Electrolytes and Fluid Balance

Intracellular and Extracellular Electrolytes

Electrolytes are minerals that carry an electric charge and are essential for various physiological functions. They are distributed in the body as intracellular (inside cells) and extracellular (outside cells) electrolytes.

• Intracellular Electrolytes: Potassium (K+) and Phosphorus (PO43-) are the primary electrolytes inside cells.

• Extracellular Electrolytes: Sodium (Na+) and Chloride (Cl-) are the main electrolytes outside cells.

Relationship between Electrolyte Concentration, Water Movement, and Cell Result:

• Water moves across cell membranes by osmosis, following the concentration of electrolytes.

• If extracellular fluid is more concentrated (hypertonic), water leaves the cell, causing it to shrink.

• If extracellular fluid is less concentrated (hypotonic), water enters the cell, causing it to swell.

Major Functions of Electrolytes:

• Regulate fluid balance

• Enable nerve impulse transmission

• Support muscle contraction

Vitamins, Minerals, and Associated Deficiencies

Key Vitamins and Minerals

• Calcium: Essential for bone health, muscle contraction, and nerve signaling.

• Magnesium: Involved in over 300 enzymatic reactions, including energy production and muscle function.

• Chloride: Maintains fluid balance and is a component of stomach acid (HCl).

• Phosphorus: Important for bone structure and energy metabolism (ATP).

• Potassium: Maintains fluid balance, nerve transmission, and muscle contraction.

• Beta-carotene: A precursor to vitamin A and an antioxidant.

• Vitamin E: An antioxidant that protects cell membranes from oxidative damage.

Deficiencies and Associated Conditions

• Calcium deficiency: Osteoporosis, muscle spasms.

• Magnesium deficiency: Muscle cramps, seizures, irregular heartbeat.

• Vitamin D deficiency: Rickets in children, osteomalacia in adults.

• Vitamin C deficiency: Scurvy (bleeding gums, poor wound healing).

• Iron deficiency: Anemia, fatigue.

Rich Food Sources

Vitamins/Minerals Synthesized in the Body

• Vitamin D: Synthesized in the skin upon exposure to sunlight.

• Vitamin K: Some produced by gut bacteria.

• Niacin: Can be synthesized from tryptophan (an amino acid).

Antioxidants and Free Radicals

Role of Antioxidants

Antioxidants are compounds that neutralize free radicals, preventing cellular damage.

• Antioxidant Vitamins: Vitamin C, Vitamin E, and beta-carotene (pro-vitamin A).

• Function: Donate electrons to free radicals, stabilizing them and preventing damage to DNA, proteins, and cell membranes.

Free Radicals

• Definition: Unstable molecules with unpaired electrons that can damage cells.

• Formation: Produced during normal metabolism, exposure to pollution, radiation, and smoking.

• Damaged Sites: DNA, cell membranes, proteins.

• Associated Issues: Aging, cancer, cardiovascular disease.

Risk Factors for Free Radical Damage

• Smoking

• Pollution

• Radiation

• Poor diet (low in antioxidants)

Reducing Cancer Risk

• Increase: Fruits, vegetables, whole grains, antioxidants.

• Decrease: Processed meats, excessive alcohol, high-fat diets.

Bone Health and Development

Bone Development Processes

• Osteoblasts: Cells that build new bone tissue.

• Osteoclasts: Cells that break down bone tissue.

• Order of Bone Development: Bone formation begins in the embryo (around 8 weeks gestation), continues through childhood and adolescence, and peaks in early adulthood.

Relationship Between Vitamin D and Calcium

• Vitamin D enhances calcium absorption in the intestines.

• Deficiency in vitamin D can lead to poor calcium absorption and bone disorders.

Hypercalcemia

• Definition: High levels of calcium in the blood.

• Associated Problems: Kidney stones, impaired kidney function, confusion, abnormal heart rhythms.

Blood and Immunity

Leukocytes

• Definition: White blood cells involved in immune defense.

• Function: Protect the body against infection and foreign invaders.

Heme vs Non-Heme Iron

• Heme Iron: Found in animal products (meat, poultry, fish); more easily absorbed.

• Non-Heme Iron: Found in plant foods (beans, lentils, spinach); less efficiently absorbed.

Water, Hydration, and Temperature Regulation

Functions of Water

• Maintains body temperature (sweating)

• Transports nutrients and waste

• Lubricates joints

• Protects organs and tissues

Factors Affecting Body Water Percentage

• Age (decreases with age)

• Gender (males typically have higher water content)

• Body composition (more muscle = more water)

Thirst Mechanism

• Triggered by increased blood osmolality or decreased blood volume.

• Regulated by the hypothalamus in the brain.

Dehydration and Heat-Related Illnesses

• Dehydration: Excessive loss of body water.

• Heat Cramps: Muscle spasms due to electrolyte loss during intense activity.

• Heat Exhaustion: Heavy sweating, weakness, rapid pulse; caused by loss of water and salt.

• Heat Stroke: Life-threatening; body temperature rises above 40°C (104°F), confusion, unconsciousness.

Energy Drinks

• Contain caffeine, sugar, and sometimes vitamins or herbal extracts.

• May increase alertness but can cause dehydration and heart issues if consumed in excess.

Dietary Considerations

High and Low Sodium Foods

• High Sodium: Processed foods, canned soups, deli meats, snack foods.

• Low Sodium: Fresh fruits and vegetables, unprocessed grains, fresh meats.

Maintaining Normal Blood Pressure Through Diet

• Reduce sodium intake.

• Increase potassium, calcium, and magnesium intake.

• Follow the DASH diet (Dietary Approaches to Stop Hypertension).

Other Key Concepts

Pro-vitamin

• Definition: A substance that can be converted into a vitamin in the body (e.g., beta-carotene is a pro-vitamin for vitamin A).

Neural Tube Defect

• Birth defects of the brain, spine, or spinal cord (e.g., spina bifida).

• Often related to folate deficiency during pregnancy.

Summary Table: Key Nutrients and Functions

Additional info: Academic context and definitions have been added to expand on the brief review points and ensure the notes are self-contained for exam preparation.