SLCC EXAM #3 QUESTIONS AND
ANSWERS
Sarcolemma - Answer-plasma membrane of a muscle fiber
sarcoplasmic reticulum - Answer-stores calcium,smooth ER
Myofibrils - Answer-Microscopic protein filaments that make up muscle cells.
T tubules - Answer-- Carry AP deep into the inner SR
Also called transverse tubules, these are deep invaginations of the plasma membrane
found in skeletal and cardiac muscle cells. These invaginations allow depolarization of
the membrane to quickly penetrate to the interior of the cell.
A-band - Answer-Full length of myosin
I band - Answer-only actin
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.
H zone - Answer-only myosin
Titian - Answer-Provides structural support
termination of contraction - Answer-Ca2+ must leave troponin, allowing tropomyosin to
cover myosin binding sites on actin
To remove Ca2+ from cytosol
Ca2+-ATPase in the sarcoplasmic reticulum
Transports Ca2+ from cytosol into the sarcoplasmic reticulum
isotonic twitch - Answer-a twitch during which a muscle shortens and lifts a constant
load
Tension - Answer-Produced by each fiber
Isometric twitch - Answer-A twitch during which a muscle generates for but does not
shorten
Best tension - Answer-Right in the middle w/ the cross bridges
motor unit - Answer-a motor neuron and all the muscle cells it stimulates
, recruitment - Answer-stimulus is sent to more muscle fibers, leading to more precise
control
Slow oxidation fibers - Answer-Appear dark red because they contain large amounts of
myoglobin and many blood capillaries. Generate ATP mainly by aerobic respiration
fast oxidative fibers - Answer-contract quickly, have fast myosin ATPases, and have
moderate resistance to fatigue, Aerobic
fast glycolytic fibers - Answer-Important for short-term intense, powerful movements.
Prefer glycolysis to make atp
muscle spindles - Answer-receptors sensitive to change in length of the muscle and the
rate of that change
Golgi tendon organs - Answer-Receptors sensitive to change in tension of the muscle
and the rate of that change
coronary circulation - Answer-supplies blood to the muscle tissue of the heart
series flow - Answer-Capillary bed from one to another
pacemaker cells - Answer-a group of cells located in the right atrium that sends out
signals that make the heart muscle contract and that regulates heartbeat rate
Fastest cells= pacemaker= set rate for rest of the heart
P wave - Answer-atrial depolarization
QRS complex - Answer-ventricular depolarization and atrial repolarization
T wave - Answer-ventricular repolarization
PQ segment - Answer-AV nodal delay
QT interval - Answer-ventricular systole
TQ interval - Answer-ventricular diastole
Systole - Answer-ventricular contraction
Diastole - Answer-ventricular relaxation
End Diastolic Volume (EDV) - Answer-Volume of blood in the ventricles at the end of
diastole ("preload")
pressure in aorta during ejection - Answer-afterload
ANSWERS
Sarcolemma - Answer-plasma membrane of a muscle fiber
sarcoplasmic reticulum - Answer-stores calcium,smooth ER
Myofibrils - Answer-Microscopic protein filaments that make up muscle cells.
T tubules - Answer-- Carry AP deep into the inner SR
Also called transverse tubules, these are deep invaginations of the plasma membrane
found in skeletal and cardiac muscle cells. These invaginations allow depolarization of
the membrane to quickly penetrate to the interior of the cell.
A-band - Answer-Full length of myosin
I band - Answer-only actin
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.
H zone - Answer-only myosin
Titian - Answer-Provides structural support
termination of contraction - Answer-Ca2+ must leave troponin, allowing tropomyosin to
cover myosin binding sites on actin
To remove Ca2+ from cytosol
Ca2+-ATPase in the sarcoplasmic reticulum
Transports Ca2+ from cytosol into the sarcoplasmic reticulum
isotonic twitch - Answer-a twitch during which a muscle shortens and lifts a constant
load
Tension - Answer-Produced by each fiber
Isometric twitch - Answer-A twitch during which a muscle generates for but does not
shorten
Best tension - Answer-Right in the middle w/ the cross bridges
motor unit - Answer-a motor neuron and all the muscle cells it stimulates
, recruitment - Answer-stimulus is sent to more muscle fibers, leading to more precise
control
Slow oxidation fibers - Answer-Appear dark red because they contain large amounts of
myoglobin and many blood capillaries. Generate ATP mainly by aerobic respiration
fast oxidative fibers - Answer-contract quickly, have fast myosin ATPases, and have
moderate resistance to fatigue, Aerobic
fast glycolytic fibers - Answer-Important for short-term intense, powerful movements.
Prefer glycolysis to make atp
muscle spindles - Answer-receptors sensitive to change in length of the muscle and the
rate of that change
Golgi tendon organs - Answer-Receptors sensitive to change in tension of the muscle
and the rate of that change
coronary circulation - Answer-supplies blood to the muscle tissue of the heart
series flow - Answer-Capillary bed from one to another
pacemaker cells - Answer-a group of cells located in the right atrium that sends out
signals that make the heart muscle contract and that regulates heartbeat rate
Fastest cells= pacemaker= set rate for rest of the heart
P wave - Answer-atrial depolarization
QRS complex - Answer-ventricular depolarization and atrial repolarization
T wave - Answer-ventricular repolarization
PQ segment - Answer-AV nodal delay
QT interval - Answer-ventricular systole
TQ interval - Answer-ventricular diastole
Systole - Answer-ventricular contraction
Diastole - Answer-ventricular relaxation
End Diastolic Volume (EDV) - Answer-Volume of blood in the ventricles at the end of
diastole ("preload")
pressure in aorta during ejection - Answer-afterload
