Water, Electrolytes, and Acid-Base Balance

Water, Electrolytes, and Acid-Base Balance

• Overview of key components involved in maintaining homeostasis in the body.

Body Fluids

Regulation of Water Intake

• The primary regulator of water intake is thirst.

  • Other factors like saliva production and small changes in extracellular fluid (ECF) volume are less influential.

Body Fluid Compartments

• Capillary endothelium separates the following:

  • ICF (Intracellular Fluid) and ECF (Extracellular Fluid) (Cell compartments of fluids).

• Plasma and Interstitial Fluid are also distinct compartments.

Intracellular vs Extracellular Fluid

• Intracellular fluid (ICF):

  • Contains lower concentrations of sodium ions compared to ECF.

  • Contains higher concentrations of potassium ions than ECF.

Blood Pressure Effects

• A decrease in blood pressure can lead to:

  • Increased secretion of aldosterone.

  • Decreased secretion of ADH (Antidiuretic Hormone).

  • Inhibition of sympathetic stimulation and vasodilation.

Atrial Natriuretic Hormone (ANH)

• ANH secretion is stimulated by increased blood volume.

  • It decreases sodium reabsorption and fluid volume.

Electrolytes

Identification of Electrolytes

• The primary electrolytes:

  • Sodium (Na+), Chloride (Cl-), Potassium (K+), and Calcium (Ca2+).

  • H2O (water) is not an electrolyte.

Effects of Sodium on Cells

• Increased extracellular sodium levels causes:

  • Water to shift from ICF to ECF leading to potential cell dehydration.

Regulation of Calcium Levels

• ECF calcium levels are mainly regulated by:

  • Parathyroid hormone (PTH).

Phosphate Presence

• 85% of phosphate in the body is found as calcium phosphate salts in bones and teeth, true or false.

Aldosterone Secretion

• Aldosterone secretion is stimulated by:

  • Angiotensin II and elevated potassium levels.

Acid-Base Balance

Definition of an Acid

• An acid is defined as a substance that:

  • Releases H+ ions when it dissociates.

pH Regulation Mechanisms

• Respiratory regulation of pH depends primarily on:

  • The carbonic acid/bicarbonate buffer system.

Blood CO2 Levels and pH Variations

• An increase in blood carbon dioxide leads to:

  • An increase in H+ concentrations (lowering pH).

Urine pH Response

• If blood pH decreases, urine pH will likely:

  • Decrease as the body attempts to excrete more acid.

Hyperventilation Effects

• Hyperventilation due to emotional states typically leads to:

  • Respiratory alkalosis (raising blood pH).

Clinical Focus

Hypocalcemia Symptoms

• Symptoms of hypocalcemia include:

  • Muscle spasms and fatigue among others.

Diuretics Description

• A diuretic is defined as:

  • A substance that causes increased urine production.

Effects of ADH Hyposecretion

• Hyposecretion of ADH can cause:

  • Diabetes insipidus.

CO2 Elimination Issues

• Reduced elimination of CO2 results in:

  • Respiratory acidosis.

Causes of Metabolic Acidosis

• Common causes of metabolic acidosis exclude:

  • Ingestion of sodium bicarbonate.

Grab Bag Questions

• Loss of a large volume of sweat makes body fluids:

  • Hypertonic, causing a decrease in plasma volume.

Smallest Source of Water Loss

• The smallest source of water loss typically comes from:

  • Feces.

CO2 and H2O Reaction

• The reaction between CO2 and H2O is catalyzed by:

  • Carbonic anhydrase.

Calcium Ion Transport

• The necessary substance for the transport of Ca2+ ions is:

  • Vitamin D.

Effects of Acidosis and Alkalosis

• Acidosis affects the nervous system leading to:

  • Depression, whereas alkalosis leads to:hyperexcitability.

Final Round

• In metabolic acidosis caused by E. coli infection:

  • Blood pH decreases and respiratory rate increases to mitigate acidosis.