Fluid Balance and Disorders

Excess Water Retention

• Excess water retention dilutes the sodium in the extracellular fluid (ECF).
• This can be caused by excessive secretion of anti-diuretic hormone (ADH), which causes the kidneys to reabsorb more water.

Hypernatremia

• Hypernatremia is an increase in plasma sodium concentration.
• Causes include:
  • Loss of water from the ECF, concentrating sodium ions. This can occur in cases of dehydration.
  • Excess sodium chloride added to the ECF, for example, excessive secretion of the hormone aldosterone.

Edema

• Edema is visible swelling caused by fluid accumulation in interstitial spaces.
• Becomes apparent when interstitial fluid volume increases by 2.5 to 3 liters.
• The pathophysiological mechanisms of edema formation are:
  • Increased capillary filtration pressure
  • Decreased capillary colloidal osmotic pressure
  • Increased capillary permeability
  • Obstruction to lymph flow

Increased Capillary Filtration Pressure

• As capillary filtration pressure rises, the movement of vascular fluid into the interstitial spaces increases.
• Factors increasing capillary pressure include:
  • Decreased resistance to flow through the precapillary sphincters
  • Increased venous pressure or resistance to outflow at the post-capillary sphincters

Decreased Capillary Colloid Osmotic Pressure

• Plasma proteins exert capillary osmotic pressure, pulling fluid from the tissue back into the capillaries.
• Albumin, a plasma protein, plays a major role in this osmotic pressure.
• Edema caused by a decrease in capillary colloidal osmotic pressure results from inadequate production of albumin.
• Factors decreasing capillary pressure include:
  • Severe illness
  • Starvation and malnutrition (lack of amino acids needed for albumin production)
  • Kidney diseases (inability to produce albumin or leakage of proteins into urine)

Increased Capillary Permeability

• Damaged capillary pores lead to increased permeability, allowing fluid to move into interstitial spaces.
• Factors increasing capillary permeability include:
  • Burn injury

This quiz explores key concepts related to fluid balance and disorders such as excess water retention, hypernatremia, and edema. Questions will cover the physiological mechanisms behind these conditions and their implications for health. Educate yourself on the factors affecting fluid retention and electrolyte balance.