is found solely in the heart within the borders of the
endocardium
What are similarities and differences between cardiac Cardiac myocytes: muscle only found in the heart; involuntary muscle; single
and skeletal muscle? central nucleus; large numbers of mitochondria; aerobic metabolism;
intercalated discs; cardiac muscle can contract without stimulus from the
nervous system from it's pacemaker cells/nodes
Both: striated (actin and myosin); repeating units of sarcomere; regulatory
molecules troponin and tropomyosin; T-tubules amp sarcoplasmic reticulum for
Ca2+ storage and release
Skeletal: tectonic contractions; acetylcholine
T or F? Cardiac muscle cells are smaller than skeletal True
muscle fibers, and generally have a single nucleus.
Why is excitation-contraction coupling in the cardiac The mechanism: a small amount of extracellular Ca2+ enters the cell and binds
muscle referred to as calcium-induced calcium release? to the ryanodine receptor on Ca2+ channels in the sarcoplasmic reticulum
membrane. This triggers the release of a larger amount of Ca2+ from the
sarcoplasmic reticulum
Which of the following choices lists a correct sequence calcium ion influx through sarcolemma, calcium release into cytosol, actin and
of events following the depolarization of transverse myosin attach, thin myofilaments slide toward the middle of sarcomeres
tubules in excitation-contraction coupling in cardiac
muscle?
How does the organization of thick and thin filaments in Smooth muscle fibers are long spindle-shaped cells with no striations because
smooth muscle fiber differ from that in strained muscle their actin and myosin filaments are not arranged in sarcomeres; smooth
fibers? muscle does not contain troponin; single nucleus; under involuntary control
(autonomic nervous system)
organization of the smooth muscle cell: dense bodies (similar to Z lines) in
parallel and diagonal which allows them to contract on multiple axis
What is the difference between single-unit and multi- Single-unit: arranged in layers and respond to stimulus as a single unit because
unit smooth muscles? the cells are connected by gap junctions. This can produce wave-like
contractions called peristalsis
Multi-unit: organized into motor units that are innervated but the nervous
system. Multiunit smooth muscles contain cells that respond to stimuli
independently, ands they contain few gap junctions
T or F? Multi-unit smooth muscle is characterized by False. Multi-unit
many gap junctions between cells?
T or F? Smooth muscle does not have thick and thin False. Smooth muscle does have thick and thin filaments but no troponin
filaments.
https://quizlet.com/543519454/bio-2350-human-physiology-exam-2-flash-cards/ 1/11
, T or F? In cardiac muscle cells the release of Ca2+ False. In cardiac muscle cells, the release of Ca2+ through L-type Ca2+
through L-type Ca2+ channels depolarizes the channels depolarizes the sarcoplasmic reticulum and CAUSES the release of
sarcoplasmic reticulum and inhibits the release of any Ca2+ necessary for excitation-contraction coupling
additional Ca2+ necessary for excitation- contraction
coupling?
What types of stimuli cause smooth muscle to contract? the overall amount of smooth muscle contraction depends on the relative
How do these stimuli alter the amount of smooth intensity of the various stimuli. The one thing that all these input have in
muscle contraction? common is that they all influence contractile activity by altering the
concentration of calcium in the cytosol.
Examples of inputs influencing smooth muscle contractile activity
-spontaneous electrical activity in the plasma membrane of the muscle cell
-neurotransmitter released by autonomic neurons
-hormones
-locally induced changes int he chemical composition (paracrine factors,
acidity, oxygen, osmolarity, and ion concentrations) of the extracellular fluid
surrounding the cell
-stretch
The stimuli alter the amount of smooth muscle contraction
Smooth muscle tension can be increased by increasing the amount of Ca2+ in
the cytosol
slow waves A pattern if spontaneous, period depolarization of the membrane potential
seen in smooth muscle pacemaker cells
Which of the following statements is false? Contractile activity of smooth muscle cells does not normally required Ca2+
T or F? In smooth muscle cells that can produce action False. In smooth muscle cells that can produce action potentials, cell
potentials, cell membrane depolarization usually opens membrane depolarization usually opens voltage-sensitive Ca2+ channels
voltage-sensitive sodium channels.
T or F? Smooth muscle cells may contract in the True
absences of neuronal stimulation.
Smooth muscle cells may contract in the absence of neuron all stimulation
because of pacemaker cells that spontaneously depolarize.
Describe the neural control of smooth muscle activity. Smooth: autonomic nervous system innervates it
How does it different from that of skeletal muscle? - lack of a motor end-plate regions; instead they have varicosities
- a single neuron influence several smooth muscle cells
- a single smooth muscle cell may be influenced by neurotransmitters from
more than one neuron
- hormones (catecholamines)
skeletal muscle: under voluntary control
T or F? A Ca2+ binding protein in smooth muscle is True.
called calmodulin
https://quizlet.com/543519454/bio-2350-human-physiology-exam-2-flash-cards/ 2/11
