P-Wave
depolarization of SA node in atria
P-R Interval
beginning of atrial excitation to beginning of ventricular excitation
QRS Wave
ventricular depolarization and atrial repolarization
T-Wave
ventricular repolarization
S-T Segment
entire ventricular myocardium depolarized
Q-T Interval
beginning of ventricular depolarization through ventricular repolarization
Systole
heart contraction (depolarization)
Diastole
heart relaxation (repolarization)
Cardiac Cycle
blood flow through heart during one complete heartbeat
Ventricular Filling
Pressure = low.
Blood passively flows in, then atria depolarize to release the rest of the blood to ventricles
Atrial Contraction
Atria depolarize after sensing from AV node
P-Wave
End Diastolic Volume
volume of blood in each ventricle at end of ventricular diastole
Isovolumetric Contraction
All valves are closed
End Systolic Volume
volume of blood remaining in each ventricle after systole (contraction)
Isovolumetric Relaxation
Occur after T-Wave (ventricular repolarization) so ventricles are relaxed
SA Node
Pacemaker of heart in right atria-generates impulses. Decreases heart rate to 75. Without SA node, heart rate = 100
AV Node
delays impulses. at the bottom of right atria . If damaged = heart block
Bundle of His
electrical connection b/w atria and ventricles
Bundle Branches
Carry electrical signal through intravenetricular septum
Cardiac Output (CO)
Volume of blood pumped by each ventricle in 1 minute
CO (5.25) = HR (75) x SV (70 mL)
Stroke Volume (SV)
volume of blood pumped out by one ventricle with each beat.
Affected by preload, contractility, and afterload
Heart Rate (HR)
number of beats per minute
Preload
degree which cardiac muscle cells are stretched just before they contract.
Venous Return = important (amt of blood returning to heart)
Contractility
Contractile strength at given muscle length
Increased contractility lowers ESV
Decreased contractility by acidosis
What component of the body is dominant in heart rate?
Parasympathetic nervous system. Specifically the vagal nerve.
Tachycardia
> 100 bmp (fast heart rate)
Bradycardia
<60 bpm (slow heart rate)
Blood Pressure
measured by contraction of ventricles.
determined by CO, blood volume, and vascular resistance
sphygmomanometer
used to measure blood pressure
Pulse
feeling of the arteries dialation
Pulse points
Temporal artery, cartoid, apical pulse, brachail pulse, radial, femoral, popliteal artery, posterior tibial artery, and pedal
Pulse Pressure
avg: 120/80 (normal) systolic/diastolic
Mean Arterial Pressure (MAP)
MAP= (systolic +2(diastolic))/3
Average pressure in arteries for one cardiac cycle.
Total Peripheral Resistance
TPR= MAP/CO
Resistance in blood flow
atherosclerosis
build up of fat in artery walls. (leads to heart attack/cardiac arrest)
