B3W1 Flashcards
Pathway of circulation throughout the heart and blood. Starting in the (R) atria
(R) atria - tricuspid valve - (R) ventricle - Pulmonary semi lunar valve - Pulmonary arteries - pulmonary circulation - pulmonary veins - (L) atria - mitral valve - (L) ventricle - aortic semilunar valve - aorta - systemic circulation - inferior/superior vena cava
S1 and S2 heart sound (what do they correspond to mechanically?)
S1 = closing of AV valves S2 = closing of SL valves
Which artery is responsible for supplying the heart with blood?
Coronary artery
Ejection Fraction EQ and what does it mean
EF = SV/EDV (shows the percentage of blood which is ejected from each ventricular contraction)
Stroke Volume EQ and what does it mean AND what is the average value
SV = EDV - ESV (meaning how much volume is being pumped into circulation from each ventricular contraction)
Average value = 70 mL
Mean Arterial Pressure EQ and what does it mean AND average value
MAP = 2/3 DBP + 1/3 SBP (average pressure during one cardiac cycle)
Average value = 95 mm Hg
Compliance EQ and what does it mean
Compliance = change in volume / pressure (the ability of a vessel to “comply” or stretch to a volume load
Flow EQ’s / Pousielle’s EQ (what does it mean)
Determines flow
pressure = flow * resistance
F=Change in pressure / Resistance
F = Change in pressure * (pi)(r^4)/8(viscosity)(length)
Cardiac output EQ and what does it mean AND average value
CO = HR * SV (amount of blood pumped in a minute)
Average = 5 L / min
Cardiac Output EQ (from Ficks Principle)
CO = Rate of O2 consumption / O2 in artery - O2 in vein
Resistance EQ and what does it tell you
R= 8(viscosity)(length) / (pi)(r^4)
Resistance of a vessel
How to calculate a capillary bed resistance in parallel v series
Series = R1+R2+R3….
Parallel = 1/R1 + 1/R2 + 1/R3…..
Average HR v Tachycardia v Bradycardia
60 bpm - 100 bpm = average
> 100 = tachycardia
< 60 = bradycardia
Average systolic and diastolic blood pressures
SBP = 120 mm Hg
DBP = 80 mm Hg
Reynold’s number EQ and what does it mean AND average values
Re = 2rvp / n (helps in determining laminar flow v tubular flow)
< 2000 = laminar
2000-3000 = transitional flow
>3000 = tubular
Draw out a pressure loop and explain it to yourself
-do it-
Flow, Resistance and Pressure differences across the cardiovascular system
Flow and resistance tend to have high variability
Pressure remains fairly constant
In terms of viscosity… describe the relationship to anemia/polycythemia
Anemia = less RBC = lower viscosity = lower hematocrit
Polycythemia = more RBC = higher viscosity = higher hematocrit
Examples of capillary beds in series vs parallel
Series = portal systems (renal, hypophyseal, hepatic)
Parallel = regular capillary beds you think of
common sites of tubular flow in the body
Aorta, sites of branching
What are the three pressures which are present in circulation
Hydrostatic, Transmural, Driving
What is driving pressure
The main pressure involved in blood pressure setting , and the main pressure in blood flow
What is transmural pressure
Difference in pressure across a capillary wall
transmural pressure has to have a higher pressure inside than outside or a vessel will collapse
What is hydrostatic pressure
pressure due to gravity
Blood Flow : velocity and area relationship of vessel
As area increases, velocity decreases to balance flow
Ex. aorta has a high velocity because of small area
Ex. capillaries have a high area, and a low velocity
Bernoulli’s Effect
-Fluid flows from a area of high to low pressure to conserve total energy
-when there is a stenosis of a vessel there is a localized increase in velocity and a decrease in pressure which then makes the whole net movement from low pressure to high pressure
-connects both kinetic and potential energy
-velocity = kinetic energy
-pressure = potential energy
Organization of the vascular system and describe the elastance/compliance of each
-Arteries = high pressure, high elastic (distribution system)
-Capillaries = diffusion and filtration systems
-Veins = high compliance, low pressure (holding system)
Aggregate vs individual chart
-REVIEW it-
Aggregate ____ remains constant throughout the body
Flow
Composition of arteries v capillaries v veins
Arteries: endothelial cells, elastic fibers, smooth muscle, collagen fibers
Capillaries: endothelial cells (NO VSMC)
Veins: endothelial cells, elastic fibers, smooth muscle, collagen fibers
EQ for how to determine pressure in capillary
Pressure in capillary = R post / R pre
Increasing capillary pressure leads to _____ (systemic problem)
edema
Compliance v Elastance
Compliance is the ability of a vein to stretch and “comply” for contents, elastance is the rubber band ability of a vessel (how it can stretch and come back)
A high youngs modulus vs a low youngs modulus
High young modulus = there is more elastance and the vessel is stiffer
low young modulus = there is more compliance there fore leading to a more elastic vessel
Capacitance vs resistance vessels
Capacitance vessels = veins
resistance vessels = arteries
Changes that lead to high physiological pressure changes will rupture what kind of vessel
veins
Why is the aorta being compliant important?
Think the windkessel effect. By allowing for a compliant tissue there will be oscillating periods of high and low pressure which causes there to be no STOP GO STOP GO STOP GO movement. it is continuous
Arteriosclerotic changes
as we age, vessels become stiffer and increase in rigidity leading to an increase in pressure and decrease in compliance
What is blood pressure measuring (general)
measuring the pressure exerted by the blood against the walls of the vessels
What is BP measuring (systolic v diastolic)
SBP: measuring pressure exerted in the arteries by blood leaving the heart
DBP: measuring pressure exerted in the arteries during ventricular filling
what do you use to measure BP
sphygmomanometer
Auscultation method of taking BP
using stethescope listen for systolic v diastolic
systolic - Korotkoff sounds - you are hearing turbulent blood as it moves past the cuff
diastolic - you are hearing an absence of the tubular flow and restoration of laminar flow in vessels
Papatory method of taking BP
assess the radial pulse (on the wrist) while inflating the cuff
Why would MAP be important to calculate in a clinical setting
MAP = average blood pumped through 1 cardiac cycle
can be used to assess tissue perfusion (low MAP could be showing signs of ischemia)
Pulse Pressure EQ and what does it mean
EQ: Systolic BP - Diastolic BP (equals the force generated at each contraction)
High pulse pressure v low pulse pressure
High = high PP equals high SV = increased risk of turbulent flow
small = slow PP equals small SV = decrease in blood being pumped from heart
cardiac tamponade (pathology and diagnosis)
blood fills the pericardial sac and decreases the ability to expand, which decreases SV
diagnosed using Becks Triad (hypotension due to small PP, JVD, diminished heart sounds)
Aortic valve stenosis
narrowing of the aortic valve leading to a decrease in radius, less SV and decreased PP
Wider pulse pressures lead to a ______in aortic compliance, ________ in aortic radius and a _________ of arteries.
decrease, decrease, stiffening
Ficks Law of Solute Movement
movement of solutes into blood or interstitial space is based off the equation of:
Jx= Lp [(Pc - P if) - sigma ((pi)c - (pi) if)]
Positive Jx means
net filtration - water is leaving the capillary
Negative Jx means
net absorption - water is entering the capillary
Factors that increase filtration
(+) Pc
(-) Pif
(-) (pi) c
(+) (pi) if
Factors that increase absorption
(-) Pc
(+) P if
(+) (pi) c
(-) (pi) if
Physiological changes that cause Pc to rise (increasing hydrostatic pressure)
standing up increases hydrostatic pressure, pulmonary edema leads to excess filtration without absorption, increases in venous pressure which leads to (R) heart failure
Physiological changes that cause (pi)c to fall
nephrotic syndrome, pregnancy, malnutrition
If there is an increase in lymphatic drainage impairment……
there is a decrease in Jv
lymphatics drain interstitial fluid, therefore if there is a block then there will be an increase in pressure on the if side leading to net absorption of capillaries
Fick Law v Ficks Principle
Ficks Law = Jv (think J and L are close)
Ficks Principle = (think P and O are close) oxygen
Factors that can lead to increase in O2 uptake
increasing the HR, increasing SV, increasing O2 extraction
Factors that inhibit O2 extraction
decreasing cardiac output, increasing afterload, increasing blood flow
Wiggers Diagram
-read it- learn it - love it -
4 phases of heart contraction (according to Wiggers)
- diastasis and atrial contraction (diastole)
- isovolumetric contraction
- ejection (sytole)
- isovolumetric relaxation
Vascular Smooth Muscle Contraction Mechanism
Calmodulin is activated by an increase in Ca. Ca binds to calmodulin which then binds and activates MLCK. Phosphorylation of MLC by MLCK leads to activation
Increasing cAMP in vascular smooth muscle leads to….. by ……
leads to muscle relaxation by increasing the activity of PKA which phosphorylates MLCK, which can no longer phosphorylate MLC leading to muscle relaxation
increasing cGMP in vascular smooth muscle leads to ….. by…..
leads to muscle relaxation by increasing the activity of PKG which phosphorylates MLCK, decreasing MLC phosphorylation leading to relaxation
What are the 4 general ways to modify vascular tone?
- vasomotion
- nervous system control
- humoral control
- local control
What is vasomotion
Vasomotion = spontaneous contractions caused by rhythmic oscillations in Ca and Vm which leads to vasulcar tone
Mechanism of vascular tone
-intermittent Ca release from the SR and intermittent release of NO from endothelial cells lead to the activation of cGMP
-cGMP leads to SERCA uptake of Ca
-cGMP and Ca activated chloride channels then depolarize cells
-depolarization leads to ca voltage channel activation which will increase intracellular Ca
-gap junctions will cause group depolarization
influx of Ca from the SR causes Ca release and depolarization
How does the nervous system cause vascular tone regulation
ATP, neuropeptide Y, and Epi/NE
Humoral Control of Vascular Tone regulation
Endocrine and paracrine mechanisms that consist of use of Angiotensin II (increases BP), serotonin (increases), Neuropeptide Y (increases), ADH (increases CO and BP)
Another word for local control is…..
autoregulation
Autoregulation/local control of Vascular Tone (what are the general mechanisms)
myogenic response, metabolic control, endothelial control
What are three important areas in which autoregulation is important
coronary circulation, cerebral circulation, renal circulation
What is the myogenic response and mechanism
Myogenic = autoregulation regulation of vascular tone
Mechanism =
-stretching of VSMC leads to the activation of stretch sensitive non selective Ca channels which depolarize cells
-depolarization leads to increase in Ca leading to increase in contraction and constriction
-after contraction, stretch sensitive non selective cation channels close and there is muscle relaxation
Metabolic control - what is it and what is the mechanism in regards to vascular tone
Metabolic control = autoregulatory pathway of vascular tone
Mechanism =
increase metabolism leads to vasodilation (decrease in O2, increase in CO2, decrease in pH, accumulation of K and lactate, decrease of ATP, increase of ADP and adenosine) , decrease metabolism leads to vasoconstriction (all the opposite of above)
What is endothelial control in regards to vascular tone
Endothelial control = autoregulation of vascular tone (controlling NO and endothelin)
Mechanism of NO sheer stress in vasodilation
-stress on cell or NO dependent vasodilator binds to an endothelial cell
-leads to an increase in Ca in endothelial cell
-leads to the activation of cNOS which converts L-arg to NO (cNOS = calcium dependent NOS)
- NO diffuses across endothelial cell to smooth muscle cell and binds to GC
-GC hydrolyzes GTP to cGMP
-rises in cGMP leads to phosphorylation of the SERCA pump leading to Ca reuptake and MLCK deactivation leading to vasodilation
Mechanism of endothelin in vascular tone regulation
uses Gq pathway to raise intracellular Ca to cause vasoconstriction
Factors that maximize and inhibit O2 extraction (ficks principle)
Maximize: increasing SV, HR (to increase metabolism)
Inhibit: increasing afterload, decreasing cardiac output, increasing flow
What do the heart sounds mean
S1 = mitral valve closing
S2 = aortic valve closing
S3 = ventricular rapid filling ending
S4 = atrial contraction
