Lecture Exam 3 Review

Water and Electrolytes

Description and Role of Water

  • Water constitutes approximately 60% of the human body.

  • Crucial for cellular homeostasis and the solvent for biochemical reactions.

Functions of Water

  • Blood contains about 90% water, essential for transportation of nutrients and waste.

  • Serves as a medium for metabolic processes.

Location of Water in the Body

  • Intracellular: Water within cells.

  • Extracellular: Water outside cells, including both interstitial fluid and vascular fluid.

    • Interstitial: Fluid between cells.

    • Vascular: Fluid within blood vessels.

Osmosis

  • Movement of water between compartments.

  • Hypotonic: Lower solute concentration, water moves in.

  • Hypertonic: Higher solute concentration, water moves out.

  • Isotonic: Equal solute concentration, no net movement.

  • Key Concept: Water moves towards hypertonic environments.

Thermoregulation

  • The hypothalamus is the organ responsible for regulating body temperature through water's cooling effect via sweat.

Regulation of Water

  • Consider water input and output: intake from drinks and food vs. loss through urine, sweat, and respiration.

Adequate Intake (AI) for Water

  • Recommended intake varies: 3.7 liters/day for males, 2.7 liters/day for females.

Thirst Regulation

  • The hypothalamus also plays a role in signaling thirst and fluid balance.

Role of ADH and Aldosterone

  • ADH (Antidiuretic Hormone): Increases water reabsorption in kidneys.

  • Aldosterone: Regulates sodium and water balance, impacting blood volume.

Definitions

  • Anion: Negatively charged ion.

  • Cation: Positively charged ion.

  • Solute: Substance dissolved in a solvent.

  • Solvent: Substance that dissolves solute (commonly water).

  • Electrolytes: Ionic substances in solution that conduct electricity.

Role of Sodium

  • Functions: Regulates fluid balance, nerve transmission, and muscle function.

  • Upper Limit (UL): 2,300 mg/day for adults.

Hyponatremia

  • Definition: Abnormal low sodium levels in the blood, leading to cellular swelling and associated symptoms.

Role of Chloride

  • Maintains fluid balance and is essential for digestion (components of stomach acid).

  • Symptoms of Low Chloride: Dehydration, muscle cramps.

  • Cystic Fibrosis: A genetic disorder affecting chloride channels, leads to thick mucus production.

Role of Potassium

  • Vital for nerve function and muscle contraction.

  • Hypokalemia: Low potassium levels leading to weakness, fatigue, and arrhythmias.

  • Hyperkalemia: High potassium levels causing potentially dangerous heart rhythms.

  • Most common cause of hypokalemia: excessive loss through urine or sweat.

Signs of Imbalances

  • Dehydration Symptoms: Thirst, dry mouth, dark urine.

  • Overhydration/Hyponatremia Symptoms: Confusion, seizures, swelling.

  • Heat Exhaustion/Stroke: Heavy sweating, high body temperature, confusion.

  • Hypertension Symptoms: Elevated blood pressure, potential headaches.

Waterborne Illnesses Trends

  • Trends: Increase in awareness and prevention efforts in the U.S., yet outbreaks still occur.

Aging and Dehydration

  • Relationship: Elderly individuals are at higher risk for dehydration due to decreased thirst sensation and body water.

  • Insensible vs. Sensible Water Loss: Insensible loss (unnoticed, e.g., respiration) vs. sensible loss (noted, e.g., urine).

Water Treatment

  • Effective in reducing diseases like cholera and typhus, wherein water treatment leads to significant health improvements.

  • Leading cause of child mortality worldwide from dehydration-related illnesses.

Vitamins

Overview of Vitamins

  • Definition: Organic compounds that are essential for normal growth and nutrition, usually required in small quantities.

  • Pro-vitamins: Precursors to vitamins that convert into active forms in the body.

  • Vitamins do not provide energy, but are crucial for metabolism.

  • Two categories: Water-soluble and fat-soluble vitamins.

Absorption and Regulation

  • Most vitamins absorbed in the small intestine.

  • Supplement Regulation: Not universally monitored by the FDA.

Antioxidants

  • Certain vitamins act as antioxidants, protecting cells from damage.

  • Only small amounts needed because they work to neutralize free radicals.

Fat-Soluble Vitamins

Vitamin A

  • Functions: Vision support, immune function, maintains epithelial tissues.

  • Deficiency Symptoms: Night blindness, xerophthalmia.

  • Food Sources: Liver, fish, dairy, orange and green vegetables containing beta-carotene.

Vitamin D

  • Roles: Calcium and phosphorus metabolism, bone health.

  • Deficiency Symptoms: Rickets in children, osteomalacia in adults.

  • Sunshine Vitamin: Synthesized in skin upon exposure to sunlight.

  • Key Organs for Synthesis: Skin, liver, kidneys.

Vitamin E

  • Functions: Antioxidant; protects cell membranes.

  • Deficiency Symptoms: Impaired immune function, RBC hemolysis (destruction).

  • Interactions: Can affect blood clotting in other vitamins.

Vitamin K

  • Roles: Important in blood coagulation.

  • Administered to newborns to prevent hemorrhage.

  • Primarily produced in the gut by bacteria.

Water-Soluble Vitamins (B and C)

  • B Vitamins: Act as coenzymes in metabolic reactions.

    • Deficiencies: Can lead to specific pathologies like anemia, neurological issues.

    • Noteworthy: B12 requires intrinsic factor for absorption, often lacking in elderly.

    • Vitamin C: Essential for collagen synthesis, antioxidant. Deficiency leads to scurvy.

Supplemental Considerations

  • Raw Egg Whites: Contain avidin, which inhibits B7 (biotin) absorption.

  • Vitamin Depletion: Certain vitamins susceptible to destruction from cooking and light exposure.

Major Minerals

  • Differences: Minerals are inorganic elements required for body functions.

  • Major Minerals Include: Sodium, potassium, chloride, calcium, phosphorus, magnesium, sulfur.

    • Each plays broader roles – e.g., calcium and bone health, potassium in fluid balance.

Trace Minerals

  • Definition: Required in smaller amounts than major minerals; important for various bodily functions.

    • Includes iron, zinc, copper, selenium.

General Mineral Functions

  • Absorption Factors: Impaired by phytates and polyphenols; specific nutrients can enhance absorption (e.g., vitamin C for iron).

  • Toxicity Risks: Typically, more concerning for iron due to storage and accumulation.

Food Safety

  • Health Issues: Knowledge of safe food handling can reduce disease outbreaks.

  • Pathogens of Concern: Salmonella, E. coli, Listeria, viral pathogens like Norovirus.

  • Food Preservation Techniques: Include pasteurization and food irradiation to prevent contamination.

  • GMO Considerations: A method for increasing food productivity while raising discussions on safety and regulation.