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70 Cards in this Set
- Front
- Back
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What does heart contraction result from?
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A series of changes in electrical potential (waves of depolarization) that travel through the heart PRIOR to each beat
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How does cardiac muscle beat?
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intrinsic
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What are the 2 types of controls that exert their effects on heart activity? What do they do?
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Autonomic nervous system: accelerate or decrease the heart rate depending on which division is activated
Intrinsic Conduction: consists of speacialized noncontractile myocardial tissue. |
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what is another name for intrinsic conduction?
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nodal system of the heart
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What does the intrinsic conduction of the heart consist of?
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specialized noncontractile myocardial tissue.
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What ensures that the heart muscle depolarizes in an orderly and sequential manner and that the heart beats as a coordinated movement?
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Intrinsic conduction or nodal system of the heart.
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What are the components of intrinsic conduction system/
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SA node, AV node, Bundle of His, pukinje fibers
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Where is the SA node located?
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in the right atrium just inferior to the entrance to the superior vena cava
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Where is the AV node located?
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in the lower atrial septum at the junction between the atria and ventricles
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Where is the bundle of His located?
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located in the interventricular septum
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What ramify within the muscle bundles of the ventricular walls?
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purkinje fibers
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Where is the purkinje fiber network much denser and more elaborate? Why?
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in the left ventricle because of the larger size of the chamber
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What has the highest rate of discharge?
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SA node
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What happens when an impulse travels from the SA node to the AV node? Why is this function important
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it is momentarily delayed at teh AV node, important for allowing the atria to complete their contraction
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What separates the atria and ventricles? Why is this region of separation important?
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contains ELECTRICALLY INERT connective tissue, important so the wave of depolarization can be transmitted to the ventricles only through the tract between the AV node and the AV bundle.
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What insulates damage to the AV node-bundle pathway the ventricles from the influence of the SA node?
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The electrically inert connective tissue
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What is the machine that records the conduction of impulses through the heart?
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electrocardiograph
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what is he graphic recording of the electrical changes (depolarization followed by repolarization) occurring during the cardiac cycle?
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electrocardiogram
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What are the 3 recognizable waves called that a typical ECG (electrocardiogram) consists of?
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deflection waves
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What does the P wave indicate?
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indicates depolarization of the atria immediately BEFORE atrial contraction (systole)
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What happens during the PQ segment?
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The atria contract
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What results from ventricular depolarization, has a complicated shape, and precedes ventricular systole?
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QRS complex
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What results from the T wave you'd see on a electrocardiogram?
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currents propagated during ventricular repolarization (relaxation of the muscle, or diastole)
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Which wave results in relaxation of the muscle, or diastole?
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T wave
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repolarization of the atria occurs during what interval? What is it generally obscured by?
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QRS interval, obscured by the large QRS complex
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What is an ECG a record of?
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Voltage and time--nothing else!
electrical events occurring in relatively large amounts of muscle tissue NOT the activity of nodal tissue |
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Does muscle contraction always follow its excitation?
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nope
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What type of tissue can ECG record?
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electrical events occurring in relatively large amounts of muscle tissue NOT the activity of nodal tissue, which can only be inferred.
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What does the PR interval represent?
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The time between the beginning of atrial depolarization and ventricular depolarization
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What happens during the PQ segment?
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The atria contract
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What results from ventricular depolarization, has a complicated shape, and precedes ventricular systole?
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QRS complex
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What results from the T wave you'd see on a electrocardiogram?
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currents propagated during ventricular repolarization (relaxation of the muscle, or diastole)
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Which wave results in relaxation of the muscle, or diastole?
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T wave
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repolarization of the atria occurs during what interval? What is it generally obscured by?
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QRS interval, obscured by the large QRS complex
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What is an ECG a record of?
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Voltage and time--nothing else!
electrical events occurring in relatively large amounts of muscle tissue NOT the activity of nodal tissue |
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Does muscle contraction always follow its excitation?
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nope
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What are ECG useful for detecting?
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Abnormalities in the deflection waves and changes in the time interval to detect myocardial infarct/ problems with the conduction system
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What type of tissue can ECG record?
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electrical events occurring in relatively large amounts of muscle tissue NOT the activity of nodal tissue, which can only be inferred.
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What does the PR interval represent?
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The time between the beginning of atrial depolarization and ventricular depolarization
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A long interval of the P-R (P-Q) waves suggests what?
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May suggest a partial AV heart block caused by damage to the AV node.
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What happens in total heart block to the waves?
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no impulses are transmitted through the AV node, and the atria and ventricles beat independently of one another--the atria at the SA node rate and the ventricles a the intrinsic rate, which is considerably lower.
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What would a prolonged QRS interval suggest?
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R or L bundle branch block in which one ventricle is contracting later than the other
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As the heart rate increases, what happens to the Q-T interval?
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it becomes shorter,
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what happens to the Q-T interval as the heart rate drops?
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It is longer
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what happens during the Q-T interval?
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includes the time of ventricular contraction
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What is tachycardia?
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A heart rate greater than 100 beats per minute
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What is bradycardia?
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a rate<60 beats/min
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A heart rate greater than 100 beats per minute is known as what?
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Tachycardia
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what is the amount of blood ejected by a ventricle with each contraction called?
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stroke volume
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What is stroke volume?
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The amount of blood ejected by a ventricle with each contraction
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How is bradycardia beneficial (include key word)
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Because stroke volume increases with physical conditioning, the heart can contract more slowly and still meet circulatory demands.
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What would ventricular fibrillation look like?
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ls;afjk;lsafj ;lsdjf ;kj
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How many standard leads are used to record and ECG?
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12
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How many leads are bipolar? unipolar?
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3, 9
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What does the electrical activity recorded by any lead depend on?
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The location and orientation of the recording electrodes
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where is it clinically assumed the heart lies?
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in the center of a triangle ( Einthoven's triangle)
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Where are electrodes connected to each arm and to the left leg considered to connect?
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At the triangular vertices (referring to Enthoven's triangle)
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The current of L1 and L3 is equal to what?
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L2
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What is the significance of Enthoven's triangle? What is this called?
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The sum of the voltages of leads I and III equals that in lead II (Enthoven's law)
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If the voltages of 2 of the standard leads are recorded, who can the 3rd lead be determined?
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mathematically L1 + L3=L2
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What kind of cream was applied before the electrodes were attached?
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keratin cream
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What is the normal BP Range?
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95-135 for systolic
50-90 for diastolic |
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What is blood pressure above 140 called?
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hypertension
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what do the sounds concerned in the auscultatory method owe their origin to? DUMB question
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Vibrations of the arterial wall when the normal circular form of the artery is, in the compression area, more or less distroted by external pressure.
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What artery is cut off to hear the sounds of the blood pressure? What are the sounds called?
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Brachial artery korotkoff sounds
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How do you obtain systolic pressure? How is it often discernable
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cut off artery, a clear sharp sound as blood first begins to pass through the compressed area. (Often discernable for a 10-mm drop in pressure)
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how is diastolic pressure discernable?
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the disappearance of all sound
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What is recorded at the point where sound disappears?
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The diastolic blood pressure
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What is a normal heart rate?
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60-80 bpm
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What artery is used to detect heart rate?
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Radial artery
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