missed stuff Flashcards
what is the formula for cardiac index
CI= (SVxHR)/body mass
what is the formula for systemic vascular resistance
SVR = (MAP - RAP)/(CO) x 80
The “transient outward” currents are most prominent in what phase of the cardiac myocyte action potential
phase 1; these are the K+ and Cl- channels that cause early repolarization
Hyperkalemic solutions, usually 24 mEq of K or more, are clinically used in cardiac surgical procedures to effect cardioplegia. Which of the following is the most likely reason that a cardioplegia solutions obtain cardiac standstill
Hyperkalemia depolarizes the cell membranes so that normal activation processes do not activate.
On close examination of the electrocardiogram of a 65-year-old woman, the PR interval was measured to be 250 ms. All other parameters of the electrocardiogram were in the normal range. What was the most likely cause for this abnormal observation?
Slow conduction of impulses in the AV node
During what phase of the “working” cardiac myocyte action potential do the L-type Ca channels start activating?
phase 0
The rate at which the cell membrane depolarizes during phase 4 of the nodal cells can be influenced by which of the following factors interacting with the channels that carry the depolarizing current
cAMP
Which of the following is the most likely reason that the wave of repolarization in the ventricles travels from epicardium to endocardium?
Myocytes of the epicardium have the shortest duration of the action potential and those of the endocardium have the longest.
A 65-year-old patient with chronic kidney disease is admitted to the hospital with hyperkalemia. The patient is mistakenly administered a potassium bolus, resulting in life-threatening arrhythmias. Which of the following mechanisms best explains this complication
impaired repolarization of cardiac myocytes; excess potassium decreases the outflow of potassium ions during phase 3 (repolarization). this impairs repolarization, which screws up the ability of the heart’s depolariztion-repolarization cycle needed to work properly
what is the function of phospholamban
it inhibits SERCA. if we phosphorylate it, we can activate SERCA nad uptake more calcium into the SR
the sternal angle is at the level of which rib
2
does inhibition of phospholamban cause increased or decreased contractility
increased; lets SERCA uptake calcium which gets the myocyte through the phases faster
what does the internal thoracic artery branch off of
the subclavian artery
the azygous veins are found in which division of the mediastinum
posterior mediastinum
which vein originates from the left and crosses the midline to merge with the SVC
left brachiocephalic
why can ACE inhibitors and ARBs be an issue in those with bilateral renal stenosis?
the ability of these drugs to lower ang II ability limits the ability of the already struggling kidney to properly filter blood. these kidneys rely on ang II to constrict the efferent arteriole to promote filtration, and these drugs prevent this process and can cause acute kidney failure
what do superior costal facets articulate with
head of rib of the same number
which nerve helps elevate the ribs during inspiration
the intercostal nerve
what area of the heart is most prone to ischemia
subendocardium
an abcess may lead to what other issue in a vessel
aneurysm
what condition tends to cause valve fushion
acute rheumatic endocarditis
local edema following a sprained ankle is likely due to…
increased capillary permeability; the vascular injury causes local edema
what is the equation for resistance
deltaP/flow
In a patient with aortic stenosis, which of the following would be the most likely reason that a high-velocity jet is observed across the aortic valve during ejection
blood is being ejected through a narrowed valve
give ficks equation for arterial and venous blood
CO= (Vo2)/(ca - cv)
In a patient with heart failure who is generally sedentary, the systemic arteriovenous oxygen difference is measured to be more than doubled when compared to normal values. What is the most likely reason for this observation
In a patient with heart failure, a common finding would be a reduction in cardiac output and lower flow of blood through capillary beds all through the body. This allows tissue to extract more oxygen from the blood, reducing the oxygen content in venous blood - and widening the arteriovenous oxygen difference.
how to we calculate transcapillary pressure?
(plasma hydrostatic pressure + tissue oncotic pressure) - (tissue hydrostatic pressure + plasma oncotic pressure)
which organs have high interstitial hydrostatic pressure
kidney and brain
what are specialized pericytes in the brain called
astrocytes
what keeps the ductus arteriosus open
PGE2 and hypoxia
the ___ separates the left vagus and phrenic nerves
intercostal vein
Which muscles are recruited to reduce thoracic volume during forced expiration?
internal instercostals, abdominal muscles
