LESSON 15 - heart and circulation : central Flashcards
what are the four major parts of the cardiovascular system ?
- heart “pump”
- arteries “outflow conduits”
- capillaries “drop/pickup site”
- veins “return flow conduits”
how many chambers are there of the heart ?
four
what are the four chambers of the heart ?
right and left atria (top receiving)
right and left ventricles (bottom pumping)
what type of circulation is the right circulation ?
pulmonary
what type of circulation is the left circulation ?
systemic
what type of blood does the right heart pump
pumps deoxygenated blood from body to lungs
how does the right heart circulate blood ?
superior/inferior vena cavae → RA → tricuspid valve → RV → pulmonary valve → pulmonary arteries → lungs
how does the left heart circulate blood ?
lungs → pulmonary veins → LA → mitral valve → LV → aortic valve → aorta
what type of blood does the left heart pump ?
oxygenated blood from lungs to body
how do cardiac muscles contract ?
contracts as one single unit
how are individual cardiac muscles fibers interconnected ?
end-to-end by intercalated dics
what type of fibers are present in cardiac muscle ?
only one fiber type, similar type 1 fibers in skeletal muscle
what is the primary blood supply to heart ?
by coronary arteries which arise from aorta
what do cardiac veins return ?
deoxygenated blood
cardiac veins return deoxygenated blood to …
the inferior and superior vena cavae
how do we match O2 supply with O2 demand ?
moves simultaneously together
why does the heart generate pressure ?
to drive oxygenated blood through vessels to skeletal muscle
the heart is driven by the deans of active skeletal muscle for O2 but also :
- removes CO2 and other wastes
- transports hormones and other molecules
- supports temperature balance and controls fluid regulation
- maintains acid-base balance
when matching systemic VO2 supply with O2 demand what is the formula ? O2 =
VO2 = CO x a-vO2diference
how do you calculate cardiac output ?
HR x SV
what is cardiac output ?
how much blood is pumping out per min
what does increase O2 mean for CO ?
increase CO
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cardiac output relates closely to O2 by a ratio of ____
6 : 1
what is fick’s principal ?
VO2 = CO x a-vO2difference
what is heart rate ?
the # of times the heart contracts in 1 min (beats/min)
how many mechanisms does the cardiac muscle possess by which rhythm is controlled ?
two
what are the two mechanisms the cardiac muscle posses ?
- intrinsic control and 2. extrinsic control
what is intrinsic control ?
cardiac muscle has ability to generate its own electrical signal (spontaneous rhythmicity)
what establishes sinus rhythm ?
pacemaker (SA node)
without external control what does intrinsic control average ?
100 beats per min (transplant)
what is extrinsic control ?
system that modulates intrinsic electric impulses and causes heart to speed up (anticipation) or speed down
is it intrinsic or extrinsic that adjusts HR to 35 to 30 beats min -1 at rest in endurance athletes ?
extrinsic
in extrinsic control, during maximal effort, HR can hit ___- beats per min ?
220
whats the simplest difference between intrinsic and extrinsic control ?
Intrinsic comes from within, while extrinsic arises from external factors
(intrinsic control) from within the heart include what four things ?
- SA node
- AV node
- bundle of his
- purkinje fibers
what does the SA node do ?
sets pace (pacemaker)
what does the AV node do ?
calms it down to happy level
anything outside of the heart is intrinsic or extrinsic ?
extrinsic (ex. working out, muscles, brain, telling the heart to speed up)
describe the normal route of myocardial impulse transmission of intrinsic regulation of HR …
SA node → atria → AV node → AV bundle (purkinje fibers) → ventricles
what part of the intrinsic control “spontaneously depolarizes and reploarizes to provide “innate” heart stimulus”
Sinoatrial node (SA)
what part of the intrinsic control “delays impulse about 0.10 sec to provide sufficient time for atria to contract and dolce blood into ventricles”
atriventrical (AV) node
what part of the intrinsic control “speeds up impulses rapidly through ventricles”
purkinje fibers
what are the three extrinsic systems that module heart rate ?
- parasympathetic nervous system
- sympathetic nervous system
- endocrine system (NE, ACh, E)
what is the parasympathetic nervous system ?
rest and digest
what is the sympathetic nervous system ?
fight and flight
what is vagus ?
control parasympathetic nerve to heart
what is stroke volume ?
volume of blood pumped in one heartbeat (mL)
what are the two end - blank - volumes …
end-diastolic and end-systolic volume
which one is end diastole volume ?
the top / higher one
which one is the end systolic volume ?
the bottom / lower one
which EDV/ESV just pumped everything out ?
ESV
highest point - smallest point on cardiac cycle table =
SV
how do we calculate stroke volume ?
EDV - ESV
what happens during systole ?
most (not all) blood is ejected
how do we calculate ejection fraction (EF) ?
% of EDV pumped
what does EF stand for ?
ejection fraction
how do we calculate EF ?
SV/EDV
when measuring what do u multiply SV / EDV (in mL) by ?
multiply by 100%
what is the clinical index of heart contractile function ?
ejection fraction
what is ejection fraction ?
what % is pumped out of the heart
what is preload ?
how much blood is sitting in ventricle before the pump
what term is used to describe “volume of blood received by the heart during RDV” ?
preload
what is end diastolic filling ?
the amount of blood that is in the ventricles before the heart contracts
describe the frank-starling law of the heart :
describe the relationship between contractile force and resting length of the heart’s muscle fibers
what is the force of contraction fo cardiac muscle proportional to ?
its initial length
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the ______ stretched the ventricle in diastole to produce a more forceful ejection of blood
preload
if you have an increase in EDV what does this mean for stroke volume ?
increase
what does it mean when you have an increase in venous return ?
more blood coming back to the heart
does the heart extend or shorten as we put more blood in it ?
extend
what is the term used for “how much volume of the blood is being pushed” ?
stroke volume
what is inotropy ?
the strengthening/weakening function of the cardiac tissue
what term is used to describe “enhanced contractile force to augment stroke power and facilitate emptying” ?
intropy
what is length independent ?
inotropy
can inotropy change the force ?
inotropy
cardiac muscle cannot modulate force through changes in motor neuron activity …
inotropy
increased inotropy = …
increased muscle tension for a given preload (or EDV) and rate of muscle tension development
what does an increased inotropy mean for stroke volume ?
increased stroke volume
what happens to inotropy during exercise ?
increases
during an increase of inotropy what is happening with the firing of sympathetic nerves innervating the ventricles ?
increased firing of sympathetic nerves innervating ventricle
during an increase of inotropy what is happening with the firing of activity of parasympathetic nerves ?
decreases
during an increase of inotropy what is happening with the circulating catecholamines (Epi and NE) ?
increases
what is after load ?
pressure heart must generate to open aortic valve
what is term used for when pressure in LV needs to generate to open aortic valve ?
afterlaod
what is needed to open aortic valve ?
pressure
what happens with after load in stroke volume ?
decreases in SV
how does stroke volume x oxygen uptake look on a graph ?
gradually increases together
what are the three determinants of cardiac output ?
- preload
- contractibility
- afterload
how do we measure cardiac output ?
heart rate and stroke volume
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maximal cardiac output relates to O2 max by a ratio of ____
6 : 1
what principal says “how do we match O2 supply with O2 demand” ?
the fick principal
