Cardiac Physiology

Question 1

What is the pericardium

Answer 1

Serous membrane that surrounds the heart

Question 2

What is the myocardium

Answer 2

Muscle of the heart

Question 3

What is the endocardium

Answer 3

Innermost layer of connective and epithelial tissue

Question 4

What is the compact myocardium and spongy myocardium

Answer 4

Outer layer of cells arranged in regular pattern
Spongy is the inner layer of mesh work of cells

Question 5

From superficial to deep what are the layers of cardiac muscle

Answer 5

Fibrous pericardium, parietal pericardium, pericardial fluid, visceral pericardium, myocardium, endocardium which is continuous with epithelium

Question 6

What are the components of a fish heart

Answer 6

Sinus venosus which is the site of blood entry
Atrium which is the receiving chamber
Ventricle which is the muscular chamber
Bulbous arteriosus which is the main vessel leading out the heart

Question 7

What are the components of the amphibian heart

Answer 7

Three chambered heart with two atria and one ventricle
Trabeculae carnae help keep oxygenated and deoxygenated blood separate
The spiral fold helps with blood flow out of the ventricle

Question 8

What are the components of the mammal heart

Answer 8

Four chambers separated by septa and valves
Two atria and two ventricles
Right side is deoxygenated blood
Left side if oxygenated blood

Question 9

What are the atria and ventricles used for

Answer 9

Atria receives blood and gets blood from venous system
Ventricles send blood and push blood to arterial system

Question 10

What kind of muscles are located in the right atrium

Answer 10

Pectinic muscles

Question 11

Why is the tricuspid, tendonae, and capillary muscles important

Answer 11

Atrioventricular or tricuspid valve separates right atrium and ventricle
Cordae tendonae and papillary muscles keep the valve from flipping on itself

Question 12

What is the overall flow of blood

Answer 12

Right atrium, right atrioventricular valve, right ventricle, pulmonary valve, pulmonary trunk, pulmonary arteries, lungs, pulmonary veins, left atrium, left atrioventricular valve, left ventricle, aortic valve, aortic arch, body, vena cava

Question 13

Characteristics of cardiac muscle

Answer 13

Striated and Uninucleated
Many mitochondria and t tubules are wider
Intercalated discs which connect adjacent cells together
Functions as single syncytium
Uses aerobic respiration only and tetanic contractions aren’t possible

Question 14

What are pacemaker cells

Answer 14

Small non contractile cells that have unstable resting membrane potentials
Contain channels that open during hyper polarization (HCN channels)
Can generate atp without an input

Question 15

Why are hyper polarization activated cyclic nucleotide cation channels important

Answer 15

They are activated at hyper polarization
Made up of cyclic nucleotides
Allow cations to fluctuate across the cell membrane
As long as they are activated they keep going

Question 16

What is the process to get HCN channels

Answer 16

Epinephrine targets B1 receptors in heart which activates camp which activates protein kinase and finally the HCN channels

Question 17

How does the conduction network work for the heart

Answer 17

An action potential is fired in the SA node at the ceiling of the right atrium then through the backhmans branches to the AV node in the floor of the RA
AV node sends the signal to the Bundle of His and then into the left and right bundle branches which then leads to the perkinje fibers

Question 18

What is heart rate set by and why is this important

Answer 18

Set by the SA node because the SA nodes depolarize the fastest

Question 19

What is cardiac output

Answer 19

Stroke volume x heart rate
Amount of blood pumped out by the ventricle per minute

Question 20

What is stroke volume

Answer 20

End diastolic volume minus end systolic volume
Amount of blood pumped out by the left ventricle

Question 21

What happens if after load increase? What about preload?

Answer 21

If after load increases then ESV increases and stroke volume and cardiac output decrease
If preload increases the force and ESV will decrease

Question 22

How is a cardiomyocyte action potential generated

Answer 22

Depolarization by influx of ions from pacemaker and muscle cells
Threshold is reached and VG Na channels open
Plateau phase reached then when Na channels close VG Ca channels open
They last as long as as the refractory period prevents another contraction

Question 23

What is the plateau phase

Answer 23

Stops the heart from beating too fast
Point of reset
Prevents tetanic contractions

Question 24

Myofilaments are dependent on what

Answer 24

Calcium levels
If calcium increases contraction is increased and visa versa

Question 25

What are the steps of the cardiac cycle

Answer 25

Atria in diastole and ventricle in systole then AV valve opens so blood flows from atria to ventricles with passive filling AP is then fired from the SA node and atria contracts now using active filling AV node then fires and signal moves to Bundle of His where the atria are relaxed and ventricles are contracted Blood then pushes on valves causing them to shut and signal moves down the bundle branches Ventricle systole occurs keeping all gates closed and then isovolumetric contraction causes forces in the SL valves open (this is when ventricular pressure exceeds arterial pressure) Ventricular ejection occurs causing blood to move from ventricles to arteries and you have end systolic volume Then ventricular diastole occurs which causes isovolumetric relaxation Then ventricular filling occurs which drops the pressure low enough to pop the av valves open

Question 26

What is isovolumetric contraction

Answer 26

Point before you start refilling the ventricles Essentially after load

Question 27

What is ventricular ejection

Answer 27

Movement of blood from ventricles to arteries

Question 28

What is isovolumetric relaxation

Answer 28

No blood moving from the ventricles which is during ventricular diastole

Question 29

What is end diastolic volume

Answer 29

Amount of blood in the ventricles at the end of diastole

Question 30

What is preload

Answer 30

All blood that flows into the ventricles with passive and active filling How much the ventricles have stretched

Question 31

What is after load

Answer 31

How much force it takes to send blood out of How much pressure is put on the arteries based on the amount of blood in the ventricles

Question 32

True or false: one cardiac cycle involves ALL heart muscles

Answer 32

True

Question 33

How are electrical changes in the heart monitored

Answer 33

EKG

Question 34

What does the p wave indicate

Answer 34

Atrial depolarization

Question 35

What does the QRS complex indicate

Answer 35

Ventricular depolarization

Question 36

What does the t wave indicate

Answer 36

Ventricular repolarization

Question 37

What is einthovens triangle

Answer 37

Triangle formed by electrodes placed on arms and legs One lead has a positive and negative electrode Each lead forms a vector

Question 38

What is used to determine cardiac axis

Answer 38

Wheel of leads

Question 39

What is the cardiac reserve

Answer 39

Difference between resting and maximal cardiac output

Question 40

What is the difference between brachychardia and tachycardia

Answer 40

Bradycardia is slow heart rate Tachycardia fast heart rate

Question 41

What is the frank sterling law

Answer 41

Relationship between force-tension in the heart

Question 42

What is a dicrotic notch

Answer 42

Uptick in aortic pressure caused by closure of the aortic valve

Question 43

What is L-R shunting

Answer 43

Supplies heart with oxygen Increased when increased activity in reptiles

Question 44

What is R-L shunting

Answer 44

Increases during dives because there is no need to send blood to the lungs