fluid and electrolyte balances Flashcards
Describe the fluid compartments in the body and how each contributes (proportionally) to total
body water.
- extracellular fluid (~40%) : blood plasma (~8%), interstitial fluid(~32%)
- intracellular fluid (~26%)
- electrolytes
Compare osmotic and hydrostatic pressures in relation to water movement between fluid
compartments
- osmotic pressure drives water movement based on solute concentration differences
- hydrostatic pressure pushes fluid out of capillaries into the interstitial space
- These pressures interact to regulate fluid balance between compartments in the body
Describe the routes of water gain and loss from the body
water loss:
- sensible loss: urine, feces
- nonsensical loss: skin, sweat
- obligatory loss: minimum amount of urine that must be produced per day in order to maintain healthy functions
water gain:
- ingested: food, liquids
- formed: metabolism
Describe the mechanisms that regulate water intake and output, and explain how dehydration
and overhydration develop
- Dehydration results from a deficit in body water volume
- overhydration occurs when there is an excess of body water volume.
Summarize the function of the most prevalent electrolytes found in body fluids
- Sodium (Na⁺): Maintains fluid balance, regulates blood pressure, facilitates nerve impulse transmission, and supports muscle function.
- Potassium (K⁺):Essential for nerve impulse transmission, muscle contraction (including heart muscle), and maintaining fluid balance within cells.
- Chloride (Cl⁻): Helps maintain fluid balance, aids in digestion (as a component of stomach acid), and plays a role in maintaining the body’s acid-base balance.
- Calcium (Ca²⁺): Supports bone and teeth health, muscle contraction, nerve function, blood clotting, and enzyme regulation.
- Magnesium (Mg²⁺): Essential for muscle and nerve function, energy metabolism, bone health, and maintaining electrolyte balance.
Describe the hormonal regulation of electrolyte levels in the plasma, explain the factors that determine the pH of blood and describe how it is maintained within its normal range
Buffer Systems:
- Bicarbonate Buffer System: Bicarbonate ions (HCO₃⁻) can act as a weak base to neutralize excess hydrogen ions (H⁺) in the blood, helping to maintain pH within a normal range.
- Protein Buffer System: Proteins, particularly hemoglobin and albumin, can bind to hydrogen ions, buffering changes in pH.
- Phosphate Buffer System: Phosphate ions (HPO₄²⁻) can act as a weak acid or base to help maintain pH balance.
Respiratory Regulation:
- The respiratory system regulates blood pH by adjusting the levels of carbon dioxide (CO₂) through respiration. Increasing ventilation removes CO₂, decreasing carbonic acid (H₂CO₃) formation and lowering blood acidity. Conversely, decreased ventilation leads to CO₂ retention, increasing blood acidity.
Renal Regulation:
- The kidneys regulate blood pH by excreting hydrogen ions (H⁺) or reabsorbing bicarbonate ions (HCO₃⁻) in response to changes in blood pH. This renal regulation occurs more slowly than respiratory regulation but has a more long-lasting effect on pH balance.
Describe the buffer systems that help to keep the pH of the body’s fluids stable
- Bicarbonate Buffer System:
Components: Bicarbonate ions (HCO₃⁻) and carbonic acid (H₂CO₃).
Function: Bicarbonate ions act as weak bases, while carbonic acid acts as a weak acid. They can accept or release hydrogen ions (H⁺) to maintain pH balance. - Protein Buffer System:
Components: Proteins, particularly hemoglobin and albumin.
Function: Proteins contain ionizable groups that can bind to or release hydrogen ions (H⁺) to buffer changes in pH. - Phosphate Buffer System:
Components: Phosphate ions (HPO₄²⁻ and H₂PO₄⁻).
Function: Phosphate ions can act as weak acids or bases, accepting or donating hydrogen ions (H⁺) to maintain pH balance.
Describe the role of the respiratory system in regulating blood pH, and predict how hypo- and
hyperventilation will affect blood pH
- hypoventilation leads to respiratory acidosis, characterized by a decrease in blood pH, while - hyperventilation leads to respiratory alkalosis, characterized by an increase in blood pH.
- These conditions reflect the respiratory system’s role in regulating blood pH by adjusting CO₂ levels through respiration.
Describe the relationship of CO2 and H+ to blood pH
- increased levels of CO₂ lead to increased H⁺ ions and decreased blood pH
- decreased levels of CO₂ lead to decreased H⁺ ions and increased blood pH.
- this relationship demonstrates how changes in CO₂ levels affect blood pH through alterations in H⁺ ion concentration.
Discuss the concept of compensation to correct respiratory and metabolic acidosis and alkalosis
- Respiratory Compensation:
In respiratory acidosis, the kidneys increase reabsorption of bicarbonate ions (HCO₃⁻) and excrete hydrogen ions (H⁺) to restore pH balance.
In respiratory alkalosis, the kidneys decrease reabsorption of bicarbonate ions (HCO₃⁻) and retain hydrogen ions (H⁺) to restore pH balance. - Metabolic Compensation:
In metabolic acidosis, the respiratory system increases ventilation to remove excess carbon dioxide (CO₂), which decreases carbonic acid (H₂CO₃) formation and increases blood pH.
In metabolic alkalosis, the respiratory system decreases ventilation to retain carbon dioxide (CO₂), which increases carbonic acid (H₂CO₃) formation and decreases blood pH.
Provide specific examples to demonstrate how the cardiovascular, endocrine, and urinary
systems response to maintain homeostasis of fluid volume, electrolyte concentration, and pH in
the body
- Cardiovascular System:
Fluid Volume: The cardiovascular system regulates fluid volume by adjusting blood pressure and blood volume. For example, when blood pressure decreases due to dehydration, the cardiovascular system can increase heart rate and vasoconstriction to maintain blood pressure and restore fluid volume. - Endocrine System:
Electrolyte Concentration: The endocrine system, particularly the adrenal glands, regulates electrolyte concentration. For instance, aldosterone, released by the adrenal glands, increases sodium reabsorption and potassium secretion in the kidneys, helping to maintain electrolyte balance. - Urinary System:
pH Balance: The urinary system helps regulate pH balance by excreting excess acids or bases in the urine. For example, when blood pH decreases (acidosis), the kidneys excrete hydrogen ions (H⁺) and retain bicarbonate ions (HCO₃⁻) to increase blood pH.
