Human Physiology: Fluid Compartments

Fluid Compartments

A fluid compartment is a space within the body that contains a fluid, such as blood, lymph, or interstitial fluid.

Types of Fluid Compartments

• Intravascular compartment: The space within blood vessels that contains blood.
  • Accounts for approximately 5% of total body fluid.
  • Contains plasma and formed elements (red blood cells, white blood cells, and platelets).
• Interstitial compartment: The space outside blood vessels and within tissues that contains interstitial fluid.
  • Accounts for approximately 15% of total body fluid.
  • Interstitial fluid surrounds cells and facilitates exchange of nutrients and waste.
• Intracellular compartment: The space within cells that contains intracellular fluid.
  • Accounts for approximately 40% of total body fluid.
  • Intracellular fluid is the fluid within cells and plays a crucial role in cellular functions.

Fluid Shifts

• Fluid shift: The movement of fluid from one compartment to another.
• Causes of fluid shifts:
  • Changes in blood pressure
  • Changes in osmotic pressure
  • Inflammation
  • Infection
  • Surgery
  • Trauma
• Effects of fluid shifts:
  • Edema (swelling)
  • Hypovolemia (decreased blood volume)
  • Hypervolemia (increased blood volume)

Regulation of Fluid Compartments

• Regulation mechanisms:
  • Osmoreceptors
  • Baroreceptors
  • Hormonal regulation (e.g., antidiuretic hormone, aldosterone)
  • Renal regulation (e.g., kidney function)
• Importance of regulation: Maintains fluid balance, blood pressure, and electrolyte balance.

Fluid Compartments

• The body contains three fluid compartments: intravascular, interstitial, and intracellular.

Types of Fluid Compartments

• Intravascular compartment: Contains blood, accounts for 5% of total body fluid, and includes plasma and formed elements (red blood cells, white blood cells, and platelets).
• Interstitial compartment: Contains interstitial fluid, accounts for 15% of total body fluid, and surrounds cells to facilitate exchange of nutrients and waste.
• Intracellular compartment: Contains intracellular fluid, accounts for 40% of total body fluid, and plays a crucial role in cellular functions.

Fluid Shifts

• Fluid shift: The movement of fluid from one compartment to another due to changes in blood pressure, osmotic pressure, inflammation, infection, surgery, or trauma.
• Effects of fluid shifts: Edema (swelling), hypovolemia (decreased blood volume), and hypervolemia (increased blood volume).

Regulation of Fluid Compartments

• Regulation mechanisms: Osmoreceptors, baroreceptors, hormonal regulation (e.g., antidiuretic hormone, aldosterone), and renal regulation (e.g., kidney function).
• Importance of regulation: Maintains fluid balance, blood pressure, and electrolyte balance.