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Newhall - cardio
Fundamentals- Cardio
Question | Answer |
---|---|
What vessel is the site of greatest resistance to flow? | Arterioles |
What effect does Alpha receptor stimulation have on arterioles? | Constriction |
T/F vascular resistance is modified by parasympathetic nervous activity only? | False. Modified by sympathetic activity and vasoactive substances |
What shift in blood would tx with a sympathetomimetic cause? | Depends on the receptor. Alpha would cause vascular constriction and arterial shift. Beta-2 would dilate the veins causing venous shift. |
Pt has large amount of blood loss. What can their body (autonomic nervous system) do to compliance of the veins to ensure adequate circulating blood flow? | Inc'd sympathetic tone --> decrease compliance --> dec'd capacitance --> blood shifted to arterial side. |
Pt has pulmonary edema resulting from CHF. How can you treat by changing venous compliance? | CHF can result from dec'd peripheral venous compliance. Blood shifted to arterial side and inc'd pressure aorta has to pump against --> inc'd pressure in pulmonary system --> pulmonary edema. Tx by increasing venous compliance (VASO ACTIVE SUBSTANCE). |
What is the most important factor in blood flow resistance? | Radius |
Will dilating a capillary bed inc or dec total resistance (assuming parallel system) and blood pressure? | Dec'd resistance and BP. |
What causes non-laminar flow? | blood flowing over obstruction |
Pulse pressure | systolic-diastolic pressure |
Mean arterial pressure | diastolic pressure + 1/3 pulse pressure |
Stroke volume | volume of blood ejected from one ventricle in a single cycle. |
In what tissue of the heart are conducting cells found? | SA node, AV node, bundle of His, purkinje fibers. |
An increase in conduction velocity of the AV node will do what to stroke volume/ CO? | Decrease SV and CO. The ventricle won't have sufficient time to fill before contracting. |
What is unique to cardiac AP in regards to depolarized membrane potential? | It is relatively stabilized during phase 2. |
If SA node is blocked/damaged which latent pacemaker takes over and roughly what will HR be? | AV node, 40-60 |
What are the unique features of SA node AP? | NO PHASE 1 or 2. NO PLATEAU. UNSTABLE MEMBRANE POTENTIAL. "funny" inward Na current causes slow depolarization of phase 4 --> next AP. |
Which phase of SA node AP accounts for its automaticity? | Phase 4- Longer than normal. Repolarization slowed by SLOW Na+ channels. These channels also --> next AP |
Parasympatomimetic will affect what region of the heart? | Atria only. |
A drug that reduces inward flow of Ca+ during phase 2 (plateau) will have what effect on contractility and likely belongs to what class of drug? | Dec'd contractility, parasympatomimetic. |
An increase in HR has what effect on contractility? | Inc'd. Staircase effect. Less time for Ca+ to be reabsorbed. |
Which drug will results in inc'd SV and EF: positive ionotropic or negative ionotropic? | Positive ionotropic |
How will inc'd preload affect ventricular pressure-volume loop? | Shift to the right. Greater volume at same phases/pressure. |
Which is more costly for the heart (in terms of inc'd myocardial O2 consumption) : Pressure work (from afterload) or volume work? | Pressure work is much more costly. Small inc in BP very costly compared to much inc'd volume at same BP. |
Common pathology r/t chronic excessive workload? | ventricular hypertrophy. |
How does ventricular hypertrophy effect CO? |