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What is the function of the cardiovascular system?
to circulate blood at a rate that is consistent with metabolic demand while also maintaining low filling pressure and adequate perfusion pressure
What is perfusion pressure?
pressure needed to push blood to vital organs and other body systems
What is filling pressure?
a combination of the blood entering the heart and blood left over in the heart after a pump
What four things can blood carry?
nutrients
gas
waste
electrolytes
What is oxygen bound to?
hemoglobin
How do gas/nutrients/waste get exchanged in the blood?
capillaries
What are the two types of circulation?
Systemic and pulmonary
What is stroke volume?
the amount of blood that leaves the heart during systole
What is cardiac output?
the amount of blood that leaves one side of the heart in one minute
What is the equation for cardiac output?
stroke volume x heart rate
What are the pulmonary and aortic valves also known as?
Semilunar valves
What happens to pressure when a ventricle constricts?
pressure increases in comparison to atrial pressure
When do the AV valves close?
When ventricular pressure increases greater than atrial pressure
When do AV valves open?
when atrial pressure is higher than ventricular pressure
When do semilunar valves open?
when ventricular pressure exceeds great artery pressure
When do semilunar valves close?
when arterial pressure exceeds ventricular pressure
What is diastole?
when atria and ventricles are relaxed
What is sytole?
When atria or ventricles are contracted (ventricular contraction occurs shortly after atrial contraction)
What is the right AV valve also known as?
the tricuspid valve
What is the left AV valve also known as?
mitral valve
What is the difference in shape between the left and right ventricles?
Right ventricle is crescent shaped while the left ventricle is cylindrical
What is the shape of the right ventricle?
Crescent
What is the shape of the left ventricle?
cylindrical
What is the important physical difference between right and left ventricles?
Left ventricle is thick walled while the right ventricle is thin walled
Which ventricle is considered a pressure pump?
left ventricle because it is systemic circulation
Which ventricle is considered a volume pump?
right ventricle
Where does blood in veins go?
to the heart
Where does blood in arteries go?
away from the heart
What term can be used to describe the pattern of blood vessels around/on the heart
fractal branching
What are capillaries made of?
single layer of endothelial cells
What are large arteries made of?
elastin
What do veins not usually contain?
elastin because they dont need stretch (want to increase pressure)
How is blood flow to tissues controlled?
Local vasoconstriction and vasodilation
What is the fibrous skeleton responsible for?
electrically isolating the atria and ventricles
What is the difference between a working cardiomyocyte and a special cardiomyocyte?
Working cardiomyocytes do not spontaneously depolarize while special cardiomyocytes do
Where can you find working cardiomyocytes?
fibrous skeleton
When do working cardiomyocytes depolarize?
When their neighbors do
Why is low filling pressure important?
to avoid congestion
What are the components of the conduction system?
special cardiomyocytes
AV node
SA node
Bundle of His
Purkinje Fibers
Where is the AV node located?
Atrial septum
Where is the SA node located?
Right atrium
What gives rise to purkinje fibers?
bundle of his
What is the electrical connection between the atria and ventricles?
bundle of his
What is the bundle of his?
electrical connection between atria and ventricles
What gives rise to the Bundle of His?
AV node
What makes special cardiomyocytes so special?
automaticity/ spontaneous depolarization
What is the purpose of the conduction system?
allow communication between atria and ventricles with slight pause
What is Ohm's law?
pressure difference= cardiac output x resistance
What is resistance?
forces that must be overcome to establish flow
What is current equivalent to?
cardiac output
What is voltage equivalent to?
pressure difference
What does Poiseuille's Law relate?
Radius and distance
What happens to resistance when radius is increased?
resistance is decreased
What happens to resistance when radius is decreased?
resistance is increased
What is laminar flow?
smooth flow
What is turbulent flow?
unorganized flow
What factors are related to laminar flow becoming turbulent flow?
tube diameter, viscosity, density (all affect reynold's number)
What kind of pressure system is systemic circulation?
high pressure
What kind of pressure system is pulmonary circulation?
low pressure
What kind of oxygen system is systemic circulation?
high O2
What kind of oxygen system is pulmonary circulation?
low O2
What kind of resistance system is systemic circulation?
high resistance
What kind of resistance system is pulmonary circulation?
low resistance
What is heart rate?
number of cardiac cycles in one minute
What is normal membrane potential?
negative interior, positive exterior
Why are cardiomyocytes excitable?
membrane potential
What leads to an initial depolarization in the heart?
Excitation of cardiomyocytes
What is a depolarization?
momentary reversal of the membrane potential (becomes more positive inside)
What does an initial depolarization lead to?
Action potential
What is the formula for conductance?
reciprocal of resistance
What is conductance?
How easily ions flow
How does membrane potential change?
ions flow in and out via special channels
What part of the conduction system has the highest inherent rate of automaticity?
SA node
What part of the conduction system has the lowest inherent rate of automaticity?
bundle of his
What is pressure?
Force over a given area
Where is the most blood found at any given time?
Systemic veins
What are the units for pressure?
mmHg
What determines venous return?
intravascular blood volume and venous tone
Where is the greatest vascular resistance found?
Arterioles because they are more rigid
How is tendency for laminar flow to turn into turbulent flow determined?
Factors that impact Reynold's number
What factors impact reynold's number?
density, velocity, density, viscosity, diameter of vessel
What is impedence?
forces that oppose pulsatile flow
How does the heart contract?
myocardial shortening
What are the most important ions involved in heart conductance?
calcium, sodium, potassium
What controls cardiac rhythm?
SA node
Why is working cardiomyocytes considered a functional syncitium?
intercalated discs and gap junctions allow it to function as one unit
What are the three ways resting membrane potential is created?
ATPase
Donnan Effect
Selective permeability of membrane (leaky K but not permeable to Na)
What are the two types of potassium channels?
1.voltage-gated channels 2. inward rectifier
What are voltage-gated K+ channels for?
repolarization
What are inward rectifiers (K+) for?
maintaining resting potential
How does the duration of a cardiac action potential compare to that of a nerve cell?
It is much longer than that of nerve cell AP
Why does a cardiac AP have a plateau?
to avoid tetanus
What does inward Na+ flow cause during phase 0?
Initial depolarization of purkinje and working myocardium
What does slow Ca channels inward flow cause?
phase 2 plateau of specialized cardiomyocytes AND upstroke of working cardiomyocytes in phase 0
What ion causes initial depolarization of working cardiomyocytes?
sodium
What causes initial depolarization of specialized cardiomyocytes of nodes?
calcium
What cells DO NOT spontaneously depolarize?
atrioventricular cells (working cardiomyocytes)
What is overdrive supression?
spontaneous depolarization is suppressed if depolarization rate is higher than inherent rate in specialized cardiomyocytes
What can change rate of spontaneous depolarization?
autonomic influences
What is phase 2 of the action potential in heart?
plateau
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