Unit 6 - Cardiovascular Physiology Flashcards
why do we have a cardiovascular system?
- diffusion is not adequate to exchange nutrients/ waste to cells because the distance is too large
- circulation provides a steep concentration gradient in close proximity to every cell allowing for RAPID exchange of materials
what are hemodynamics?
looks at the laws that govern blood flow
what is the equation for flow?
F = (delta)P / R
where:
- F = flow
- (delta)P = pressure difference between two fixed points
- R = resistance to flow
true or false: to have flow, pressure must be greater than resistance
true
pressure exerted by a fluid
hydrostatic pressure
what happens if there is no pressure difference?
there will not be any flow. it is the pressure difference, not the absolute pressure, that creates flow
what creates blood flow?
a pressure gradient
cardiovascular pressure is created from:
contraction of heart chambers and pressure of blood on walls of blood vessels and heart chambers
friction between molecules of a flowing fluid
viscosity
determines the amount of contact between moving blood and stationary wall of vessel
length and diameter
in small blood vessels, there is less blood in the _______ and on the ________
center, vessel wall
in large blood vessels, there is more blood in the ______, which creates ______
center, less friction
what is poiseuilles equation?
R = (8nl) / (pi*r^4)
where:
- R = resistance to blood flow
- n = viscosity of blood
- l = length of vessel
- r = radius of vessel
true or false: poisseuilles equation applies to all types of blood flow
false, it only applies to laminar (smooth) blood flow
in fluid dynamics, __________ is characterized by fluid particles following smooth paths in layers, with each layer moving slowly
laminar flow
at forks in the blood vessels, is flow more laminar or turnbulent?
turbulent
what are the four main functions of the cardiovascular system?
1) delivery of oxygen and nutrients and removal of waste products
2) fast chemical signalling to cells by circulating hormones and neurotransmitters
3) thermoregulation
4) mediation of inflammatory and host defense responses against invading microorganisms
what are the three main components of the cardiovascular system?
1) the heart
2) blood vessels
3) blood
small branching vessels with high resistance
arterioles
transport blood between small arteries and venules; exchange of materials
capillaries
carries blood with a mostly high oxygen content away from the heart
arteries
carries blood with mostly low oxygen content towards the heart
veins
what does it mean to have a closed circulatory system?
blood never leaves the vessels/ chambers of the heart
how many chambers are in the heart?
four. two atria, two ventricles
- thin-walled
- low pressure chambers
- receive blood returning to the heart
atria
responsible for the forward propulsion of blood
ventricles
the two sides of the heart are divided by the:
septa
separates the left and right atria
interatrial septum
separates the left and right ventricles
interventricular septum
the circulatory system consists of two circuits. what are they?
- pulmonary circulation
- systemic circulation
- blood to and from the gas exchange surfaces of the lungs
- blood entering lungs = poorly oxygenated blood
- oxygen diffuses from lung tissue to blood
- blood leaving lungs= oxygenated blood
these are all chracteristics of:
pulmonary circulation
- blood to an from the rest of the body
- blood entering tissues = oxygenated blood
- oxygen diffuses from blood to body tissues
- blood leaving tissues = poorly oxygenated bloos
- blood to and from the rest of the body
- blood entering tissues = oxygenated blood
- oxygen diffuses from blood to body tissues
- blood leaving tissues = poorly oxygenated blood
These are all characteristics of:
Systemic circulation
Receives blood from pulmonary circulation and pumps to systemic circulation
Left heart
Receives blood from systemic circulation and pumps to pulmonary circulation
Right heart
Blood flows in a _____
Series/ sequence
Blood must pass through the pulmonary and systemic circuits in _________
Sequence
What is parallel flow within the systemic circuit?
- each organ is supplied by a different artery
- independently regulate flow to different organs
What is the exception to parallel flow?
The digestive system. Blood flows from the aorta to the digestive system and then to the liver (about 75% of the blood that the liver receives is from the digestive system).
At rest, the body pumps the entire blood volume in a loop every minute. How much blood is this?
5L/min
During strenuous exercise, the body pumps your entire blood volume around the circuits 3.5 times per minute. How much blood is this?
17.5L/min
Fibrous sac surrounding the heart and roots of great vessels
Pericardium
What are the four main functions of the pericardium?
1) holds the heart in place in the thoracic cavity
2) protection of the heart from mechanical trauma and infection
3) secretes pericardial fluid to reduce friction
4) limits overfilling of the chambers, prevents sudden distension
What are the three layers to the pericardial structure?
1) fibrous pericardium
2) parietal pericardium
3) visceral epicardium
How much fluid does the pericardial cavity hold?
15-20mL
Pericardial fluid decreases _______
Friction
The “organ” attached to the heart
The visceral layer
Inflammation of the pericardium
Pericarditis
Compression of heart chambers due to excessive accumulation of pericardial fluid
Cardiac tamponade
True or false: the left ventricular wall is thicker than the right ventricle
True
covers the outer surface of heart
epicardium
the muscular wall, contains myocytes, blood vessels, nerves
myocardium
endothelium covering inner surfaces of the heart and heart valves
endocardium
cardiac muscle cells
myocyte
- branched and joined longitudinally
- striated
- one nucleus per cell
- many mitochondria
these are characteristics of:
myocytes
interdigitated region of attachment (desmosomes and gap junctions)
intercalculated disk
anchor calls together in tissues subject to considerable stretching, mechanically couples cells
desmosomes
transmembrane channels linking adjacent cells, used for communication between cells
gap junctions
allows the passage of small molecules and ions, spreading action potentials across the atria/ ventricles
gap junctions
consists of interlacing bundles of muscle fibers arranged spirally around the circumference of the heart?
myocardium
why do the myocardium muscle fibers have a spiral arrangement?
when the cardiac muscles contract, a wringing effect occurs, which efficiently pushes heart up to exit the heart
thin flaps of flexible, endothelium-covered fibrous tissue attached at the base to rings
valves
made of cartilage and are the site of attachment for the heart valves
valve rings
how do the valves function to provide unidirectional flow of blood through the heart?
- forward pressure gradient opens the one-way valve
- backward gradient closes the one-way valve but it cannot open in the opposite direction
- between the atria and ventricles
- prevent backflow of blood into the atria when ventricles contract
these are characteristics of the:
atrioventricular valves
what is the tricuspid valve?
the right atrioventricular valve that is made up of three leaflets (or cusps)
what is the bicuspid/ mitral valve?
the left atriventricular valve that is made of of two leaflets
what components make up the AV valve apparatus?
cusps, chordae tendineae and papillary muscles
tendinous type tissue which extends from the edges of each leaflet of the AV valves to the papillary muscle
chordae tendineae
cone shaped muscles which cause the chordae tendineae to become taut when contracting
papillary muscles
what is the function of the AV valve apparatus?
prevents the AV valves from turning inside out during contraction of the ventricles
true or false: valves open and close due to contraction and relaxation of the papillary muscles
false: they open and close due to pressure gradients
- located between the ventricles and arteries
- prevent backflow of blood from the arteries into ventricles when the ventricles relax
arterial (semilunar) valves
how many cusps does each semilunar valve have?
three
where is the pulmonary valve located?
between the pulmonary trunk and the right ventricle
where is the aortic valve located?
between the aorta and the left ventricle
do the semilunar valves have chordae tendineae and papillary muscles?
no
movement of blood through the tissues of the heart
coronary circulation
originate at aortic sinuses at the base of the ascending aorta
coronary arteries
drain into the coronary sinus, which empties into the right atrium
coronary veins
where does the coronary sinues empty?
the right atrium
collection of veins joined together to form a large vessel that collects blood from the myocardium of the heart
coronary sinus
in coronary circulation, at what point does myocardial blood flow almost cease?
systole (contraction)
in coronary circulation, at what point does myocardial blood flow peak?
diastole (relaxation)
a condition where arteries supplying blood to the heart become hardened and narrow due to plaque in the arterial walls
atherosclerosis
a condition where blood flow to the heart muscle is reduced, causing chest pain or discomfort
angina
a condition where blood supply to the heart is completely blocked and the muscle dies
myocardial infarction (heart attack)
- dense connective tissue between the valve rings
- separates atria from ventricles
- electrically inactive
- provides support for the heart (point of attachment for valve leaflets)
these are characteristics of the:
cardiac skeleton
myocytes communicate with one another, and this arrangement is called a:
syncytium
what is a syncytium?
a set of cells that act together
in a functional syncytium, if one cell is excited, the excitation spreads over:
both ventricles/ atria
how many syncytia systems are there?
- an atrial syncytium and a ventriculat syncytium
true or false: the cardiac sycytium has an all-or-none property
true
the heart is capable of generating its own ________ without nervous or hormonal stimulation
action potentials
what are the two types of myocytes?
contractile cells and conducting cells
myocytes which do the mechanical work of pumping, propel blood; do not initiate action potentials
contractile cells
myocytes which initiate and conduct the action potentials responsible for contraction of the contractile cells
conducting cells
what are the six key components of the conducting system?
1) sinoatrial (SA) node
2) internodal pathways
3) atrioventricular (AV) node
4) bundle of His (AV bundle)
5) bundle branches (left and right)
6) purkinjie fibers
the only electrical connection between the atria and ventricles
AV node and bundle of His
known as the cardiac pacemaker which initiates action potentials and sets the heart rate
sinoatrial (SA) node
passes stimuli to the contractile cells of both atria and to the AV node
internodal pathways
how long is the AV nodal delay?
100 msec
what is the purpose o the AV nodal delay?
ensures that the atria depolarize and contract before the ventricles, and gives the ventricles time to fill completely before they contract
where do the bundle branches travel along?
the interventricular septum
- large number
- diffuse distribution
- fast conduction velocity
these are all properties of the:
purkinjie fibers
the purkinjie fibers ensure that the right and left ventricles contract _______
simultaneously
what is the sequence of the conducting system?
SA node –> internodal pathway –> atrial myocardium –> AV node –> bundle of His –> right and left bundle branches –> purkinjie fibers –> ventricular myocardium
provides another electrical pathway where stimulus can pass backwards into the atria
the accessory pathway
irregular heart rate which doesn’t allow the chambers to fill with blood
arrhythmia
how many types of action potentials are in the cardiovascular system?
two
where does the fact action potential occur?
atrial myocardium, ventricular myocardium, bundle of His, bundle branches, purkinjie fibers, and internodal pathways
where does the slow action potential occur?
SA node, and AV node
phases of the cardiac action potential are associated with changes in permeability of the cell membrane mainly to what ions?
Na+, K+, and Ca2+
what is the function of the pacemaker potential?
allows the heart to generate its own action potential
- slow depolarization to threshold
- regular spontaneous generation of action potentials
these are characteristics of:
the pacemaker potential
list the channels involved in the pacemaker potential
- K+ channels: iK
- F-type channels (funny): iNa
- T-type channels (transient): iCa
what are the ion channels involves in SA node depolarization?
L-type channels (long lasting): iCa.
which is open longer: T-type or L-type channels?
L-type
during the slow action potential, the depolarization phase is slow due to:
slow movement of Ca2+
which rises to threshold quicker, the SA node or the AV node?
SA node
during ventricular muscle cell action potential, the “notch” occurs due to:
transient opening of K+ channels (slight repolarization)
during ventricular muscle cell action potential, the plateau occurs due to:
Ca2+ entering through L-type channels and slow oppening of K+ channels that will repolarize the cell
during ventricular muscle cell action potential, repolarization occurs due to:
opening of K+ channels and closing of Ca2+ channels
during ventricular muscle cell action potential, the stable resting phase occurs due to:
the Na+/K+ pump continuously pumping ions in and out of the cells
during ventricular muscle cell action potential, depolarization occurs due to:
opening of fast voltage-gated Na+ channels at threshold
what is responsible for AV nodal delay?
- no fast voltage-gated Na+ channels in AV node
- depolarization slow due to L-type Ca2+ channels
what is an electrocardiogram (ECG)?
a graphical recording of elevtrical activity of the heart detected on the surface of the body
voltage gradients in the heart may be as much as ____mV, this is translated to changes of up to ____mV at the skin surface
100mV, 1mV
in an ECG recording, what does the P-wave represent?
the spread of depolarization across the atria
in an ECG recording, what does the QRS complex represent?
spread of depolarization across ventricles
in an ECG recording, what does the T-wave represent?
ventricular repolarization
why doesn’t the SA node action potential show up on an ECG?
the signal isn’t strong enough to get to the surface of the skin
why doesn’t atrial repolarization show op on an ECG?
it is too smal of an electrical event to be recorded
in an ECG recording, what does the PR interval respresent?
atrial depolarization and physiological delay of the stimulus in the AV node
in an ECG recording, what does the QR interval represent?
ventricular depolarization and repolarization
in an ECG recording, what does the ST-segment represent?
isoelectric period of depolarized ventricles; end of QRS to beginning of T-wave
in an ECG recording, what does it mean if every second P-wave is not followed by a QRS complex?
there is a partial AV node block
in an ECG recording, what does it mean if there is no synchrony between atrial and ventricular electrical activities
there is complete AV node block
the cell membrane of the muscle cell
sarcolemma
stores calcium ions for contraction (acts like smooth ER)
sarcoplasmic reticulum
invaginations of the sarcolemma; transmit depolarization of membrane into interior of muscle cell
T-tubules
what are myofibrils made of?
contractile proteins
what regulates the contraction of cardiac muscle?
calcium ions
what is a calcium-dependent calcium release?
calcium ions bind to ryanodine receptors, releasing calcium from the sarcoplasmic reticulum
contains binding sites for calcium and tropomyosin, and regulates access to myosin binding sites
troponin
partially cover the myosin binding sites on actin at rest, preventing cross-bridges from making contact with actin
tropomyosin
how is Ca2+ returned to the sarcoplasmic reticulum?
Ca2+ ATPase
how does Ca2+ leave the cardiac muscle cell?
through an Na+/Ca2+ exchanger
a period of time in which a new action potential cannot be initiated
refractory period
how long does the absolucte refractory period in a cardiac muscle cell last?
~250 msec
a pro-longed, smooth contraction; great for skeletal muscle, not good for cardiac muscle
tetanic contraction
how is tetanus prevented?
the refractory period
true or false: the AV node can act as a pacemaker if SA node becomes damaged
true
true or false: long absolute refractory period in myocytes prevents summation of contraction
true
true or false: if the fast Na+ current fails, the L-type Ca2+ current can cause depolarization
true
true or false: IK1 keeps resting potential more negative so that more stimulus is needed to reach threshold, preventing spontaneous activity
true
ventricular/atrial contraction and ejection
systole
ventricular/atrial relaxation and blood filling
diastole
why is diastole longer than systole?
because you have to ensure the chamber fills with blood
all heart valves closed, blood volume in ventricles remains constant, pressures rise. muscle develops tension but cannot shorten.
isovolumetric contraction
pressure in ventricles exceeds that in arteries, semilunar valves open and blood ejected into the artery. muscle fibers of ventricles shorten
ventricular ejection
volume of blood ejected from each ventricle during systole
stroke volume
how much blood is ejected in the stroke volume?
~70 - 75mL
true or false: during ejection, the chambers of the heart are completely emptied of blood
false
all heart vavles closed, blood volume remains constant, pressures drop
isovolumetric ventricular relaxation
AV valves open, blood flows into ventricles from atria, ventricles receive blood passively.
ventricular filling
atria contract at the end of ventricular filling in order to top up the blood volume in the ventricle
atrial kick
true or false: Wigger’s diagram represent the left side of the heart due to increased pressure
true
_________ is the key to understanding blood flow patterns and opening/closing of valves
pressure
blood flows from regions of _________ to regions of ________
higher pressure, lower pressure
the amount of blood in each ventricle at the end of ventricular diastole
end-diastolic volume
the amount of blood in each ventricle at the end of ventricular systole
end-systolic volume
what is the equation for stroke volume?
SV = EDV - ESV
during systole, which ventricle develops lower pressure?
the right ventricle
what does the “lub” sound of the heart represent?
closure of the AV vlaves
what does the “dub” sound of the heart represent?
closure of the semilunar valves
what does it mean for the heart to “murmur”?
turbulent blood flow that makes a sound
blood flows rapidly through a narrowed valve; leaflets do not open completely
stenosis
blood flows backward through leaky valve; leaflets do not close completely
insufficiency
the ability of a blood vessel to stretch
compliance
what is the formula for compliance?
compliance = (change in volume) / (change in pressure)
large arteries function as pressure reservoirs due to:
elastic recoil
what does elastic recoil of arteries do?
pushes blood forward
where does the sympathetic nervous system act in the heart?
atria, ventricles, SA node, AV node
where does the parasympathetic nervous system act in the heart?
atria, SA node, AV node
what does parasympathetic innervation do to the SA node?
decreases the rate of depolarization to threshold; decreasing heart rate
what does parasympathetic innervation do to the AV node?
decreases conduction; increases AV nodal delay
what does parasympathetic innervation do to the artial muscles?
decreases contractility
what does parasympathetic innervation do to the ventricular muscles?
no effect
what does sympathetic innervation do to the SA node?
increases the rate of depolarization to threshold; increases heart rate
what does sympathetic innervation do to the AV node?
increases conduction; decreases AV nodal delay
what does sympathetic innervation do to the atrial muscles?
increases contractility
what does sympathetic innervation do to the ventricular muscles?
increases contractility
the amount of blood pumped by each ventricle in one minute
cardiac output
what is the equation for cardiac output?
cardic output (CO) = heart rate (HR) * stroke volume (SV)
what are the two main factors that affect cardiac output?
- altering the activity of the SA node
- altering the contractility of the ventricular myocardium
heart rate is increased by:
increasing sympathetic activity
heart rate is decreased by:
parasympathetic activity
sympathtic stimulation to the heart increases _____ and ____ channel permeability
L-type, T-type
parasympathetic stimulation to the heart deacreases ______ channel permeability
F-type
what are the three main factors that affect stroke volume?
1) end-diastolic volume (EDV)
2) contractility of ventricles
3) afterload
the tension or load on the myocardium before it begins to contract. aka: the amount of filling of ventricles at the end of diastole
preload
what does the Frank-Starling mechanism measure?
the relationship between EDV and SV
the main determinent of the length of the cardiac muscle fiber (sarcomere) is:
the degree of diastolic filling (aka: preload)
the strength of contraction at any given EDV
contractility
the fraction of the EDV that is ejected
ejection fraction
what is the equation for the ejection fraction?
EF = SV / EDV
how does sympathetic stimulation affect contractility?
it increases contractility
do epinephreine/norepinephrine increase or deacrease contractility of the heart?
increase
tension (or arterial pressure) against which the ventricles contract
afterload
what happens to the stroke volume as the afterload increases?
SV decreases
any factor that restricts blood flow through the arterial system will ________ afterload
increase
the endothelium of vessels is continuous with:
the endocardium of the heart
smooth, single-celled layer of endothelial cells
endothelium
- many elastic fibers, few smooth muscle cells
- expand and recoil in response to pressure changes
these are characteristics of:
elastic arteries
- many smooth muscle cells, few elastic fibers
- distribute blood
these are characteristics of:
muscular arteries
- 1-2 layers of smooth muscles
- resistance vessels
these are characteristics of:
arterioles
which is higher: pulmonary vascular resistance or systemic vascular resistance
systemic vascular resistance
what are the two main functions of the arterioles?
1) regulate blood flow to organs
2) determine mean arteriole pressure (MAP)
relaxation of arteriolar smooth muscle; increases blood flod to organs
vasodilation
contraction of arteriolar smooth muscle; decreases blood flow to organs
vasoconstriction
arterioles are high resistance vessels due to:
their small size
true or false: both extrinsic and intrinsic factors can alter basal tone
true
what are the extrinsic factors which can alter basal tone?
nerves and hormones
what are the intrinsic factors which can alter basal tone?
local controls: organs and tissues alter their own arterioloar resistances independent of nerves/hormones
norepinephrine causes _______ in the arterioles
vasoconstriction
nitric oxide causes _______ in the arterioles
vasodilation
epinephrine from the adrenal medulla can cause _______ or ______ in the arterioles
vasoconstriction, vasodilation
arteriolar smooth muscle is sensitive to local chemical changes, which are the result of:
chances in metabolic activity
what is hyperemia?
an excess of blood in the blood vessels
increased metabolic activity results in _______ of arterioles and _______ blood flow
vasodilation, increased
arterioles change theri resistance to maintain constant blood flow in the presence of a:
pressure change
what are the two local controls which alter arteriolar resistance?
- active hyperemia
- flow autoregulation
flow autoregulation may also be mediated by the:
myogenic response
direct response of arteriolar smooth muscle to stretch
myogenic response
how thick are capillaries?
one endothelial cell thick
is there smooth muscle or elastic tissue in capillaries?
no
what is the function of capillaries?
the site of exchange of material between blood and interstitial fluid
narrow, water-filled space at the junctions between cells
intercellular clefts
made up of glycoproteins, provides support and capillary attachment
basement membrane
true or false: capillaries can be made up of one or more endothelial cells
true
what are the three types of capillaries?
1) continuous capillaries
2) fenestrated capillaries
3) sinusodal capillaries
the type of capillary where endothelial cells form an uninterrupted tube, surrounded by complete basement membrane
continuous capillaries
the continuous capillaries are the site of exchange of:
water, small solutes, and lipid-soluble materials
where are continuous capillaries present?
most tissues
pores that penetrate the endothelial lining
fenestrae
fenestrated capillaries are surrounded by a:
complete basement membrane
fenestrated capillaries are the site of rapid exchange of:
water and solutes
where are fenestrated capillaries present?
endocrine organs, choroid plexus, GI tract, kidneys
discontinuous capillaries; flattened and irregularly shaped capillaries
sinusoids
where are sinusodal capillaries located?
liver, bone marrow, and spleen
sinusodal capillaries are the site of exchange of:
water, solutes (red blood cells, debris, proteins)
the use of vesicles to cross endothelial cells
transcytosis
transcytosis occurs at the:
intercellular clefts, fenestrae, and fused vesicle channels
movement of protein-free plasma across the capillary wall
bulk flow
movement of protein-free plasma from capillary ro interstitial fluid
filtration
movement of protein-free plasma from interstitial fluid to capillary
reabsorption
pressures that drive fluid movement into and out of the capillary
hydrostatic pressure
fluid pressure exerted on the outside of the capillary wall by itnerstitial fluid, favours fluid movement into the capillary
interstitial fluid hydrostatic pressure
which is negligible, capillary hydrostatic pressure or interstitial fluid hydrostatic pressure
IF hydrostatic pressure
osmotic pressure due to non-permeating plasma proteins inside the capillaries, favours fluid into capillaries
blood colloid osmotic pressure
small amount of plasma proteins may leak out of the capillaries into the interstitial space (negligible)
interstitial fluid collid osmotic pressure
positive filtration pressures favour:
filtration
negative filtration pressures favour:
absorption
transition point between filtration and reabsorption lies closer to ________ end of capillary
venous
the pressure needed to drive blood into tissues
mean arterial pressure (MAP)
how is mean arterial pressure calculated?
MAP = diastolic pressure + (pulse pressure/3)
OR
MAP = cardiac output (CO) * total peripheral resistance (TPR)
what is the average arterial pressure during one cardiac cycle
~90 mmHg
is there enough pressure to move blood at 60 mmHg?
no
pulse pressure ________ as distance from the heart ________
decreases, increases
mean arterial pressure _______ as distance from heart _______
decreases, increases
largest drop in pressure occurs across the ________
arterioles
why is there such a dramatic decrease in pressure at the arterioles?
parallel flow
what is the average systolic/diastolic pressure?
120/80 mmHg
how is pulse pressure calculated?
pulse pressure = systolic - diastolic
maximum blood pressure during ventricular systole?
systolic pressure
minimum blood pressure at the end of ventricular diastole?
diastolic pressure
a condition characterised by chronically increased arterial blood pressure
hypertension
a condition characterized by abnormally low blood pressure
hypotension
- seconds to hours
- baraoreceptors reflexes
- adjusts cardiac output and total peripheral resistance
these are characteristics of:
short-term regulation of MAP
- adjust blood volume
- restore normal salt and water balance through mechanisms that regulate urine output and thirst
these are characteristics of:
long-term regulation of MAP
mechanoreceptors found in major artery walls
baroreceptors
respond to changes in pressure when walls of vessel stretch/relax
baroreceptors
when looking at baroreceptor action potential frequency, the rate ofdischarge is proportional to:
the mean arterial pressure
the medullary cardivascular center (medulla oblongata) receives input from:
baroreceptors
the medullary cardiovascular center alters _______ stimulation to the heart and _______ stimulatio to the heart, arterioles and veins
parasympathetic (vagal), sympathetic
baroreceptors adapt to sustained changes in:
arterial pressure
pressure volume loops are generated by real-time measurement of pressure and volume within the:
left ventricle
on a pressure volume loop, the slope of the line tangential to the point where the aortic valve closes is the:
end-systolic pressure-volume relation (ESPVR)
describes the maximal pressure that can be developed by the ventricle at any given left ventricular volume
end-systolic pressure-volume relation (ESPVR)
does increasing the preload increase the ESPVR?
no
does increasing contractility increase the ESPVR?
yes
does increasing the afterload increase ESPVR?
no
