Apex- Cardiac A&P Flashcards
Does hypokalemia increase or decrease RMP?
Decrease
hyperkalemia increases RMP (just think, physically increases it closer t
Hypocalcemia (increases/decreases) threshold potential
What is TP?
decreases
TP = -70mV
T/F: the wave of depolarization throughout the heart is facilitated by t-tubules
False - gap junctions
T/F- ventricular myocytes contain more mitochondria than skeletal myocytes
True
Which phase of the ventricular action potential is associated with the GREATEST calcium conductance?
1,2,3,4
2
What happens during the 5 phases of the myocytes action potential? (0-4)
- Phase 0- Depolarization → Sodium in (+++)
- Phase 1- Inital repolarization → Cl- in and K+ out (-)
- Phase 2- Plateau → Calcium in and K+ out
- Phase 3- Repolarization → K+ out (—)
- Phase 4- Maintenance of TP → (K+ out & NA/K-ATPase function)
Match with Phase 0, 1, 2, 3, 4
- ST segment
- Potaassium Leak
- Plateau
- Isoelectric EKG
- Q wave
- Final Repolarization
- Depolarization
- Potassium Efflux
- Calcium influx
- T-Wave
- Sodium influx
- Resting phase
Phase 0 - Q-Wave, depolarization, NA++ influx
Phase 2 - ST segment, plateau , Ca++ influx
Phase 3- final repolarization , K+ efflux, T-wave
Phase 4 - potassium leak, isoelectric ECG, resting phase
Which current is responsible for sponatenous phase 4 depolarization in the SA node?
A. I-NA
B. I-K
C. I-Ca
D. I-f
D (I-funny channels)
How can volitale anesthetics cause a junctional rhythm?
By depressing automaticity of the SA node
What are the 3 phases of action potential in the SA and AV node?
Phase 4 = Spontaneous depolarization → Na+ in (I-f) then Ca ++ in (T-type)
Phase 0 = Depolarization → CA++ in (L-type)
Phase 3 = Repolarization → K+
Where are action potentials propagated after the SA node (course through the heart)
SA node → internodal tracts → AV node → Bundle of His → Left and Right Bundle Branches → Purkinje Fibers
What is the intrinsic firing rate of the SA node vs AV node vs Purkinje fibers?
SA node → 70-80
AV node → 40-60
Purkinjes → 15-40
What is the Keith-Flack node and where does it reside?
It’s the SA node and it resides in the right atrium
What is the expected o2 delivery of a 70kg adult?
A. 20ml/dL
B. 1000ml/min
C. 250ml/min
D. 15ml/dL
Can you identify the other numbers? They are signify something lol
B. 1,000 mL/min
A. 20ml/dL = Arterial o2 content (CaO2)
B. 1,000mL/min = Oxygen delivery (DO2)
C. 250ml/min = O2 consumption (VO2)
D. 15ml/dL = Venous o2 content (CvO2)
How do you calculate o2 delivery (DO2)?
CO x CaO2 x 10
CaO2 = O2 bound + O2 dissolved
CaO2 = (Hgb x SaO2 x 1.34) + (PaO2 x 0.003)
The amount of oxygen dissolved in blood (PaO2) follows what law?
Henrys
-at a constant temp, the amount of gas that dissolves in a solution is directly proportional to the pressure of that gas
Blood flow is inversely propostional to:
A. Body temp
B. Vessel Diameter
C. Afrteriovenous pressure difference
D. Hematocrit
D. Hematocrit
What 3 things does poiseuille’s law consider?
which one impacts blood flow the most?
Vessel diameter (R^4)
Viscosity
Tube length
*changing diamater is best way
Doubling radius → flow increase 16 fold ; Tripling radius → increases 81 fold ; Quadrupling → 256 fold
What reynold’s number predicts that flow will be mostly laminar vs mostly turbulant vs transitional?
<2,000 = laminar
>4,000 = turbulant
2,000-4,000 = transitional
Why do we combine PRBCs with normal saline anad run it through a warmer? What’s the overall purpose?
To improve flow
-adding saline reduces viscosity and improves flow
-warming fluid reduces viscosity and improves flow
2 ways to calculate MAP
SBP + (2)DBP / 3
(CO x SVR)/ 80 + CVP
SVR = MAP - CVP/CO * 80
CPP autoregulates between what
MAPs between 60-140mmHg
What is PAOP the same as?
LVEDP
CPP =
DBP- PAOP (or LVEDP)
CPP is the driving force of coronary blood flow