Cardiovascular worksheet PDF

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CARDIOVASCULAR SYSTEM WORKSHEET 1. Describe the basic structure of the cardiovascular system. Trace the flow of blood throughout the cardiovascular system and the heart. Make sure to name all the valves that the blood must pass through. - Vena cava ฀ RA (tricuspid valve) ฀ RV (pulmonary valve)฀ pulmonary artery ฀ lungs ฀ increased oxygen ฀ pulmonary veins ฀ LA (Mitral valve) ฀ LV (Semilunar/Aortic Valve)฀ aorta ฀ capillaries ฀ venuoles ฀ veins ฀ vena cava - As the right atrium is receiving blood from the vena cava the left atrium is receiving blood from the pulmonary veins at the same time - Both atria contract ฀ both ventricles contract - The right ventricle only needs enough force to pump to the lungs which are right next doors. - The left ventricle has to pump to the rest of the body therefore needs more force and is a thicker muscle - RV/LV is separated by a septum - Pulmonary circulation: Closed loop of vessels carrying blood between heart and lungs - Systemic circulation: Circuit of vessels carrying blood between heart and other body systems 2. Describe in detail how arteries differ from veins. - Arteries oxygenated - Veins deoxygenated 3. What factors insure the unidirectional flow of blood in the cardiovascular system? - AV Heart Valves: Ensure unidirectional blood flow through the heart o Atrioventricular (AV) valves: Lie between the atria and the ventricles, AV valves prevent backflow of blood into the atria when ventricles contract - Chordae tendineae anchor AV valves to papillary muscles - The AV valve that separates the right atrium from the right ventricle= Tricuspid Valve - The AV valve that separates the left atrium from the left ventricle= Mitral valve (or Bicuspid) - Semilunar Heart Valves o Aortic semilunar valve lies between the left ventricle and the aorta ฀ aortic valve o Pulmonary semilunar valve lies between the right ventricle and pulmonary trunk ฀ pulmonary valve o Semilunar valves prevent backflow of blood into the ventricles 4. Diagram the structure of the heart. 5. Compare and contrast the pulmonary the systemic circulations. - Pulmonary circulation: Closed loop of carrying blood between heart and lungs - Systemic circulation: Circuit of vessels carrying blood between heart and other systems 6. Liquids (and gases for that matter) flow areas of high pressure to areas of low pressure.

with vessels

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7. How does the cardiovascular system create a region of higher pressure? - Liquids and gases flow down pressure gradients from regions of high to low pressure 8. As blood moves away from the heart, what happens to the pressure? Why? - As blood moves away from the heart the pressure decreases since blood goes from areas of higher pressure to areas of lower pressure.

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Pressure decreases due to friction

9. The highest pressure in the blood vessels is found in the arteries (aorta and systemic arteries) and the lowest pressures are found in the veins (vena cavae). 10. What happens to the pressure exerted on blood when the heart contracts? What happens to pressure exerted on the blood when the heart relaxes or the blood vessels dilate? - Contracts – BP increases - Relaxes/dilates – BP decreases 11. What is a pressure gradient? What is the relationship between a pressure gradient and flow? - When the pressure gradient is large enough, there is a linear relationship between the fluid velocity and pressure gradient. However, when the pressure gradient is small, there is no flow rate. As the pressure gradient becomes larger than a certain value called threshold pressure gradient (TPG), the flow occurs. 12. Fluid is flowing through two identical tubes. In tube A, the pressure at one end is 150 mm Hg and the pressure at the other end is 100 mm Hg. In tube B, the pressure at one end is 75 mm Hg and the pressure at the other end is 10 mm Hg. Which tube will have the greatest flow? - 150-100 mmHg = 50 mmHg - 75 -10 mmHg = 65 mmHg ฀ greatest flow because the higher the pressure the higher the flow - F = P/R 13. Write the mathematical expression that relates flow and resistance. What happens to flow when resistance increases? What happens to flow when resistance decreases? - Resistance is a force that opposes the flow of a fluid. In blood vessels, most of the resistance is due to vessel diameter. As vessel diameter decreases, the resistance increases and blood flow decreases. - The smaller the vessel the more friction and more friction. - The larger the blood vessel double the diameter and less friction and resistance. 14. Write the mathematical expression that relates resistance and the radius of a blood vessel. When the radius of a blood vessel increases or decreases, what happens to the resistance of that blood vessel? What happens to flow through that blood vessel if its radius changes? - Opposition of blood flow through a vessel - Referred to as peripheral resistance (PR) or (TPR) - Depends on 3 things: a) Blood viscosity b) Vessel length ▪ the longer the vessel ฀ ↑the resistance c) Vessel radius or diameter - Major determinant= vessel’s radius - Slight change in radius ฀ ↑ change in blood flow - R is proportional to 1/r4 - ↓radius or diameter of blood vessel ฀↑friction ฀↑↑ R 15. Define vasoconstriction and vasodilation in terms of diameter and resistance. - vasomotion – changes in diameter of the blood vessel brought about by smooth muscle contraction or relaxation ฀ Tunica Media - Arterioles are the major determinants of TPR - Mechanisms involved in adjusting arteriolar resistance: o Vasoconstriction: ↓vessel lumen size ฀ ↑resistance o Vasodilation: ↑ vessel lumen size ฀ ↓ resistance

16. Blood is flowing through a vessel at a constant rate of flow. What happens to the velocity of flow if the vessel suddenly narrows? - Resistance ฀ Turbulence of blood flow can also ↑ TPR 17. Define mean arterial pressure (MAP) and show the mathematical relationship of the two main parameters influencing MAP. - Average pressure driving blood forward into tissues throughout cardiac cycle - MAP or BP = CO x TPR - Dependent on two factors: o Elasticity of blood vessels closest to the heart ฀ compliance o Volume of blood forced into them/time - C = V/P - A change in volume (V) causes < of an ↑ in transmural pressure (P) in a more compliant vessel - A vein is 24 times more compliant than its corresponding artery. 18. The heart is a muscle that lies in the center of the thoracic cavity (mediastinum), surrounded by a membrane called the pericardium. 19. The left and right sides of the heart are separated by a wall known as the Septum. 20. The ventricles are the lower chambers and the atrium are the upper chambers. Which chambers have the thickest walls? - In a normal heart: the thickest wall is that of the left ventricle, which pumps against the systemic arterial blood pressure. (90 mm Hg or more). Pumping against this relatively high pressure is hard work and requires a thicker muscular wall. The right ventricle pumps against the pressure in the lungs. 21. What are the chordae tendineae and what is their function? How are chordae tendineae related to papillary muscles? - Chordae tendineae anchor AV valves to papillary muscles - The chordae tendineae are a group of tough, tendinous strands in the heart. They are commonly referred to as the “heart strings” since they resemble small pieces of string. 22. Compare and contrast the two AV valves and two semilunar valves - AV Heart Valves o Ensure unidirectional blood flow through the heart o Atrioventricular (AV) valves: ▪ Lie between the atria and the ventricles

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▪ AV valves prevent backflow of blood into the atria when ventricles contract o Chordae tendineae anchor AV valves to papillary muscles o The AV valve that separates the right atrium from the right ventricle= Tricuspid Valve o The AV valve that separates the left atrium from the left ventricle= Mitral valve (or Bicuspid) Semilunar Heart Valves o Aortic semilunar valve lies between the left ventricle and the aorta ฀ aortic valve o Pulmonary semilunar valve lies between the right ventricle and pulmonary trunk ฀ pulmonary valve o Semilunar valves prevent backflow of blood into the ventricles

23. Describe the differences between myocardial autorhythmic cells and myocardial contractile cells. Draw in detail the action potentials for an autorhythmic cells and for a contractile cell. Make sure to label those action potentials with the difference phases of the action potential and describe which ion/s are coming into the cell or going out. Autorhythmic cells

Contractile cells:

o The P4 phase is further away from threshold thus takes a lot of energy to get to threshold.

24. What are intercalated disks? What role do desmosomes and gap junctions play? - Interconnected by intercalated discs and form functional syncytium - Within intercalated discs – two kinds of membrane junctions o Desmosomes o Gap junctions

25. Diagram the mechanism for E-C coupling in cardiac muscle. Why is this also called Ca2+-induced Ca2+ release?

1. AP conducts along surface membrane and down into T-tubules 2. Depolarization of T-tubules activates Ca2+ influx via slow inward Ca2+ current 3. Influx of Ca2+ binds to and opens SR Ca2+ release channels (ryanodine receptors) 4. Ca2+ release from SR binds to troponin C to initiate cell contraction 5. Process known as Ca2+-induced Ca2+ release (CICR) 6. Contraction is maintained as long as cytosolic Ca2+ remains elevated 7. Relaxation is initiated when cytosolic Ca2+ is removed by: a. SR Ca2+ uptake (80%) (SERCA pump) b. Ca2+ efflux via Na/Ca exchange (18%) c. Ca2+ efflux via sarcolemma Ca2+ pump (2%) 26. In the myocardial contractile cell, the rapid depolarization phase is due to the entry of Na+. 27. The rapid depolarization phase in pacemaker cells is due to the entry of Ca2+. 28. The repolarization phase in autorhythmic cells is due to K+ outflow. How does this compare to a contractile cell? - In a contractile cell there is an early repolarization phase – Ca2+ open, fast K+ channels close - Later repolarization phase – Ca2+ channels close, slow K+ channels open 29. Where do electrical signals in the heart originate? - electrical signals originate in the SA node, and the signal then travels through your heart, triggering the 2 atria and then the 2 ventricles. 30. If you cut all nerves leading to the heart, will it continue to beat? Explain. - The heart has its own electrical system that causes it to beat and pump blood. Because of this, the heart can continue to beat for a short time after brain death, or after being removed from the body. The heart will keep beating as long as it has oxygen. 31. What cell structures allow electrical signals to spread quickly to adjacent cells? - Gap junctions within the intercalated disks allow impulses to spread from one cardiac muscle cell to another, allowing sodium, potassium, and calcium ions to flow between adjacent cells, propagating the action potential, and ensuring coordinated contractions. 32. Starting at the sinoatrial (SA) node, diagram the spread of electrical activity through the heart. - SA Node ฀ AV Node ฀ Purkinje Fiber ฀ contractile working cells 33. What is the purpose of AV node delay? - A normal AV node is important to the efficient functioning of the heart. The brief delay in the electrical impulse caused by the AV node optimizes cardiac function. That delay permits the atria to finish beating so that the ventricles completely fill with blood before the ventricles themselves begin to beat.

34. If the SA node is damaged, will the heart continue to beat? At the same rate? Explain. - If the SA node is damaged, the AV node takes over and since the AV node beats at a slower rate, the heart beats slower. 35. What is an electrocardiogram (ECG)? What information does an ECG show? 36. Name the waves of the ECG, tell what electrical event they represent, and name the mechanical event with which each wave is associated. 37. Define systole and diastole. - Systole – contraction of heart muscle ฀ first the atria contract as one, then the Ventricles - Diastole – relaxation of heart muscle 38. Is the heart in atrial and ventricular systole at the same time? Explain. 39. Briefly describe the major events that happen during each phase of the cardiac cycle. Indicate contraction and relaxation states for the chambers, pressure-volume changes for the chambers, heart sounds, and whether heart valves are open or closed. 40. Define end-diastolic volume (EDV). 41. Define stroke volume. How do you calculate it? (Give units.) 42. Define cardiac output (CO). What information does CO tell us? 43. Identify the mechanisms by which the parasympathetic and sympathetic divisions control heart rate. Specify the neurotransmitters/neurohormones, receptors, ions, and any second messengers that might be involved. 44. As sarcomere length increases, what happens to force of contraction? - As sarcomere length increases, the force of contraction increases. 45. Describe the Frank-Starling law of the heart. - Normal heart pumps during systole all the blood it receives in diastole - The Frank-Starling Law states that the stroke volume of the left ventricle will increase as the left ventricular volume increases due to the myocyte stretch causing a more forceful systolic contraction. - The more blood the heart receives the more blood it will pump because there is more tension is generated because of better alignment. - Because of the length-tension relationship, the more volume the more stretch - As the ventricle stretched with more blood, more optimal alignment of actin and myosin is attained. 46. Define venous return. What cardiac volume does it determine? - Venous return refers to the flow of blood from the periphery back to the right atrium, and except for periods of a few seconds, it is equal to cardiac output. - Volume of blood pumped by ventricle/beat - Determined by extent of venous return and by sympathetic activity - SV = EDV (end diastolic volume) – ESV (end systolic volume) 47. What are three factors that affect venous return? Name them and briefly describe how they influence venous return. - Venous BP alone is too low to promote adequate blood return and is aided by the: a. Respiratory “pump”: Pressure changes created during breathing b. Muscular “pump”: Contraction of skeletal muscles in the legs “milk” blood toward the heart c. Valves in the veins prevent backflow during venous return...