Understanding Nutrition Chapter 12: Water and the Major Minerals

Comprehensive vocabulary flashcards covering Chapter 12: Water and the Major Minerals, including fluid compartments, hormonal electrolyte regulation, the RAAS pathway, acid-base buffering, and key mineral profiles.

Water in Body Weight

The proportion of water in an adult's body, constituting approximately $60\%$ of total body weight (higher in children, lower in females and the elderly).

Intracellular Fluid (ICF)

The fluid residing inside the cell, accounting for roughly two-thirds of total body water or about $40\%$ of body weight.

Extracellular Fluid (ECF)

The fluid residing outside of the cells, accounting for approximately one-third of total body water or $20\%$ of total body weight.

Interstitial Fluid

Extracellular fluid located between and surrounding the cells (intercellular fluid), making up approximately $15\%$ of body weight.

Intravascular Fluid

Extracellular fluid (blood plasma) contained within the blood vessels, making up about $5\%$ of body weight.

Body Fluid Distribution

The compartmental breakdown of total body water ($60\%$ of body weight), divided into intracellular volume ($40\%$ of body weight) and extracellular volume ($20\%$ of body weight, which consists of $15\%$ interstitial fluid and $5\%$ intravascular fluid).

Extracellular Electrolytes

Mineral ions that reside predominantly outside the cell, primarily sodium ($Na^+$), chloride ($Cl^-$), and calcium ($Ca^{2+}$).

Intracellular Electrolytes

Mineral ions that reside predominantly inside the cell, primarily potassium ($K^+$), magnesium ($Mg^{2+}$), phosphate ($P$), and sulfate ($S$).

Antidiuretic Hormone (ADH / Vasopressin)

A water-conserving hormone released by the posterior pituitary (signaled by the hypothalamus) that stimulates the kidneys to reabsorb water.

Renin

An enzyme secreted by the kidneys in response to low blood pressure that hydrolyzes angiotensinogen into angiotensin I, prompting sodium and water reabsorption.

Angiotensin-Converting Enzyme (ACE)

An enzyme produced primarily in the lungs that catalyzes the conversion of inactive angiotensin I into active angiotensin II.

Angiotensin II

A potent vasoconstrictor that narrows blood vessels to raise blood pressure and signals the adrenal cortex to release aldosterone.

Aldosterone

A hormone secreted by the adrenal glands that signals the kidneys to retain sodium and water while excreting potassium, expanding blood volume.

Renin-Angiotensin-Aldosterone System (RAAS)

The physiological cascade triggered by low blood pressure or fluid volume in which renal renin converts hepatic angiotensinogen to angiotensin I, pulmonary ACE converts it to angiotensin II, and angiotensin II triggers vasoconstriction and aldosterone release to retain sodium and water.

Bicarbonate-Carbonic Acid Buffer System

The primary chemical buffer system regulating blood pH, characterized by the reversible reaction: $CO_2 + H_2O \rightleftharpoons H_2CO_3 \rightleftharpoons H^+ + HCO_3^-$.

Blood pH Regulation Ranges

The physiological pH range of blood, normally maintained between $7.35\text{ and }7.45$, where deviations below $7.35$ indicate acidosis (death below $6.8$) and deviations above $7.45$ indicate alkalosis (death above $8.00$).

Acidosis

An abnormal physiological condition where blood pH drops below $7.35$, driven by a high concentration of hydrogen ions ($H^+$).

Alkalosis

An abnormal physiological condition where blood pH rises above $7.45$, driven by a low concentration of hydrogen ions ($H^+$).

Major Minerals (Macrominerals)

Essential inorganic nutrients needed by the body in relatively large quantities, including calcium, phosphorus, potassium, sulfur, sodium, chloride, and magnesium.

Trace Minerals (Microminerals)

Essential inorganic nutrients required by the human body in small amounts (such as iron, zinc, copper, manganese, iodine, and selenium) that remain vital for health.

Body Mineral Abundance (60-kg Adult)

The comparative quantities of minerals found in a 60-kilogram human body, where only calcium ($1150\,g$) and phosphorus ($600\,g$) exceed one pound ($454\,g$), followed by potassium ($210\,g$), sulfur ($150\,g$), sodium ($90\,g$), chloride ($90\,g$), and magnesium ($30\,g$).

Sodium ($Na$)

The principal extracellular cation responsible for regulating fluid volume, maintaining acid-base balance, transmitting nerve impulses, and facilitating muscle contraction.

Hypernatremia

Abnormally high sodium concentration in the blood that can lead to dehydration, increased blood pressure, and renal strain.

Hyponatremia

Abnormally low sodium concentration in the blood characterized by headache, confusion, fatigue, and potentially seizures.

Sodium Dietary Recommendations

The recommended maximum dietary intake of $2300\,mg$ per day, compared to the current average United States intake of $3400\,mg$ per day.

Chloride ($Cl$)

The major extracellular anion that moves passively across membranes, associates with sodium and potassium, and helps maintain fluid and electrolyte balance.

Hyperchloremia

Elevated chloride levels in the blood, which typically develops as a result of dehydration or water deficiency.

Potassium ($K$)

The principal intracellular cation that maintains cell integrity, regulates fluid balance, and aids in nerve impulse transmission and muscle contraction.

Hyperkalemia

Potassium toxicity resulting in muscle weakness, paralysis, cardiac arrhythmia, chest pain, and cardiac arrest if administered directly into a vein.

Adequate Intake (AI) for Potassium

The recommended daily intake of potassium set at $3400\,mg/\text{day}$ for men and $2600\,mg/\text{day}$ for women.

Calcium ($Ca$)

The most abundant mineral in the human body, stored primarily in bones and teeth ($99\%$) where it forms a structural matrix and acts as a reservoir to maintain blood concentrations.

Calcium Balance Regulation

The hormonal homeostatic system that responds to low blood calcium via parathyroid hormone and vitamin D to stimulate kidney reabsorption, bone breakdown by osteoclasts, and gut absorption; and responds to high blood calcium via thyroid-derived calcitonin to inhibit these pathways.

Normal Serum Calcium Reference Range

The tightly controlled total serum calcium range in blood, normally spanning from $8.5\text{ to }10.4\,mg/dL$.

Hypocalcemia

A condition characterized by serum calcium levels falling below the normal reference range of $8.5\,mg/dL$.

Hypercalcemia

A condition characterized by serum calcium levels rising above the normal reference range of $10.4\,mg/dL$.

Parathyroid Hormone (PTH)

A hormone released by the parathyroid glands when blood calcium is low that stimulates vitamin D activation, prompts renal calcium reabsorption, and triggers osteoclasts to release calcium from bone.

Calcitonin

A hormone released by the thyroid gland when blood calcium is high that inhibits vitamin D activation, stops kidney calcium reabsorption, and prevents osteoclasts from breaking down bone.

Calcium Bioavailability Inhibitors

Dietary components like oxalates (in spinach and rhubarb), phytates (in grains and legumes), and dietary fiber that bind calcium in the gut and hinder its intestinal absorption.

Phosphorus ($P$)

The second most abundant mineral in the body; a component of hydroxyapatite crystals, ATP energy metabolism, phospholipids in cell membranes, DNA, RNA, and biological buffer systems.

Magnesium ($Mg$)

A major mineral found primarily in bone ($>50\%$) that acts as a cofactor for ATPase enzymes in ATP synthesis, maintains bone health, and inhibits muscle contraction and blood clotting.

Tetany

A condition marked by intermittent muscular spasms and abnormal nerve excitation that can be caused by severe magnesium deficiency.

Sulfate ($SO_4^{2-}$)

An oxidized form of sulfur provided by dietary proteins and beverages that is involved in the synthesis of certain vitamins and bodily organic compounds.