Electrolyte Substance when dissolved in solution separates into ions & is able to carry an...
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Transcript of Electrolyte Substance when dissolved in solution separates into ions & is able to carry an...
Electrolyte
Substance when dissolved in solution separates into ions & is able to carry an electrical current
Solute substances dissolved in a solution. These may be electrolytes or non-electrolytes
Electrolytes have an electrical charge when they are dissolved in water
Electrolytes that have a positive charge are called cations
Electrolytes with negative charge are anions
Cations
Cations include sodium (Na+), potassium (K+), calcium (Ca+), Magnesium (Mg+), and hydrogen (H+)
The number of cations must equal the number of anions
The combining power of electrolytes is measured in milliequivalents (mEq)
It is the measure of charge concentration
Anions
Include chloride ions, bicarbonate ions, phoshate ions, sulphate ions, organic acids, and proteins
Measurement of solute concentration in body fluids is based on fluid’s osmotic pressure, expressed as osmolarity
Osmolarity is the number of osmols (standard unit of osmotic pressure) per liter of solution
Electrolyte
Electrolytes are the major components of body fluids. They enter the body through the food we eat and the beverages that we drink.
Electrolytes leave the body by way of urine, skin and feces.
The concentration of electrolyte must be maintained within specific limits
Solute Overview: Intracellular vs. Extracellular
Ionic composition very different Total ionic concentration very similar
METHODS OF FLUID & ELECTROLYTE MOVEMENT
Diffusion Osmosis Active
Transport
Electrolyte Functions
Controlling fluids movements between compartments
The movement of fluids across cell membrane differs from the movement of fluids between interstitial compartment and plasma
Fluid Movements across cell membrane
Electrolytes moves across cell membrane through ion channels and ion pumps that are selective for specific ions
Na-K ATPase in the membrane: move ions against their concentration gradients
Channels specific for Na ions allow the ions to diffuse from area of higher concentration to areas of lower concentration
Channels specific for K allows K ions to move across the membrane from areas of higher to lower concentration
Differences in ion concentration between intercellular and intracellular fluids are caused by these selective ion channels
Water move freely through water channel, which moves from higher water concentration to lower concentration
Through osmosis water moves to the side of membrane of higher solute concentration
Na exerts significant effect on water movements.
Fluid movement between ISF and Plasma
Ions and water can move freely between plasma and ISF
Proteins too big to leave the capillaries Protein concentration in the plasma is
higher than in ISF Protein in the plasma exerts colloid
osmotic pressure. Water moves from ISF to plasma
Capillary hydrostatic pressure forces fluid out of the capillary
Sodium Major cation in ECF (positively charged) Responsible for extracellular osmotic
pressure Regulated by Aldosterone and the
kidneys Increases sodium reabsorption in DCT of
nephron Normal serum concentration in ECF
ranges from 135-146 mEq/L
Sodium Functions
Sodium maintains ECF osmolality, ECF volume, and influences water distribution (where salt goes water follows)
It affects the concentration, secretion, and adsorption of potassium
It also help aid the impulse transmission of nerve and muscle fibers
Imbalances
Hyponatremia less than 130 mEq/L)-low sodium level-may cause headache, hypotension, decreased body temp, nausea, vomiting, and possible coma.
Hypernatremia occurs when plasma Na more than 150 mEq/L) -high sodium level-usually indicates water deficit in ECF-symptoms include thirst, dry sticky tongue, confusion, disorientation, hallucination, lethargy, seizures, coma, agitation
Sodium Regulation
Na is filtered through glomerulus
Na is reabsorbed to plasma at proximal convoluted tubule (PCT) and the loop of Henle
In the presence of Aldosterone, Na reabsorbed at the distal convoluted tubule (DCT)
Aldosterone: steroid H from adrenal cortex Stimulates Na+ uptake (& K+ secretion) channel synthesis
Mechanism of Na+ Selective Reabsorption in Collecting Duct
Mechanism of Na+ Selective Reabsorption in Collecting Duct