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116 Cards in this Set
- Front
- Back
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What does the cardiac cycle describe?
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The rhythmic pumping of the heart and is divided into systole and diastole
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What happens during ventricular systole?
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At the onset of systole, the AV valves close causing the first heart sounds. For a split second, the semilunar valves are also closed and no blood leaves the heart. This leads to a rapid increase in ventricular pressure that eventually exceeds the pressure of the pulmonary artery and aorta. When this occurs, the semilunar valves open signaling the second phase of systole, ejection
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What causes the first heart sound?
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Closure of the AV valves
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What causes the second heart sound?
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Closure of the semilunar valves
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If a 3rd heart sound was heard on your patient, where would you hear it and what is it associated with?
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You would hear it on the left midaxillary line at the 5th intercostal space. It is associated with fluid overload or increased volume like 3rd trimester of pregnancy, mitral valve regurgitation, tricuspid valve regurgitation, CHF
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What is being heard on the 3rd heart sound?
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Rapid filling of ventricles during diastole
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What is the 4th heart sound?
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Atrial contraction
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What is the 4th heart sound associated with?
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Stiffness of the ventricle (aortic stenosis, CAD, HTN, normal finding in athletes)
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What happens to cardiac output during rapid tachycardia?
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It decreases because there is less time for the ventricles to fill
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What is the a wave on the arterial line represent?
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Atrial contraction
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What does the c wave on an arterial pressure line represent?
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The bulge of the tricuspid valve into the right atrium during systole
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What does the v wave on an arterial pressure line represent?
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The slow buildup of blood in the atria at the end of systole
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What does the x descent on an arterial pressure line represent?
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Atrial relaxation
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What does the y descent on an arterial pressure line represent?
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Ventricular relaxation
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What is cardiac output and what is the formula?
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Cardiac output is the volume of blood ejected by the heart each minute. CO=HRxSV
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What is preload?
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It is the volume of blood imposed on the heart before contraction. It is the left ventricular end diastolic volume (LVEDV)
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What dictates your LVEDV?
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Venous return
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What is inotropy?
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The force of contraction of the heart
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What is peripheral vascular resistance?
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The resistance encountered by the blood as it enters the systemic circulation
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What factors affect peripheral vascular resistance?
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Volume, pressure, resistance, and flow
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Where are the neural control centers for cardiac function and control of blood pressure?
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Bilaterally in the medulla oblongata
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What is intra-capillary fluid pressure?
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The force within the capillary that pushes fluid out into the interstitium
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What is interstitial fluid pressure?
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The force within the interstitium that pushes fluid into the capillary
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What is plasma colloidal osmotic pressure?
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Osmotic pressure within the capillary that draws fluid into the capillary
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What is interstitial colloidal osmotic pressure?
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Osmotic pressure within the interstitium that draws fluid into the tissue
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What is edema?
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Excess fluid within the interstitium
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Where are impulses generated within the cardiac conduction cycle?
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SA node
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What vessel supplies blood to the SA node?
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Right coronary artery (RCA)
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What is the resting membrane potential of the heart?
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-90mv
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Can you have depolarization in the absolute refractory period?
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No
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In what phase of the cardiac conduction cycle will dysrhythmias occur?
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Relative refractory period
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What are the two types of cardiac muscle channels?
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Fast sodium channels and slow calcium channels
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What channels are used by the SA and AV nodes?
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Slow calcium channels
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What is automaticity?
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Spontaneous generation of an action potential
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Something externally that causes an action potential within the heart is called what?
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Ectopic pacemaker
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What is excitability?
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The ability of the heart to generate an action potential
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What determines end-organ perfusion?
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Blood pressure
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Why is diastole important?
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The coronary arteries are behind the aortic valve and are not perfused during systole
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What are baroreceptors and where are they?
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Baroreceptors are receptors that are found in the carotids and aorta that are sensitive to changes in stretch. They send an impulse to the medulla oblongata which counteracts with appropriate HR and vascular tone responses
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How do arterial chemoreceptors work?
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Arterial chemoreceptors are found in the aortic arch and are sensitive to changes in O2, CO2, and H+. They regulate ventilation in response to these changes
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What does renin do?
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Renin converts angiotensinogen to Angiotensin 1
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How is Angiotensin I converted to Angiotensin II?
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Angiotensin converting enzyme, found in the lungs, converts AT1 to AT2
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What does Aldosterone do?
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It regulates sodium and water retention/excretion
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What is essential hypertension?
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Chronic elevation of blood pressure in the absence of disease
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What is secondary hypertension?
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Elevated BP in the presence of disease
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What kind of damage is caused by hypertension?
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Stroke, transient ischemic attacks, retinopathy, CAD, Left ventricular hypertrophy, angina, MI, chronic kidney disease, and peripheral vascular disease
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What are some non-pharmacologic treatments for HTN?
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Exercise, weight reduction, reduced salt intake (DASH), cessation of smoking and drinking
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What are the pharmacologic treatments for HTN?
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Diuretics, B-adrenergic blockers, Alpha1 adrenergic receptor blockers, Alpha2 agonist, ACE inhibitors, Angiotensin II receptor blockers, calcium channel blocking drugs, vasodilators
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What causes orthostatic hypotension?
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Decreased venous return secondary to pooling of blood in the lower part of the body and inadequate circulatory response to decreased CO and BP
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What causes cardiac tamponade?
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A rapid or slow filling of blood, pus, or fluid in the pericardial sac
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What is the key finding in cardiac tamponade?
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Pulsus paradoxus-a 10mmHg or more fall in arterial BP during normal breathing
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What are the three types of chronic ischemic heart disease?
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Stable angina, unstable angina, and variant angina
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Chronic stable angina is associated with what type of obstruction?
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A fixed coronary obstruction
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What precipitates chronic stable angina?
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Anything that increases the work demands of the heart (i.e. exercise, heat, cold, stress)
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What relieves chronic stable angina?
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Rest and/or nitroglycerin
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What populations are affected by silent myocardial ischemia?
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People w/o evidence of CHD, people w/ history of MI that continue to have silent ischemic attacks, and people with a history of angina who also have silent ischemic attacks
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What disease population is high risk for silent myocardial ischemia?
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Diabetes mellitus
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What causes unstable angina?
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Platelet aggregation, atherosclerotic plaque disruption, and secondary hemostasis
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What are some characteristics of unstable angina?
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Occurs at rest, lasts longer than 20 minutes, severe/frank pain of new onset, and pattern is more severe, frequent and prolonged than previously experienced
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What characterizes variant angina?
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Spasm of coronary arteries, occurs at rest or w/minimal exercise, and nocturnally
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Acute coronary syndromes include what?
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Unstable angina, non-ST segment elevation, MI, and ST-segment elevation
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Infective endocarditis causes what?
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Friable and bulky vegetative bacterial growths that destroys the underlying cardiac tissue
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What disease commonly causes mitral valve stenosis?
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Rheumatic fever
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What is mitral valve stenosis?
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The fibrous replacement of valvular tissue that causes fixed positioning of the leaflets into the left ventricle and shortening of the chordae tendinae ultimately leading to a restricted opening of the mitral valve
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What happens physiologically as mitral valve stenosis progresses?
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The increasing pressure produced by the stenotic mitral valve causes dilation of the left atrium and pulmonary congestion, fatigue, nocturnal paroxysmal dyspnea, and orthopnea. Late stage could lead to pulmonary hypertension and eventually right-sided heart failure
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How does the cardiovascular center transmit parasympathetic nerve impulses to the heart?
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Via the vagus nerve
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How does the cardiovascular center transmit sympathetic impulses?
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Via the spinal cord and peripheral sympathetic nerves
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What is the Frank-Starling mechanism?
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The increase force in contraction that accompanies an increase in ventricular end-diastolic volume
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What does the Frank-Starling mechanism allow?
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The heart to adjust its pumping ability to various levels of venous return
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What is congestive heart failure?
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Heart failure characterized by impaired pumping ability and congestion of bodily tissues
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What type of failure causes an increase in right-ventricular end diastolic pressure, right atrial pressure, and systemic venous pressures?
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Right-sided HF
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What are the manifestations of right-sided heart failure?
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Weight gain, peripheral edema, hepatomegaly, visceral congestion
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What are the manifestations of left-sided heart failure?
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Pulmonary congestion/edema leading to decreased CO and impaired gas exchange. Clinically, the patient will demonstrate fatigue r/t hypoxia, cyanosis, dysypnea, activity intolerance
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What are the four classifications of shock?
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Cardiogenic, hypovolemic, distributive, and obstructive
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What is cardiogenic shock?
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Failure of the heart to pump adequately
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What is the most common cause of cardiogenic shock?
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Myocardial infarction
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What clinical signs are seen with cardiogenic shock?
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Decreased CO, fluid overload e/b increased CVP and PCWP
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What is hypovolemic shock?
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Inadequate fluid/blood volume to fill vascular compartments
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What are the compensatory mechanisms of early hypovolemic shock?
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Tachycardia, increased cardiac contractility, vasoconstriction, increased sympathetic response
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How does shock affect the body at the cellular level?
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The circulation is unable to supply the cells with the oxygen and nutrients needed for ATP production
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What is glycolysis?
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The conversion of glucose to ATP and pyruvate
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Is glycolysis aerobic or anaerobic?
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Anaerobic
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What happens to pyruvate in the presence of oxygen?
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Pyruvate moves into the mitochondria, enters the citric acid cycle and is transformed into ATP, carbon dixoide and water
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What happens to pyruvate in the absence of oxygen?
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It is converted to lactic acid
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What happens at the cellular level if ATP is insufficient?
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Sodium-potassium pumps shut down causing increased intracellular sodium with swelling and destruction of enzyme systems and increased serum potassium
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What happens in obstructive shock?
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Blood flow or venous return is obstructed
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What is the most common cause of obstructive shock?
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Pulmonary embolism
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What are the three types of distributive shock?
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Neurogenic, anaphylactic, septic
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What are the conductive airways?
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Air passages through which air travels. They include the nasopharynx, oropharynx, larynx, and tracheobronchial tree
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What are the respiratory tissues?
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Tissues where gas exchange occurs which includes the lungs and alveoli
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What are the functions of the larynx?
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Production of speech, conduction of air, and the prevention of aspiration
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What supplies the pulmonary circulation?
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The pulmonary artery for gas exchange
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What supplies the bronchial circulation?
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The thoracic aorta supplies the lungs and other lung structures with oxygen
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Which alveolar cells are responsible for gas exchange?
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Type I
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Which alveolar cells produce surfactant?
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Type II
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What nerve innervates the diaphragm and what level is this nerve at?
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Phrenic nerve at C3-C5
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What is lung compliance?
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The change in volume that occurs in the lungs with a change in respiratory pressure
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What is the formula for lung compliance?
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C = change in volume/change in pressure
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What is a pleural effusion?
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An abnormal collection of fluid in the pleural cavity
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What is normal compliance in the average adult?
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200ml/cm H2O
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What is surface tension?
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The tension formed by the thin layer of water molecules on the alveoli. It contracts and makes it difficult to inflate the alveoli
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What reduces surface tension?
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Surfactant
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What is dead space?
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Air that moves within each breath and does not participate in gas exchange
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What is anatomic dead space?
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Air within the conducting airways that does not participate in gas exchange
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What is alveolar dead space?
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Air within the alveoli that does not participate in gas exchange
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How much dead space is fixed in the typical adult?
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150-200ml
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What is a shunt?
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The movement of blood from the right side to the left side circulation without passing through the lungs
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What happens in an anatomic shunt?
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Blood shifts from the right side of the heart to the left side of the heart and skips the lungs
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What happens in a physiologic shunt?
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There is a mismatching of ventilation to bloodflow so that inadequate oxygenation of blood is occurring
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What are the 3 ways in which carbon dioxide is transported?
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Bound to hemoglobin, as bicarbonate, and as dissolved CO2
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What is carbon dioxide more soluble than?
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20X more soluble than oxygen
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What enhances the binding of carbon dioxide to hemoglobin?
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The release of oxygen to tissues
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What facilitates the release of carbon dioxide to the lungs?
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The uptake of oxygen
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What does surfactant do?
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It reduces surface tension, equals out alveolar inflation, and increases compliance
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What are the signs and symptoms of influenza?
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Acute onset of fever and chills for differential diagnosis. Malaise, muscle aches, headache, runny nose, sore throat
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What does a tuberculin skin test indicate?
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That a person had launched a cell-mediated response to M. Tuberculosis. At some point in time, they were infected. It does not indicate active infection
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