A & P Flashcards
V1 and V2
- septal leads
- septal perforators off of LAD
V3 and V4
- anterior lead
- LAD
L1 and V5 and V6 and aVL
- lateral wall leads
- left circumflex artery
L2 and L3 and aVF
- inferior leads
- right coronary artery
First branch off off right coronary artery
conus
Afterload
resistance to ejection of blood from ventricles
Afterload - Increased in
- vasoconstriction as from sympathetic nervous system stimulation or vasopressors
- hypertension
- aortic valve disease
- hypercoagulability
- pulmonary hypertension
Afterload - Deceased in
- hypotension
- vasodilation
- vasodilators
Preload
end-diastolic; “filling pressure”
Preload - Increased in
- heart failure
- hypervolemia
- bradydysrhythmias
Preload - Decreased in
- hypovolemia
- excessive vasodilation
- increased intrathoracic pressure
- cardiac tamponade
- right ventricular failure or infarction
- tachydysrhythmias
- loss of atrial contraction
Cardiac Output
- the amount of blood pumped by the heart in liters per minute
- calculated as heart rate x stroke volume
- normal range is 4.0 to 6.0 liters per minute
Rapid diastolic filling
passive filling
Reduced diastolic filling
“diastasic”
-coronary blood flow is optimal
Atrial contraction
- this subphase is also referred to as “atrial kick” or “atrial systole”
- contributes to 15 to 30% of diastolic filling volume
Isovolumetric contraction
- contraction increases pressure in the ventricles, but there is no change in volume due to the AV valves are closed and the semilunar valves have not yet opened
- this subpage accounts for 2/3 of oxygen consumption of the ventricles
Rapid ventricular ejection
aortic and pulmonary arterial pressures increase rapidly and ventricular volume decreases rapidly
Reduced Ejection
“protodiastole”
Isovolumetric Relaxation
- relaxation occurs and ventricular pressure decreases
- volume does not change because the semilunar valves are closed and the atrioventricular valves have not yet opened
Chemoreceptors
input from carbon dioxide-sensing cells in the carotid bodies and the aorta
Baroreceptors
pressure - sensing cells in the carotid bodies (located at the carotid bifurcation) and the aortic arch
Medullary Ischemic Response
cerebral perfusion in the difference between mean arterial pressure and intracranial pressure
Increased Inotropy
- stroke volume and cardiac output
- increases workload of the heart and myocardial oxygen requirements
- sympathetic stimulation
Decreased Inotropy
- myocardial ischemia or infarction
- cardiomyopathy
- hypoxemia
- acidosis
