Alterations in Water and Sodium balance Flashcards
Water Balance
- Determined by osmotic gradients established by sodium concentrations
- Antidiuretic hormone (ADH) regulates water balance (kidney gets rid of h20)
Sodium balance and functions
-Sodium accounts for 90% of the ECF cations
- Maintains extracellular osmolarity
- maintains resting membrane potential (RMP) and needed for depolarization
Aldosterone
Regulates plasma sodium
^ aldosterone = ^ Na+ reabsorption = ^ h20 reabsorp. = ^ BV= ^ BP
Isotonic Alterations in Sodium and Water balance
-Changes in total body water (TBW) accompanied by proportional changes in electrolytes
isotonic alteration types
FLUID OVERLOAD; administration of intrvenous normal saline solutions/hypersecretion of aldosterone (hyperaldosteronism) (^ aldost. = ^ retention of h20 and Na)
HYPOVOLEMIA; hyposecretion of aldosterone, sweating
( v aldosterone = v retention of h20 and Na)
Hypotonic alterations; Hyponatremia (and causes)
LOW SODIUM IN THE BLOOD (lower than 35)
causes;
-Vomitting;gastric suctioning
loss of sodium and acid levels
-inadequate sodium intake
-excessive oral water intake
dilutes plasma sodium to a dangerous level
-Excessive ADH secretion (syndrome of inappropriate elevated ADH -SIADH)
too much ADH = too much water retention
Hyponatremia patho
- Shift of h20 from ECF to cyotplasm (ICF)
- too much h20 into icf will cause cell to burst
LOWER RMP
… less Na+ in cell drops memb. potential making it more negative, harder to depolarize & get AP
hyponatremia clinical manifestations
NEURONAL SWELLING
- lethargy and confusion,seizures, comas
- gait disturbance, falls
FLUID OVERLOAD
- weight gain
- edema
hypertonic alteration; hypernatremia (and causes)
HIGH SODIUM IN THE BLOOD (greater than 145)
causes;
(usually developed w/ kidney malfunction)
-Dietary sodium excess
- administration of hypertonic saline solution
- insufficient intake/ dehydration
-decreased ADH secretion (diabetes insipidus)
( v ADH = v water retention)
What is ADH and where is it produced?
antidiueratic hormone… pituitary gland
Hypernatremia patho
Shift of water from cytoplasm to ECF
- diluting Na+ in the blood raising blood volume
- cells shrink and become dehydrated
HIGHER RMP high Na+ in the cell memb making it more positive -Closer to threshold -neuromuscular excitability -more AP fired
hypernatremia clinical manifestations
DUE TO SYSTEMIC DEHYDRATION
-thirst
-low bp and increased heart rate (tachycardic)
….high heart rate trying to keep bp up
-dry mucous membranes
…chronic tissue and cell dehydration
-poor skin tugor
..tissue not well hydrated if it doesn’t return quickly
-weight loss
-decreased urine output and concentrated urine
…kidneys working hard to retain water
Potassium balance
- major intracellular electrolyte
- plasma concent 3.5-5.5 mEq/L in blood
Regulation of plasma potassium by the kidneys
- Potassium normally secreted by renal tubules and excreted in urine
- aldosterone stimulates K+ excretion by kidneys
Insulin
-Cells requires insulin to uptake glucose into the cell
-insulin is produced by the pancreas
-
..as insulin binds to insulin receptor, K+ and glucose enter the cell
Hypokalemia and causes
TOTAL BODY DEFICIT OF POTASSIUM
causes;
-shifts of K+ from ECF to ICF
-gastrointestinal (diarrhea)
….washing GI tract out, K+ cant get absorbed
-Renal Losses (diuresis)
..washes K+ out by urine
-Shift of K+ form ECF to ICF
..insulin overdose, too much K+ enters cell lowering blood K+ levels
^ insulin + ^ glucose = v K+ plasma levels (in blood bc goes to ICF)
Hypokalemia patho
-Lower RMP, harder to reach threshold
Sodium imbalances affect;
Effect CNS (neurological)
K+ imbalances effect
Effect muscle tissue (ex; heart)
Hyperkalemia and causes
TOTAL BODY EXCITATION OF K+
causes;
-Renal failure
..kidnye cant get rid of excess K+
-Increased K+ intake
-Shift of K+ from ICF to ECF
.. ex; crush injuries: cell lyse/die go to ecf and gets in blood stream
-Insulin deficiency
..no insulin= no glucose or K+ intake
Hyperkalemia patho
- higher RMP
- mild-moderate; increased muscular excitability
- sever hyperkalemia- cells unable to repolarize
- cells depolarize and can never repolarize, heart pumps and cant relax
