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Week 1 Electrolytes Part 1 michelle_cameron5 Save Histopathology & MTLE Teacher 69 terms atom_14Preview

Chapter 19 : Fluid, Electrolyte, and A...

23 terms brooklynn225Preview Liver Function 44 terms greenjujubean Preview Brainst 40 term hpo Electrolytes ◼ Electrolytes are ionic compounds held together by electrostatic attraction between ions of opposing charges!◼ Compound has NO charge but when in water dissociates into charged ions in solution ◼ Ions are ANIONS (NEG charge) or CATIONS (POS charge) ◼ Ions able to conduct electrical current

◼ 3 major sources of Electrolytes:

◼ Acids ◼ Bases ◼Salts • Salts required by body to function properly • Salts are acquired by foods consumed

"Most important" electrolytes in the human body:

◼ CATIONS:

◼ Sodium (Na+ ) ◼ Potassium (K+ ) ◼ Calcium (Ca2+) ◼ Magnesium (Mg2+)

◼ ANIONS:

◼ Chloride (Cl- ) ◼ Bicarbonate (HCO3 - ) ◼ Phosphate (H2PO4 - ) In the clinical laboratory "Electrolytes" refers to ◼Na+, K+, Cl-, (TCO2) -ordered as a panel "Lytes" ◼ Assayed together as changes in concentration of one almost always accompanied by changes in concentration of one or more of the others.◼Calcium, magnesium, phosphorus referred to as electrolytes but NOT part of clinical panel "Lytes"

ELECTRONEUTRALITY:

POS charged particles balance, or electrically neutralize, NEG charged particles = sum of all cations equals sum of all anions

◼ Disturbances to electrolyte balance are common:

◼ Arise in many clinical situations ◼ Severe disturbances are life-threatening and require immediate treatment ◼ Considered "CRITICAL CARE" tests ◼ Often ordered STAT!◼ Also very commonly prone to variability and pre-analytical/analytical errors!!!◼ =extremely important and really easy to mess up!Main Functions of Electrolytes ◼ Transmission of electrical impulses along cell membranes of neurons and muscle (Na+, K+, Ca2+ play major role) ◼ Act as co-factors in enzymatic reactions (Ex. Mg+, Ca2+, K+, Cl-, Fe+, Zn+) ◼ Aide in hormone release (ex. Na+, K+) ◼ Regulate volume and osmotic pressure between intra- and extracellular fluid compartments (all involved but Na+ major) ◼ Regulate electrical balance between fluid compartments (all involved but Na+, Cl- major) ◼ Involved in blood coagulation (Ca2+) Why test for electrolytes?"Lytes" are usually the highest volume test in the lab (sometimes second to CBC) WHY???◼ Identify if clinical symptoms related to electrolyte abnormality ◼ Detect abnormality upon hospital admission ◼ Monitor as markers of response to treatment ◼ Identify disturbances that arise as a result of treatment ◼ Monitor side effects of treatment (hypertensive drugs) Electrolyte Review ◼Water regulation is extremely important to maintain water and electrolyte balance ◼ Water is the medium in which electrolytes are dissolved in.

◼ Before we learn about the individual electrolytes we must review:

◼Kidney function and the movement of solutes in the filtrate ◼ Regulation of fluid and electrolyte balance

Types of Fluid/Electrolyte Imbalances ◼ Healthy individuals have balanced water and electrolyte levels

◼ There are different processes that can lead to imbalances:

• Fluid Volume Imbalance

◼ Composition and concentration of electrolytes is normal BUT there is an excess or deficit of water

• Fluid Concentration Imbalance

◼ Fluid volume and electrolyte composition remain normal but due to disease processes there is an overall excess or deficit of electrolytes

• Fluid Composition Imbalance

◼ Fluid volume and overall electrolyte concentration is normal but the composition of electrolytes changes Kidney Function Review

• Which solute(s) in the glomerular filtrate are not normally detected in the urine?
• Which solute(s) in the glomerular filtrate are not at all reabsorbed?

Renin-Angiotensin-Aldosterone System (RAAS):

◼ Endocrine pathway that regulates fluid balance of extracellular volumes including blood plasma, lymph, and interstitial fluid, electrolytes, and arteriole vasoconstriction.

• MAJOR regulation of Blood Pressure!

◼ Activated in presence of LOW blood volume (need appropriate volume to deliver blood to tissues) or DROP in blood pressure (dehydration, hemorrhage) ◼ Results in Increased Fluid Retention and in Vasoconstriction which raises blood pressure

• MAJOR regulation of Electrolytes!

◼ Activated by decreased renal perfusion (low filtrate volume) or decreased Na+/Cl- levels in the distal convoluted tubules (DCT) or juxtaglomerular apparatus of the kidney ◼ Affects electrolyte (fluid) balance!!!!

Water Regulation -ADH

Diuretic: increased passing of urine

Arginine VasoPressin (AVP = ADH) -Peptide hormone from hypothalamus that causes insertion of water channels into membranes lining the collecting ducts ADH acts to water REABSORPTION

ADH: ADores H2O

• Note: whatever stimulates ADH release also stimulates THIRST!

◼ KIDNEYS: control body fluid volume by adjusting amount of water excreted in urine in response to ADH release:

◼ To conserve water: RELEASE ADH

kidneys retain (reabsorb) water ◼ Results in elimination of concentrated urine

◼ To reduce water: INHIBIT ADH kidneys lose water

◼ Produces what kind of urine?◼ What color?Na+ Regulation -Aldosterone Aldosterone: from adrenal cortex acts on renal tubules to reabsorb (RETAIN) Na+ and Cl- in exchange for (secretion of) K+ or H+ AldoSterone Saves Sodium

◼ To increase Na+: RELEASE Aldosterone -> Na+ reabsorption

◼ produces dilute urine What will the S.G. be? 1.005

◼ To reduce Na+: INHIBIT Aldosterone -> Na+ not reabsorbed

◼produces concentrated urine What will the S.G. be? 1.025 ◼ NOTE: Aldosterone works in combo with ADH: if ADH worked alone, plasma OSM would decrease CRITICALLY (can lead to swelling of the brain and coma)!!