Kin 470 1st EditionExam # 2 Study Guide Lectures: 10-16 KIN 470 Exam II Study Guide (bring a calculator to the Exam) 1. How does the timing of systole and diastole change from rest to maximal exercise? o During heavy exercise the demand may be 15 to 25 times greater than at resto The respiratory stem adds oxygen and removes carbon dioxide from the blood, while the circulatory system is responsible for the delivery of oxygenated blood and nutrients to the tissue in accordance with their needso To meet the increased oxygen demands of muscle during exercise there are two major adjustments- increased cardiac output and a redistribution of blood flow from inactive organs to active skeletal muscleso This is accomplished by maintaining blood pressureArteries- blood travels away from the heartVeins- blood returns to the heartAt restDiastolic is .5 secondsSystole is .3 secondsHeart Rate= 75 beats per minuteAT REST DASTOLIC IS LONGER THAN SYSTOLICSystole occupies 33% of the total cardiac cycle at restBlood pressure- 120/80 mmhg80mmhg + .33 (120-80)MAP= 93 mmhgDuring ExerciseDiastole is .13 secondsSystole is .2 secondsHeart Rate = 180 beats per minuteDURING EXERCISE BOTH SYSTOLC AND DIASTOLE ARE SHORTERSystole acconts for 66% of the total cardiac cycleBlood pressure 180/80 mmhg 80 mmhg + .67 (180-80)Pressure changes during the cardiac cycleDiastole- pressure in the arteries during cardiac relaxation-pressure in ventricle is low-filling with blood from the atria-AV value opens when ventricle pressure is less than atrial pressureSystole- pressure in the arteries generated by ventricular contractions-pressure in ventricles rises-blood ejected in pulmonary and systemic circulation-semilunar values opens when ventricular pressure is greater than aortic pressure- 2/3 blood is ejected from ventricles per beatHeart Sounds-first: closing of the AV values-second: closing of aortic and pulmonary valvesPulse pressure= systolic- diastolicMean arterial pressure- average pressure in the arteries determines rate of systemic blood floeMAP= Diastolic + 1/3 (pulse pressure)High blood pressure is 140/90 mmHgFactors that influence arterial blood pressure-blood viscosity increases-blood volume increases-heart rate increases-stroke volume increases-peripheral resistance increases2. What factors regulate stroke volume of the heart? Cardiac output- Q= HR * SVStroke volume is regulated by-end diastolic volume (EDV)- the volume of blood in the ventricles at the end of diastole- preload-influences stroke volume by the FRANK STARLING LAW-strength of ventricular contraction increases with an enlargement of EVD-the increase of the EDV results in a lengthening of cardiac fibers which improves the force of contraction in a manner similar to that seen in skeletal muscle-an increase in the length of the cardiac fibers increases the number of myosin cross bridge interaction with actin, resulting in creased force production-a rise in cardiac contractility results in an increase in the amount of blood pumped per beat-the rate of venous return to the heart-an increase in the venous return results in a rise in EDV and therefore, an increase in stroke volume.-regulate venous return-constriction of veins (venoconstrition)-increases venous return by reducing the volume capacity of the veins tostore blood. The end result of a reduced volume capacity in veins is to move blood back towards the heart-pumping action of contracting skeletal muscles (muscle pump)-result of the mechanical action of rhythmic skeletal muscle contractions. - When muscle contracts during exercise they compress veins and push blood back towards the heart. -Between contractions blood refills the veins and the process is repeated. -Blood is prevented rom flowing away from the heart between contractions by the one way values located in the large veins. -During sustained muscular contractions (isometric exercise) the muscle pump cannot operate and venous return to the heart is reduced- pumping action of the respiratory system ( respiratory pump)- rhythmic pattern of breathing also provides a mechanical pump which venous return is promoted-the average aortic blood pressure-pressure the heart must pump against to eject blood (afterload)mean arterial pressure-in order to eject blood the pressure generated by the left ventricle must exceed the pressure in the aorta.-the aortic pressure ( afterload) represents a barrier to the ejection of blood from the ventricles-stroke volume is inversely proportional to the afterload-increased aortic pressure produces a decrease in stroke volume-afterload is minimized during exercise due to arteriole dilation-arterial dilation in the working muscles reduces afterload and makes it easier for the heart to pump a large volume of blood-the strength of t contraction-effect of circulating catecholamines (epinephrine and norepinephrine) and direct sympathetic stimulation of the heart by cardiac accelerator nerves--- this increases cardiac contractility by increase the amount of calcium available to the myocardial cell-both epinephrine and norepinephrine both increase the entry of extracellular calcium into the cardiac muscle fiber which increases cross- bridge activation and force production*** increase contractility increases stroke volume-circulating epinephrine and norepinephrine-increase force of contraction in the heart-increases the amount of calcium in the heart muscle and the sensitivity to the calcium-more calcium equals more circulating blood which in turn equals more force3. What factors determine vascular resistance and of these which is the most important? Vascular resistance is the sum of resistance to blood flow provided by all systemic blood vessels-blood viscosity -peripheral resistance-blood is composed of plasma and cells-blood flow through the vascular system is directly proportional to the pressure at the two ends of the system and inversely proportional to resistanceBLOOD FLOW= CHANGE IN PRESSURE / RESISTANCE-the most important factor determining resistance to blood flow is the radius of the blood vesselRESISTANCE= LENGTH * VISCOSITY/ RADIUS-the greatest vascular resistance to blood flow is offered in the arterioles- Length of the vessel- Viscosity of the blood- Radius of the vessel (Most important)- Sources of vascular resistanceo MAP decreases throughout the systemic circulation Largest drop occurs across the arterioles- Arterioles are called “resistance vessels”4. What mechanical events occur in the