EMS-153.txt

an impulse that travels through the conduction system in the correct direction

an impulse that travels through the conduction system in the reverse direction

a broad term indicating any kind of abnormal impulse

As potassium levels rise (normal 3.5-5.0 mEq/L) T-waves become higher and more peaked

communication between two or more vessels

a low of physiology stating that blood flow through a vessel is directly proportional to the radius of the vessel to the 4th power

the period of time from the end of one cardiac contraction to the end of the next

Rest - the period of time when the myocardium is relaxed and cardiac filling and coronary perfusion occur

Contraction - the period of the cardiac cycle whrn the myocardium is contracting

ratio of blood pumped from the ventricle to the amount remaining at the end of diastole

the amount of blood ejected by the heart in one cardiac contraction

the pressure within the ventricles at the end of diastole, commonly called the end-diastolic volume

law of physiology stating that the more the myocardium is stretched, up to a certain amount, the more forceful the subsequent contraction will be

the resitance against which the heart must pump

• Preload
• Cardiac Contractility
• Afterload

the amount of blood pumped by the heart in 1 minute (Stroke Volume x heart rate = Cardiac Output)

pertaining to heart rate

pertaining to cardiac contractile force (Strength)

pertaining to the speed of impulse transmission (Electrical Conductivity)

specialized bands of tissue inserted betwen myocardial cells that increase the rate in which the action potential is spread from cell to cell

group of cardiac muscle cells that physilogically function as a unit

• Sodium (Na+)-Major role in depolarizing the myocardium
• Calcium (Ca++) takes part in myocardial depolarization and myocardial contraction,
• Potassium (K+) influences repolarization
• Chloride (Cl-)
• Magnesium (Mg++)

• increase in serum calcium
• increased myocardial contractility
• shortens repolarization, ST segment shortens (sometimes T-wave looks as if it's on QRS)
• Adrenal insuffciency, hyperthyroidism, Kidney Failure, Lidney Disease

decrease in serum calcium, decreased myocardial contractility and increased electrical irratibility, prolongs repolarization, prolongs ST segment

• Normal Potassium 3.5-5.0mEg/L
• increase in Potassium, decreases automaticity and conduction
• Tall T-Waves
• suspect in PT's with Hx of renal failure

decrease in Potassium, increases irritability, Flattened T-waves, Prominent U-waves

return of a muscle cell to its preexcitation resting state

the ability to be simulated to contract, respond to electrical stimulus

the ability to transmit(propagate) an electrical impulse from one cell to the another

Atrio-Ventricular, Semi-Lunar

• Tricuspid between the Right Atrium and Right Ventricle
• Bicuspid (Mitral) between the Left Atrium and Left Ventricle.

• Pulmonic between the RV and Pulomary Artery
• Aortic between the Left Ventricle and Aorta

Between the Pulmonary Vein and the Left Atrium. CHF, blood backs up into the lungs from the heart.

Body > RA > Tricuspid > RV > Pulmonary Valve > Pulomary Artery > Lungs > Pulmonary Vein > LA > Mitral (Bicuspid) Valve > LV > Aortic Valve > Aorta

Arterial, Venous, Capillary, Circuits

• Tunica Intima, Inner layer, one cell thick, smooth, reduces friction
• Tunica Media, middle layer, elastic fibers/ muscle for strength and recoil, thickest in arteries
• Tunica Adventicia, outer fibrous covering, withstands high pressure

pacemaker cells capability to self-depolarize, the ability to selfgenerate an impulse

the ability of the muscle fibers to contract, shortening of the muscle fibers (mechanical property)

Connect the SA node to the AV node

deflection on the ECG produced by factors other than the hearts electrical activity, such as muscle tremors, shivering, patient movement, loose electrodes, 60 hertz interference, machine malfuntion

ECG leads applied to the arms and legs that contain 2 electrodes of opposite (+ & -) polarity. Leads I, II and III

the triangle around the heart formed by the bipolar limb leads

the period of time when myocardial cells have not yet completely repolarized and cannot be stimulated again.

the period of the cardiac cycle when stimulation will not produce any depolarization whatever.

The period of the cardiac cycle when a sufficiently strong stimulus may produce depolarization.

The normal electrical state of the cardiac cells

A reversal of charges at a cell membrane so that the inside of the cell becomes positive in relation to the outside; the opposite of the cells resting state in which the inside of the cell is negative in relation to the outside.

Ischemia (lack of O2), Injury, Necrosis (cell death, infarction)

Lack of O2

Cell Death

area of dead tissue caused by lack of blood

V1-V6 (Chest) Horizontal Plane of the Heart

aVR, aVL, aVF (Augmented)

I, II, III(LA) (Limb Leads)

considered normal (<.04 sec)

shows previous MI, permanent damage (>.40)

a progressive, degenerative disease of the midsize and large arteries

a thickening, loss of elasticity, and hardening of the walls of the ateries from calcium deposits

the ballooning of an arterial wall

the junction between the end of the QRS and the beginning of the ST segment

ST depression - ischemia, ST elevation - injury, T-wave inversion - late ischemia, Pathologic Q-waves - infarct

ST segment on baseline, t-wave = large tomb stone

ST Segment more than 1 small box elevation, t-wave = large tomb stone

ST segment more than 1 small box elevation, t-wave = large tomb stone, negative deflection q-wave normal

ST segment on baseline, pathologic Q-wave (>.04)

stretching; enlargement without any additional cells

V1(right hand) & V6(left hand), If terminal deflection is positive in V1 with negative in V6 its a RBBB and vice-versa

Lead I or V6(usually), short p wave (2 small boxes), no pr interval,R-wave starts immediately after P-Wave with a Delta wave (slurred beginning) on R wave, wide qrs (almost 3 boxes) in the R