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Slid e 1 “BASIC SUMMARY” of CARDIOVASCULAR PHYSIOLOGY  The purpose/goal of C.V.S. is : adequate PERFUSION of the Tissues  PERFUSION = BLOOD FLOW,  THUS,

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Presentation on theme: "Slid e 1 “BASIC SUMMARY” of CARDIOVASCULAR PHYSIOLOGY  The purpose/goal of C.V.S. is : adequate PERFUSION of the Tissues  PERFUSION = BLOOD FLOW,  THUS,"— Presentation transcript:

1 Slid e 1 “BASIC SUMMARY” of CARDIOVASCULAR PHYSIOLOGY  The purpose/goal of C.V.S. is : adequate PERFUSION of the Tissues  PERFUSION = BLOOD FLOW,  THUS,  DELIVERY of vital O 2 nutrients, etc,  REMOVAL of wastes.  “HEMODYNAMICS” refers to ALL the mechanisms  (blood moving/changing) involved in keeping blood flow ‘normal’

2 Slid e 2 DETERMINANTS OF PERFUSION:  1) CARDIAC OUTPUT Proper Electrical and Mechanical Function of the HEART as a PUMP 2) BLOOD VOLUME the vascular ‘tank’ must be adequately filled with fluid to supply the need 3) BLOOD PRESSURE : “ FLOW” of a fluid is dependent upon PRESSURE - and is always from “high” pressure area to lower pressure area.

3 Slid e 3 At rest, typically, Cardiac Output is 5 liters per minute (recall that an average man’s total Blood Volume is ~ 5 liters)

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6 Slid e 6 CARDIAC OUTPUT depends on 2 ‘functions’ of the heart:  A) ELECTRICAL function (Conduction system) Generation and Propagation of a coordinated Impulse to contract, from atrium to ventricle Conduction system: SA node, AV node, AV Bundle, R and L Bundle Branches, Purkinje system (graphic measure of conduction: electrocardiogram) ECG = “EKG” p wave, QRS complex, t wave B) MECHANICAL FUNCTION 1. CONTRACTILITY of the Myocardium ( strength / force of the contractions) 2. VALVULAR function

7 Slid e 7 AV Bundle, (Bundle of His) Cardiac conduction system: SA node AV node Bundle of His Right Bundle Branch Left Bundle Branch Purkinje Fibers

8 Slid e 8 ELECTRICAL FUNCTION  REGULATED RATE AND RHYTHM:  Rate -- optimal rate depends on demand.  normal at rest bpm (Lance Armstrong’s is in the 30’s )  abnormal rates: bradycardia too slow  tachycardia too fast  RHYTHM -- SHOULD BE REGULAR  not skippy or chaotic

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12 Slid e 12 Nor Normal sinus, rate ~64 bpm Onset, supraventricular tachycardia, rate ~120 Normal sinus rhythm, rate ~72 bpm Atrial fibrillation, V.rate varies, ~ Ventricular fibrillation, a terminal rhythm Rhythm strips

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14 Slid. e 14 MECHANICAL FUNCTION  CONTRACTILITY of the MYOCARDIUM:  the strength / force & completeness  of the Contractions  (effects of ischemia / necrosis; CAD, HTN drugs, etc)  The essence of “Congestive Heart Failure” is usually that of INADEQUATE squeeze capacity of the heart muscle

15 Slid e 15 Cardiac Cycle  DIASTOLE - atria contract,  Vent. relax; blood flows thru the AV valves, fills Ventricles. (P wave on the EKG)  SYSTOLE –Ventricles contract,  Blood EJECTED into Aorta and Pulm. Trunk, Art. (QRS complex on the EKG)

16 Slid e 16 VALVULAR FUNCTION  NARROWED VALVE: STENOSIS diminished outflow  INCOMPETENT VALVE: REGURGITATION or INSUFFICIENCY: abnormal “Backflow “ the “ Heart Sounds “ are made by the valves closing – ‘ Lub Dupp lub dupp lub dupp Murmur : swishing sound, made by TURBULENCE of flow can be either from Stenosis or Regurgitation *** abnormal valvular function affects Cardiac Output directly, and indirectly by eventually affecting Contractility of the muscle

17 CARDIAC OUTPUT  CARDIAC OUTPUT - HOW MUCH BLOOD CAN BE PUMPED each minute?  normal, resting ~ 5 liters / min (roughly the entire blood volume makes one cycle in one minute)  CO = HR x SV CARDIAC HEART RATE X STROKE VOLUME OUTPUT pulse amt blood ejected beats per minute each beat Slid e 17

18 Slid e 18 BLOOD VOLUME Euvolemia hypovolemia volume overload  Multiple variants:  “Hydration” status (intake -- outgo) diuresis, diarrhea, vomiting, sweating, hyperthermia/ fever,  Proper blood production by bone marrow  Lack of ‘hemorrhage’, or blood loss  complex regulatory mechanisms involving kidney function, endocrine regulatory centers, plasma protein conc., & others

19 Slid e 19 BLOOD PRESSURE  1. It takes adequate BLOOD Volume for normal BP  2. It takes adequate ‘FORCE’ on the FLUID  to make it FLOW:  A. Contractions of the Heart generate initial  PRESSURE SURGE, but, the chief determinant of Blood pressure is:  B. VASCULAR RESISTANCE- affects the BLOOD VOLUME IN THE ARTERIES:  Increased resistance VASOCONSTRICTION ^’s BP  (but less flow)  Decreased resistance decr’s BP: VASODILATION  (more flow)

20 Slid e 20 REGULATION of Arterial Resistance  The regulation / changes made in Arterial resistance  in the various ‘REGIONs’ of the body Account for the Alterations /adjustments in  BLOOD FLOW to those areas (increased flow to MUSCLES during exercise,  Incr. Flow to Digestive tract after meals,  ^ flowed to skin to dissipate heat, Whereas Blood Flow to BRAIN and KIDNEYS must remain rel. CONSTANT



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24 Slid e 24 other important effects (on CO, and PERFUSION)  VENOUS RETURN:  THE FLOW OF BLOOD BACK TO THE HEART AFTER  DELIVERY TO THE CAPILLARIES  VEINS:  larger diameter, with elastic walls, increased  CAPACITANCE compared to corresp. Artery  IMPORTANT - GRAVITY generally impedes VENOUS return so,  VEINS have series of one way VALVES - which keep  the blood from flowing backwards

25 Slid e 25 Also:  There are 2 FUNCTIONAL VENOUS  ‘PUMPS’:  1. SKELETAL MUSCLE CONTRACTIONS, and  2. RESPIRATORY MOTIONS create negative inspiratory pressure, which ‘’SUCKS’ VENOUS BLOOD INTO THE THORAX, TOWARD THE HEART

26 Modifications that promote venous return:  Large lumens  Valves  Muscular pump – skeletal muscle activity “milks” blood toward heart  Respiratory pump – pressure changes during breathing move blood toward heart

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28 Slid e 28 And FINALLY: CAPILLARIES  must mention : CAPILLARIES –  Where the ‘ACTION IS’ regarding EXCHANGE of  substances between the Vascular &  INTERSTITIAL spaces, at the  Cells / Tissues level. (fluid, o2, co2 WBC’s, molecules, etc ) can diffuse back and forth ( importance of hydrostatic and osmotic pressure )

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30 Slid e 30 Structure of Capillaries: ONLY 1 layer of endothelium and A basement membrane, with “SPACES” for DIFFUSION - no muscle or connective tissue covering. A large number of capillaries in a specific region is called a CAPILLARY BED

31 5. Circulatory Shock (or circulatory failure, a state of hypoperfusion) Inadequate blood flow to meet cellular needs.  Hypovolemic shock – due to decreased blood volume.  Septic shock (or vascular shock) – due to inappropriate vasodilation, brought about by response to overwhelming infection.  Cardiogenic shock – due to poor heart function.

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