Cardiac Flashcards
Lumen
The space in the vessel
Tunica Adventitia
Outer-most layer of the vessel. Provides durability against high pressure.
Tunica Media
The middle layer of the vessel. Provides elasticity and muscle for constriction/dilation.
Tunica Intima
Inner-most layer of the vessel. 1 cell thick.
Cardiac Output
Amount of fluid pumped by each ventricle (usually about the same).
5-6L/min is typical.
Cardiac Output = Stroke Volume (60-100ml) x Heart Rate (60-100/min)
Pre-load
The pressure from the amount of fluid that enters the ventricle and stretches it. Higher volume and stretch = higher cardiac output during ventricular contraction.
Afterload
The pressure detected in the aorta as the heart pumps blood to the rest of the body.
Sinoatrial Node
The pacemaker of the heart located near the superior vena cava. Right coronary arteries fuel the SA node, and if the artery becomes occluded, this can cause an MI and subsequent ischemia.
Atrial Kick
The contraction of the atria to push the remaining 30% of blood to the ventricles (70% of blood that moves from atria to ventricle is through gravity).
Atrioventricular Node
Gatekeeper to the ventricles. Electrical impulses are sent from the SA node 0.12s later to allow the ventricle to fill.
Depolarization
The process in which muscle fibers are stimulated to contract.
The myocardial cells receive a stimulus and open up a channel to depolarize the polarized (resting) cell by allowing sodium+ to rush in.
Calcium+ also enters, but slower, and keeps it depolarized. With the help of calcium, the cell fully depolarizes and contraction is stimulated.
- The polarized (resting) myocardial cell is stimulated and opens up channels.
- Sodium+ rushes in, and Calcium+ enters slower, depolarizing the cell.
- As the cell fully depolarizes, calcium ions help stimulate the contraction.
Repolarization
The process in which muscle fibers repolarize so they can be prepared to contract once again.
- Sodium and calcium channels close, stopping flow of + ions
- Potassium+ that were inside the cell, escape through their channel to recreate a negative charge.
- Sodium+ is pushed out (3), and Potassium+ re-enters (2) into their respective location [Sodium-Potassium Pump]
Sodium-Potassium Pump
A repolarizing pump of the myocardial cells. The ATP uses active transport to move against the natural gradient, moving 3 sodium+ out of the cell, and 2 potassium+ back into the cell.
Chronotropes
Affects heart rate
Dromotropes
Affects rate of electrical conduction in the heart’s nodes
Inotropes
Affects the amount of force used in contractions
Anaerobic Metabolism
The process in which ATP is fueled with carbohydrates because oxygen is not present
Ischemia
Lack of tissue perfusion (reversible)
Infarction
Death of tissue cells due to ischemia (irreversible)
Necrosis
Premature death of cells due to disease, trauma, other conditions
Absolute Refractory Period
The cell is depolarized completely and will not initiate a new cycle
Relative Refractory Period
The cell is partially depolarized and should not initiate a new cycle, but it’s possible
Alpha Drug/Receptor
Arteries constrict, lungs mildly constrict.
Beta 1 Drug/Receptor
Affects heart through : chronotropes, dromotropes, and inotropes.
Beta 2 Drug/Receptor
Arteries dilate, lungs dilate.
Atherosclerosis
Buildup of fat material in the artery wall. Causes diseases either gradually or acutely (such as plaque rupture/thrombus).
Peripheral Arterial Disease
Affects perfusion of the peripheral body parts. Can cause ischemia to limbs, form thrombi, and cause an embolus elsewhere (thromboembolism).
Stable Angina
Chest pain caused by mild atherosclerosis, exacerbated by exercising or other HR/BP raising activities. Disappears after resting.
Unstable Angina
Chest pain caused by moderate to severe atherosclerosis. Onset can occur during rest. Lasts more than 15 minutes. (Treat as an MI)
Left-sided Heart Failure
Pulmonary edema, crackles.
Right-sided Heart Failure
Pedal edema, jugular vein distention.
Sinus Rhythm
Normal rhythm
Sinus Tachycardia
Normal rhythm, faster than 100bpm
Sinus Bradycardia
Normal rhythm, slower than 60bpm
Atrial Fibrillation
QRS Irregularly irregular rhythm, >100bpm
Atrial Flutter
2:1 / 3:1 / 4:1 blocks
P wave present but abnormal
Multifocal Atrial Tachycardia
Irregularly irregular rhythm, >100bpm
1st Degree Block
PR interval >0.2s
2nd Degree Block (Type 1)
Regularly irregular rhythm. PR interval gradually widens until it resets.
2nd Degree Block (Type 2)
Regularly irregular rhythm. PR interval normal ‘when present’ (SA fires at AV, only some go through).
3rd Degree Block
SA and AV nodes perform independently and are uncoordinated between each other.
Asystole
Flat line. Can be a bit wavy, but slow.
