EEOB 2520 Exam 11 with Complete
Solutions
myocardium ANSWER-heart muscle cells, striated, autonomic, parallel myosin and actin
-myofibers can have short branches: must have strong connections to prevent ripping
(intercalated discs = junction between 2 myofibers). Desosomes are used. Gap junctions
(electrical communication) are used to synchronize contractions
contraction of heart: at rest ANSWER-myosin head is deflexed and binding is blocked by
tropomyosin
Ca2+ induced Ca2+ release ANSWER-AP on plasma membrane goes into transverse
tubules that carry the AP into the cell. V-gated Ca2+ channels are in the TTs and fluid in TTs is
extracellular interstitial fluid, therefore, Ca2+ comes from outside the cell into cytosol. Ca2+
binds to troponin and starts CBC. There are channels in SR then Ca2+ can bind to troponin or
ligand-gated channel again. Ca2+ can open channel and flow through it, gives graduated
amount of tension (toothpaste example- squeeze lightly when full, and a lot when empty).
Relaxation of the myocardium ANSWER-remove Ca2+ by use of ATPase pumps that pump
Ca2+ back into SR and extracellular fluid.
pattern of contraction ANSWER-1. starts with action potential from CNS (efferent;
autonomic)
2. sinoatrial node in R atrium sets heart rate at 70 bpm.
3. the atrial cells contract and transmit the signal from top down (most efficient way to make
blood move down into left ventricle). Cannot pass AP into ventricle cells because of white
protective fat layer.
4. AV node
5. bundles of His- runs within interventricular septupm- conduct without contraction
6. purkinje fibers: release AP to ventricle cells at bottom to top to make blood go up to lungs.
, p-wave of EKG ANSWER-atrial depolarization; AP is in atria
QRS complex ANSWER-ventricular depolarization: squeeze from bottom up. (lub)
T-wave ANSWER-ventricular repolarization (dub)
blood pressure's effect on cardiac cycle ANSWER-due to space constriction as volume
decreases, pressure increases. Need to increase pressure to force blood to move to lower
pressure area.
2 phases in one cycle ANSWER-systole and dystole
systole ANSWER-contraction to empty ~1/3 of the time
dystole ANSWER-relaxation to fill ~2/3 of time
Stroke Volume (SV) ANSWER-end diastolic volume (EDV) - end systolic volume (ESV)
End Diastolic Volume (EDV) ANSWER-pre-contraction volume (max V ~ 135 mL)
End Systolic Volume (ESV) ANSWER-post-contraction; min V ~ 65 mL
heart rate ANSWER-strokes or cycles per min
unit= bpm
cardiac output ANSWER-stroke volume x heart rate
Solutions
myocardium ANSWER-heart muscle cells, striated, autonomic, parallel myosin and actin
-myofibers can have short branches: must have strong connections to prevent ripping
(intercalated discs = junction between 2 myofibers). Desosomes are used. Gap junctions
(electrical communication) are used to synchronize contractions
contraction of heart: at rest ANSWER-myosin head is deflexed and binding is blocked by
tropomyosin
Ca2+ induced Ca2+ release ANSWER-AP on plasma membrane goes into transverse
tubules that carry the AP into the cell. V-gated Ca2+ channels are in the TTs and fluid in TTs is
extracellular interstitial fluid, therefore, Ca2+ comes from outside the cell into cytosol. Ca2+
binds to troponin and starts CBC. There are channels in SR then Ca2+ can bind to troponin or
ligand-gated channel again. Ca2+ can open channel and flow through it, gives graduated
amount of tension (toothpaste example- squeeze lightly when full, and a lot when empty).
Relaxation of the myocardium ANSWER-remove Ca2+ by use of ATPase pumps that pump
Ca2+ back into SR and extracellular fluid.
pattern of contraction ANSWER-1. starts with action potential from CNS (efferent;
autonomic)
2. sinoatrial node in R atrium sets heart rate at 70 bpm.
3. the atrial cells contract and transmit the signal from top down (most efficient way to make
blood move down into left ventricle). Cannot pass AP into ventricle cells because of white
protective fat layer.
4. AV node
5. bundles of His- runs within interventricular septupm- conduct without contraction
6. purkinje fibers: release AP to ventricle cells at bottom to top to make blood go up to lungs.
, p-wave of EKG ANSWER-atrial depolarization; AP is in atria
QRS complex ANSWER-ventricular depolarization: squeeze from bottom up. (lub)
T-wave ANSWER-ventricular repolarization (dub)
blood pressure's effect on cardiac cycle ANSWER-due to space constriction as volume
decreases, pressure increases. Need to increase pressure to force blood to move to lower
pressure area.
2 phases in one cycle ANSWER-systole and dystole
systole ANSWER-contraction to empty ~1/3 of the time
dystole ANSWER-relaxation to fill ~2/3 of time
Stroke Volume (SV) ANSWER-end diastolic volume (EDV) - end systolic volume (ESV)
End Diastolic Volume (EDV) ANSWER-pre-contraction volume (max V ~ 135 mL)
End Systolic Volume (ESV) ANSWER-post-contraction; min V ~ 65 mL
heart rate ANSWER-strokes or cycles per min
unit= bpm
cardiac output ANSWER-stroke volume x heart rate
