Cardiovascular Physiology Flashcards
Rationale for higher blood velocity in the aorta than in the sum of all of the capillaries?
Aorta: small cross-sectional area
Capillaries: large cross-sectional area
Rationale for large cross-sectional areas in capillaries?
Large cross-sectional areas = lower velocity of blood in the capillaries optimizes the conditions for exchange of substances across capillary wall.
Equation / formula used resistance?
Poiseuille equation:
R= 8nl / πr to the power of 4
Where:
R= resistance
n= viscosity of blood
l= length of blood vessels
r4= radius of blood vessels to the fourth power
Describes the distensibility of blood vessels?
Capacitance ( Compliance)
C= V/P
Where:
C= Capacitance of Compliance (mL/mm Hg)
V= Volume (mL)
P= Pressure (mmHg)
Decrease in venous capacitance effect of unstressed and stress volume?
Decreases unstressed volume and Increases stressed volume by shifting blood from the veins to the arteries.
Effect of decrease AV node conduction on PR interval ?
PR interval increases
Refers to the increase force of contraction in a stepwise fashion as the intracellular calcium increases cumulatively?
Positive Staircase / Bowditch Staircase / Treppe
- increased heart rate increases the force of contraction in a stepwise fashion as the intracellular calcium increases cumulatively over several beats.
Refers to the beat that occurs after an extrasystolic beat that has increased force of contraction?
Post-extrasystolic potentiation
- the beat that occurs after an extrasystolic beat has increased force of contraction because “extra” Ca has entered the cells during the extrasystole.
70kg man, has a Resting O2 consumption of 250mL / min; Systemic arterial O2 of 0.20ml O2/ mL; Systemic mixed venous O2 of 0.15mL O2/mL ; Heart rate of 72 beats/ min.
What is the Cardiac Output?
What is the stroke volume?
CO= 5000mL/min
SV= 69.4 mL / beat
CO= O2 consumption / O2 pulmonary artery- O2 pulmonary veins
CO= 250ml/min / (0.20 - 0.15) = 5000ml/ min?
SV= CO / HR
SV= 5000ml /72 beats / min
SV= 69.44 mL / beat
At the arteriolar end of capillary:
Capillary HP: 30mmHg
Capillary OP: 28 mmHg
Interstitial HP : 0 mmHg
Interstitial OP: 4mmHg
Filtration or Absorption?
Filtration
(30mmHg- 0mmHg ) - (28mmHg-4mmHg)
= +6mmHg
At the venous end of capillary:
Capillary HP: 16mmHg
Capillary OP: 28 mmHg
Interstitial HP : 0 mmHg
Interstitial OP: 4mmHg
Filtration or Absorption?
Absorption
(16-0)-(28-4)
= - 8 mmHg
Response of vessels in myogenic hypothesis during an increase in perfusion pressure?
Vasoconstriction
- without vasoconstriction, blood flow would increase as a result of increased pressure
50% narrowing of an artery leads to how much decrease in blood flow?
Decrease to 1/16
-if the radius is decreased by 1/2 , then the resistance would increase by 2(4) of 16. But since blood flow is inversely proportional to resistance , flow will decreased to 1/16.
Cardiac contractility compensation during change from supine to standing position?
Increased contractility
Baroreceptors detect the decrease in arterial pressure and thus activated the sympathetic outflow and decreases parasympathetic outflow.
SBP is highest in which vessel?
Choices:
a. Renal artery
b. Renal vein
c. Aorta
d. Pulmonary artery
Renal artery
-pressure on the venous side is lower than the arteria side. Systolic pressure is slightly higher in the downstream arteries than in the aorta because of the reflection of pressure waves at branch points.
Where is the pacemaker?
(-) P wave, (+) QRS complex, (+) T wave
AV Node
The absent P wave indicates that the atrium is not depolarizing and therefore, the pacemaker can not be in the SA Node. Both QRS & T wave are positive, indicating that the depolarization and repolarization of the ventricles occured in the normal sequence.
Increase in ejection fraction causes decrease in what cardiac parameter ?
ESV
In ventricular extrasytoles , what is extrasystolic beats effect on pulse pressure?
Decrease pulse pressure because stroke volume is decreased.
In ventricular extrasystoles, next normal contractions effect on pulse pressure ?
Increased pulse pressure because the contractility of the ventricle is increased.
True or False.
On the extrasystolic beat, pulse pressure decreases because there is an inadequate ventricular filling time, the ventricle beats too soon.
True
True or False.
Postextrasystolic contraction produces increased pulse pressure because contractility is increased.
True
True or False.
Extra Ca enters the cell during the extrasystolic beat.
True
Increase in contractility causes ________ in CO for given end-______ volume.
Increased in cardiac output for a given end-diastolic volume.
________ contraction occurs during ventricular systole, before the aortic valve opens.
Isovolumetric contraction
In isovolumetric contraction, ventricular pressure _________, But volume remains__________ because blood cannot be ejected into the aorta against a closed valve.
Choices
a. Constant , Increased
b. Constant , Deceased
c. Increase, Decreased
d. Increased , Constant
e. Decreased, Constant
Increased , Constant
From points 1-4, locate the isovolumic contraction?
Points 1-2
From points 1-4, locate where the Aortic valve closes?
Point 3
From points 1-4 , locate what point where all the valves are closed.
Point 3
Points 1-4: Locate the Isovolumic relaxation
Points 3-4
Points 1-2 : Isovolumic contraction
Points 1-4. Locate the first heart sound.
Point 1
The _____ heart sound corresponds to the closure of the AV valves.
First
Absorption or Filtration?
Capillary HP = 30mmHg
Capillary OP = -2mmHg
Interstitial HP= 25mmHg
Interstitial OP= 2 mmHg
Filtration
[(30-(-2)] - [(25-2)]
= 32 - 23
= +9mmHg
What is the rate of water flow across the capillary wall?
Capillary HP = 30mmHg
Capillary OP = -2mmHg
Interstitial HP= 25mmHg
Interstitial OP= 2 mmHg
Kf x net pressure = 0.5 x 9mmHg = 4.5mL / min
Kf= 0.5
Net pressure = 9
Net pressure = [(30-(-2)] - [(25-2)]
= 32 - 23
= +9mmHg
Factors of turbulent blood flow? (3)
- Decreased viscosity
- Increased velocity
- Partial occlusion of a blood vessel
66 M, S/P Sympathectomy , experiences a great fall in arterial pressure upon standing up. Explanation?
A suppressed response of the baroreceptor mechanism.
Normal baroreceptor mechanism responds to a decrease in arterial pressure through the vasomotor center by increasing sympathetic outflow and decreasing parasympathetic outflow; In sympathectomy , sympathetic component baroreceptor mechanism is absent.
Normal baroreceptor mechanism responds to a __________ in arterial pressure through the vasomotor center by ___________ sympathetic outflow and __________ parasympathetic outflow.
a. Decrease, decreasing, increasing
b. Increase, increasing, decreasing
c. Decrease, increasing , decreasing
d. Increase, decreasing, increasing
Decrease, Increasing , Decreasing
Ventricles are completely depolarized in which portion of the ECG?
ST Segment
Pulmonary blood flow is greater than aortic blood flow in which type of shunt?
Left to right ventricular shunt
The change indicated by the dashed lines on the cardiac output/ venous return curves shows?
Increased mean systemic filling pressure.
The shift in the venous return curve to the right is consistent with an increase in blood volume as a consequence , mean systemic filling pressure.
2 P waves preceding each QRS complex. Interpretation?
Decreased conduction through the AV Node.
This pattern indicates that only every other P wave is conducted through the AV node to the ventricle.
Compensatory change in the carotid sinus during acute decrease in arterial blood pressure?
Decreased firing rate of the carotid sinus nerve.
Decrease parasympathetic outflow.
Tendency for an edema to occur will be increased by ______ venous pressure?
Increased venous pressure
Edema occurs when more fluid is filtered out of the capillaries than can be returned to the circulation by the lymphatics.
Rationale for inspiratory split of the second heart sound.
The aortic valve closes before the pulmonic valve.
Rationale for decrease in total peripheral resistance during exercise?
Increase in local metabolites on skeletal muscle arterioles causes vasodilation.
Increase in arteriolar resistance, without a change in any other component. Effect on arterial pressure?
An increase in arterial pressure
What is the patients cardiac output?
HR : 70 bpm
Systemic Arterial O2: 0.24 ml O2 / mL
Mixed Venous O2: 0.16 mL O2/mL
Whole body O2 consumption: 500mL / min
Ans: 6.25 L per min
CO= 500mL / (0.24-0.16)
CO= 6250 mL/ min or 6.2L /min
Result of an inward Na+ current?
Upstroke of the action potential in atria, ventricles and purkinje fibers .
Result of an inward Ca+ current?
Upstroke in SA node
True or False.
End diastolic volume and Right atrial Pressure are related and can be used interchangeably.
True
Rationale for why the greatest pressure decrease occurs across the arterioles?
They have the greatest resistance.
True or False.
The greater the distance is ,the greater the decrease in arterial pressure.
True
Pulse pressure is determined by what cardiac parameter?
Determined by Stroke volume
-pulse pressure is the difference between the highest and lowest arterial pressue; reflects the volume ejected by the left ventricle.
______________ is the difference between the highest and lowest arterial pressure; reflects the volume ejected by the_________ ventricle.
a. Pulse pressure , Right Ventricle
b. Pulse pressure, Left Ventricle
c. Stroke Volume , Right Ventricle
d. Stroke Volume , Left Ventricle
Pulse Pressure, Left Ventricle
_______________ is the volume of blood pumped out by the __________ ventricle during each systolic cardiac contraction.
a. Pulse pressure , Right Ventricle
b. Pulse pressure, Left Ventricle
c. Stroke Volume , Right Ventricle
d. Stroke Volume , Left Ventricle
Stroke volume, Left Ventricle
Stroke volume = EDV - ESV
What conductance is increased in phase 4 depolarization of SA Node?
An increase in Na+ conductance
Receptor responsible for the increased splanchnic vascular resistance?
Alpha-1 receptor
During which phase of the cardiac cycle is aortic pressure highest?
Reduced ventricular ejection
- Aortic pressure reaches its highest level immediately after the rapid ejection of blood during the left ventricular systole. This highest level actually coincides with the beginning of the reduced ventricular ejection phase.
True or False.
Aortic pressure reaches its highest level immediately after the rapid ejection of blood during the left ventricular systole. This highest level actually coincides with the beginning of the reduced ventricular ejection phase.
True
Myocardial contractility is best correlated with what intracellular concentration?
Calcium
Effect of histamine on arterioles?
Vasodilation
Carbon dioxide regulates blood flow in which organ?
Brain
-Blood flow of the brain is auto-regulated by carbon dioxide.
-Increased PCO2 will cause cerebral vasodilation,
-Decreased PCO2 will cause cerebral vasoconstriction
Blood flow of the brain is auto-regulated by ____________.
a. Oxygen
b. Carbon dioxide
Carbon dioxide
Increased PCO2 will cause cerebral ______________.
Vasodilation
Decreased PCO2 will cause cerebral _______________.
vasoconstriction
Cardiac output of the right side of the heart is what percentage of the cardiac output of the left side?
100%
CO of the left and right sides of the heart are equal.
Rationale for relatively slow conduction through the AV node?
It allows sufficient time for filling of the ventricles
Blood flow to which organ is controlled primarily by the sympathetic nervous system?
Skin
Effect on total peripheral resistance during exercise?
Decreased TPR
Although increased sympathetic outflow to the blood vessels might be expected to increase TPR. It does not because there is an overriding vasodilation of skeletal muscle arterioles as a result of the buildup of vasodilator metabolites
( lactate & K+ adenosine).
72/W , being treated with propranolol. Blockade of which receptor is responsible for the decrease in cardiac output?
Beta-1 receptor
Ventricular volume is lowest in which phase of cardiac cycle ?
Isovolumetric ventricular relaxation
- ventricular volume is at its lowest value while the ventricles is relaxed (diastole) , just before ventricular filling begins
Heart size that causes an increase in myocardial O2 consumption ?
Increased size of the heart
- Myocardial O2 consumption is determined by the amount of tension developed by the heart
Crosses capillary walls primarily through waterfilled clefts between the endothelial cells.
Choices:
a. Glucose
b. O2
c. CO2
d. CO
Glucose
O2, CO2, and CO are lipophilic , they cross primarily by diffusion through endothelial cell membranes.
24/ W with severe diarrhea;
Supine BP : 90/60
Supine HR: 100 bpm
Standing HR: 120bpm
What increase further HR after standing?
Decreased venous return
Diarrhea causes loss of ECF volume, which already decreases arterial pressure that then increases HR in supine.
Upon standing blood pulls in the leg decreasing venous return and further decreasing arterial pressure and further activating the baroreceptor and further increasing HR on standing.
60/ M , BP of 185/130 mmHg , increase in plasma renin activity, plasma aldosterone level, and left renal vein renin level is decreased. Cause of hypertension?
Left renal artery stenosis
- Right renal artery is non-stenotic since it is able to detect the increase in blood pressure, decreasing its renin secretion.
Phase where membrane potential is closest to the K+ equilibrium potential?
Phase 4
Phase 4 is the resting membrane potential. Because the conductance K+ is highest, the membrane potential approaches the equilibrium potential of K+
Phase where calcium conductance is highest?
Phase 2
During this phase, the conductance to Ca2+ increases transiently. Ca2+ that enters the cell during the plateau is the trigger that releases more Ca2+ from the sarcoplasmic reticulum for contraction.
Phase where ventricular action potential coincides with diastole?
Phase 4 - Electrical Diastole
Propranolol effect of the heart rate?
Decrease heart rate
Receptor that mediates slowing of the heart?
Muscarinic Receptor (Parasympathetic)
Neurotransmitter with negative inotropic effect on the heart?
Acetylcholine (Parasympathetic)
Allow for the spread of action potentials between myocardial cells?
Gap junctions
Released after a hemorrhage and causes an increase in renal Na+ reabsorption?
Aldosterone
Angiotensin II , ADH and Aldosterone increases after decreased renal perfusion, of all these, only aldosterone has a direct function of increasing renal Na+ reabsorption.
Cardiac cycle phase where mitral valve opens?
Rapid ventricular filling / Isovolumetric Ventricular Relaxation
Blood rapidly flows from atrium to ventricles when the ventricular pressure is less than the atrial pressure.
What valve opens when the left atrial pressure becomes higher than the left ventricular pressure. This occurs when the left ventricular pressure is at its lowest
Mitral Valve
What is the patients end diastolic volume?
Ejection fraction: 0.4
Heart Rate: 95bpm
Cardiac Output: 3.5L/min
92 ml
EDV = SV/ EF
SV= 3500ml / 95 bpm
SV= 36.8mL
EDV = 36.8ml / 0.4
EDV= 92 ml
38/ M with vomiting, diarrhea, light headed upon standing. Pathophysiology ? (3)
1.Decreased blood volume
2.Decreased preload
3.Decreased cardiac output
70kg / M healthy with HR 60bpm what’s the CO?
CO= HR x SV
CO= 60 bpmx 70ml
CO= 4,200 ml / min
Drugs that decreases heart rate?
B-1 blockers
What happens when VE increases?
CO also increases
- based on Frank-Starling & Bainbridge Reflex
50% narrowing of left renal artery , expected change in flow?
Decrease to 1/16
Hypoxemia produces hyperventilation by direct effect on the ________ and ________.
Carotid and Aortic Body Chemoreceptors
Effect of digoxin?
It increases cardiac contractility
AV Node: ___________
choices
a. Inotropy
b. Chronotroph
c. Dromotropy
d. Lusitropy
e. Bathmotopy
a. Inotropy - Contractility
b. Chronotropy - Rate (SA Node)
c. Dromotropy - Conduction (AV Node)
d. Lusitropy - Relaxation
e. Bathmotopy - Excitation
Two valves that open during systole?
Pulmonic & Aortic Valve ( Semilunar Valves)
Released by ventricular myocytes due to increased tension?
B-Type Natriuretic Peptide
(B-NP / Brain Natriuretic Peptide)
AV block that does not require treatment?
1st degree AV block
Effects of ACE-Inh ? (4)
- Decreased arteriolar vasoconstriction
- Decreased arteriolar resistance
- Increased sodium excretion by the kidneys to the urine
- Decreased Cardiac Output
Most cases of patient recovery from coronary occlusion is due to?
Presence of collateral vessels
Deug that can cause torsades de pointes?
Macrolides ( Clarithromycin, Azithromycin, Erythromycin)
Ciprofloxacin
Levofloxacin
Fluconazole
Aortic pressure is highest during this cardiac cycle phase?
Between Rapid Ventricular Ejection & Reduced Ventricular Ejection
Vitamin deficiency that can cause heart failure?
Vit B1 - Thiamine can cause CHF / Wet Beriberi
Increased contractility in the Frank-Starling diagram is demonstrated by ?
Increased Cardiac Output for a given EDV
Components of thin filament of cardiac muscle ? (3)
- Actin
- Troponin
- Tropomyosin
Formula that relates to the blood flow, velocity and cross-sectional area?
Bulk Blood Flow
V= Q/ A
Where:
V= Velocity
Q= Blood flow
A= Cross sectional area (cm2)
Volume ejected from the ventricle after each heart beat?
Stroke Volume
Formula of Ohm’s Law?
Q= delta P/ R
Based on Ohm’s law , pulmonary vascular resistance is (Pulmonary Artery Pressure- L Atrial Pressure over _____________.
Cardiac output
Conditions associated with exaggeration of normal splitting (Wide Split S2)? (4)
- Right Bundle Branch Block
- Pulmonary Stenosis
- Mitral Valve Regurgitation
- VSD
Fixed splitting is auscultatory hallmark of ___________?
ASD
Some important cardio formulas? (2)
- EF = SV/ EDV
- CO= HR x SV
Cardiac chamber to measure central venous pressure?
Right Atrium
ECG waves indicating ventricular repolarization?
T wave
Causes spike potential in SA Node AP?
Calcium Influx
What happens during S2?
Closure of AV valves ( Tricuspid , Mitral)
RighT - Tricuspid
Left - MitraL
Systemic diseases that can cause 3rd degree AV Block? (3)
- SLE
- Amyloidosis
- Sarcoidosis
Drugs that can cause 3rd degree AV Block?
- Anti- arrhythmic from all 4 classes
- Digoxin
Primer pumps of the heart?
Atria
Longest phase of the cardiac cycle?
Reduced Ventricular Filling
Vasoconstrictor of the afferent arteriole?
Adenosine
Which instrument is used to measure Pulmonary Capillary Wedge Pressure (PCWP) ?
Swan-Ganz Catheter ( Balloon- Tipped, Multi-lumen Catheter)
This estimates left atrial pressure
Ejection fraction formula?
EF= SV / EDV
Normal = 55%
Phase of the cardiac cycle where ventricular volume at its lowest?
Isovolumic relaxation
Which part of the ECG corresponds to Ventricular repolarization?
T- wave
What is the pacemaker of the heart?
SA Node
What is the basis for decompression sickness?
Rapid ascent causing nitrogen bubbles that block blood vessels.
In which blood vessel does gas exchange occur?
Capillaries
Action Potential is caused by the following respectively:
Phase 4, 0, and 3 of the SA Node
Phase 4: Slow Na Influx
Phase 0: Ca Influx
Phase 3: K Influx
4 Na! OCa , 3K
Which part of the cardiac cycle will you see closure of AV valves and semilunar valves respectively that causes S1 & S2?
S1 : Isovolumic Contraction
S2: Isovolumic Relaxation
What is the formula of Cardiac output?
CO= HR x SV
COHRS- Corazon
What percentage of blood goes to the kidney from the heart ?
Percentage Cardiac Output of the Kidneys : 22-25%
Normal Ejection Fraction?
0.55
Triggers of ANP Secretion?
Increased Intravascular Volume that leads to increased systemic vascular resistance
Baby’s first breath causes?
- Inc PaO2
- Dec Pulmonary vascular resistance
- Inc Systemic Vascular Resistance
In comparison to term infant to preterm infants has?
- Increased pulmonary vascular resistance
- Increased Pulmonary Artery Pressure
- Increased Pulmonary Capillary Hydrostatic Pressure
- Increased Pressure Gradient from Pulmonary Artery to the Aorta
- Decreased Pulmonary Blood Flow
