fluid  electrolytes

fluid electrolytes PowerPoint PPT Presentation

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Distribution of Body Fluids. Water is the largest single component of the body60% of adult's weight is waterHealthy people can regulate balance. Compartments . IntracellularWithin the cellsContains dissolved solutes essential to balanceExtracellularOutside of the cellInterstitialBetween and around the cellsIntravascular Also lymph and organ fluidsWithin the blood vesselsPlasma.

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fluid electrolytes

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1. Fluid & Electrolytes

3. Intracellular Within the cells Contains dissolved solutes essential to balance Extracellular Outside of the cell Interstitial Between and around the cells Intravascular Also lymph and organ fluids Within the blood vessels Plasma

4. Composition of Body Fluids Water Electrolytes Separates into ions when dissolved Carries an electrical charge Positive charge – CATIONS Sodium, Potassium, Calcium Negative charge – ANION Bicarbonate, Chloride

5. Cell membranes are selectively permeable Water passes through easily Most ions and molecules move through much slower

6. Osmosis Moving a liquid through the membrane from lesser to greater solute concentration Rate depends on concentration Temperature Electrical charges Differences between osmotic pressures Works at equalizing concentration

7. Osmotic Pressure (Osmolarity) Pulling power for water Depends on number of molecules in solution Higher the concentration, greater pulling power (higher osmotic pressure) Rate is quicker Continues until equilibrium is reached

8. Osmolarity Hypertonic Higher osmotic pressure than RBC’s Pulls fluid from cells Shrinks cell Isotonic Same osmotic pressure as RBC’s No fluid shift Hypotonic Lower osmotic pressure than RBC’s Fluid moves into cells Enlarges cell

9. Osmotic Pressure (cont) Affected by plasma proteins Albumin Keeps fluid in intravascular compartment using osmotic pressure Hydrostatic pressure draws fluid back into capillaries Force of fluid pressure outward against surface

10. Diffusion Moving a solid across the semipermeable membrane From higher concentration to lower To reach equilibrium Difference between the two is concentration gradient

11. Filtration Both water and solids move together in response to fluid pressure Seen in capillary beds ACTIVE Transport Requires energy Moves against gradient Sodium and potassium pump Uses carrier molecule Glucose entering cell

12. Regulation of Body Fluids To maintain homeostasis, fluids are regulated by: Fluid intake Hormonal controls Fluid output

13. Fluid Intake Regulated primarily by thirst mechanism In the hypothalamus Osmoreceptors monitor serum osmotic pressure Hypothalamus stimulated when osmolarlity increases Thirst mechanism stimulated With decreased oral intake Intake of hypertonic fluids Loss of excess fluid Stimulation of renin-angiotensisn-aldosterone mechanism Potassium depletion Psychological factors Oropharyngeal dryness

14. Fluid Intake (cont) Average adult intake 2200-2700 cc/day Oral – 1100-1400 Solid foods – 800-1000 Oxidative metabolism – 300 By-product of cellular metabolism of ingested foods

15. Fluid Intake (cont) Must be alert Able to perceive mechanism Able to respond to mechanism **At risk for dehydration: Elderly Very young Neurological disorders Psychological disorders

16. Hormonal regulation ADH Stored in posterior pituitary gland Released in response to changes in blood osmolarity Makes tubules and collecting ducts more permeable to water Water returns the systemic circulation Dilutes the blood Decreases urinary output

17. Hormonal regulation (cont) Aldosterone Released by adrenal cortex In response to increased plasma potassium Or as part of renin-angiotensin-aldosterone mechanism Acts on distal tubules to increase reabsorption of sodium and water Excretion of potassium and hydrogen

18. Hormonal regulation (cont) Renin Secreted by kidneys Responds to decreased renal perfusion Acts to produce angiotensin I Causes vasoconstriction Converts to Angiotensin II Massive selective vasoconstriction Relocates and increases the blood flow to kidney, improving renal perfusion Stimulates release of aldosterone with low sodium

19. Fluid Output Regulation Kidneys Major regulatory organ Receive about 180 liters of blood/day to filter Produce 1200-1500 cc of urine Skin Regulated by sympathetic nervous system Activates sweat glands Sensible or insensible-500-600 cc/day Directly related to stimulation of sweat glands Respiration Insensible Increases with rate and depth of respirations, oxygen delivery About 400 cc/day Gastrointestinal tract In stool Average about 100-200 GI disorders may increase or decrease it.

20. Regulation and Movement of Sodium Most abundant cation in ECF Major contributor to maintaining water balance By effect on serum osmolality, nerve impulse transmission, regulation of acid-base balance and participation in chemical reactions Regulated by dietary intake and aldosterone Normal level : 135-145

28. Regulation works in both directions

36. Regulation works in both directions

38. Osmoreceptors are the main controllers of ADH levels, but other factors include.. Alcohol (inhibits ADH) Nicotine (stimulates ADH) Increased circulating volume(Atrial stretch, ANP release,ADH release inhibited)... seelater

39. Volume Regulation Since the osmolarity (i.e. concentration) of ECF is tightly controlled, the volume of the ECF is determined by the total quantity of solute (mainly NaCl), so regulation of ECF volume is all about Sodium Balance

40. Volume Regulation .. The total amount of Sodium in ECF dictates volume of ECF

41. The Sensor

42. The Juxtaglomerular Apparatus

43. The Juxtaglomerular Apparatus

44. Renin may be released by: ­ sympathetic activity (n.b. baroreceptor response to low BP) ¯ wall tension in afferent arteriole (? drop in mean or pulse pressure) ??? a fall in Sodium delivery to Macula Densa i.e. Low Blood Volume (Hypovolemia)

45. The Juxtaglomerular Apparatus

46. The Juxtaglomerular Apparatus

47. The Juxtaglomerular Apparatus

48. Renin may be released by: ­ sympathetic activity (n.b. baroreceptor response to low BP) ¯ wall tension in afferent arteriole (? drop in mean or pulse pressure) ??? a fall in Sodium delivery to Macula Densa i.e. Low Blood Volume (Hypovolemia)

56. Aldosterone Increases Na+ reabsorption in DCT as well as from : gut sweat glands salivary glands

57. Aldosterone Increases Na+ reabsorption in DCT as well as from : gut sweat glands salivary glands

58. Another volume sensor.... The Atria Atrial Natriuretic Peptide (ANP) released when atria stretched (­ blood volume)causing: ¯ Aldosterone secretion ¯ Renin release ¯ ADH release (emergency response)

59. Regulation and Movement of Potassium Major cation in intracellular compartments Regulates metabolic activities, necessary for glycogen deposits in liver and skeletal muscle, transmission and conduction of nerve impulses, normal cardiac conduction and skeletal and smooth muscle contraction Regulated by dietary intake and renal excretion Normal level – 3.5-5.0 Body conserves potassium poorly Increased urine output decreased serum potassium

60. Movement and Regulation of Calcium Stored in bone, plasma and body cells (Cation) 90% in bones 1% in ECF In plasma, binds with albumin Necessary for bone and teeth formation, blood clotting, hormone secretion, cell membrane integrity, cardiac conduction, transmission of nerve impulses, and muscle contraction Normal level – 4.5-5.5 Regulated by bone resorption

61. Movement and Regulation of Magnesium Cation Normal 1.5-2.5 Regulated by dietary, renal and PTH

62. Movement and Regulation of Chloride Major anion in ECF Normal level – 95-108 Follows sodium Regulated by dietary intake and the kidneys

63. Major chemical base buffer in the body Carbonic acid-Bicarbonate buffering system Needed for acid-base balance Normal level 22-26 Regulated by kidneys

64. Movement and Regulation of Phosphate Buffer anion found mainly in ICF Assists in acid-base balance Inversely proportional to calcium Helps maintain healthy bones and teeth, neuromuscular activity, and CHO metabolism Absorbed through GI tract Normal level 2.5-4.5 Regulated by dietary intake, renal excretion, intestinal absorption and PTH

65. Common Disturbances Electrolyte Balance Sodium Hypernatremia (Na > 145, sp gravity < 1.010) Caused by excess water loss or overall sodium excess Excess salt intake, hypertonic solutions, excess aldosterone, diabetes insipidus, increased s water loss, water deprivation S&S: thirst, dry, flushed skin, dry, stick tongue and mucous membranes Hyponatremia (Na < 135, sp gravity > 1.030) Occurs with net loss of sodium or net water excess Kidney disease with salt wasting, adrenal insufficiency, GI losses, increased sweating, diuretics, SIADH S&S: personality change, postural hypotension, postural dizziness, abd cramping, n&v, diarrhea, tachycardia, convulsions and coma

66. Common Disturbances Electrolyte Balance Potassium Hyperkalemia (K > 5.3; EKG irregularities-bradycardia, heart block, wide QRS pattern-cardiac arrest) Primary cause: renal failure; major symptom: cardiac irregularity Fluid volume deficit, massive cell damage, excess K+ given, adrenal insufficiency, acidosis, rapid infusion of stored blood, potassium-sparing diuretics S&S: dysrhythmias, paresthesia Hypokalemia (K < 3.5; EKG irregularities-ventricular) Most common electrolyte imbalance; affects cardiac conduction and function. Most common cause: potassium wasting diuretics Diarrhea, vomiting, alkalosis, excess aldosterone secretion, polyruia, extreme sweating, insulin to treat diabetic ketoacidosis S&S: weakness, ventricular dysrhythmias, irregular pulse

67. Common Disturbances Electrolyte Balance Calcium Hypercalcemia (Ca > 5; x-rays show calcium loss, cardiac irregularities) Frequently symptom of underlying disease with excess bond resorption and release of calcium Hyperparathyroidism, malignant neoplastic disease, Paget’s disease, Osteoporosis, prolonged immobization, acidosis S&S: anorexia, nausea and vomiting, weakness, kidney stones Hypocalcemia (Ca < 4.0, EKG abnormalities) Seen in severe illness Rapid blood transfusion with citrate, hypoalbuminemia, hypoparathyroidism, Vitamin D deficiency, Pancreatitis, Alkalosis S&S: numbness and tingling, hyperactive reflexes, positive Trousseau’s sign (wrist), positive Chvostek’s sign (cheek), tetany, muscle cramps, pathological fracture

68. Common Disturbances Electrolyte Balance Chloride Usually seen with acid-base imbalance Hyperchloremia (Na >145, Bicarb <22) Serum bicarbonate values fall or sodium rises Hypochloremia (pH > 7.45) Excess vomiting or N/G drainage; loop of thiazide diuretics because of sodium excretion Leads to metabolic alkalosis due to reabsorption of bicarbonate to maintain electrical neutrality

69. Common Disturbances Fluid Balance Isotonic imbalances When water and electrolytes are gained or lost in equal proportions Osmolar imbalances Loss or gain of only water Osmolality is affected

70. Isotonic imbalances Fluid volume deficit (Sp Gravity > 1.025, Hct >50%, BUN > 25) GI losses, loss of plasma or whole blood, excess perspiration, fever, decreased intake, diuretics S&S: postural hypotension, tachycardia, dry mucous membranes, poor skin turgor, thirst, confusion, rapid weight loss, slow vein filling, lethargy, oliguria, weak pulse, sunken, dry conjunctiva Fluid volume excess (Hct < 38%, BUN < 10 Congestive heart failure, renal failure, cirrhosis, increased aldosterone and steroid levels, excess sodium intake S&S: rapid weight gain, edema, hypertension, polyuria, neck vein distention, increased venous pressure, crackles in lungs

71. Osmolar Imbalances Dehydration (Hyperosmolar imbalance) (Na > 145) Diabetes insipidus, neurological damage to block thirst drive, diabetic ketoacidosis, osmotic diuresis, hypertonic IV fluids of tube feedings S&S: dry, sticky mucous membranes, flushed and dry skin, thirst, elevated temp Water Excess (Hypoosmolar imbalance) (Na < 135) SIADH, excess water intake S&S: decreased level of consciousness, convulsions, coma

72. Variables Affecting Normal Fluid, Electrolyte and Acid-Base Imbalances Age Orientation status Mobility level Prolonged illness Cancer, CHF, endocrine disease, COPD Medications Diuretics, steroids, IV therapy, TPN Gastrointestinal losses

73. Clinical Assessment for Fluid, Electrolyte and Acid-Base Imbalances Pre-existing disease processes Cancer, cardiovascular, renal, GI Age Infants have higher % water- loss felt faster Elderly –kidneys decreased filtration rate, less functioning nephrons, don’t excrete mediations as fast, lung changes may lead to respiratory acidosis Acute illness Surgery, burns, respiratory disorders, head injury Environmental Vigorous exercise, temperature extremes Diet Fluids and electrolytes gained through diet Lifestyle Smoking or alcohol Medications Side-effects may cause fluid and/or electrolyte imbalances

74. Medications Likely to Cause F&E Imbalances Diuretics Metabolic alkalosis, hyperkalemia, hypokalemia Steroids Metabolic alkalosis Potassium supplements GI disturbances Respiratory center depressants (narcotic analgesics) Respiratory acidosis Antibiotics Nephrotoxicity, hyperkalemia, hypernatremia Calcium carbonate (TUMS) Metabolic alkalosis Magnesium hydroxide (Milk of Mag) hypokalemia

75. References To be added

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