Chapter 18- Cardiac output
Chapter 18- Cardiac output KNR 182
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This 31 page Bundle was uploaded by Christina on Monday October 26, 2015. The Bundle belongs to KNR 182 at Illinois State University taught by Dr. Rinaldi-MIles in Summer 2015. Since its upload, it has received 69 views. For similar materials see Human Anatomy and Physiology II (lecture) in Kinesiology at Illinois State University.
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Date Created: 10/26/15
HUMAN ANATOMY amp PHYSIOLOGY KNR 182 Cardiovascular System Chapter 18 Cardiac Output Cardiac Output CO Amount of blood pumped by each ventricle in one minute Lmin CO heart rate HR x stroke volume SV COHRXSV HR number of beats cardiac cycles per minute beatsmin SV volume of blood pumped out by a ventricle with each beat Lbeat Cardiac Output CO At rest CO Lmin HR 75 beatsmin gtlt SV 70 mlbeat 525 Lmin aka average blood volume Maximal CO is 4 5 times resting CO in nonathletio people Maximal CO may reach 35 Lmin in trained athletes Regulation of Stroke Volume SV end diastolic volume EDV end systolic volume ESV SV EDV ESV End diastolic volume EDV is equal to the amount of blood in the ventricle at the end of filling right before the ventricle contracts Lmin End systolic volume ESV is equal to the amount of blood in the ventricle at the end of ejection or emptying Lmin Atrium In a healthy person End of ventricular contraction an eleCtlon 30th IS 6000 a b Blood vessels EDV 100 ml ESV 40 ml SV 60 ml c 42oo mlmin it 42 Lmin A Figure 76 Calculations of a stroke volume 8V which is the difference between enddiastolic volume EDV and endsystolic volume ESV b ejection fraction EF and 0 cardiac output 0 Regulation of Stroke Volume SV EDV ESV Three main factors affect SV Preload Contractility Afterload Hiegulation of Stroke Volume Preload degree of stretch of cardiac muscle cells before they contract FrankStarling law of the heart influences end diastolic volume Cardiac muscle exhibits a lengthtension relationship exhibited by cardiac muscle cells and skeletal muscle cells At rest cardiac muscle cells are shorter than optimal length Slow heartbeat and exercise increase venous return Increased venous return or volume distends stretches the ventricles and increases contraction force t in speed of venous return 1 EDV1 SV Increase of venous return increase EDV SV Regulation of Stroke Volume Contractility contractile strength at a given muscle length Sympathetic stimulation increases contractility Independent of muscle stretch and EDV Increased sympathetic stimulation increased contractility SIContractilityf volume ejected lESVt Regulation of Stroke Volume Afterload pressure that must be overcome for ventricles to eject blood Healthy individuals afterload is not a major determinant of sv Hypertension increases afterload resulting in increased ESV and reduced SV Increase afterload increase ESV Decrease SV a Preload Copyright 02001 Beniamin Cummings an Imprint oi Addison Wesiey Lo b Afterload Copyright 2001 Benjamin Cummings an imprint ol mason Wesley Longnan Inc E lectrical Activity SA node Intranodal amp Intraatrial Fibers AV node Bundle of His R amp L Bundle Branches Purkinje Fibers Mechanical Event Atrial Systole Ventricular Systole Pressure Change Atrial Pressure Ventricular Pressure Aortic Pressure Blood FlowCardiac Output w Lrgin l 1 Stroke Volume X Heart Rate Lbeat btsmin w Lrgin l 1 Stroke Volume X Heart Ratel Lbeat btsmin w Lrgin l 1 Stroke Volume X Heart Ratel Lbeat btsmin Cardiac Output LIllin I 3 Stroke Volume X Heart Rate Lbeat l btsmin l T 1 End Diastolic End Systolic Volume 1 Volume Lbeat Lbeat T l venous Return Lmin T l 1 Stroke Volume X Heart Rate 1 Lbeat btsmin 1 T 1 T1 End Diastolic End Systolic Volume Voume Sympathetic Parasympathetic Lbeat Lbeat Nervous Nervous T System System venous Return C 39 mmwwam Sympathetic trunk Sympathetic Copynml 2001 Benjamin Cummlngs an Imprint a mason Wesley Longnan Inc Lmin T l 1 Stroke Volume X Heart Rate 1 Lbeat btsmin 1 T 1 3 End Diastolic End Systolic Volume Volume Sympathetic Parasympathetlc Lbeat Lbeat Iquot Nervous Nervous T Sys tem Sys tem 1 Contractility 1 Venous Central Nervous System Return Factors Affecting Venous Return Blood Volume Breathing Responses Valsalva Maneuver Skeletal Muscle Pump w Lmin T l 1 Stroke Volumel X Heart Rate 1 Lbeat btsmin i T i 3 End Diastolic End Systolic I 1 I Voiumel l Volumet Sympathetic Parasympathetic Lbeat Lbeat Nervous Nervous System System 1 I Contractility 1 1 I Venous 1 Central Nervous System Return w Lmin T l 1 Stroke Volume X Heart Ratel 1 Lbeat btsmin T End Dilastolic End S stolic l at Volume Voume Sympathetic Parasympathetic Lbeat Lbeat Nervous Nervous 1 t l SysAtem SysAtem l Contractility I 1 39 Venous Central Nervous System Return Autonomic Nervous System Regulation Sympathetic nervous system is activated by emotional or physical stressors Norepinephrine causes the pacemaker to fire more rapidly and at the same time increases contractility Autonomic Nervous System Regulation Parasympathetic nervous system opposes sympathetic effects Acetylcholine hyperpolarizes pacemaker cells by opening K channels Exercise by t Heart rate Bloodborne Exercise fskeletal muscle and auows more epinephrine fright anxiety respiratory pumps time for thyroxine see Chapter 19 ventricuar excess Ca2 filling J lVenous fSympathetic tParasympathetic L return J bcontractlllt d L activity J L activity J V1 I tEDV l preload L ESV J 1 Stroke f Heart volume rate tCardiac output 1 Initial stimulus Physiological response i Result Figure 1822 1 If heart rate increases cardiac output increases It heart rate decreases cardiac output decreases 2 If stroke volume increases cardiac output decreases If stroke volume decreases cardiac output decreases 3 If end diastolic volume increases stroke volume increases It end diastolic volume decreases stroke volume decreases 4 If end systolic volume increases stroke volume increases It end systolic volume decreases stroke volume decreases 5 If end diastolic volume increases stroke volume increases and cardiac output increases 6 If end diastolic volume decreases stroke volume decreases and cardiac output decreases 7 If end systolic volume increases stroke volume decreases and cardiac output decreases 8 If end systolic volume decreases stroke volume increases and cardiac output increases Redistribution of Blood Flow Cardiac output is distributed to different regions of the body depending on the need for blood tlow within that particular region Under resting conditions the needs are different as compared to exercise situations As we change the metabolic demands we nd that the cardiovascular system accommodates these changes by distributing lood trom areas of low metabolic activity to areas of hih metabolic activity is accomplished mainly through central nervous system control ot the arterioles the major site of resistance to blood How By closing the arterioles in one vascular region and opening the arterioles in another vascular region blood ow can be redistributed This works much in the same way that water distribution occurs in many houses We know that when someone is taking a shower and the water is turned on another region of the house ie ushing the toilet water distribution changes All of a sudden the water temperature in the shower changes and becomes extremely hot or cold A good tactic to use when ettin even with our roomates brothers or sisters when they are shower Opps I am sorry it was an accident l didn t know that you were in there Blood ow redistribution across vascular areas within the body between rest and exercise situations 14 12 39th 3 5 lilRest EXEFCWSIE Your body can re distribute the amount of blood flow to certain parts of the body depending on activity Brain Heart Skeletal muscle Abdomen Other Total blood ow dunng strenuous exercise 17500 mIImin Copyright 2001 Benjamin Cummings an lmprlnl ol Addlsm Wesley Longman Inc Cardiac Output Representative values Lbeat for EDV and ESV at rest amp during exercise The heart is a muscle The more you work it the better it works The trained people are able to eject more blood EDV is different btw trained and untrained SV End End Systolic Lbeat Diastolic Volume Volume Lbeat Lbeat Rest 007 012 005 Exercise 012 016 004 untrained Exercise 019 022 003 trained Cardiac Output Representative values mlbeat for EDV and ESV at rest amp during exercise SV End End Systolic mlbeat Diastolic Volume Volume mlbeat mlbeat Rest 70 120 50 Exercise 120 160 4O untrained Exercise 190 220 30 trained Average values for cardiac output and it s components for different types of individuals at rest and during exercise Stroke Type of subject Cardiac Output Heart Rate Volume and condition Lmin btsmin x Lbeat Rest 56 80 x 0070 untrained Max Ex 234 untrained Max Ex 2868 trained Max Ex 3610 highly trained Cardiac Output Lmin T l 1 Stroke Volume X Heart Rate 1 Lbeat btsmin End Diastolic End Systolic Ll o Volume Volume Sympathetic Parasympathetlc Lbeat Lbeat gervous gervous stem ystem T Vt t Contractlllty 1 Venous Central Nervous System Return E lectrical Activity SA node Intranodal amp Intraatrial Fibers AV node IMPORTANT FOR TEST Bundle of His R amp L Bundle Branches Purkinje Fibers Mechanical Event Atrial Systole Ventricular Systole Pressure Change Atrial Pressure Ventricular Pressure Aortic Pressure V Blood FlowCardiac Output
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