Normal Cardiac Anatomy & Physiology Flashcards
(36 cards)
What is the normal anatomy of the canine and feline heart?
- 4 chambers: 2 atria, 2 ventricles
- 2 great vessels: aorta, pulmonary artery
- 4 valves: tricuspid, mitral, pulmonic, aortic
What is cardiac conduction and function like?
electrical —> fill ventricles during diastole and eject during systole
What is cardiac output?
volume in liters pumped by the left ventricle each minute
How do the atria and ventricles compare?
ATRIA = reservoirs for ventricular filling during systole and conduits during diastole with a normal pressure of 0-12 mmHg
VENTRICLES = develop pressure necessary to open semilunar valves and expel blood into the great arteries
How do the right and left ventricles compare?
R = act as a bellow to eject blood into the pulmonary circulation at a relatively low pressure (0-8/15-25 mmHg)
L = conical-shaped chamber that must generate pressure 5-6x higher than pulmonary circulation at 4-12/110-130 mmHg) —> thicker myocardium
What happens in the ventricles during diastole?
both have very low pressure (<12 mmHg) and usually close to 0 mmHg
Heart chambers, pressure:
How does blood flow through the cardiovascular system?
arteries —> small arteries —> arterioles —> capillaries —> venules —> veins
- each circuit delivers the same volume of blood each minute to the opposite side of the heart
What part of the cardiovascular system represents the major storage compartment of blood in the body?
veins
What determines blood pressure?
BP = CO x SVR
- arterial pressure and vascular resistance are much higher on the systemic side
How does pulmonary veins’ limited capacity to store blood matter clinically?
increasing blood or plasma volume elevates venous pressure more rapidly in the pulmonary circulation than in the systemic circulation —> when the left heart fails, pressure builds up in the pulmonary circulation and results in fluid leaking out of the capillaries and into the interstitium = PULMONARY EDEMA
What kind of pressure system is pulmonary circulation? Why?
LOW - 15-25 mmHg systolic, 8-12 mmHg diastolic
allows for flow equal to systemic flow
At what 3 levels does pulmonary vascular resistance occur?
- left atrium
- arterioles, precapillary
- capillaries
What are some pre-capillary, capillary, and post-capillary causes of pulmonary hypertension?
arterial thromboembolism, reactive vasoconstriction
pulmonary parenchymal disease
left heart disease
What kind of pressure system is systemic circulation? Why?
HIGH - 110-140 mmHg systolic, 70-80 mmHg diastolic
high diastolic pressure must be maintained in the aorta so regional circulations can be perfused (CO is the same as the right ventricle = high systemic vascular resistance)
What is the major level of systemic vascular resistance?
arterioles
What does persistent hypertension indicate?
abnormally high SVR or CO
What is the cross-sectional area of pulmonary capillaries like? How does blood flow?
larger
flows slow to allow for gas exchange
(total blood in capillaries is small, much larger in veins)
What determines CO?
CO = HR x SV (stroke volume)
What is Ohm’s law?
flow = pressure difference / resistance
If cardiac output remains the same, how does HR affect the heart?
determines how much it can fill
What is blood pressure maintenance important for?
provides constant flow to vital organs
What 7 things happen during systole?
- AV valves close (S1)
- ventricular depolarization
- isovolumetric contraction
- aortic/pulmonic valves open
- maximal/rapid ejection
- ventricular pressures fall with repolarization
- aortic and pulmonary valves close (S2, end of T wave)
systole = LV contraction
What 6 things happen during diastole?
- isovolumetric relaxation, ventricular pressures drops
- atria fill with blood
- mitral valve opens
- LV fills rapidly
- slow LV filling (diastasis)
- atrial systole (kick)
diastole = LV relaxation
