Electrolytes

Electrolytes

Sodium, Na+
1. Main cation in ECF Promotes water retention Maintains blood pressure Resting membrane potential Maintains blood volume
2. RDI = 1500 mg/day • Many people > 3000mg/day
  1. Adults need about 0.5 g of sodium each day, many people get over 7g
3. Homeostasis
  1. Aldosterone
    1. When BP is to low - kindeys to retain sodium
  2. • Anti-Diuretic Hormone (ADH)
    1. When BP is to low and blood osmolarity is high - targets kindeys to retain water
  3. Atrial Natriuretic Peptide (ANP)
    1. When BP is to HIGH -hormone is excreted by HEART - Tells kindeys to dump sodium and to urine - H20
4. In balances
  1. Hypernatremia
    1. Dehydration, H2O deprivation - Normally caused by to much NA+ in diet
      1. Symptoms - Thristy, hypertension, oedema, agitation and convulsions
  2. Hyponatremia
    1. Cause: ↓ diet Na+ , ↑ ↑ H2O, vomiting
      1. Symptoms: Muscular weakness, dizziness, hypotension
Total body water content – thirst • Distribution within body compartments • Fluid shifts between ECF and ICF • Intracellular dehydration and oedema • Osmosis • Nerve impulse conduction and muscle contraction • Action potentials https://www.youtube.com/watch?v=u6njr0nZcCU
Potassium, K+
1. Main cation in ICF Small amounts in ECF Maintain normal ICF volume Neuromuscular function • Resting membrane potential
2. RDI = 3500 mg/day
3. Homeostasis
  1. • Aldosterone
  2. • Closely linked to sodium homeostasis • Excess excreted in urine
4. In balances
  1. Hyperkalemia
    1. Causes: Renal failure, Crush injury
      1. Symptoms: Irritability, nausea, vomiting, diarrhoea, cardiac irregularities → arrest
  2. Hypokalemia
    1. Causes: rolonged vomiting/diarrhoea, kidney disease, diuretics
      1. Sympotoms: Muscle fatigue, confusion, Cardiac irregularities → arrest
Chloride, Cl
1. Functions • Stomach Acid • Main Anion in ECF • Regulating pH
2. Homestastis
  1. Linked to sodium… • Strong attraction
3. Imbalances • Disturbed Acid-Base Balance • Hyperchloremia • Dietary excess? • IV saline solution • Hypochloremia • Side effect of hyponatremia • Hyperkalemia? Acidosis?
Calcium, Ca2+
1. Functions • Skeletal strength • Muscle contractions • Neurotransmitter • Blood clotting
2. Homeostasis
  1. Hormonal Control • Parathyroid Hormone • Calcitrol/Calcitonin
3. Imbalances • Hypercalcemia • Reduced membrane Na+ permeability • Depressed reflexes, muscular weakness, cardiac arrhythmias • Hypocalcemia • Abnormal nervous & muscular excitement • Weak bones
Phosphates
1. Functions • Energy • Components of phospholipids and nucleic acids • Activating enzymes & metabolic pathways • Regulating pH - Main anion in ICF
2. Homeostasis
  1. Renal control • Parathyroid Hormone
3. Imbalances • Not as critical – we can tolerate broad variations

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	Created by Clarissa Mackay over 9 years ago