Cardiac

Question 1

Striated special heart muscle?

Answer 1

Intercalated disks with gap junctions –> serial, low resistance connections that allow rapid & organized contractions

Question 2

Calcium mediated contraction

Answer 2

Calcium binds troponin and exposes active sites for myosin –> Magnesium-dependent ATPase (ATP consumption)

Question 3

Force of cardiac contraction related to?

Answer 3

amount of calcium influx!!!!

Question 4

Parasympathetic Innervation of Heart

Answer 4

atria and conducting fibers - M2 receptors –> ACh (-) chronotropic, inotropic and dromotropic - decreases cAMP and depletes Ca2+

Question 5

Sympathetic Innervation of Heart

Answer 5

widely distributed in heart - T1-4 –> cervical ganglia (accelerator fibers) - beta1 receptors –> increased Ca2+ and cAMP which increases contractility

Question 6

Determinants of ventricular function

Answer 6

1. Preload 2. Afterload 3. Heart rate 4. Contractility

Question 7

Starling Curve

Answer 7

Question 8

Mixed Venous Oxygen Saturation

Answer 8

Measure of oxygen consumption in relation to CO

• low SvO2 = inadequate perfusion

Question 9

Preload

Answer 9

LVEDV –> the distention of the ventricle

Question 10

Determinants of ventricular filling

Answer 10

1. Overall blood volume
2. Heart Rhythm
3. Heart rate

Question 11

Most important aspect of preload?

Answer 11

Venous return!

Question 12

Afterload

Answer 12

ventricular wall tension or arteriole impedence

Question 13

LaPlace’s Law

Answer 13

Stress = P x R / 2xH

Question 14

SVR Calculation

Answer 14

80 x MAP - CVP / CO

Question 15

PVR Calculation

Answer 15

80 x mPAP - LAP / CO

Question 16

Contractility

Answer 16

intrinsic ability of heart muscle to pump (dP/dT)

Question 17

Things that depress contractility

Answer 17

1. Hypoxia
2. Acidosis
3. Depleted Catecholamines
4. Ischemia

Question 18

Immediate control of BP

Answer 18

Autonomic Nervous System

1. Baroreceptors –> common carotid (IX) and aortic arch (X)
   - carotid sinus is responsible for tone

Question 19

Intermediate control of BP

Answer 19

Renin-Angiotensin Aldosterone System

• Ang II –> Arginine Vasopressin –> V1 receptors
• fluid retention

Question 20

Left ventricle perfused during when?

Answer 20

during diastole so coronaries have flow through them

Question 21

Right ventricle is perfused when?

Answer 21

Throughout cardiac cycle as right side has lower pressure

Question 22

Blood flow to myocardium?

Answer 22

It proceeds epicardial –> endocardial

Question 23

Right Coronary

Answer 23

supples R atrium & ventricle and inferior wall of LV

• PDA determines dominance

Question 24

Left Coronary

Answer 24

• supplies L atrium, IV septum and most LV
• LAD and circumflex

Question 25

Coronary Perfusion Pressure

Answer 25

CPP = Aortic DP - LVEDP