Cardiology Anatomy and Function

Question 1

Trace the blood flow through the body
starting with the vena cava

Answer 1

Vena cava > right artria > tricuspid valve > right ventricle > pulmonic valve > pulmonary artery > lungs > pulmonary vein > left atria > mitral valve > left ventricle > aortic valve > aorta > tissues > vena cava

Question 2

Where is the tricuspid valve?

Answer 2

Between the right atria and ventricles
(Right AV valve)

Question 3

Where is the mitral valve?

Answer 3

Between the left atria and ventricles
(Left AV valve)

Question 4

Layers of the heart + pericardium from internal to external

Answer 4

Endocardium > myocardium > epicardium (visceral layer of serous pericardium) > pericardial cavity > parietal layer of serous pericardium > fibrous pericardium

Question 5

What color is fluid usually on US?

Answer 5

Black

Question 6

What type of muscles are found in the auricles?

Answer 6

Pectinate muscles

Question 7

What three vessels enter the right atrium?

Answer 7

Cranial vena cava, caudal vena cava, coronary sinus

Question 8

What muscles are connected to the mitral/tricuspid valves via the chordae tendinae?

Answer 8

Papillary muscles

Question 9

Which side of the heart is naturally higher pressure?

Answer 9

Left

Question 10

What kind of valves are the aortic and pulmonic?

Answer 10

Semi-lunar

Question 11

When do the AV valves open and close?

Answer 11

Open in diastole
Closed in systole

Question 12

What is the most important heart disease of dogs?

Answer 12

Myxomatous mitral valve degeneration

Question 13

When are the semilunar valves open and closed?

Answer 13

Open in systole
Closed in diastole

Question 14

Where do the coronary arteries arise from and when does coronary arterial flow occur?

Answer 14

Arise from aorta
Coronary arterial flow occurs in DIASTOLE
(b/c in systole everything is too tight to flow)

Question 15

Where do cardiac impulses start?

Answer 15

Sinoatrial (SA) node

Question 16

What are the two primary differences between fetal and adult circulation?

Answer 16

Flow across the atrial septum (foramen ovale)
Flow between aorta and pulmonary artery (ductus arteriosus)

Question 17

What defines the onset of systole?

Answer 17

Mitral/tricuspid closure

Question 18

What defines the onset of diastole?

Answer 18

Aortic/pulmonic closure

Question 19

Defintion of Stroke Volume

Answer 19

Vol of blood efected from ventricle in one cycle
SV = End diastolic vol - end systolic vol

Question 20

What is the ejection fraction?

Answer 20

% of blood leaving the ventricle with each cycle
SV (EDV-ESV) /EDV
Normal = >50-60%

Question 21

What is cardiac output?

Answer 21

CO = SV x HR
total vol pumped into Aorta AND Pulmonary artery in 1 min
(L/min)

Question 22

What is happening during S1 (lub)?

Answer 22

Closure of the AV valve
(Beginning of isovolumetric contraction)

Question 23

What is happening during S2 (dub)?

Answer 23

Aortic valve closure

Question 24

What does lusitropy refer to?

Answer 24

Relaxation
Ventricular compliance & diastolic function

Question 25

What does inotropy refer to?

Answer 25

Contractility Degree muscle fibers shorten independent of load

Question 26

What is preload?

Answer 26

Diastolic wall stress or pressure just prioir to contraction.

Question 27

What is afterload?

Answer 27

Systolic wall stress or pressure (load or force on contracting cardiomyocyte)

Question 28

Why does CO begin to fall at very high HRs?

Answer 28

Less diastolic filling time

Question 29

What is the most important factor affecting preload?

Answer 29

Venous return/blood volume

Question 30

What affects afterload?

Answer 30

Systemic vascular resistance (arterial blood pressure) Compliance of aorta and arteries Left ventricular outflow tract anatomy (stenosis) etc

Question 31

What is LaPlace's Law?

Answer 31

Wall stress = (pressure x radius) / (2x wall thickness) Wall thickens to reduce wall stress (more fibers share load)

Question 32

What group of drugs do we give to decrease afterload?

Answer 32

Vasodilators

Question 33

What do positive inotropes achieve?

Answer 33

Increase contractility by increasing Ca++ influx or sensitivity to Ca++

Question 34

Do increased preload and afterload effect contractility?

Answer 34

No

Question 35

What is MVO2 and what are its determinants?

Answer 35

Myocardial oxygen consumption/demand Energy delivered via coronary arteries in diastole -HR -Wall stress/pressure -Contractility an increase in any of these will increase MVO2

Question 36

What are drugs that reduce MVO2?

Answer 36

Beta blockers

Question 37

What percentage of blood is in the systemic circulation vs the pulmonary?

Answer 37

Systemic: 84% Pulmonary: 16%

Question 38

Systemic veins = major _______ reservoir

Answer 38

Volume Expand and contract to meet demands, high compliance

Question 39

Systemic arteries = major ________ reservoir

Answer 39

Pressure Preserve pressure to propel blood, low compliance

Question 40

What type of vessel controls resistance and therefore blood pressure?

Answer 40

Arterioles

Question 41

What is Ohm's law for fluid?

Answer 41

ΔP = Q x R P= perfusion pressure Q = flow R= resistance Blood flow through vessels is dependent on: -Pressure difference/gradient: force pushing blood thru -Vascular resistance: friction of blood along endothelium

Question 42

What is Poiseuille's Law?

Answer 42

Can predict flow (or resistance) based on geometry of tube (vessel) Factors = viscosity, length of vessel, radius Clinically: altering blood vessel DIAMETER (radius) is a powerful tool to alter blood flow

Question 43

What is the hematocrit?

Answer 43

% of blood that's red blood cells affects blood viscosity and thus flow

Question 44

What is Reynold's number?

Answer 44

The velocity where blood transitions from laminar to turbulent b/c of increasing blood flow and pressure

Question 45

What is MAP?

Answer 45

Mean arterial pressure MAP = (Systolic + 2x diastolic) / 3 Normal: 120/80 (93)

Question 46

Which anatomic alignment reduces vascular resistance: Series or parallel?

Answer 46

Parallel arrangement

Question 47

Why are arterioles not capillaries the site of highest resistance?

Answer 47

Arteries distribute the blood to many capillaries (parallel resistance)