Chapter 12 - Water and the Major Minerals

Vocabulary flashcards covering key terms related to water, fluid balance, electrolytes, acid-base balance, and associated regulatory mechanisms in the body.

Water (body composition)

Constitutes approximately 60% of an adult's body weight, with a higher percentage in children and lean tissue, and a smaller proportion in females, obese people, and the elderly due to less lean tissue.

Functions of Water in Body Fluids

Carries nutrients and waste products, maintains molecular structure, participates in metabolic reactions, serves as a solvent, acts as a lubricant and cushion, aids in temperature regulation, and maintains blood volume.

Fluid Balance (body)

Maintenance of a balance where 2/3 of body fluids are inside cells (intracellular) and 1/3 are outside cells (extracellular).

Intracellular fluid

Fluid located inside cells.

Extracellular fluid

Fluid located outside cells.

Interstitial fluid

Extracellular fluid that surrounds cells.

Intravascular fluid

Extracellular fluid found in the blood vessels.

Electrolytes

Mineral salts that dissolve in water, dissociate into ions (cations and anions), conduct electricity, and form solutions with balanced positive and negative charges.

Cation

A positively charged ion, such as sodium (Na+).

Anion

A negatively charged ion, such as chloride (Cl-).

Milliequivalents per liter (mEq/L)

A unit used to measure anion and cation concentrations in electrolyte solutions.

Electrolyte Balance

The state where electrolytes are predominantly found inside or outside the cell, attracting water, and cell membranes are selectively permeable.

Selectively permeable

A characteristic of cell membranes that allows the passage of some molecules but not others.

Osmosis

The movement of water across a membrane towards a region with more concentrated solutes.

Osmotic pressure

The amount of pressure required to prevent the movement of water across a membrane.

Edema

Swelling caused by fluids following proteins that have leaked out of blood vessels into the spaces between cells.

Kidneys (fluid balance)

Organs central to the regulation of blood volume and blood pressure.

Antidiuretic hormone (ADH)

A water-conserving hormone released by the pituitary gland (stimulated by the hypothalamus) that stimulates the kidneys to reabsorb water, triggers thirst, and raises blood volume to restore homeostasis.

Renin

An enzyme released by the kidneys when blood pressure is low; it causes kidneys to reabsorb sodium, leading to water retention, and hydrolyzes angiotensinogen to angiotensin I.

Angiotensin II

A potent vasoconstrictor that raises blood pressure and stimulates the adrenal glands to release aldosterone.

Aldosterone

A hormone stimulated by Angiotensin II, released by the adrenal glands, which signals the kidneys to excrete potassium and retain more sodium and water, thereby increasing blood volume and pressure.

Fluid and Electrolyte Imbalance

A condition caused by severe, prolonged vomiting, diarrhea, heavy sweating, burns, or traumatic wounds, requiring medical intervention.

Oral rehydration therapy (ORT)

A simple solution of sugar, salt, and water, taken by mouth, used to treat dehydration caused by diarrhea.

Acid-Base Balance

The body's crucial maintenance of blood pH within a narrow range to prevent life-threatening consequences, defended by buffers, respiration in the lungs, and excretion in the kidneys.

pH Scale

A measure of the concentration of hydrogen ions (H+), where a high concentration is acidic and a low concentration is basic.

Acidic

A condition characterized by a high concentration of hydrogen ions (H+).

Buffers (body fluids)

Substances in the body fluids, such as bicarbonate, carbonic acid, and proteins, that protect against changes in acidity by neutralizing acids or bases, ensuring optimal blood pH.

Carbonic acid-bicarbonate buffer system

A crucial buffer system in the blood involving carbon dioxide, water, and carbonic acid, which dissociates into hydrogen ions and bicarbonate ions to maintain optimal blood pH.

Lungs (acid-base balance)

Organs that control the concentration of carbonic acid by adjusting the respiration rate to regulate blood pH.

Kidneys (acid-base balance)

Organs that control the concentration of bicarbonate by either reabsorbing or excreting it to regulate blood pH.

Obligatory water excretion

The minimum amount of water the body must excrete daily (at least 500 mL) to carry away waste products generated by metabolic activities.

Thirst

A signal initiated by the hypothalamus when blood becomes concentrated and the mouth dries, prompting drinking behavior.

Dehydration

A condition resulting from inadequate water intake, with initial symptoms including thirst, progressing to fatigue, weakness, exhaustion, delirium, and potentially death.

Dehydration Symptoms (1-2% body weight loss)

Thirst, fatigue, weakness, vague discomfort, loss of appetite.

Water intoxication

A rare condition caused by excessive water intake (e.g., 10-20 L in a few hours) and/or kidney disorders, leading to symptoms like confusion and convulsions.

Hyponatremia

A condition where excessive water ingestion dilutes the sodium concentration of the blood.

Metabolic water

Water generated as an end product during condensation reactions and the oxidation of energy-yielding nutrients.

Hard water

Water with higher concentrations of calcium and magnesium.

Soft water

Water with higher levels of sodium or potassium, which may dissolve contaminant minerals like cadmium and lead from old pipes, and can aggravate hypertension and heart disease.