How does blood flow through the heart?
Diastole
relaxation, blood fills ventricles
Systole
when the ventricles contract
Normal Cardiac Output
4-6 L/Min
Preload
- increased in hypervolemia
Frank Starling Law
as a larger volume of blood flows into the ventricle, the blood will stretch the walls of the heart, causing a greater expansion during diastole, which in turn increases the force of the contraction and thus the quantity of blood that is pumped into the aorta during systole.
Afterload
Stroke Volume
amount of blood ejected by the left ventricle in one contraction (can be left or right)
Positive Inotropic Agents
Negative Inotropic
- Acetylcholine from Vagus nerve
P Wave
QRS
- 0.04
QT
- 0.42
Cardiac Output
Cardiac Index
- Normal is 2.8-4.2 L/min/m2)
Sympathetic Nervous System: Effects on the Heart
increases heart rate by the beta adrenergic receptors
Peripheral Nervous System: Effects on the Heart
decreases heart rate by the vagus nerve
Sympathetic Nervous System: Effect on Blood Vessels
increases vasoconstriction by a1-adrenergic receptors, decreases vasodilation by a1-adrenergic receptors
Baroreceptors
sensitive to stretch or pressure with the arterial system (aortic arch and carotid sinus) Fast response in changes in blood pressure
Chemoreceptors
capable of causing changes in respiratory rate and BP in response of increased CO2 (aortic/carotid bodies and medulla)
Cardiovascular Disease Risk Factors
Hypertension
Hypertension: Patient Evaluation
Values: Mild Hypertension
140/90