1. Heart sounds are the lub-dup we are all familiar with; the lub occurs when the AV valves shut, and the dup occurs when the semilunar valves shut, but the sound itself is the turbulent flow of blood against the closed valves
2. Stroke volume is the amount that a full ventricle can hold, which is normally 70 mL in humans; cardiac output is the stroke volume times the heart rate = 70 mL x 70 beats/min = 4900 mL/min
3. this occurs when the incoming blood (or cardiac return) causes the cardiac muscle to stretch, increasing the force of the next contraction; increasing cardiac return causes an increase in the whole system! It is based on need…
4. PARASYMPATHETIC – vagus nerve uses Ach to hyperpolarize the nodal cells it innervates, decrease rate of APs, decrease heart rate (if you cut the vagus nerve, heart rate will increase)
   SYMPATHETIC – cardiac nerve uses nor/epinephrine to depolarize the nodal cells and ventricular muscles it innervates, increase conductance of APs, increase heart rate
5. right we totally already answered this in #3
6. hmmm…

VASCULAR RESISTANCE – friction with the blood vessel wall that will increase or decrease with blood vessel diameter (how?)
VISCOSITY – a fluid resistance; friction against itself (i.e. water is 1, blood is 5, honey is a lot more)