To the body; From the left side of the heart.
To the lungs; From the right side of the heart.
Blood Flow through the Heart
Coronary Sinus -> Right Atrium -> Tricuspid Valve -> Right Ventricle -> Pulmonary Semilunar Valve -> Pulmonary Trunk -> Lungs -> Pulmonary Veins -> Left Atrium -> Mitral Valve -> Left Ventricle -> Aortic Semilunar Valve -> Aorta -> BODY
Circulation: Delivery, removal, transportation of hormones.
Regulation: Maintenance of acid-base balance, thermoregulation, immune function
Heart Muscle: Cells are anatomically interconnected end to end, has gap junctions & desmosomes, calcium induced calcium release contractions.
Specialized cardiac muscle fibers located in the upper posterior wall of the right atrium. Initializes contraction.
Located in the right atrial wall, it conducts the impulse from the atria to ventricles. There is a .13 sec delay as signals pass through the av node to allow for complete ventricular diastole.
Bundle of His (AV bundle)
Travels along the ventricular septum sending bundle branches to both ventricles to relay the electrical impulse toward the apex of the heart & outwards
Terminal branches of the AV bundles which transmit the impulse 6X faster that the rest of the system allowing the ventricles to contract as a single unit.
Extrinsic control of Heart Rate
Parasympathetic Nervous System
Sympathetic Nervous System
Parasympathetic NS & HR
Acts through the vagus nerve by sending impulses to the SA & Av nodes
-Absence of vagal tone = 100 bpm
-Max vagal tone = 20-30 bpm
At rest = PNS
Sympathetic NS & HR
Increases the rate of impulse generation & conduction speed in order to increase heart rate and force of contraction.
Max sympathetic HR = 250 bpm
SNS during Stress (HR>100 bpm)
Endocrine System & HR
Epinepherine & Norepinephrine increase heart rate & contractility and are triggered by the sympathetic nervous system.
Resting Heart Rate
60 - 100 BPM
But can decrese with endurance training via increased parasympathetic stimulation & reduced sympathetic stimulation.
Picture of the electrical activity of the heart recorded with 10 electrons which correspond to 12 different views of the heart. P wave, QRS complex, and T wave are the components.
Atrial Depolarization: small bump in graph
Q - Downward point
R - Large upward spike
S - Downward spike
Atrial Repolarization which occurs during ventricular depolarization: post spike hump
An abnormal rate or rhythm of muscle contractions in the heart
Abnormally slow heartbeat (usually applied to heart rates slower than 60 bpm)
Abnormally rapid heartbeat (over 100 beats per minute)
Premature Ventricular COntractions
Skipped or extra beats from impulses originating outside the SA Node (wide, bizarre QRS complexes)
Serious: Atria contract at a rate between 200 & 400 bpm
Serios: Atria contract in a rapid & uncoordinated way
Serious: Three or more consecutive PVC's
Serious: Contracts of the ventricular tissue is uncoordinated and can result in cardiac death
The mechanical & electrical events that occur during one heart beat (Systole to Systole)
The contraction phase during which the chambers expel blood: QRS to T wave
The relaxation phase during which the chambers fill with blood: T wave to QRS (takes twice as long as systole)
Stroke Volume (SV)
Volume of blood pumped per contraction:
End-diastolic Volume (EDV)
Volume of blood in ventricle just before contraction: About 100 mL
End-systolic Volume (ESV)
Volume of blood in ventricle just after contraction: About 40 mL
Ejection Fraction (EF)
Proportion of blood pumped out of the left ventricle with each beat:
EF = SV/EDV = (60/100 or 60% at rest)
Cardiac Output (Q)
Total volume of the blood pumped b the ventricle per minute:
Q(L/min) = HR(bpm) X SV(L/beat)
Q = 70bpm X 60 mL/beat = 4.2 - 5.6 L/min at Rest