Cardiology Anatomy and Function Flashcards
Trace the blood flow through the body
starting with the vena cava
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
Where is the tricuspid valve?
Between the right atria and ventricles
(Right AV valve)
Where is the mitral valve?
Between the left atria and ventricles
(Left AV valve)
Layers of the heart + pericardium from internal to external
Endocardium > myocardium > epicardium (visceral layer of serous pericardium) > pericardial cavity > parietal layer of serous pericardium > fibrous pericardium
What color is fluid usually on US?
Black
What type of muscles are found in the auricles?
Pectinate muscles
What three vessels enter the right atrium?
Cranial vena cava, caudal vena cava, coronary sinus
What muscles are connected to the mitral/tricuspid valves via the chordae tendinae?
Papillary muscles
Which side of the heart is naturally higher pressure?
Left
What kind of valves are the aortic and pulmonic?
Semi-lunar
When do the AV valves open and close?
Open in diastole
Closed in systole
What is the most important heart disease of dogs?
Myxomatous mitral valve degeneration
When are the semilunar valves open and closed?
Open in systole
Closed in diastole
Where do the coronary arteries arise from and when does coronary arterial flow occur?
Arise from aorta
Coronary arterial flow occurs in DIASTOLE
(b/c in systole everything is too tight to flow)
Where do cardiac impulses start?
Sinoatrial (SA) node
What are the two primary differences between fetal and adult circulation?
Flow across the atrial septum (foramen ovale)
Flow between aorta and pulmonary artery (ductus arteriosus)
What defines the onset of systole?
Mitral/tricuspid closure
What defines the onset of diastole?
Aortic/pulmonic closure
Defintion of Stroke Volume
Vol of blood efected from ventricle in one cycle
SV = End diastolic vol - end systolic vol
What is the ejection fraction?
% of blood leaving the ventricle with each cycle
SV (EDV-ESV) /EDV
Normal = >50-60%
What is cardiac output?
CO = SV x HR
total vol pumped into Aorta AND Pulmonary artery in 1 min
(L/min)
What is happening during S1 (lub)?
Closure of the AV valve
(Beginning of isovolumetric contraction)
What is happening during S2 (dub)?
Aortic valve closure
What does lusitropy refer to?
Relaxation
Ventricular compliance & diastolic function
What does inotropy refer to?
Contractility
Degree muscle fibers shorten independent of load
What is preload?
Diastolic wall stress or pressure just prioir to contraction.
What is afterload?
Systolic wall stress or pressure (load or force on contracting cardiomyocyte)
Why does CO begin to fall at very high HRs?
Less diastolic filling time
What is the most important factor affecting preload?
Venous return/blood volume
What affects afterload?
Systemic vascular resistance (arterial blood pressure)
Compliance of aorta and arteries
Left ventricular outflow tract anatomy (stenosis)
etc
What is LaPlace’s Law?
Wall stress = (pressure x radius) / (2x wall thickness)
Wall thickens to reduce wall stress (more fibers share load)
What group of drugs do we give to decrease afterload?
Vasodilators
What do positive inotropes achieve?
Increase contractility by increasing Ca++ influx or sensitivity to Ca++
Do increased preload and afterload effect contractility?
No
What is MVO2 and what are its determinants?
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
What are drugs that reduce MVO2?
Beta blockers
What percentage of blood is in the systemic circulation vs the pulmonary?
Systemic: 84%
Pulmonary: 16%
Systemic veins = major _______ reservoir
Volume
Expand and contract to meet demands, high compliance
Systemic arteries = major ________ reservoir
Pressure
Preserve pressure to propel blood,
low compliance
What type of vessel controls resistance and therefore blood pressure?
Arterioles
What is Ohm’s law for fluid?
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
What is Poiseuille’s Law?
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
What is the hematocrit?
% of blood that’s red blood cells
affects blood viscosity and thus flow
What is Reynold’s number?
The velocity where blood transitions from laminar to turbulent b/c of increasing blood flow and pressure
What is MAP?
Mean arterial pressure
MAP = (Systolic + 2x diastolic) / 3
Normal: 120/80 (93)
Which anatomic alignment reduces vascular resistance: Series or parallel?
Parallel arrangement
Why are arterioles not capillaries the site of highest resistance?
Arteries distribute the blood to many capillaries (parallel resistance)
