Quiz 2 PDF

13. Describe how each segment of an ECG (P, QRS, T waves) corresponds to the electrical activity and contraction of the myocardium. - Electrocardiograms are composite recordings of all electrical activity in the heart, not one action potential and not just one cell) - They contain a P wave, QRS...

13. Describe how each segment of an ECG (P, QRS, T waves) corresponds to the electrical activity and contraction of the myocardium. - Electrocardiograms are composite recordings of all electrical activity in the heart, not one action potential and not just one cell) - They contain a P wave, QRS complex, T wave, ST segment, and PQ segment - P wave: SA node depolarizes and Atrial depolarization - PQ segment: Atrial Contraction - QRS complex: Ventricular Depolarization (Atrial repolarization as well but can’t see it) - ST segment: Ventricular contraction - T wave: Ventricular repolarization 14. Describe the phases, timing, pressure changes, volume changes, and heart sounds associated with the cardiac cycle. - The Cardiac Cycle = one complete contraction and relaxation of all four chambers ( Pressure in atria’s - Leads to the AV valves close, which is the “Lub” sound, which is called S1 - Contraction is tension with no blood flow - * Heart sounds occur when valves close* - Phase 3 (Ventricular Ejection – blood flowing out of the ventricles)  - Atria are relaxed and ventricles are contracted causing the AV valves to close (Pressure in ventricles > Pressure in atria) while the Aortic and Pulmonary valves are open (Pressure in ventricles > Pressure in arteries). - Pressure in ventricles builds > Pressure in arteries, which causes the semilunar valves to open - The amount of blood ejected is called Stroke Volume, which is about 70 mL - The amount of blood remaining is called End Systolic Volume (ESV), which is about 60 mL - Ejection Fraction (EF) = % Ejected and you take the Stroke Volume and divide it by the End Diastolic Volume = an important measure of cardiac health, anything below 50% is bad - Phase 4 (Isovolumetric Ventricular Relaxation – volume stays the same because all valves are closed) - The atria and ventricles are both relaxed, leading to both sets of valves being closed - The AV valves being closed indicates that the pressure in your ventricles is greater than the pressure in your atria - The closed aortic and pulmonary valves indicate that the pressure in the arteries is higher than the pressure in your ventricles. - As the ventricles relax, the pressure in the arteries will exceed the pressure in the ventricles, which causes the semilunar valves to close, creating the “Dub” sound, which is also called S2 - Volume Changes - ESV 60 mL - + passive filling +30mL - + atrial contraction +40 mL - equals the EDV which is 130 mL - Subtract SV which is -70mL - Equals ESV which is 60mL - must be equal for both ventricles or blood will pool 15. Describe disorders related to the heart (myocardial infarction, arrhythmia, fibrillation, congestive heart failure, etc). - Congestive Heart Failure = failure of either ventricle to pump blood properly - Pulmonary edema is failure of the left ventricle 1. Right Ventricular output exceeds left ventricular output. 2. Pressure backs up 3. Fluid accumulates in pulmonary tissue - Systemic Edema is the failure of the right ventricle, which occurs in the abdominal cavity and the feet and ankles 1. Left ventricular output exceeds right ventricular output. 2. Pressure backs up 3. Fluid accumulates in systemic tissues. - Myocardial Infarction (Heart Attack)  - Blocked coronary arteries à Angina chest pain caused by temporary blood deficiency à Myocardial Infarction (MI) - When part of the myocardium dies - Can be fatal - Weakened Heart wall, poor electrical conduction - Angiography is a way to prevent it (Balloon Angioplasty or coronary bypass) - - Sinus rhythm: normal heartbeat triggered by SA node (~75 bpm) 0.8 seconds - Ectopic focus: Site other than the SA node acts as pacemaker - Ex: Nodal rhythm (AV node) = 40-50 bpm (can survive but anything requiring exertion or exercise can be dikicult) - Purkinje fibers = 20-40 bpm and it is not enough to sustain life - Arrhythmia: any abnormal cardiac rhythm - Bradycardia: resting HR 100 bpm - Fibrillation: irregular and chaotic electrical activity - V-fib (ventricle) - A-fib (atrial) 16. Define and explain the relationship among: heart rate, stroke volume, end diastolic volume, end systolic volume, ejection fraction, and cardiac output. - Heart Rate (HR): Taken on the brachial artery around the wrist and it is how many times you can feel blood pump through the artery in a minute. - Stroke Volume (SV): Blood Ejected and should be around 70 mL (Phase 3) - End Diastolic Volume (EDV): should be around 130 mL per ventricle (Phase 1) - End Systolic Volume (ESV): Blood remaining (Phase 3) and should be around 60 mL - Ejection Fraction (EF): Percent of blood ejected (Phase 3) and is an important measure of cardiac health and should not be lower than 50% - Cardiac Output (CO): Amount of blood ejected in one minute 17. Explain the regulation of heart rate, stroke volume, and cardiac output. - Cardiac Output (CO) = Heart Rate (HR) x Stroke Volume (SV) - CO = 75 bpm x 70 = 5,000 mLs/min = 5 L/min - Regulation of Heart Rate - Positive chronotropic agents: increase HR up to 230 bpm - Exercise = increases CO to about 20 L per minute - EX: SNS (norepinephrine), Epinephrine and norepinephrine, cakeine, and nicotine - Negative chronotropic agents decrease HR down to 20 bpm - PSNS (Acetylcholine) via the Vagus nerve - Vagal Tone à always output from the vagus nerve to the heart and holds the resting heart rate at 75 bpm - Regulation of Stroke Volume - Preload (EDV): Amount of blood in ventricles before contraction - Increases venous return à increases EDV à Increases stretch/tension in ventricles à increased SV à increased CO (Frank-Starling Law)  - Contractility: how hard the heart contracts for a given preload - increased Ca2+ (via SNS, Epi) = increased contractility = increased SV = increased CO BLOOD VESSELS AND HEMODYNAMICS 1. Contract the structure and function of arteries, capillaries, and veins. o Vessel walls are Tunica interna (simple squamous epithelium), Tunica media (smooth muscle (+/- elastic tissue)), and Tunica Externa (Connective Tissue) o Arteries: carry blood away from the heart o “Resistance vessels” = can withstand high BP o Lots of elastic tissue o Capillaries: exchange vessels o Contains pores and clefts o Has an endothelium and no muscle or connective tissue o Have sphincters and most of the time, most of the capillaries are closed o Veins: carry blood towards the heart (“capacitance vessels” = storage) o Expands easily to accommodate high volume o No or very little elastic tissue o Still has muscle o Thin walls because of low BP (~10 mmHg) o Contains valves which keep blood flowing in one direction o Has venules, medium veins (arms and legs), and large veins o Arteries will remain open after death o Veins don’t hold their shape 2. Define the anastomosis and portal system. o Portal system: (2 capillary beds) o Hepatic o Hypothalamus to anterior pituitary gland o Kidney (nephron) o Arteriovenous Anastomosis (shunt) = 2 vessels verge with no capillaries in between o Venous anastomosis § Very common o Arterial anastomosis § Joints, brain, heart 3. Describe the pathway of circulation going to and from the heart, including major branches of the aorta. o Ascending Aorta à Aortic Arch o Brachiocephalic arch § Right subclavian artery: upper extremities § Right common carotid artery: head, face, and brain  o Left common carotid artery o Left subclavian artery o Descending aorta, thoracic (posterior to the heart): lower body extremities 4. Describe the purpose and trace the circulation pathway through the pulmonary and hepatic portal systems. o Pulmonary Circulation= Exchanges O2 and CO2 o Enters the lungs via the right and left pulmonary artery (carrying deoxygenated blood) o Meets the alveolar capillaries and then goes back into the lungs via the pulmonary veins o Low pressure (25/10) o Slow flow through the capillaries in the lungs allows time for gas exchange o Hepatic Portal System (goes toward an organ) = 2 capillary beds before returning to heart o Arteries to GI tract à capillaries in GI tract (absorb nutrients) à GI veins à hepatic portal vein (toward liver) à Liver à capillaries in liver (blood is “clean”, modify nutrient concentration à hepatic veins (away from heart) à inferior vena cava à heart 5. Explain factors that regulate blood flow. o Hemodynamics: Pressure o F = change in P/ Resistance à pressure dikerence (gradient), not an absolute pressure o Increase in flow = increase in change in pressure 6. Describe how blood pressure is measured and state normal values. o Steps o No sound; cuk pressure above systolic pressure; artery completely occluded during cycle o Cuk pressure just below systolic pressure; first sounds heard; soft, tapping, and intermittent o Sounds loud, tapping, and intermittent o Low mukled sound lasting continuously o Cuk pressure below diastolic pressure; thus, the vessel is always open; no turbulence, no sound o Measured with a sphygmomanometer on the brachial artery o Systolic / Diastolic = 120/80 mmHg 7. Define and be able to calculate pulse pressure and mean arterial pressure. o Pulse Pressure: Pressure in arterioles o PP = systolic – diastolic o PP= 120-75 = 45 mmHg o Mean Arterial Pressure: “Average BP” (throughout the whole body) o MAP = diastolic + PP/3 o MAP = 75 + 45/3 = 90 mmHg 8. Define and discuss the causes and ekects of hypertension, hypotension, arteriosclerosis, and atherosclerosis. o Hypertension: Chronic high BP >130/80 at rest o Causes: obesity, smoking o Results in: heart/kidney failure from weakened vessels o Hypotension: chronic low BP o Causes: dehydration, blood loss o Results in: low O2 to brain and heart o Arteriosclerosis: Arteries lost elasticity (“hardening of the arteries) o Contribute to high BP with age o Results in: heart disease, kidney failure, stroke o Atherosclerosis (form of Arteriosclerosis): Accumulation of lipid deposits that degrade/block arteries o Contribute to high BP with age o Results in: heart disease, kidney failure, stroke 9. Discuss the importance of arterial elasticity and describe pressure changes within the cardiovascular system. o Arterial elasticity o In systole, the arteries are dilated, which leads to a systolic value of ~120 mmHg o In diastole, the arteries are constricted, which leads to a diastolic value of ~ 75/80 mmHg o If the arteries are rigid (no elasticity) for systole, the BP would be 380 mmHg with very fast blood flow o If the arteries are rigid (no elasticity) for diastole, the BP would be zero mmHg with no blood flow o Elastic recoil: Exerts pressure on the arteries to… § Keep blood flow during diastole § Decrease pressure fluctuations § Decrease stress on heart and vessels o Pressure changes with distance throughout the body o Blood pressure is pulsatile in arteries because of their elasticity o As the distance increases from the left ventricle, the Systemic blood pressure decreases § Aorta à Large arteries à small arteries à arterioles à capillaries à Venules à Small veins à Large veins à Venae Cavae Not pulsatile in capillaries or veins because they are not elastic and farther from the heart (friction over distance) Veins have the lowest pressure and have to because of how fluid flows from high pressure to low pressure 10. Discuss factors that akect peripheral resistance and describe how peripheral resistance is regulated. o Resistance is 8 L viscosity/ pie x radius to the 4th power o Radius is adjusted by vasomotion  § Vasodilation: increased radius à decrease resistance à increase flow § Vasoconstriction: decreased radius à increase resistance à decrease flow o Resistance in vessels is called: Total Peripheral Resistance (TPR) § Vasodilation = decreased TPR § Vasoconstriction = increased TPR o Peripheral Resistance o A small change in radius has a big ekect on flow o Vasoconstriction makes blood flow very slowly 11. Explain how and why the body redirects blood flow. o The body redirects blood flow by doing it in parallel o Same quality of blood to all tissues o Can regulate what tissues get blood 12. Describe the purpose and mechanisms of capillary exchange. 13. Explain the slow rate of blood flow through capillaries. 14. Discuss the impact of dikerent pressures on filtration and reabsorption. 15. Define and describe causes of edema. 16. State mechanisms that aid in venous return. 17. Explain what varicose veins are and what causes them. 18. Describe factors that determine blood pressure. 19. Explain in detail the local, neural, and hormonal mechanisms for controlling blood pressure. 20. Name the location of the baroreceptors and explain their function in blood pressure regulation.