Cardioviscular Physiology 3

Question 1

Explain the Diastole period!

Answer 1

After blood got pushed out of the ventricles: more blood in the aorta and pulmonary trunk than in the ventricles, and more blood in the ventricles than in the atria

aorta > Left ventricle > Left atrial
Pulm. trunk > right ventricle > right atrial

Isovolumetric ventricular relaxation

Question 2

What is the Isovolumetric ventricular relaxation?

Answer 2

no change of the volume in the ventricular, all valves are closed,
ventricular is relaxing after pushing out the blood to the aorta/pulmonary trunk

Question 3

What is the quiescent period?

Answer 3

atria is relaxed, ventricle is relaxed –> passive flow blood from atria to ventricle

Question 4

State of pressure when ventricles are filling?

Answer 4

aorta still has the highest pressure, semilunar valves are closed

aorta > left atrial > left ventricle

pulmonary trunk > right atrial > right ventricle

Question 5

Explain the Systole process!

Answer 5

After atrial contraction, all blood is pushed to the ventricle -> AV closes, and semilunar valves are closed too because the ventricles are about to contract and build up to pressure (which will open semilunar valves)

–> Isovolumetric ventricular contraction - no change of volume, all valves closed

pressure same as Isov. ventr. relaxation
aorta > Left ventricle > Left atrial
Pulm. trunk > right ventricle > right atrial

Question 6

State of pressure when blood gets pushed out?

Answer 6

Left ventricular > aortic > Left atrial

Right ventricular > pulmonary trunk > right atrial

Question 7

What is the cardiac output (CO)?

Answer 7

amount of blood pumped out by each ventricle per minute
so, how often does the heart pump - heart rate
how much does it pump per beat - stroke volume

CO = HR * SV

Question 8

How is stroke volume (SV) calculated?

Answer 8

How much blood comes into the heart after diastole? EDV
How much blood remains in the heart after it pumps? ESV

SV = EDV - ESV -> it will tell us how strong the stroke volume is -> how much we pump out per contraction

Question 9

What factors will affect heart rate?

Answer 9

Sympathetic will increase slope to reach AP quicker -> increase of HR
Parasympathetic vice versa -> decrease of HR

Epinephrine secreted by the adrenal medulla -> increase of heart rate

Question 10

What factors will affect stroke volume?

Answer 10

Preload: amount ventricles are stretched by contained blood, how much blood comes back (EDV) - increased SV with increased venous return - Frank Starlin law
-> increase stroke volume

Contractility: cardiac cell contractile force by factors other than EDV (ESV is decreased!!, more contractile force) - comes from Ca2+ by increasing sympathetic input!! -> more contracting cross bridging in sarcomeres
-> increase stroke volume

Afterload: back pressure exerted by blood in the large arteries leaving the heart (ESV) - it is harder to overcome the pressure of arteries when there is much blood there -> if it is hard to overcome the pressure, there will be less blood pumped out -> more ESV ->
DECREASE stroke volume

Question 11

How can Contractillity be increased?
What is its effect?

Answer 11

By Ca2+ -> by an increase of sympathetic or epinephrine input to the heart or drugs

Decrease of ESV and thus increase of stroke volume

Question 12

What is the consequence of afterload?

Answer 12

more force is needed to overcome pressure in ventricles to pump blood -> so increase of ESV
-> high blood pressure increase afterload

Question 13

What is the consequence of increased venous return?

Answer 13

Increase of preload (EDV) -> the heart’s ability to stretch more, when EDV is increased -> increase of stroke volume

Question 14

When do we see a big increase of SV?

Answer 14

Increased EDV and increased Contractility by sympathetic NS or epinephrine (ESV down)
up to 5x increase of CO

Question 15

Frank-Starlin law of the heart

Answer 15

The heart can adapt to EDV -> the more blood flows into the ventricle (EDV), the harder it can pumps (SV) -> also makes sense with SV = EDV - ESV

Question 16

PRELOAD
How can cardiac muscle adapt to the increase in EDV?

Answer 16

at normal EDV flow, there is an overlap in the sarcomere

when EDV increases sarcomere length reaches the optimal length

venous return determines how well cardiac muscle will stretch -> and thereby pump

Question 17

What is the stimulus of Contractility

Answer 17

Ca2+

Contractility is independent of EDV and stretch, it has to do with how well the heart contracts
also has to do with how much blood is left over after contraction = ESV

Question 18

Where do we get Ca from in cardiac muscles

Answer 18

L-type Ca channels and from ryanodine receptors in Sarcoplasmic reticulum

Question 19

Describe the role of myosin heads during a contraction!

Answer 19

Normal contractility: there is not as much Ca present -> not all myosin heads are involved in filament binding

Increased contractility: more Ca released -> more myosin involved in binding filaments -> optimal length reached -> more contraction

Question 20

What is the function of beta blockers?

Answer 20

they can reduce blood pressure, by reducing the heart rate and force of contraction of the heart

Question 21

How can Cardiac output be increased efficiently

Answer 21

By increasing SV rather than heart rate, because with every heart rate we consume blood

Question 22

What happens in case of high blood pressure?

Answer 22

increased afterload -> increase of O2 consumption -> the heart has to work more -> weighs on vascular system

Question 23

What does the P-wave represent?

Answer 23

Atrial depolarization -> SA node firing

Question 24

What does the QRS-wave represent?

Answer 24

-Ventricular depolarization -> Perkunjie fibers firing

-at the same time atrial repolarization but masked by ventricular depolarization

Question 25

What does the T-wave represent?

Answer 25

Ventricular repolarization