Week 5- Electrolytes Flashcards
1
Q
What are the electrolytes?
A
- Calcium
- Sodium
- Potassium
2
Q
Calcium
A
- Extracellular cation (Ca++)
- Comes in food, supplements, stored in bones and excreted in urine and feces
- Balance is controlled by:
- PTH (Parathyroid Hormone) and calcitonin
- Influenced by vitamin D and phosphate levels
3
Q
What is the role of calcium?
A
- Structural strength for bones & teeth
- Stability of the nerve membrane- controls the permeability and excitability needed for nerve conduction
- Muscle contractions
- Metabolic processes and enzyme reactions like blood clotting
4
Q
What are the causes of hypocalcemia?
A
- Hypoparathyroidism (decreased parathyroid hormone secretion
- Malabsorption
- Renal failure (retention of phosphates- loss of calcium) (Vitamin D is not activated)
5
Q
What happens with hypocalcemia pt’s?
A
- Increases the permeability and excitability of the nerve membranes- spontaneous stimulation of the skeletal muscles (muscle twitching, carpopedal spasms)
- Severe: laryngospasms & airway obstruction
- Heart: contractions are weak, conduction delayed, arrhythmia develop, cardiac output drops
6
Q
What is the difference between heart and skeletal muscles?
A
- Skeletal muscle: Increased irritability of the nerve that control muscle fibers, calcium is stored in the muscle to provide for the contractions
- Cardiac: There are no nerves, Contraction is directly affected by calcium levels only available through calcium channels
7
Q
What causes hypercalcemia?
A
- Cancer
- Neoplasms (uncontrolled release of calcium)
- Hyperparathyroidism (increased PTH secretion)
- Immobility- disease stress on bones and demineralization
- Increased intake through diet, Vitamin D
- Overdose of milk and antacids
8
Q
What happens with hypercalcemia pts?
A
- Depress neuromuscular activity- muscle weakness. Loss of tone
- Interfere with ADH- less absorption of water- polyuria (increased urination)
- Severe: blood volume drops, renal function impaired, wastes accumulate- cardiac arrest
- Heart: contractions increase in strength and duration with dysrhythmia developing
- Bones: Excess PTH, calcium intake- bone density and strength affected
9
Q
S/S of hypocalcemia
A
- Tetany, muscle spasms
- Tingling fingers, mental confusion, irritability
- Arrhythmias, weak contraction of the cardiac muscles
10
Q
S/S of hypercalcemia
A
- Lethargic, anorexia, nausea, constipation, polyuria, thirst
- Kidney stones
- Arrhythmia- prolonged cardiac contractions
- Increased BP
11
Q
Sodium
A
- Extracellular cation (Na+)
- Transport across cell membrane is controlled by the Sodium-Potassium pump or active transport- higher levels outside the cells (fluids)
- Salts: sodium chloride, bicarbonate
- Ingested in foods and drinks
- Lost in perspiration, urine, feces
- Primarily controlled by the kidney via aldosterone (responsible for maintaining proper levels)
12
Q
What is sodium’s function?
A
- Extracellular fluid volume (affects osmotic pressure)
- Force with which a solvent (fluid) passes through a membrane separating solution of different concentrations
- Nerve impulse conduction
- Muscle contraction
13
Q
What are the causes of hyponatremia?
A
- Excessive sweating, vomiting, diarrhea
- Diuretic medications used with low salt diets
Hormonal imbalances:
- Insufficient aldosterone secretion
- Adrenal insufficiency
- Excessive ADH secretion
- Chronic renal failure
- Excessive water intake
14
Q
What happens to hyponatremia pts?
A
- Impaired nerve conduction- slower
- Fluid imbalances (fatigue, muscle cramps, abdominal discomfort or cramps with nausea and vomiting)
- Decreased osmotic pressure outside cells- fluid shift into the cells- hypovolemia and drop in blood pressure
- Brain swelling- CNS effects (headache, confusion, seizures)
15
Q
What are the causes of hypernatremia?
A
- Ingestion of large amounts of sodium
- Disproportionate water intake
- Insufficient ADH
- Loss of thirst mechanism
- Watery diarrhea
