BRS - Cardiovascular Physiology 2 Flashcards

Terms Definitions
What degrades angiotensin II?
Angiotensinase
Type I hyperlipidemia
high chylomicrons
What is Captopril?
An ACE inhibitor
What are some vasodilatory metabolites?
CO2
H
K
Lactate
Adenosine
relationship between:

blood flow
pressure gradient
resistance
Q = dP/R
represents ventricular repolarization on EKG
T wave
What sympathetic adrenergic receptor mediates vasoconstriction?
Alpha 1
What does ADH do?
Causes vasoconstriction
Increases water reabsorption
Both of these factors tend to increase blood pressure
What are venules?
Formed from merged capillaries
anemia:
effect on reynold's number
increased (decreased viscosity)
Bowditch staircase
increased heart rate increases strength of contraction in a stepwise fashion b/c as intracellular Ca++ increases over several beats
vessels with largest total cross sectional and surface area of circulation
capillaries
What maintains the ionic gradient across the cardiac cell membrane?
Na-K ATPase
How does histamine affect vasoactivity?
Arteriolar dilation
Venous constriction
This results in increased capillary hydrostatic pressure, which can increase filtration and cause local edema
What part of the cardiovascular system contains the highest amount of blood?
Veins
site of highest resistance in the cardiovascular system
arterioles
Type III hyperlipidemia
high chylomicrons and IDL (intermediate density lipoprotein)
interval representing entire period of depolarization and repolarization of ventricle
QT interval
What controls the vasoactivity of arterioles in the skeletal muscle?
Sympathetic innervation
Local metabolic factors
What is systolic pressure?
Measured after heart contraction (systole) and blood is ejected into the arterial system
This is the highest arterial pressure in the cardiac cycle
How does lymph flow?
It is unidirectional
One-way flap valves allow interstitium fluid to enter the lymph vessels, but that fluid is unable to leave
One-way valves and skeletal muscle contractions aid in the unidirectionality of flow
Formula for stroke volume
SV = EDV - ESV
What are bruits?
Audible vibrations in the blood vessels due to turbulent flow
Formula for cardiac output
CO = SV x HR
Reynold's number
predicts whether blood flow will be laminal or turbulent
post extrasystolic potentiation
the beat *following* an extrasystolic beat has increased strength of contraction

***increased intracellular Ca++
What parts of the heart have parasympathetic vagal innervation?
SA node
Atria
AV node
What are T tubules?
Contiguous with the cell membrane
They invaginate the cells at the Z lines and carry action potentials to the cell interior
Well developed in the ventricles, less developed in the atria
Form dyads in the sarcoplasmic reticulum
What is the mean pressure of the arterioles?
50 mmHg
What is a wheal?
Local edema resulting from histamine release, which increases capillary filtration
What happens when you hemorrhage?
Decreased blood volume decreases cardiac output and arterial pressure
Carotid sinus baroreceptors detect decreased pressure
Increased sympathetic outflow and decreased parasympathetic outflow
Peripheral chemoreceptors detect hypoxia and supplement the baroreceptor mechanism by increasing sympathetic outflow
Cerebral ischemia increases PCO2, which activates central chemoreceptors to increase sympathetic outflow
Arteriolar vasoconstriction, which decreases Pc and favors capillary reabsorption
Adrenal medulla releases epinephrine and norepinephrine
RAS is activated by decreased renal perfusion pressure
ADH is released
When do the atria begin filling?
During rapid ventricular ejection
Type V hyperlipidemia
very similar to Type I (high cholymicrons), but with high VLDL
What produces the second heart sound?
Closure of the semilunar valves
Refer to the pressure-volume loop on BRS p82. What is represented in 4-->1?
Ventricular filling
When atrial pressure exceeds ventricular pressure, the mitral and tricuspid valves open and the ventricles fill
This causes the ventricular volume to increase
What vasoactive substance has been implicated in the genesis of migraines?
Serotonin
Thought to potentially cause vascular spasms
What is the myogenic response?
Vascular smooth muscle contracts when it is stretched
When there is increased perfusion, vasoconstriction increases resistance to maintain constant blood flow
What is the sarcoplasmic reticulum?
Small-diameter tubules that are in close proximity to the contractile elements of the cell
Site of storage and release of Ca for excitation-contraction coupling
What determines the hydrostatic pressure of the capillary?
Arterial and venous pressures and resistances
What are the sympathetic adrenergic receptors in the vascular smooth muscle?
Alpha 1 and beta 2
stroke work equation
stroke work = stroke volume * aortic pressure
What is the "blip" in the aortic pressure tracing of the cardiac cycle after the closure of the aortic valve?
The dicrotic notch or incisura
How does vasopressin increase low blood pressure toward normal?
Vasoconstriction via activation of V1 receptors on arterioles
Increases water reabsorption in the renal tubule via activation of V2 receptors
What do AT1 antagonists do?
They block the angiotensin receptor to prevent angiotensin II from exerting effects
This decreases blood pressure
How does temperature regulation in the skin work?
High ambient temperature causes cutaneous vasodilation, which allows excess body heat to dissipate
How do inotropic agents change the cardiac output curve?
They increase contractility and cardiac output, so stroke volume increases
This shifts the cardiac function curve up
What is the dromotropic effect of vagal stimulation of the heart?
Decreased conduction velocity through the AV node
This is because there is a decreased inward Ca current and an increased outward K current
What is the Em of the ventricles, atria, and Purkinje system?
-90 mV
This approaches Ek
Formula for capacitance
C = V / P
V = volume
P = pressure
Where is cardiac conduction velocity fastest? Slowest?
Fastest in the Purkinje system
Slowest in the AV node
What factors increase the mean systemic pressure?
Increase in blood volume
Decrease in venous compliance (shift of blood into the arterial compartment)
What does the vascular function (venous return) curve show?
Venous return decreases as atrial pressure increases
SA nodal action potential phases (#'s)
0 (Ca++)
3 (K+)
4 (Na+ current, I*f*)
What is the effective refractory period?
The period during which a conducted action potential cannot be elicited
Seems to be the same as the absolute refractory period except slightly longer
Formula for mean arterial pressure
MAP = Pdiastolic + (pulse pressure / 3)
What is the metabolic hypothesis?
Tissue supply of oxygen is matched to the tissue's demand for oxygen
Vasodilator metabolites are produced in response to metabolic activity?
What are some important features of capillary walls?
Single layer of endothelial cells
Thin walls
Site of exchange for nutrients, water, and gases
What types of walls do arteries have?
Thick walls, with extensive elastic tissue and smooth muscle
What is the mean systemic pressure?
The point at which the vascular function curve intersects the x-axis
It is equal to the right atrial pressure when blood flow is arrested throughout the body (cardiac output and venous return are 0, and pressure is the same everywhere)
Measured when the heart is experimentally stopped
A negative dromotropic effect would have what effect upon the PR interval?
It would increase it, because the conduction velocity through the AV node is decreasing
How does the cardiac sarcomere shorten?
Like in skeletal muscle, this occurs using the sliding filament model
Thin filaments slide along thick ones by forming and breaking cross-bridges between actin and myosin
What is the significance of Kf?
It is the hydraulic conductance (water permeability) of the capillary wall
What does the PR interval on an EKG represent?
Conduction velocity/time through the AV node
There is an increase in the PR interval if there is a AV nodal block
How do changes in blood volume or venous compliance change the vascular function curve?
Increased blood volume or decreased venous compliance both increase mean systemic pressure, which shifts the curve to the right
This increases both cardiac output and right atrial pressure
How does increased preload affect the ventricular pressure-volume loop?
It increases the stroke volume, and therefore increases the width of the loop
What is the difference between laminar and turbulent flow?
Laminar flow moves in straight lines or lamina, and turbulent flow does not
What determines the amount of Ca released from the sarcoplasmic reticulum?
The amount of Ca previously stored
The magnitude of the inward Ca current
What causes phase 4 (resting membrane potential)?
The inward and outward currents (Ik1) are equal
Em approaches Ek
How does resistance relate to the radius of a blood vessel?
It is inversely related to the 4th power of the radius, so if radius decreases by a factor of 2, resistance increases by a factor of 16 (2^4), and blood flow will also decrease by a factor of 16
What is the first enzyme to come into play in the RAS?
Renin -- cleaves angiotensinogen to angiotensin I
Formula for the velocity of blood flow
V = Q/A
Q = blood flow
A = cross-sectional area
Velocity is directly proportional to blood flow and inversely proportional to the cross-sectional area
Is the action of aldosterone fast or slow?
Slow, because it requires new protein synthesis
Where in the body do we find resistances in series?
Blood vessels within a given organ (that is supplied by one artery)
What does the ST segment on an EK represent?
The period where the ventricles are depolarized
This segment is (or should be) isoelectric
Formula for the Starling equation
J = Kf[(Pc - Pi) - (PIc - PIi)]
J = fluid movement
Kf = hydraulic conductance
P = hydrostatic pressure of the capillary and interstitium
PI = colloid osmotic pressure of the capillary and interstitium
What is the structure of the cardiac sarcomere?
This is the contractile unit of the myocardial cell
Delineated as the area between two adjacent Z lines
Contains thick filaments (myosin) and thin filaments (actin, troponin, tropomyosin)
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