heart as a pump Flashcards
function of the heart is to supply
oxygen to peripheral tissue
metabolic substrates to peripheral tissue
supply of oxygen is mainly provided by what side of the heart
left
the cardiac cycle is associated with how many beats?
1
in one cardiac cycle, the 2 atria contract and 2 ventricles relax
together
when the chambers are relaxed they
fill up with blood
both the atria and ventricles
pump an equal amount of blood
systole is
contraction
distole is
relaxation
left atrium receives oxygenated blood from
then it is ejected by the left ventricle into the
pulmonary veins
AORTA
what are the 2 valves in the left heart?
mitral valve (atrioventricular)
semilunar valve (aortic valve)
the mitral valve serves for
allowing blood to flow from the left atrium to the left ventricle prevents blood from returning into left atrium
the semilunar valve serves for
allowing blood to flow from left ventricle to aorta
preventing blood form returning into the left ventricle
the right side of the heart receives deoxygenated blood from the and it is ejected by the right ventricle into the
cranial and caudal vena cava
pulmonary artery to the lungs
what are the two valves in the right heart?
tricuspid valve (atrioventricular)
semilunar valve (pulmonic valve)
the tricuspid valve
allows blood to flow from atrium to ventricle
prevents blood from returning to right atrium
pulmonic valve
allows blood to flow from right ventricle to the pulmonary artery
prevents blood from returning to right ventricle
each ventricle works in a cycle
relaxation= take the volume of blood from the atria
contraction= eject blood into the arteries
t/f the left and right ventricles receive and eject a similar amount of blood
true
ventricular diastole
ventricular relaxation and filling with blood
ventricular systole
ventricular contraction and ejection of blood
atrial diastole
atrial filling
atrial systole
atrial contraction
t/f for the timing of systole and diastole, the mechanical contraction follows the electrical stimulation
true
atrial systole follows the depolarization of
atrial myocytes (P wave on ECG)
ventricular systole follows the depolarization of the
ventricular myocytes (QRS on ECG)
in ventricular systole, the electrical impulse goes from the AV node to
Bundle of His, right and left bundle branches, and purkinje fibers to supply the myocardial cells
t/f In isovolumic contraction, pressure increases and volume changes
False
volume doesn’t change
in isovolumic contraction, when ventricular pressure exceeds atrial pressure the atrioventricular valves
close
pressure is still lower in the large vessels
in the ejection phase, pressure in the ventricles exceeds pressure in the large vessels and what happens
aortic and pulmonic valves open , the ventricles start ejecting blood into the large vessels
t/f in isovolumic relaxation, pressure decreases but volume is unchanged
true
in isovolumic relaxation, ventricular contraction ends and ventricular pressure
decreases
in isovolumic relaxation, aortic and pulmonic valves close when ventricular pressure is
lower than pressure in the vessels
in isovolumic relaxation, ventricular pressure is higher than
atrial presssure
the heart is relaxing but there is no change in volume
atrioventricular valves open when
ventricular pressure is lower than atrial pressure and ventricular cells are at rest
ventricullar fillling and atrial contraction is stimulated by
P wave that stimulates the atria
when the P wave stimulates the atria blood is pushed
into the already filled ventricles
P-R intervals gives time for the atria to contract before
next ventricular systole
what are the 2 phases of systole
isovolumic contraction
ejection phase
during systole, in the isovolumic contraction, what happens to the volume and pressure?
volume constant
pressure increases
during systole, in the ejection phase, what happens to volume and pressure?
volume decreases
pressure increases and the decreases
what are the 4 phases of diastole?
isovolumic relaxation
rapid filling ventricles
slow filling ventricles = diastasis
atrial contraction
diastole starts when
semilunar valves close
rapid filling ventricles during diastole occur due to the flow of blood from
atrium to ventricle
diastasis means
slower blood flow
closure of the atrioventricular valves mark the beginning of
systole
closure of the semilunar valves mark the beginning of
diastole
during systole, in relation to large vessels, the ventricles generate pressure until
equal to large vessels
during diastole, in relation to large vessels, the ventricles decrease pressure until
below atrial pressure
high pressure system
left side
atrial pressure of 5-7 mmHg
ventricular pressure: systole 120 mmHg
diastole 0 mmHg
aortic pressure: systole 120 mmHg
diastole 80 mmHg
left side
your blood pressure is related to the
aortic pressure
low pressure system
right side
atrial pressure = 2-3 mmHg
ventricular pressure
Systole: 25 mmHg
Diastole: 0 mmHg
Pulmonary artery pressure
Systole: 25 mmHg
Diastole: 15 mmHg
right side
when the atrioventricular valves are open, the pressure in the atria and ventricles is
the same
when the semilunar valves are open, pressure is
the same in ventricles and arteries
t/f Pressure generated by left ventricle is 5 times larger than pressure generated by the right ventricle
true
stroke volume is calculated
End-diastolic volume – end-systolic volume
Cardiac output systolic and diastolic output
cardiac output is calculated
Stroke Volume (SV) X Heart Rate (HR) (in the test calculate)
cardiac output is
total volume of blood pumped by each ventricle in 1 minute
stroke volume is
the volume of blood ejected during each heartbeat
heart rate is
the number of time the heart beats in one minute
how to increase End diastolic volume
Increase venous return
Increase ventricular compliance
how to decrease esv
Increase contractility
Decrease afterload
formula for increasing cardiac output
CO= (EDV-ESV)X HR
PRE LOAD
END DIASTOLIC VOLUME
Increase venous return-high volume of blood by
Increasing volume of blood entering the left side of the heart from the pulmonary veins entering the right side of the heart from the vena cava
Increase ventricular compliance
Increase ventricular elasticity (decrease stiffness)
A more compliant ventricle can accommodate more volume
Increase sympathetic tone makes the ventricles more compliant. This is a positive lusitropic (myocardial relaxation)effect
sterlings law
The greater the volume of blood entering the heart during diastole, the greater the volume of blood ejected during systole
The more the heart is stretched, the stronger it contracts
decrease ESV
Increase contractility
This is the strength of contraction, the pumping ability of the left ventricle
Increased sympathetic tone increases contractility. This is a positive inotropic effect
Decrease afterload
It is the resistance to ejection
It is equal to blood pressure
Relax
As you get older your blood pressure increases
increasing the heart rate: CO output increases with
HR if HR <160-180 beats/minutes
inceasing the heart rate: CO decreases when
HR > 180-200 bpm
When HR increases, duration of diastole decreases
Venous return decreases when diastole shortens
Stroke volume decreases
Decrease in stroke volume is not compensated by increased heart rate
