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Life Support #1
Cardiac anatomy and Physiology
Question | Answer |
---|---|
What is the Apex of the heart and where does it lie? | tip of the LV, 5th ICS at the left mid clavicular line just above diaphragm |
5 structures that compose the vascular system | Heart, arteries, capillaries, veins and blood |
Veins act as a reservoir and accommodate __% of circulating blood volume | 70% |
Aorta to right atrium, high resistance, high pressure= _________ circulation | systemic |
Pulmonary artery to LA, low resistance, low pressure= ________ circulation | pulmonary |
The body's smallest blood vessels are___ and the measure __-__ micrometers in diameter | capillaries; 5-10 |
Purpose of capillaries | connect arterioles and venules for gas and nutrient exchange bw blood and surrounding tissue |
3 layers of the heart | pericardium, myocardium, endocardium |
What is the pericardium? | outermost layer that encases the heart and attached to the great vessels |
2 layers of the pericardium and their location | parietal-outside layer and visceral-adheres to myocardium |
How much pericardial fluid separates the 2 layers of the pericardium? | 20-30ml |
This layer of the pericardium is fused to and inseparable from the fibrous pericardium | parietal |
this layer of the pericardium is part of the epicardium | visceral |
The myocardium consists of involuntary striated muscle fibers called ____ | myofibrils |
2 types of filaments that make up myofibrils and link together to cause muscle tension and shortening are | Myosin and Actin |
_____= thick protein filament responsible for skeletal movement | myosin |
___= thin protein filament responsible for aiding in contraction | actin |
Where is the endocardium and what does it do? | innermost layer lining the chambers of the heart; regulates contractility and electrophysiology of the heart |
In which layer of the heart do blood clots attach? | endocardium |
RAP= | (diastolic only) 0-8 mmHg |
RVP= | 15-25 mmHg Systolic; 0-8 mmHg Diastolic |
Pulmonary artery Pressure | 15-25 mmHg Systolic; 8-15 mmHg Diastolic |
LAP= | (Diastolic only)4-12 mmHg |
LVP= | 110-130 mmHg Systolic; 4-12 mmHg Diastolic |
Aorta pressure | =110-130mmHg Systolic; 70-80 mmHg Diastolic |
Which valves are open during diastole and closed during systole? | AV valves (bicuspid and tricuspid) |
Bicuspid valve is AKA | mitral valve |
What are Chordae Tendoneae | fibrous cords that connect the edges of the leaflets to the papillary muscles |
What are the papillary muscles? | muscular projections of the inner surface of the ventricles that tether the valves to prevent backflow to atria during systole |
These valves are open during systole and closed during diastole | semilunar valves |
Incompetence of the valve that results in back flow during systole is called | prolapse |
2 things that can cause valve prolapse | Rheumatic fever and infectious endocarditis |
Progressive narrowing of the valve orifice creating obstruction of blood flow is | stenosis |
4 causes of stenosis | congenital disorders, fibrosis, calcium build-up, Rheumatic fever |
RVEDP=___, ___, ____, ___ | CVP, RAP, RVEDV, Preload of RV |
LVEDP= ___, ___, ___ = ____ | LAP, LVEDV, Preload of LV, Pulmonary capillary wedge pressure |
Describe right heart systole | A-V equilibration, tricuspid closes, ventricles tense, RVSP>PAP, pulmonic valve opens |
At end systole RVSP= ___ and pulmonic valve closes | PASP |
Describe Left heart systole | A-V equilibration, Bicuspid closes, ventricles tense, LVSP> Aortic Pressure, Aortic valve opens |
At end systole LVSP=___ and aortic valve closes | aortic systolic pressure |
What is preload and what affects it? | amount of end-diastolic stretch on myofibrils affected by fluid volume, valvular disease |
HIgh PCWP indicates what type of disease? | lung disease |
What is afterload? | force against which the muscle fibers of the ventricles must pump against |
Right ventricular afterload= ___ ___ ___, PADP | pulmonary vascular resistance |
Left ventricular afterload = | SVR, ___ |
What does the Right Coronary Artery perfuse? | SA Node, AVN, Bundle of His, posterior 1/3 of ventricular septum |
What supplies blood to the greatest portion of the myocardium | The left main coronary artery |
2 branches of the LCA are | Left anterior descending and circumflex |
LAD supplies __-__% of the left ventricle | 45-55% |
Circumflex is located ___ and ____ and supplies __-__% of left ventricle | lateral and posterior; 15-25% |
Coronary circulation (heart) extracts approx. __% of oxygen from arterial blood supply at rest | 70% |
SvO2 of CS blood= __%, PvO2 __mmHg | 30%; 20mmHg |
Systemic circulation extracts approx __% of oxygen from arterial blood supply | 25% |
SvO2 of systemic blood= __%, PvO2 __ mmHg | 75%; 40mmHg |
Coronary artery dilation can increase perfusion volume __ times normal | 5 |
What can cause coronary artery dilation? | increase HR, stress, inotropic drugs, increase in wall tension(hypertrophy, afterload) |
What is teh major determinant of left ventricular blood flow? | aortic diastolic pressure |
Approx __% vessel occlusion is required to significantly decrease blood flow | 70% |
3 things that decrease vessel diameter | spasm, plaque, thrombus |
3 factors that determine blood flow | vessel diameter, viscosity of blood and pressure gradients |
Hct > __% is critical increase in WOH | 55% |
What is Starling Law? | the force of contraction is related to the amount of blood in the ventricles at end diastole (more volume = more stretch= more contraction) |
Starlings law is lost in what disease states | cardiomegaly/hypertrophy (overstretched muscles= less contraction) |
The force of contraction is partly related to _____ in the __cellular fluid | calcium; extracellular |
Calcium channel blockers are given to patients with ___'s to slow contraction | SVT's |
Muscle contraction occurs when calcium goes into the cell and goes into ___ | troponin |
What is troponin? | protein located on teh actin filament that initiates contraction |
Path of the electrical conduction system | SA node-Bachmans bundle(intraatrial)-AV node- Bundle of His- bundle branches- Perkinje fibers- Myocardium |
Sympathetic: Vaso___, ___HR, conduction velocity and contractility, and broncho____ | constriction; increases; dilation |
Parasympathetic: ___ HR, conduction and promotes Vaso___ | slows; vasodilation |
Intravascular= | capillary |
extravascular= | lung tissue, alveoli, interstitial space |
Normally intravascular should be ____ extravascular volume | equal to |
Capillary diffusion is dependent upon what 2 things? | capillary permeability and opposing forces of hydrostatic and oncotic forces |
Capillaries are highly permeable to ___ and relatively impermeable to _____ | electrolytes; plasma proteins (ex: albumin) |
Pressure exerted by a volume of fluid within a given space | hydrostatic pressure |
this protein keeps fluid in the capillaries | albumin |
Capillaries have > fluid pressure than alveoli, therefor forces fluid from what to what | vascular space(capillaries) to interstitial space (lung tissue) AKA pulmonary capillary hydrostatic pressure |
When insterstital hydrostatic pressure is low but alveolar and capillary pressures are normal, what occurs | fluid leaks from capillary into lung tissue |
What is the force generated by the attraction of protein molecules for H2o | Oncotic pressure |
What is Plasma oncotic pressure | holds proteins together to keep blood from leaking out of capillary |
In normal lungs how much fluid leaks into lung tissue and interstital space and is cleared by lymphatics | 20-30 ml/hr |
What is the abnormal accumulation of fluid outside of the vascular spaces of the lung | pulmonary edema |
Fluid balance is controlled by what 2 things | AC membrane permeability and Oncotic and hydrostatic forces |
Lymphatic system can compensate for an increase up to __ times to maintain dry state | 10 |
hypoalbuminemia causes a decrease in what | plasma oncotic pressure |
Causes of cardiogenic pulmonary edema | renal failure, CHF, hypervolemia, Left ventricular failure (MI, valvular disorders, htn; arrythmia) |
Assessment: Cardiogenic pulmonary edema | visible CHF pattern, crackles |
Ways to treat cardiogenic pulmonary edema | O2, Positive pressure, decrease fluid intake, diuretics, inotropes |
what are the 3 phases of cardiogenic pulmonary edema | Compensated, Interstitial, and alveolar |
Non-cardiogenic pulmonary edema usually results from what | ARDS |
Clinical findings assoc with Non cardiogenic pulmonary edema | acute onset resp distress 24-48 hrs after cause, diffuse bilat interstitial infiltrates on CXR, severe refractory hypoxemia |
Causes of ARDS | Sepsis (>30% of cases), trauma, severe lung infection, aspiration, near drowning, DKA |
3 phases of ARDS | exudative, proliferative, resolution |
Stage of ARDS characterized by accumulation of excessive fluids, protein and inflammatory cells in the alveoli | Exudative |
The exudative stage usually unfolds over the first __-___ days after onset of lung injury | 2-4 |
During this stage of ARDS alveolar thickening continues, the lung tissue resembles liver tissue, danger of pneumonia, sepsis | Proliferative (fibrotic) |
Lung function may continue to improve for as long as __-__ months | 6-12 |