Based on the book by Beasley, 2nd Edition
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| What is cardiac dysrhythmia? | Any abnormality in the rate, regularity or sequence of cardiac activation.
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| What are the two myocardial cell groups? | Myocardial cell groups: 1. The myocardial working cells 2. The specialized pacemaker cells of the electrical conduction system
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| What are myocardial working cells? | Myocardial working cells are responsible for generating the physical contraction of the heart muscle.
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| What are the functions of myocardial working cells? | 1. contraction 2. relaxation
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| What are the walls of the atria and ventricles constructed of? | Myocardial working cells
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| How is a myocardial contraction produced? | When the permeated contractile filaments of the myocardial working cells are electrically stimulated, a contraction is produced.
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| What generates blood flow? | The physical contraction of myocardial tissue
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| What is required to produce the physical contraction in a heart? | Organized electrical activity
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| What happens to the size of the atria and ventricles when the myocardial tissue contracts and blood is ejected from the chambers? | The size of the atria and ventrical decreases
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| How are the myocardial working cells and specialized pacemaker cells different? | The specialized pacemaker cells DO NOT contain contractile filaments & DO NOT have the ability to contract.
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| What are the specialized pacemaker cells (aka specialized group) responsible for? | Controlling the rate & rythm of the heart by coordinating regular depolarization.
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| Where are the specialized group cells found? | In the electrical conduction system of the heart.
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| What are the primary functions of the specialized myocardial pacemaker cells? | The generation and conduction of electrical impulses
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| Cardiac muscle cells have the ability to contract in response to which stimuli? (Hint: 4) | 1.Thermal 2.Chemical 3.Electrical 4.Mechanical
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| True or False:Atrial muscles contract simultaneously. | True
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| True or False: Ventrical muscles do NOT contract together. | False. Ventrical muscles contract together.
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| What does threshold refer to in heart anatomy? | A threshold refers to the point at which a stimulus will produce a response.
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| Why does cardiac muscle function on an all-or-none principle? | When a stimulus is strong enough for a cardiac cell to reach the threshold, ALL the cells will respond and will contract. If no stimulus, none of the cardiac muscles will contract.
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| What is high sodium (Na) blood levels? | Hypernatremia
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| What is low sodium (Na) blood levels? | Hyponatremia
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| What are the four primary characteristics of cardiac cells? | 1. Automaticity 2. Excitability (irritability) 3. Conductivity 4. Contractility (rhythmicity)
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| Which characteristic of cardiac cells is automatic and mechanical? | Contractility
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| Pertaining to cardiac cells, what are the electrical functions of the heart? | 1.Automaticity 2.Excitability 3.Conductivity
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| What is the ability of the cardiac pacemaker cells to generate their own electrical impulses spontaneously without external (or nervous) stimulation? | Automaticity
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| What intrinsic spontaneous depolarization frequency produces contraction of myocardial muscle cells? | Automaticity
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| What characteristic is specific to the pacemaker cell sites of the electrical conduction system (i.e., the SA node, AV junction, and the Purkinje network fibers)? | Automaticity
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| What is the ability of cardiac cells to respond to an electrical stimulus? | Excitability (or irritability)
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| What characteristic is SHARED by all cardiac cells? | Excitability and Conductivity
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| True or False: A weaker stiumulus can cause a contraction when a cardiac cell is highly irritabile. | True
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| What is the ability of cardiac cells to receive an electrical stimulus and then transmit it to other cardiac cells? | Conductivity
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| What characteristic of cardiac cells form synctium, because they function collectively as a unit? | Conductivity
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| When there is more than one unit, what is the correct term to describe synctium? | Syncytia
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| What is the ability of cardiac cells to shorten and cause cardiac muscle contraction in response to an electrical stimulus? | Contractility
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| What is the coordination of cardiac muscle cells to produce a regular heartbeat? | Contractility
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| What is the mechanical function of the heart? | Contractility
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| Why are both mechanical and electrical cardiac function influenced by electrolyte imbalances? | Because myocardial cells are bathed in electrolyte solutions.
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| What is an electrolyte? | An electrolyte is a substance (compound) whose molecules dissociate into charged components (ions) when placed in water.
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| What happens when electrolytes are placed in water? | Positive or negative charged ions are produced.
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| What is an ion with a positive (+)charge? | cation (pronounced kation)
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| What is an ion with a negative (-) charge? | anion (pronounced aneon)
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| What are the THREE major cations that affect cardiac function? | 1.Potassium (K) 2.Sodium (Na) 3.Calcium (Ca)
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| What is the fourth cation? | 4.Magnesium (Mg)
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| What are the three intracellular (inside the cell) cations? | 1.Potassium (K) 2.Magnesium (Mg) 3.Calcium (Ca)
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| What is the extracellular (outside the cell)cation? | Sodium (Na)
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| How does K (Potassium) affect major cardiac function? | Potassium performs a major function in cardiac depolarization and repolarization.
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| What is an increase in potassium blood levels? | Hyperkalemia
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| What is a decrease in potassium blood levels? | Hypokalemia
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| What role does Sodium (Na) play in cardiac function? | Na (Sodium) plays a vital part in depolarization of the myocardium.
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| An increase in sodium blood levels is known as: | Hypernatremia
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| A decrease in sodium blood levels is known as: | Hyponatremia
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| What role does Calcium (Ca) play in cardica muscle? | Calcium has an important function in myocardial depolarization and myocardial contraction.
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| What is an increase in calcium blood levels? | Hypercalcemia
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| What is a decrease in calcium blood levels? | Hypocalcemia
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| When the cardiac cells are at rest, what is happening to the Potassium (K) and Sodium (Na)ions? | In their resting state, K is greater on the inside and Sodium is greater on the outside of the cardiac cell.
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| Which ions diffuse through the membrane more readily? (Hint: Potassium or Sodium) | Potassium
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| What is the sodium-potassium exchange pump? | Potassium and Sodium ions are moved in and out of the cell through the cell membrane.
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| What is the charge of the inside of a cardiac cell during the polarized or resting state? | Negative
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| What is recorded on the EKG strip during the resting period? | A baseline or isoelectric line
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| What happens to the sodium at the end of cardiac depolarization? | The sodium actively returns to the outside of the cell and potassium returns to the inside of the cell.
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| How does the sodium and potassium exchange occur? | This exchange takes place via the sodium-potassium exchange pump.
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| What happens to the cardiac cell when they have returned to the recovered, or repolarized state? | The cardiac cell is now read to be stimulated again.
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| Which is slower, repolarization or depolarization? | Repolarization
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| Which is faster, depolarization or repolarization? | Depolarization
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| What is the LAST area to be depolarized in a healthy cardiac muscle? | The first area to be repolarized
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| True or False: Cardiac muscle tissue has a refractory period to ensure that the muscle is totally relaxed before another action potential or depolarization can be initiated. | TRUE
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| What is the refractory period of atrial muscle? | Approximately .15 seconds
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| What is the refactory period of the ventricle muscle? | Approximately .25 - .3 seconds
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| Which rate of contractions are potentially faster, ventricles or atria? | Atria
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| When do the cardiac cells have a brief resting period? | After electrical impulse stimulation and myocardial contraction
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| What is this brief resting period of the cardiac cells? | Cardiac repolarization
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| During the repolarization period, what two stages does the heart go through? | 1. Absolute refractory period 2. Relative refractory period
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| During most of the process of repolarization, the cardiac cell: (Hint: 2 responses) | 1. Is unable to respond to a new electrical stimulus.2. Cannot spontaneously depolarize
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| What is the state of an activity in which the cardiac cell cannot spontaneously depolarize? | Absolute Refractory Period
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| What is the period when repolarization is almost complete & the cardiac cell can be stimulated to contract prematurely if the stimulus to contract prematurely if the stiumulus is much stronger than normal? | Relative refractory period
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| What is the second part of the refractory period that follows the absolute refractory period? | Relative refractory period
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| Where is the relative refractory period shown on the EKG strip? | The downslope of the T wave
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| What is another name for the relative refractory period? | Vulnerable period of the cardiac cells
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| Where is the absolute refractory period on the EKG strip? | The beginning of the QRX complex to the peak of the T wave
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