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31 Cards in this Set
- Front
- Back
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How to locate the apical beat of the heart
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5th intercostal space and the mid clavicular line
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Another name for the apical beat
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Point of maximal impact
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What can cause a shift in the PMI
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A change in the anatomical position of the heart due to a pneumothorax
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cause of a Myocardial infarction
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Occluded coronary artery becomes hypoxic resulting in ischemic tissue causing death to myocardial tissue
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Cause of angina pectoris
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Ischaemia simulating pain eliciting fibers producing the pain felt in the chest left arm and neck
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Percentage of deaths in the US caused by coronary artery disease
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35%
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50 percent of people receive their blood supply to the heart through which vessel
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The right coronary artery
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What is the extraction of oxygen percent the myocardium receive from arterial blood
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70%
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Major factor governing coronary blood flow
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Myocardial oxygen need
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When most coronary perfusion
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Ventricular relaxation or diastole
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Responsibility of the SA node
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Initiating the electrical impulses that produced sequential atrial and ventricular contraction
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What the AV node and bundles do to the impulses
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Slow their velocity before transmitting to the ventricles
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The travel path of impulses generated by the SA node
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SA node to AV node to bundle of His to purkinje fibers to ventricles
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Type of sympathetic fibers distributed throughout the heart
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Beta 1
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What is the Frank Sterling mechanism
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The ability of the heart to increase its force of contraction as increasing amounts of blood flow into it
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Why is the statement of the Frank Starling mechanism "the greater the preload the greater the force of contraction" not always true
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Because too much fiber stretch decreases the force of contraction
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80% of the ventricular filling is passive what is the remaining 20 percent
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caused by that atrial kick
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Describe ventricular emptying
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Contracting ventricles rapidly build up pressure causing the AV node snap close, the pressure increases to push open the aortic and pulmonary semilunar valve against the artery pressures, ejection period after valve open
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What is afterload
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Resistance to the ejection
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What is the end diastolic volume of each ventricle
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110 to 120 milliliter
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How much blood is stroke volume
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70 ml
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How much is left at end systolic
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40 to 50 milliliters
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What percent do filled ventricles normally eject
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60% (ejection fraction)
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What does a low ejection fraction of less than 50% indicate
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Poor contractility and pumping failure
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What is the ejection fraction during exercise
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90%
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What is muscle milking and why is it important
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The veins in the legs squeezing the blood upward toward the heart important because muscular activity which aids in the milking process prevents blood from pooling in the lower extremities causing impaired venous circulation
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Four basic mechanisms the veins manage blood return to the heart
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1. muscle milking of leg veins 2. sympathetic venous constriction 3. Cardiac pumping action creating a cardiac suction 4. Sub atmospheric intrathoracic pressure during breathing
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How to calculate systemic vascular resistance SVR
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SVR=(MAP-RAP)/CO
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What is SVR measuring
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The average resistance against which the left ventricle must work to eject the stroke volume (left ventricular afterload)
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What mechanisms play a role in long-term blood pressure regulation
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1.Kidneys 2. Vasopressin mechanism 3. Peptide produced by the ventricular walls
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Essay question: what is renin and how does it work
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1. Renin is an enzyme produced in the kidneys 2. Renin acts on a plasma protein to produce angiotensin 1 3. Angiotensin 1 circulates through the body and into the lungs 4. Pulmonary endothelium produces angiotensin converting enzyme ace 5. Ace acts on angiotensin 1 to produce angiotensin 2 6. Angiotensin 2 is a powerful vasoconstrictor which increases blood pressure 7. That increase blood pressure causes the adrenal cortex to secrete aldosterone 8. Aldosterone acts on the kidney tubules to increase their reabsorption rate of sodium ions and water
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