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Cardiovascular System

Cardiovascular System. Chapter 13 – B.2. B.3.1 Define heart rate, stroke volume, cardiac output and venous return. Heart rate : number of heart contractions per minute measured by taking the pulse : alternating expansion and relaxation of elastic arteries during the cardiac cycle

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Cardiovascular System

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  1. Cardiovascular System Chapter 13 – B.2

  2. B.3.1 Define heart rate, stroke volume, cardiac output and venous return. • Heart rate: number of heart contractions per minute • measured by taking the pulse: alternating expansion and relaxation of elastic arteries during the cardiac cycle • Large animal = slow pulse • Small animal = fast pulse • Average pulse for humans = 65-75 bpm • Factors that affect heart rate or pulse: • Sex of the individual • Activity level • Emotions • Postural changes

  3. B.3.1 Define heart rate, stroke volume, cardiac output and venous return. (continued) • Stroke Volume: volume of blood pumped out by the heart with each contraction • Heart contraction = systole • Stroke volume = systolic discharge • Average SV for human = 70ml • Cardiac Output: volume of blood pumped out of the heart per minute • Stroke Volume x Heart Rate = Cardiac Output(ml/beat) (beats/min) (ml/min)

  4. B.3.1 Define heart rate, stroke volume, cardiac output and venous return. (continued) • Venous Return: volume of blood that returns to the heart via the veins each minute • affected by: • blood volume • heart contractions • muscle pumps throughout the body

  5. B.3.2 Explain the changes in cardiac output and venous return during exercise. • Exercise increases cardiac output • increased cardiac output = need for increased blood return to the heart by the venous system • so, there is an increase in squeezing action by skeletal muscles to move blood through the veins • results in increased blood volume in ventricles = increase in venous return

  6. B.3.3 Compare the distribution of blood flow at rest and during exercise. • Blood flow to the brain is constant during rest and exercise • During an exercise activity: • Increase in blood flow to organs involved • Skeletal muscles, cardiac muscles, and skin • Decrease in blood flow to: • Kidneys, stomach, intestine, other abdominal organs

  7. B.3.4 Explain the effects of training on heart rate and stroke volume, both at rest and during exercise. • During exercise, the heart undergoes hypertrophy (enlargement & strengthening) • Trained individuals benefit from: • Decrease in heart rate at rest & while exercising • Increased stroke volume at rest = increase in cardiac output • Other effects of aerobic exercise: • Decrease in blood pressure • Increase in blood volume • More effective blood distribution to body parts

  8. B.3.5 Evaluate the risks and benefits of using erythropoietin (EPO) and blood transfusions to improve performance in sports. • Blood transfusions (blood doping): artificially increases the number of RBCs in an athlete to enhance performance • EPO: stimulates production of RBCs in bone marrow • Both procedures increases oxygen carrying capacity of their blood = more efficient muscle activity

  9. B.3.5 Evaluate the risks and benefits of using erythropoietin (EPO) and blood transfusions to improve performance in sports. (continued) • Benefits of EPO and transfusions: • Treatment for anemia patients • Replacement of blood lost due to injury or surgery • Risks: • Increased blood viscosity • Increased blood pressure • Increased chance of blood clotting

  10. H.5.1 Explain the events of the cardiac cycle and heart sounds. • In an average human at rest, the entire heart cycle takes about 0.8 sec. • The cardiac muscles contract (systole) and relax (diastole) in a rhythmic cycle • During the relaxation phase (0.4 sec), blood returning from the veins flows into the atria and ventricles • A brief period (0.1 sec) of systole forces the blood from the atria into the ventricles • Last 0.3 sec, ventricular systole pumps blood into arteries

  11. H.5.1 Explain the events of the cardiac cycle and heart sounds. (continued) • The heart sounds are the closing of the valves in the heart • First sound (lub) is the blood hitting the closed AV valves • Second sound (dub) blood hitting the semilunar valves http://www.mhhe.com/biosci/esp/2002_general/Esp/folder_structure/tr/m2/s6/index.htm

  12. Define blood pressure and describe how it is measured. • Blood Pressure: The force of the fluid on the wall of the blood vessel. Creates movement. • Measured with two numbers • First number – systolic pressure • Second number – diastolic pressure • A sphygmomanometer is used • Pressure is applied until it closes the artery • The pressure is gradually released until blood flows and pulsing is heard (systolic pressure) • The pressure is further released until no sound is heard (diastolic pressure)

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