Cardiovascular System Flashcards
which circulation usually has more resistance, pulmonary or arterial
arterial circulation
Normal MAP?
70-100
the low resistance in the pulmonary circuit means what for the arterial and vensus pressures in there
only a small difference is needed between the two to maintain blood flow
most coronary venous bloods drains into where
coronary sinus by the right atrium
the right and left coronary arteries that supply blood to the heart arise from where
aortic root
what part of the heart is the most susceptible to ischemia and why
the Subendocardium, because contraction force is the highest near the endocardium, compressing the coronary vessels to supply the heart with blood
why is cardiac venous blood the most deoxygenated then any other tissue
because the myocardium extracts 60-75% of the o2 in blood that comes too it
increased 02 to the heart can only be achieved how
by increasing coronary blood flow
what are the two most important factors in in coronary blood flow autoreguliton
Adenosine and Nitrix Oxide
Adenosine is a product of?
ATP
what is the major regulator of flow-mediated vasodilation in large arteries and pre-arteriolar vessels
Nitric Oxide
What works within vascular smooth muscles via soluble guanylate cyclase enzyme to increase proaction of cGMP and cause smooth muscle relaxation
Nitric Oxide
B1 receptors cause?
Heart excitation
B2 receptors cause?
vasodialtion
what is a powerful vasoconstrictor that regulates systemic blood pressure
Angiotensin II
what is Nitric Oxide synthesized from
Arginine and O2 in the endothelial cells
Hypotension, elevated JVP, and muffled heart sounds are known as the Beck Triad and indicate what
cardiac tamponade
Late diastolic collapse of the right atrium and pericardial fluid accumulation is seen in
cardiac tamponade (due to fluid displacement when the ventricles expand)
what is the exaggerated drop is systolic BP (>10) during inspiration called
plusus paradoxus
Plusus Paradoxes can occur in what 5 pathologies?
cardiac tamponade hypovolemic shock asthma COPD constrictive pericarditis
voltage gated L-type Calcium channels with a large influx of Ca2+ into the cell open at what phase in the cardiac cycle
Phase 0: depolarization
closure of L-type Calcium channels and the opening of K+ channel is seen in which phase of the cardiac cycle
Phase 3: repolarization
slow influx of sodium beginning at the end of depolarizations happens in what phase of the cardiac cycle
Phase 4: pacemaker potential
how does adenosine slow down phase 4
it acts on the A1 receptors on the cardiac cells and activates potassium channels causing the membrane potential to remain negative for longer periods of time
also inhibits L-type calcium channels
what is useful to give for paroxysmal supra ventricular tachycardia
adenosine
what is the abrupt cessation of organized cardiac activity causing an inability to maintain adequate tissue perfusion
Suden Cardiac Death SCD
what is the most frequent mechanism of SCD in the first 48 hours after and acute MI and is related to electrical instability due to lack of perfusion to the ischemic myocardium
Ventricular Fibrillation
occlusion of the LAD most commonly present with what
ventricular septal rupture
what two things reduce the rate of phase 4
Adenosine and Ach
what type of calcium channels are opened in phase 4
t-type
