Regulation of blood pressure

• Regulation of blood pressure is the force exerted by circulating blood on the walls of blood vessels.
• It is crucial to maintain optimal blood pressure for the delivery of oxygen and nutrients to tissues and organs.
• The regulation of blood pressure involves several mechanisms:

1. Baroreceptors (Regulation of Blood Pressure)

• Location: Aortic arch and carotid arteries.
• Function: Detect changes in blood pressure.
  • Increased BP: Baroreceptors signal the medulla oblongata to activate the parasympathetic nervous system, reducing heart rate and dilating blood vessels, lowering BP.
  • Decreased BP: Signals the sympathetic nervous system, increasing heart rate and constricting blood vessels, raising BP.

2. Renin-Angiotensin-Aldosterone System (RAAS)

• Activation: Triggered by low BP or blood volume.
• Mechanism:
  • Renin (from kidneys) converts angiotensinogen into angiotensin I.
  • Angiotensin I is converted to angiotensin II by ACE.
  • Angiotensin II causes vasoconstriction and stimulates aldosterone release, promoting sodium and water retention, increasing BP and blood volume.

3. Kidneys

• Function: Regulate BP by managing fluid balance.
  • High BP: Kidneys excrete more sodium and water, lowering blood volume and BP.
  • Low BP: Kidneys retain sodium and water, increasing blood volume and BP.

4. Autonomic Nervous System (ANS)

• Sympathetic: Increases heart rate, contractility, and vasoconstriction to raise BP.
• Parasympathetic: Slows heart rate and dilates blood vessels to lower BP.

5. Local Factors(Regulation of Blood Pressure)

• Vasodilation: Local tissue hypoxia, pH changes, or chemicals like nitric oxide can cause blood vessels to dilate, reducing BP.
• Vasoconstriction: Opposite effects can increase BP.

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