Cardiac Output
Cardiac Output most used tool to measure heart function
The volume of blood ejected by the heart per minute.
CO= Heart Rate x Stroke Volume
EX: 70bt/min X 70ml/bt = 4900ml/min ~ 5L/min
Regulation of Heart Beat
HR is regulated through the balance of parasympathetic and sympathetic influence on the SA node.
1 action potential = 1 electrical impulse
Parasympathetic: Slows HR
Sympathetic: Speeds HR
Parasympathetic Regulation of HR
At rest, parasympathetic nerves will release Acetylcholine (Ach)
Ach will bind to receptors on the SA node.
Slow down the closure of Potassium channels, more potassium will flow out causing hyperpolarisation
Since resting potential is farther, takes longer to reach threshold potential, therefore slower HR.
Sympathetic Regulation of HR
Sympathetic nerves will release NE
NE binds to receptors on SA node. Speed up rate of depolarization so threshold potential is reached faster causing more frequent action potentials; therefore increasing HR
Speeds up spread of action potential throughout specialized conduction pathways
Stroke Volume
Volume of blood ejected from ventricles per beat
Two factors influences SV: Intrinsic Control & Extrinsic Control
Intrinsic:
Hearts inherent ability to control SV. More blood that goes into the heart, more blood goes out of the heart.
Direct relationship between EDV and SV. As EDV increases so does SV.
Frank Starling Law The more the ventricles stretch during diastole the more forceful the contraction during systole will be. Ex: exercise- EDV increases> stretch ventricles> increase in ventricular contraction force
Extrinsic
Control of SV by factors outside of the heart (neural, hormonal)
Sympathetic activity & Epinephrine binds to ventricular wall: Increase in heart’s contractibility and venous return (volume of blood pumped back to heart)
Coronary Artery Disease
Arteries of the heart
Provide the heart with its own blood supply
Pathological changes in the
The volume of blood ejected by the heart per minute.
CO= Heart Rate x Stroke Volume
EX: 70bt/min X 70ml/bt = 4900ml/min ~ 5L/min
Regulation of Heart Beat
HR is regulated through the balance of parasympathetic and sympathetic influence on the SA node.
1 action potential = 1 electrical impulse
Parasympathetic: Slows HR
Sympathetic: Speeds HR
Parasympathetic Regulation of HR
At rest, parasympathetic nerves will release Acetylcholine (Ach)
Ach will bind to receptors on the SA node.
Slow down the closure of Potassium channels, more potassium will flow out causing hyperpolarisation
Since resting potential is farther, takes longer to reach threshold potential, therefore slower HR.
Sympathetic Regulation of HR
Sympathetic nerves will release NE
NE binds to receptors on SA node. Speed up rate of depolarization so threshold potential is reached faster causing more frequent action potentials; therefore increasing HR
Speeds up spread of action potential throughout specialized conduction pathways
Stroke Volume
Volume of blood ejected from ventricles per beat
Two factors influences SV: Intrinsic Control & Extrinsic Control
Intrinsic:
Hearts inherent ability to control SV. More blood that goes into the heart, more blood goes out of the heart.
Direct relationship between EDV and SV. As EDV increases so does SV.
Frank Starling Law The more the ventricles stretch during diastole the more forceful the contraction during systole will be. Ex: exercise- EDV increases> stretch ventricles> increase in ventricular contraction force
Extrinsic
Control of SV by factors outside of the heart (neural, hormonal)
Sympathetic activity & Epinephrine binds to ventricular wall: Increase in heart’s contractibility and venous return (volume of blood pumped back to heart)
Coronary Artery Disease
Arteries of the heart
Provide the heart with its own blood supply
Pathological changes in the