EX 2; The Heart Flashcards
This is a rapid assessment of blood composition; the percent of the blood volume that is composed of RBCs
hematocrit; should be roughly 45%
Estimate the hematocrit of a person with a plasma volume of 3L and a total blood volume of 4.5L
- 5-3 = 1.5L
1. 5/4.5 = 33% hematocrit
The exchange of oxygen, carbon dioxide, nutrients, and metabolic end products occurs at the level of what
capillaries
Which portions of the body receive the most blood flow at rest
muscle
kidneys
abdominal organs
This is the volume per unit time
flow
What is the equation for determining flow
change in pressure/resistance
This is how difficult it is for blood to flow between 2 points
resistance
What can affect resistance
change in radius
What is the equation for resistance
8(length)(fluid viscosity(ή))
divided by
Ħ (radius)^4
This can alter the resistance and thereby flow
blood viscosity
What causes the heart valves to open and close
pressure differences
How does the electrical conduction flow through the heart
via gap junctions; allowing it to be very rapid
What is the flow of the electrical current through the heart
SA - atria - AV - bundle of His - bundle fibers - ventricles
This is the hearts pacemaker because it initiates each wave of excitation with atrial contraction
SA node
What is the role of the bundle of His and other parts of the conduction system
deliver the excitation to the apex of the heart so that ventricular contraction occurs in an upward sweep
What is the P
atrial depolarization
What is the QRS
ventricle depolarization
What is the T
ventricle repolarization
What happens to the atrial repolarization
it is “lost” in the QRS series
The rapid opening of what is responsible for the rapid depolarization phase
voltage gated sodium channels
The prolonged “plateau” of depolarization is due to what
the slow but prolonged opening of voltage gated calcium channels plus the closures of the potassium channels
This results in the repolarization phase
opening of the potassium channels