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Introduction to Blood Pressure

Introduction to Blood Pressure. Objectives. Define the term blood pressure. Define the terms: systolic blood pressure, diastolic blood pressure, mean arterial blood pressure and pulse pressure. Define the term total peripheral resistance

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Introduction to Blood Pressure

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  1. Introduction to Blood Pressure

  2. Objectives • Define the term blood pressure. • Define the terms: systolic blood pressure, diastolic blood pressure, mean arterial blood pressure and pulse pressure. • Define the term total peripheral resistance • List the short, intermediate and long term mechanisms involve on blood pressure regulation • Describe the role of baroreceptors on blood pressure regulation

  3. Blood Pressure: Generated by Ventricular Contraction

  4. Arterial Blood Pressure (ABP) Arterial Blood Pressure (ABP) is defined as the lateral pressure exerted by the blood on the arterial walls. Arterial blood pressure clinically expressed as Systolic/Diastolic blood pressure 120/80 mmHg Systolic Blood Pressure (SBP) is the maximal pressure exerted by the blood on the arterial walls during ventricular systole (100-140 mmHg). Diastolic Blood Pressure (DBP) is the minimal pressure exerted by the blood on the arterial walls during ventricular diastole (60-90 mmHg).

  5. Pulse Pressure (PP) is the difference between systolic and diastolic pressures e.g. 120 – 80 = 40 mm Hg. Mean Arterial Blood Pressure (MABP) is the average blood pressure in the arteries through out the cardiac cycle. It is calculated: MABP = DBP + 1/3 PP mm Hg. MABP = 80+1/3 40 = 93.3 mm Hg.

  6. Pulse and Mean Arterial Pressures

  7. Physiological variation of ABP • Age • Sex • Body build • Exercise • Emotions • Sleep

  8. Control of blood pressure • Mean arterial pressure is the main driving force for propelling blood to tissues • MAP must be closely regulated MAP high • Weakening of arterial walls lead to Aneurysms Risk of rupture & hemorrhage • Cerebral hemorrhage • Rupture of major artery MAP Low • Driving force for blood flow unable to overcome gravity • O2 supply to brain  • Symptoms?

  9. Factors controlling mean arterial BP MABP = CO x TPR CO Cardiac Output (SVXHR) TPR Total Peripheral Resistance (is the sum of the resistance of all peripheral vasculature in the systemic circulation)

  10. Regulation of Blood pressure • Short-term regulation • Acts with in seconds • Neural regulation (Baroreceptor reflexes >>> sympathetic and parasympathetic) • Hormones (adrenal medulla epinephrine and norepinephrine) • Long-term regulation • Acts within minutes to days (Kidney, rennin- angiotensin- aldosterone system)

  11. Cardiovascular Center

  12. Neural regulation of BP 1.Barorecptors reflexes

  13. Baroreceptor reflexes

  14. 2.Chemoreceptor Reflexes • Carotid & aortic body • Sensory receptors (detect blood levels of O2, CO2, & H ions)

  15. Hormonal Regulation Of BP 1. Adrenalin (Epinephrine) and nor-adrenaline (nor-epinephrine) Sympathetic stimulation.  Adrenal medulla releases E + NE  Vasoconstriction of arterioles & venules HR  strength of contraction  CO Increase BP

  16. 2. Renin-angiotensin- aldosterone (RAA) system

  17. 3.Anti-diuretic hormone (ADH) Synthesized in the hypothalamus and stored in the posterior pituitary gland * Dehydration or Blood Volume release of ADH  kidneys  reabsorption of H2O Blood volume BP * In large amounts ADH vasoconstriction (vasopressin)

  18. 4.Atrial natriuretic peptide (ANP) * Secreted by the atria of the heart * Blood volume stretch cells in the atria of the heart  Vasodilatation of Promote loss of Na & H2O Blood vessels  Blood volume  BP

  19. Homeostatic response to shock

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