Physiology Flashcards
Heart vessel that supplies anterior 2/3 of interventricular septum, anterolateral papillary muscle and anterior surface of left ventricle
Left anterior descending artery (LAD)
What variables maintain cardiac output during the early stages of exercise
Increased HR and SV
What variables maintain cardiac output during the late stages of exercise
HR only (SV plateaus)
What heart function is shortened by increased HR
Diastole
Effect of decreased diastole
Less filling time causing decreased cardiac output
Calculating CO
CO = HR x SV
Fick principle for calculating CO
CO = rate of O2 consumption/(arteriole O2 content - venous O2 content)
Method for calculating mean arterial pressure (MAP)
MAP = CO x TPR or MAP = 2/3 diastole + 1/3 systole
What is pulse pressure (PP)
PP = systolic pressure - diastolic pressure
Method for calculating stroke volume (SV)
SV = EDV - ESV
Variables that affect SV
Contractility, Afterload, Preload
Effect of increased contractility on SV
Increased SV
Effect of increased afterload on SV
Decreased SV
Effect of increased preload on SV
Increased SV
Effect of decreased contractility on SV
Decreased SV
Effect of decreased afterload on SV
Increased SV
Effect of decreased preload on SV
Decreased SV
Effect of catecholamine binding on contractility and SV
Both increased
Catecholamine MOA on increasing contractility and SV
Bind B-1 receptors leading to two outcomes:
1. Phosphorylate Ca channels
2. Phosphorylate phospholamban
Both increase Ca in SR through different mechanisms
Mechanisms that increase contractility and SV
- Catecholamine binding to B-1 receptors
- Increasing intracellular calcium
- Decreasing extracellular Na
- Digitalis or Digoxin
All methods increase intracellular calcium
Mechanisms that decrease contractility and SV
- B-1 blockade decreases cAMP
- HF with systolic dysfunction
- Acidosis
- Hypoxia/hypercapnia
- Non-dihydropyridine Ca channel blockers
Variables that increase myocardial O2 demand
Increased:
- Contractility
- Afterload
- HR
- Diameter of ventricle (increased wall tension)
Variable that approximates preload
EDV
Variables that affect EDV
Venous tone and circulating blood volume
Effect vasodilation has on EDV
Decreases EDV due to decreased venous return
Variable that approximates MAP
Afterload
Formula for calculating Ejection Fraction (EF)
EF = SV/EDV = (EDV - ESV)/EDV
Heart failure decreases what variable
Ejection fraction
Blood vessels with flow velocity
Capillaries (highest cross-sectional area)
Blood vessels that account for most TPR
Arterioles
Blood vessels that provide the most storage capacity
Veins
What does viscosity depend on most
Hematocrit
Condition that decreases blood viscosity
Anemia
Condition that increases blood viscosity
Polycythemia and hyperproteinemic (multiple myeloma)
In Starling forces, force of contraction is proportional to what?
End-diastolic length of cardiac muscle fiber
End-diastolic length of cardiac muscle fiber determines what?
Force of contraction
Formula for calculating change in pressure
P = Q x R
Formula for calculating Resistance
R= P/Q
Formula for calculating total parallel resistance
R = 1/(1/R1 + 1/R2 + 1/R3)
Formula for calculating total series resistance
R = R1 + R2 + R3
Effect of Vasopressors on TPR and CO for a given RA pressure or EDV
Increase TPR and decrease CO
Effect of exercise or AV shunt on TPR and CO for a given RA pressure or EDV
Decrease TPR and increase CO
Effects of increased afterload on pressure volume loop
Increased aortic pressure and ESV
Decreased SV
Effect of increased preload on pressure volume loop
Increased SV
Effect of increased contractility on pressure volume loop
Increased SV and Ejection fraction
Decreased ESV
Period between mitral valve closing and aortic valve opening
Isovolumetric contraction
Period of highest O2 contraction
Isovolumetric contraction
Period between aortic valve opening and closing
Systolic ejection
Period between aortic valve closing and mitral valve opening
Isovolumetric relaxation
Period just after mitral valve opening
Rapid filling
Period just before mitral valve closing
Reduced filling
Sound made by mitral and tricuspid valve closure
S1
Sound made by aortic and pulmonary valve closure
S2
Area S1 loudest
Mitral area
Area S2 loudest
Left upper sternal border
Heart sound associated with increased filling pressures
S3
Heart sound made by left atrium pushing against stiff LV wall
S4
Heart sound that can be normal in children and young adults
S3
Heart sound considered abnormal at any age
S4
S4 heart sound is best heard at apex in what position
Left lateral decubitus position
JVP associated with atrial contraction
a wave
JVP associated with RV contraction
c wave
JVP associated with downward displacement of closed tricuspid valve during rapid ventricular ejection phase
x descent
JVP associated with increased right atrial pressure due to filling against closed tricuspid valve
v wave
JVP associated with RA emptying into RV
y descent
Cause of normal splitting between A2 and P2
Inspiration
Cause of wide splitting between A2 and P2
Conditions that delay RV emptying (pulmonic stenosis and RBBB) - splitting exaggerated during inspiration
Cause of fixed splitting
ASD - increased RA and RV volumes causes increased flow through pulmonic valve delaying closure regardless of breath
Cause of paradoxical splitting
Conditions that delay aortic valve closure (aortic stenosis and LBBB) - P2 closes before A2 - on inspiration P2 closer to A2 paradoxically eliminating split
Murmurs heard best in Mitral area
Mitral regurgitation
Mitral valve prolapse
Mitral stenosis
Murmurs heard best in Tricuspid area
Tricuspid regurgitation
Tricuspid stenosis
VSD
ASD
Murmurs heard best in Pulmonic area
Pulmonic stenosis
Murmurs heart best in LUSB
Pulmonic regurgitation
HCM
Aortic regurgitation
Murmurs heard best in Aortic area
Aortic stenosis
Maneuver that increases intensity of right heart sounds
Inspiration (increases venous return to RA)
Increases intensity of AR and VSD murmurs
Hand grip and rapid squatting
Maneuver that decreases intensity of most murmurs including AS
Valsalva and standing up
Maneuver that decreases intensity of hypertrophic cardiomyopathy murmurs
Hand grip and rapid squatting
Increases intensity of AS
Rapid squatting
Maneuver that increases intensity of hypertrophic cardiomyopathy murmurs
Valsalva and standing up
Maneuver that causes later onset of click/murmur in MVP
Hand grip and rapid squatting
Mnemonic for Systolic murmurs
MR VP TRAPS: Mitral Regurgitation VSD Pulmonic stenosis Tricuspid Regurgitation Aortic and Pulmonic Stenosis
Mnemonic for Diastolic murmurs
MS PAID:
Mitral Stenosis
Pulmonic and Aortic Insufficiency
D - just for diastolic
Continuous murmurs
Patent ductus arteriosus
Crescendo-decrescendo systolic ejection murmur, radiates to carotids with “pulsus parvus et tardus”, heard loudest at heart base
Aortic stenosis