Electrolytes

Properties of carbon dioxide:

bound loosley to plasma albumin bicarbonate represents 90% TCO2 Undissociated carbonic acid H2CO3 carbonic anhydrase

classification of electrolytes

cations or anions depending on the charge and the direction the ions migrate in an electrical field.

chloride reference ranges:

Serum 98-106 mmol/L Urine 170-250 mmol/L

Reference ranges for NA

Serum, plasma 136-145 mmol/L Serum panic values <110 mmol/L and >170 mmol/L Urine, 24 hr 40-220mmol/day (varies w diet)

How much sodium is reabsorbed in he proximal tubule

60-75%

Reference ranges of potassium:

Serum: 3.5-5.3 mmol/L Serum Panic values <2.5->6.5mmol/L urine 25-125 mmol/24hrs.

properties of calcium

99% in teeth and bones 1% in blood and extracellular fluid regulated by PTH VIt D necessary to activate absorption

Renal NA threshold is

110-130 mmol/L

Increased sodium loss can occur with: (hyponatremia)

Decreased aldosterone production (hypoaldosteronism) Certain diuretics (thiazides) Salt-losing nephropathy with some renal tubular disease Prolonged vomiting or diarrhea or severe burns.

Osmolality iscontrolled in what two ways

Fluid intake, secretion of ADH.

The net result

Increased sodium in extracellular fluid and increased excretion of potassium, causing a decrease of potassium in extracellular fluid.

Body Fluid Compartments

Intracellular fluid, extracellular fluid.

Function of Sodium (NA)

Maintains osmotic pressure of blood. Helps regulate blood pressure. Contributes to acid/base balance. Promotes normal nerve impulse transmission and muscle contraction. Helps reabsorb water.

Reference ranges of carbon dioxide:

Serum 21-31 mmol/L serum panic <10mmol/L>40mmol/L

Properties and homeostasis of sodium (NA)

The major extracellular cation. Accounts for 90% of all extracellular cations. Largely determines the osmolality of the plasma. A normal plasma osmolality is approximately 295 mmol/L;with 270 mmol/L being the result of sodium and associated anions.

Bicarbonate

The second most abundant extracellular anion.

properties of bicarbonate

Total CO2 comprises the bicarbonate ion (HCO3) and dissolved CO2 with bicarbonate accounting for more than 90% of total CO2 at physiological pH. maintains ionic charge neutrality

Hyponatremia

a deficiency of sodium in the blood.

Clinical significance of bicarbonate

acid-base imbalances are influenced by changes in HCO3 levels and CO2 . metabolic acidosis metabolic alkalosis

Causes of hypocalcaemia

acute myocardial infarction hypoparathyroidism malabsorption vit D deficiency

RDA of sodium

adults below 2.4 g/day. this is due to efficient NA reabsorption in the kidney.

Secretion of ADH (vasopressin)

anti-diuretic (ADH) is a hormone secreted by the posterior gland in responseto increased plasma osmolality, It acts on the cells of the collecting ducts in the kidneys to increase water reabsorption, A deficiency of ADH; diabetes insipidis; results in dehydration and hypernatremia.

What is Stimulated by hypothalamus during increased osmolality

anti-diuretic hormone (ADH) secretions and sensation of thirst

Non-electrolytes

are molecules that do not dissociate into ions when placed in water. Poor conductor.

Measurement of TCO2 is chiefly done to evaluate:

bicarbonate levels.

Osmolality and what are related

blood volume. related because osmolalityof sodium is regulated by change in water balance, whereas, volume is regulated by changes in sodium balance.

clinical significance of carbon dioxide

changes in plasma HCO3 and dissolved CO2 concentrations are characteristic of acid-base imbalance. nature of imbalance cannot be determined by TCO2 testing alone.

Functions of chloride:

combines with hydrogen in gastric mucosal glands to form HCL maintenance of electrical neutrality in the body helps maintain serum osmolality and water balance has an inverse relationship to bicarbonate

Intracellular Fluid

fluid inside all body's cells; accounts for about 2/3 of total body water = 63% body fluid

Decreased aldosterone decreases....

decreases renal NA reabsorption.

Isotonic solution

equal osmolality inside and outside the cell. no net water (solvent) movement cell size remains the same.

Hypernatremia

excessive levels of sodium in the blood.

Hyperkalemia

excessive potassium in the blood

Causes of hyperchloremia:

excessive saline IV dehydration hyperaldosteronism

Direct measurement of ionized calcium

newborns transfusions hemodialysis

Extracellular Fluid

fluid outside of body's cells; accounts for the other 1/3 of total body water = 37% body fluid subdivided into two groups.

Interstitial cell fluid

fluid that surrounds the cells in the tissues.

Causes of hyperkalemia:

hemolyzed specimen burns chemotherapy acidosis hypoaldosteronism

Hypertonic solution

higher osmolality ouside than inside the cell. water moves out of cell in an attempt to equalize the solute concentration cell shrinks (crenates).

Aldosterone

hormone that regulates renal NA reabsorption.

Causes of hypophosphatemia

hyperparathyroidism alcoholism

causes of hypercalcaemia

hyperparathyroidism excessive vit D parathyroid tumors

Causes of hyperphosphatemia

hypoparathyroidism chemotherapy any major surgery with massive bone destruction

Deficiency of water results in

increased plasma osmolality, ADH secretion and thirst sensation are activated.

Metabolic alkalosis is caused by

increased renal bicarbonate reabsorption excessive alkali intake (antacids)

Metabolic acidosis is caused by

increased renal excretion of HCO3 decreased PCO2 due to compensation of hyperventilation

Increased aldosterone increases...

increases renal NA reabsorption

Fluid Intake (sensation of thirst)

increases water content in the ECF, Dilutes out the elevated sodium levels, Decreases osmolality of the plasma.

The plasma sodium concentration depends on what

intake and excretion of water.

Two subdivided groups of extracellular fluid

intravascular extracellular fluid, interstitial cell fluid.

Electrolytes

ions capable of carrying an electrical charge.

Effects of osmotic pressure on fluid distribution

isotonic, hypertonic, and hypotonic solutions.

Hypotonic solution

lower osmolality outside the cell than inside the cell. water moves into cell in an attempt to equalize the solute concentrations cell swells, with the potential to rupture (hemolysis).

Excess water intake results in

lower plasma osmolality, suppressed ADH and suppressed sensation of thirst

Chloride

major anion of the extracelular fluid

properties of chloride:

major anion that counterbalances sodium(a cation). exchanges with another extracellular anion bicarbonate absorbed by small intestine whole blood concentrations are regulated by the kidneys

Potassium:

major intracellular cation

Calcium

most abundant electrolyte in the body.

Active transport system (NaK ATPase ion pump)

moves three Na ions out of the cell in exchange for 2 potassium ions moving into the cell as ATP is converted to Adenosine diphosphate.

Anion

negitively charge; gains one or more electrons; major anions are Cl, HCO3, PO4, SO4, organic acids, and proteins.

Intravascular extracellular fluid

plasma lymph fluid made up of 93% WATER, 7% lipids and proteins.

Cation

positively charged; losses of one or more electrons; major cations are Na, K, Ca, and Mg.

It has no renal threshold

potassium

Intracellular ions

potassium, phosphate, magnesium.

Functions of phosphate

promotes energy ATP essential for health bone and teeth buffers acids and basis crucial to the muscle functions and neurologic functions

What are the three forms calcium exists....

protien bound ionized complexed

properties of phosphate

regulated by PTH

Renal regulation

regulated by the kidneys. Aldosterone, hormone that regulates renal reabsorption.

Functions of potassium:

regulation of neuromuscular/nerve impulse/muscle contraction. contraction of the heart hydrogen ion concentration maintains osmotic pressure of cells helps maintain electrical neutrality

Magnesium

second most abundant cation in intracellular fluid

Reference ranges for phosphate

serum 0.85-1.45mmol/L urine 12.9-42.0mmol/24hrs

Reference ranges of calcium

serum total 2.10-2.55mmol/L Total calcium panic <1.5ommol/L >3.5mmol/L serum ionized calcium 1.12-1.23mmol/L

Causes of hypochloremia:

sever vomiting diarrhea nasogastric suction

Causes of Hypernatremia:

severe polyuria profuse sweating diarrhea short term vomiting hyperaldosteronism excessive saline IV

levels of chloride change proportionately with what?

sodium for any given change in body water content.

Extracellular ions

sodium, chloride, bicarbonate.

Functions of calcium

structural components of bones and teeth blood coagulation muscle contraction essential for myocardial contractions neve impulse transmission

Osmolality

the concentration of osmotically active particles in solution expressed in terms of osmoles of solute per kilogram of solvent.

Osmolarity

the concentration of osmotically active particles in solution reported in osmoles per liter, not routinely used.

Phosphate

the major intracellular anion

Osmosis

the passage of solvent from a solution of leser solute concentration to one of greater solute concentration when the solutions are separated by a semi-permeable membrane. =equilibrium and requiers no energy.

Osmotic pressure

the pressure required to stop osmosis through a semi-permeable membrane between solutions of different solute concentrations. lower conc- higher conc

Causes of hypokalemia:

vomiting/diarhea hyperaldosteronism malabsorption alkalosis diuretics

Increased ADH causes:

water retention, chronic renal failure.