Cardiovascular - physiology

what are the walls of the atria and ventricle called

myocardium

how much thicker is the left ventricle then the right ventricle wall

3 x

what type of atrioventricular valve is between the left atria and ventricle

Bicuspid/mitral

what type of atrioventricular valve is between the right atria and ventricle

tricuspid

how are the AV valves held shut during ventricle contractions

connected to papillary muscles by chordae tendinea which tighten when ventricle contracts

what is produced at the SA node

action potentials to generate the heartbeat

what is 1

sinoatrial node

what is 2

internodal pathways

what is 3

atrioventricular node

what is 4

AV bundle

what is 5

purkinje fibres

what is 6

moderator band

what creates the p wave on ECG

action potential spreads through atria which depolarises

what creates the red line on this image (between the p wave and the QRS wave)

action potential spreads to AV node

what creates the start of the QRS (as on image)

action potential spreads through AV bundle

what creates the rest of QRS

action potential spreads through ventricle causing depolarisation of ventricle

what causes t wave

repolarisation of ventricle

can atrial repolarisation be seen on ECG

n o- happens at the same time as QRS and cant be seen due to the difference in size of change in electrical signal

what is the cardiac cyle

all the events involved with blood flow through the heart for a single heart beat

what are electrical events

spontaneous - depolaristion and repolarisation

what are mechanical events

follow electrical events, contraction and relaxation of the myocardium, open and closing of heart valves

how long is the diastole phase

2/3 cardiac cycle

how long is the systole phase

1/3 of the cardiac cycle

what is 1

ventricular filling 2

what is 2

isovolumetric contraction

what is 3

ventricular ejection

what is 4

isovolumetric relaxation

what is 5

ventricular filling 1

what is isovolumetric contraction

when blood has not yet left heart during contraction

what is isovolumetric contraction

no movement of blood as heart starts to relax

what happens at the start of the cardiac cycle

all four chambers are relaxed, SA node spontaneously generates action potential

at the start of the cardiac cycle do the ventricles or the atria have higher pressure

atria - causing blood flow down the pressure gradient to fill the ventricles. AV valves are open, semilunar valves are closed (pressure in artery is higher than in the ventricle

what happens during step 1 (ventricular filling 2 - diastole)

atria depolarise = ECG p wave, atria contract

during step 1 (ventricular filling 2 - diastole) what happens when the atria pressure increases slightly

atria contract to squeeze more blood into ventricles to completely fill, av valves are open, semilunar valves are shut.

what happens during step 2 (isovolumetric contraction - systole)

action potential spreads down AV bundle and ventricles, ventricles depolarise (QRS) and start to contract

during step 2 (isovolumetric contraction - systole) what happens when the pressure in teh ventricels starts to increase and becomes higher then in atria

AV valves close, semi lunar valves are still shut. - pressure builds in ventricles with no volume change (isovolumetric)

what happens during step 3 (ventricular ejection - systole)

ventricles are still depolarised, and continue to contract

during step 3 (ventricular ejection - systole) what happens when the pressure in the ventricles continues to increase

ventricular pressure is higher than in the arteries, AV valves are close, Semilunar valves are open - ventricle ejects blood into arteries

what is the amount of blood ejected into the arteries in a single pump known as

stroke volume

what happens during step 4 (isovolumetric relaxation - diastole)

ventricles repolarise - t-wave, ventricles relax

during step 4 (isovolumetric relaxation) what happens when the pressure in the ventricles decreases as blood is ejected

ventricle pressure drops lower than in arteries, AV valves and semilunar valves are closed. pressure drops in ventricles with no volume change = isovolumetric

what happens during step 5 (ventricular filling 1 -= diastole)

all chambers are repolarised and relaxed

during step 5 (ventricular filling 1 -= diastole) what happens when ventricle pressure drops back below atria pressure

av valves open, semilunar valves close. ventricles start to fill with blood passively

what makes the sound that can be heard in a stethoscope when listening to the heart

when the valves shut the cusps snap shut, this creates turbulent flow od the blood against the closed valve creating the sound

what makes the first sound of the heart

closing of AV valves as the ventricles contract -happens following the QRS complex on the ECG

what makes the 2nd sound of the heart

with the closing of the semilunar valves as the ventricle relaxes, happens following the t-wave on the ECG

what is the normal stroke volume for a healthy adult at rest

approx 70 mL

what does cardiac output equal

Hr X stroke volume

what is the normal CO (cardiac output) for an adult at rest

5L/min