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Blood Pressure

Blood Pressure. Dr. Ola Tork MD.Physiology. Factors affecting Heart rate. Autonomic nervous system Hormones Position Exercise Emotional states Gender Age Temperature Baroreceptor reflex. Arterial blood pressure :.

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Blood Pressure

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  1. Blood Pressure Dr. Ola Tork MD.Physiology

  2. Factors affecting Heart rate • Autonomic nervous system • Hormones • Position • Exercise • Emotional states • Gender • Age • Temperature • Baroreceptor reflex

  3. Arterial blood pressure: • Definition: lateral force that the blood flow exerts on the wall of blood vessel. • Systolic blood pressure • Diastolic blood pressure • Pulse pressure

  4. Physiological variation in blood pressure • Age • Gender • Race • Position • Emotions • Exercise • Gravity • Respiration

  5. Factors determine ABP& PP ABP = COP x TPR TPR : total peripheral resistance which depends mainly on the diameter of arterioles , so that VC → ↑ TPR VD → ↓ TPR

  6. ABP = SV x HR x TPR • Stroke volume: • Heart rate : • Peripheral resistance • Elasticity of aorta & big arteries

  7. Regulation of ABP: • Rapid : nervous mechanism • Intermediate: capillary fluid shift • Slow : hormonal & renal mechanism

  8. Nervous mechanism Cardiovascular centers are present in the medulla in 2 areas: Pressor area: 2 centers CSC & VCC Depressor area: 2 centers CIC & VDC

  9. The activity of these centers is modified by afferents from: • Receptors inside CVS • Receptors outside CVS • High centers • Blood gases changes: • Mild ↓ O2 & ↑ CO2 → ↑ ABP • Severe ↓ O2 & ↑ CO2 → ↓ ABP & death

  10. Vasoconstrictor center (VCC ): Has a continuous tone under resting conditions • VC of arterioles →↑TPR →↑ABP • VC of veins →↑VR →↑COP →↑ABP • Vasodilator center (VDC ): It inhibits VCC

  11. Capillary fluid Shift • It is the intermediate mechanism • If ↑ABP →↑ capillary hydrostatic pressure →↑ filtration of fluid from plasma to ISF →↓ plasma volume →↓ venous return →↓ ABP

  12. While if ↓ABP → ↓ capillary hydrostatic pressure → ↓ filtration of fluid from plasma to ISF + ↑reabsorption at venular end by osmotic pressure → ↑ plasma volume → ↑ venous return → ↑ ABP

  13. Role of the kidney & hormones in regulation of BP • It is slow mechanism • The kidney regulate ABP by regulating plasma volume & ECF • On ↓ABP , it is elevated by 2 mechanisms: • Renin- Angiotensin system • Atrial mechanoreceptors

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