Local Control of Blood Local Control of Blood FlowFlow

By:By:M. Rasjad IndraM. Rasjad Indra

Lab. Ilmu Faal FK UNIBRAWLab. Ilmu Faal FK UNIBRAW

IntroductionIntroduction The greater the metabolism The greater the metabolism the greater the greater

its blood flowits blood flow– Liver: 95 ml/min/100 g of liver tissue.Liver: 95 ml/min/100 g of liver tissue.– Kidneys: 1100 ml/min Kidneys: 1100 ml/min cleansing the blood. cleansing the blood.

The importance of blood flow control The importance of blood flow control effective & efficienteffective & efficient– Serving metabolic needServing metabolic need– Efficient heart workload.Efficient heart workload.

Mechanism of Blood Flow ControlMechanism of Blood Flow Control Acute control (rapid changes in local vasodilatation / Acute control (rapid changes in local vasodilatation /

vasoconstriction):vasoconstriction):– Effect of tissue metabolismEffect of tissue metabolism– The availability of oxygen changes.The availability of oxygen changes.– Two basic theories:Two basic theories:

Vasodilator theory: Vasodilator theory: adenosine; COadenosine; CO22; histamine; K; histamine; K++ & H & H++

Oxygen lack theory: Oxygen lack theory: vasomotion in metarterioles & precapillary vasomotion in metarterioles & precapillary sphincters.sphincters.

– Other nutrients besides Oxygen:Other nutrients besides Oxygen:– Lack of glucose Lack of glucose vasodilatation vasodilatation– Vitamin B deficiency Vitamin B deficiency vasodilatation vasodilatation

The examples of acute metabolic The examples of acute metabolic control of local blood flowcontrol of local blood flow

1.1. Reactive hyperemiaReactive hyperemia• Blocked (seconds – hours) Blocked (seconds – hours) unblocked unblocked• Blood flow increases to 4 – 7 times normalBlood flow increases to 4 – 7 times normal• Depends on how long it is blocked.Depends on how long it is blocked.

2.2. Active hyperemiaActive hyperemia• Tissue activity Tissue activity lack of nutrient & release lack of nutrient & release

vasodilator substances.vasodilator substances.• Local blood flow increases 20 times in Local blood flow increases 20 times in

muscle during heavy exercise.muscle during heavy exercise.

Blood flow control & The arterial Blood flow control & The arterial pressure changespressure changes

Acute autoregulation theory:Acute autoregulation theory:1.1. The metabolic theoryThe metabolic theory2.2. The myogenic theory (still doubtful !!)The myogenic theory (still doubtful !!)

Endothelial-Derived Relaxing Factor Endothelial-Derived Relaxing Factor “EDRF” (NO):“EDRF” (NO):

– Rapid flow of blood Rapid flow of blood shear stress shear stress NO NO release release relaxes the local arterial wall. relaxes the local arterial wall.

Long Term Blood Flow RegulationLong Term Blood Flow Regulation

1.1. Change in Tissue VascularityChange in Tissue Vascularity– Reconstruction to meet the needs of the Reconstruction to meet the needs of the

tissuestissues– Role of Oxygen in Long-Term Regulation.Role of Oxygen in Long-Term Regulation.– Vascular Endothelial Growth Factors:Vascular Endothelial Growth Factors:

1.1. VEGFVEGF2.2. FGFFGF3.3. AngiogeninAngiogenin

2.2. Collateral Circulation:Collateral Circulation:

Humoral Regulation of The CirculationHumoral Regulation of The Circulation1.1. Vasoconstrictor Agents:Vasoconstrictor Agents:

1.1. Norepinephrine & EpinephrineNorepinephrine & Epinephrine2.2. AngiotensinAngiotensin3.3. VasopressinVasopressin4.4. EndothelinEndothelin

2.2. Vasodilator Agents:Vasodilator Agents:1.1. BradikyninBradikynin2.2. HistaminHistamin

3.3. Effects of Ion & Other Chemical FactorsEffects of Ion & Other Chemical Factors1.1. Calcium Calcium vasoconstriction vasoconstriction2.2. Potasium Potasium Vasodilatation Vasodilatation3.3. Magnesium Magnesium powerful vasodilatation powerful vasodilatation4.4. Hydrogen Hydrogen vasodilatation vasodilatation5.5. Acetate & Citrate Acetate & Citrate mild degree vasodilatation mild degree vasodilatation

Humoral Regulation of The CirculationHumoral Regulation of The Circulation1.1. Vasoconstrictor Agents:Vasoconstrictor Agents:

1.1. Norepinephrine & EpinephrineNorepinephrine & Epinephrine2.2. AngiotensinAngiotensin3.3. VasopressinVasopressin4.4. EndothelinEndothelin

2.2. Vasodilator Agents:Vasodilator Agents:1.1. BradikyninBradikynin2.2. HistaminHistamin

3.3. Effects of Ion & Other Chemical FactorsEffects of Ion & Other Chemical Factors1.1. Calcium Calcium vasoconstriction vasoconstriction2.2. Potasium Potasium Vasodilatation Vasodilatation3.3. Magnesium Magnesium powerful vasodilatation powerful vasodilatation4.4. Hydrogen Hydrogen vasodilatation vasodilatation5.5. Acetate & Citrate Acetate & Citrate mild degree vasodilatation mild degree vasodilatation