Fluid Balance and Osmolarity Review

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Questions and Answers

What must be closely regulated to help maintain blood pressure?

ECF volume (correct)

ICF volume

Potassium ion concentration

Sodium ion concentration

What is necessary to prevent the swelling or shrinking of cells?

Controlling protein levels

Regulating ECF osmolarity (correct)

Maintaining ECF temperature

Balancing hematocrit

Which of the following contributes to water input in the body?

Insensible loss

Sensible loss

Sweating

Drinking liquids (correct)

Which type of loss is considered insensible?

Lungs Signup and view all the answers

What must occur to maintain stable water balance in the body?

Water input must equal water output Signup and view all the answers

What effect does increased osmolarity have on water concentration?

It decreases water concentration Signup and view all the answers

Which ion is primarily responsible for extracellular fluid (ECF) osmolarity?

Na+ Signup and view all the answers

What does ICF stand for and which ion is significant in it?

Intracellular fluid; K+ Signup and view all the answers

How does increased osmolarity affect solute concentration?

It increases solute concentration Signup and view all the answers

In which fluid is sodium the primary solute?

Extracellular fluid Signup and view all the answers

What does the equality of total concentration of Na+ and other solutes in ECF to K+ and other solutes inside the cell indicate?

The extracellular fluid is isotonic to the intracellular fluid. Signup and view all the answers

Why is it important for Na+ and K+ concentrations to be balanced across the cellular membranes?

To prevent excessive water inflow and cell swelling. Signup and view all the answers

Which of the following best describes the relationship between Na+ and K+ in terms of cellular equilibrium?

K+ concentration is higher in the cell, while Na+ is higher in ECF. Signup and view all the answers

What implication does the equal total concentration of solutes have on cellular functions?

It supports chemical reactions necessary for homeostasis. Signup and view all the answers

What occurs when there is a disturbance in the balance of Na+ and K+ concentrations?

Cellular activity may become disrupted or impaired. Signup and view all the answers

Study Notes

Fluid Balance

Two factors regulate fluid balance: ECF volume and ECF osmolarity.
ECF volume regulation is vital for maintaining blood pressure.
Long-term ECF volume regulation requires maintaining salt balance.
ECF osmolarity regulation prevents cell swelling or shrinking.
Water balance controls ECF osmolarity.

Water Input and Output

Water input comes from drinking fluids, eating solid foods, and metabolically produced water (oxidation of carbohydrates, lipids, and proteins).
Water output includes insensible loss (lungs, non-sweating skin), sensible loss (sweating, feces, urine), and excretion.

ECF Osmolarity

Increased ECF osmolarity means a higher solute concentration and lower water concentration.
Sodium (Na+) is the primary solute in ECF, determining ECF osmolarity.
Potassium (K+) is the main solute responsible for ICF osmolarity.
ECF and ICF solute concentrations are equal.
Severe hypertonicity (hyperosmolarity) of ECF can affect brain cells and function, leading to mental confusion.

Body Fluid Compartments

Blood vessel walls separate plasma and interstitial fluid.
Cellular plasma membranes separate ECF and ICF.

Factors Affecting Total Body Water

Age, lean tissue, and gender influence body water content.
Lean tissue has a higher fluid content than fat tissue.
Males have more lean tissue, resulting in more body fluids.
Body fluid decreases with age due to loss of lean tissue.

Differences Between ECF and ICF in 70 kg Adult Male

Feature	ECF	ICF
Volume	15L	25L
Na+	142 mmol/L	10 mmol/L
K+	4 mmol/L	140 mmol/L
Ca++	2.5 mmol/L	Negligible
Cl-	105 mmol/L	4 mmol/L
HCO3-	25 mmol/L	10 mmol/L
Protein-	17 mEq/L	65 mEq/L
pH	7.4	7.2
Osmolarity	280-300 mOsmol/L	280-300 mOsmol/L

Important Differences Between ECF & ICF

Feature	ICF	ECF
Na+	Low	High
K+	High	Low
Ca++	Negligible	High
Cl-	Low	High
Protein-	High	Low
Osmolarity	Equal to ECF	Equal to ICF

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Description

This quiz covers the essential concepts of fluid balance, including the regulation of ECF volume and osmolarity. You'll explore how these factors maintain blood pressure and influence water input and output. Test your knowledge about the roles of sodium and potassium in osmolarity and their effects on cellular health.