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.