Lecture 8 Flashcards
which parts of the heart contract simultaneously?
left and right pumps
which section of the heart contracts first?
atria contract first then ventricles
what is different about cardiac muscle contraction compared to skeletal?
in cardiac muscles, ALL myocytes are activated during each heart beat = non voluntary
in skeletal muscle this doesn’t happen = voluntary
how is the force of cardiac muscle increased?
- increasing cytosolic Ca2+ level
- this increases cross bridges formed
- this increases force of contraction
how does cardiac relaxation occur?
- decrease cytosolic Ca2+ levels (Ca2+ pumped back into the SR)
- cross bridges release when ATP binds to myosin
- reduction in force means heart can relax
- ALL cardiac myocytes relax each heart beat
what is distole ?
- relaxation
- falling pressure
what is systole?
- contraction
- rising pressure
what is the lubb sound (first sound) in the cardiac cycle?
AV valves closing, meaning ventricular pressure is greater than atria and the ventricles are contracting
what is the dubb sound in the cardiac cycle ?
semilunar valves closing, because ventricular pressure is lower than the aorta and the pulmonary artery
is diastole or systole usually longer ?
diastole
on the pressure graph what is systolic pressure ?
the highest point on the trace
on the pressure graph what is diastolic pressure?
lowest point on the trace
on the pressure graph what is pulse pressure?
the difference between the highest and lowest points
on the pressure graph what is the mean pressure?
the average pressure across the full cycle (usually just below half)
what is hypertension
when blood pressure is too high
