Cardiac Flashcards
How much does the average heart weigh?
About 200-300grams
How much fluid is usually in the pericardium?
About 20ml
Where do the top 3 arteries of the Aorta go to?
The brain
When do the coronary arteries fill with blood to supply the myocardium?
During diastole
Do Tachycardic conditions affect blood flow to the heart?
Yes, Tachycardia prevents proper supply of oxygenated blood to myocardium
What is the heart rate of a heart rate that is relying on the AV node for nerve impulses
40-60bpm
What is the heart rate of heart that is relying on the bundle of his and purkinje fibers?
20-40bpm
Where is potassium located in regard to the sarcomere?
Potassium is inside the sarcomere
What occurs when a sarcomere depolarizes and repolarizes?
Depolarization: Calcium channels open and Na and Ca enter the sarcomere and potassium leaves.
Repolarization: Na and Ca leave and K enters the Sarcomere
What is Stroke Volume?
The amount of blood ejected from the heart with each ventricular contraction. (about 60-130ml)
What is Cardiac Output?
SV x HR- about 4-6L per minute
What is Ejection Fraction?
The percent of end-diastolic volume ejected with each heartbeat.
SV/ End Diastolic Volume
About 55-65% of total blood volume
What 3 factors affect Stroke Volume?
Preload
Afterload
Contractility
What is Preload?
Degree of muscle stretch of the cardiac muscle fibers at the end of diastole
What is Afterload?
The resistance to ejection of blood from the ventricle
Affected by Systemic Vascular Resistance and Pulmonary Vascular Resistance
What increases Preload?
Hypervolemia
Regurgitation of Cardiac valves
What increases Afterload?
Hypertension
Vasoconstriction
Afterload increases the workload of the Heart
What is Contractility?
Cardiac Muscle forces
Inotropic capabilities
What is Starling’s Law of the Heart?
Stroke Volume of the Heart increases when End Diastolic Volume increases and all other factors remain constant.
What is Hydrostatic Pressure?
Driving force of heart, tends to push fluid out of the capillary.
What is Oncotic Pressure?
Pressure exerted by plasma proteins, tends to pull fluid into capillaries
What is Filtration Pressure?
Net force on fluid, determined by balance between Hydrostatic and Oncotic Pressure.
HP>OP-Fluid leaves capillary
OP>HP-Fluid enters capillary