Chapters 10 and 11 Presentation - Minerals

General Properties of Minerals

• All minerals share the following properties:

  • Exist in ionic form (e.g., Na+, Mg2+, Fe2+, K+, Zn2+).

  • Always accompanied by a counterion to ensure total charge neutrality.

    • Example: Na+ + Cl- → NaCl (total charge is 0).

    • Example: Mg2+ + 2Cl- → MgCl2 (total charge is 0).

  • Provide no energy to the body.

  • Generally not building blocks, except for calcium (important in bones, cartilage, and teeth).

  • Most act as co-factors; some have osmotic roles.

  • Essential: Cannot be synthesized by the body.

  • Do not spoil; for example, calcium pills remain effective for years.

Major Minerals

• Major minerals are essential minerals the body requires in larger amounts (yet still in tiny quantities).

  • Calcium (Ca2+)

    • Roles: Structure (bones, cartilage, teeth) and biochemical co-factor.

    • Exists in two main pools in the body:

      • Co-factor pool: in blood and soft tissues.

      • Bony pool: Calcium can be stored in bones (serving as a "piggy bank").

    • Excess calcium is removed from circulation and stored in bones or eliminated through urine and feces.

    • Deficit can result in bone diseases (e.g., rickets, osteoporosis).

    • Managed by vitamin D (calcitriol).

    • Critical in muscle contraction; Ca2+ triggers this process.

    • Excess lead to kidney stones or muscle cramps in some.

    • Food sources: prominent in dairy products, though absorption efficiency remains debated.

Sodium (Na+)

• Role as main extracellular osmotic ion, maintaining body hydration.

• Deficiency part of dehydration and sodium loss.

• Overconsumption risks due to presence in processed and instant foods (e.g., canned soup).

• High sodium foods can lead to high blood pressure; crucial for hypertensive individuals to limit sodium.

• DASH diet aims to lower sodium intake and manage blood pressure.

Potassium (K+)

• Main intracellular osmotic ion; maintains cytoplasmic hydration.

• Slows heart rate (note: potassium is lethal in high doses).

• Common food sources: bananas and potatoes.

• Distinction from vitamin K is crucial.

Sodium-Potassium Exchange Pump

• Key for maintaining electrical charge across cell membranes.

• Operates on a 3:2 ratio: three sodiums ejected for two potassiums.

• Driven by ATP.

• Results in a charge imbalance; outside becomes positively charged relative to the inside, leading to about -70 millivolts.

Membrane Potential

• Cell membranes maintain an electrical charge critical for functions, especially in neurons (action potentials).

Counterions

• Positive mineral ions always paired with negative counterions for neutrality.

• Common counterions include:

  • Chloride (Cl-)

  • Phosphate ((PO4)3-)

  • Sulfate ((SO4)2-)

  • Nitrate (NO3-)

• Examples of balance:

  • 3Na+ + (PO4)3- → Na3(PO4)

  • Mg2+ + 2Cl- → MgCl2

  • Mg2+ + (SO4)2- → Mg(SO4)

  • 3Ca2+ + 2(PO4)3- → Ca3(PO4)2

• Counterions also play a role in forming biological buffers that prevent pH fluctuation.

Trace Minerals

• Minimum required amounts; includes:

  • Iron (Fe2+)

    • Crucial for hemoglobin and myoglobin.

    • Deficiency can lead to anemia.

    • Present in red meats, less bioavailable in plant sources.

    • Myth about spinach’s iron content; not sufficient.

    • Excess iron can lead to oxidative damage.

  • Magnesium (Mg2+)

    • Functions as a co-factor in many biological processes.

    • Helps counteract muscle contractions (useful for cramps).

  • Zinc (Zn2+)

    • Similar to magnesium: functions as co-factor in many enzymes.

    • Plays a role in responding to viral infections; may aid in recovery from illnesses.