Fluid Systems Flashcards
About how much of the body weight in the average adult is water?
60% (overall avg. is 45-60%)
Why do we lose water body weight percentage as we age?
As we age, we tend to lose muscle and gain fat
Where is most of the body’s fluid located?
Intracellular fluid (70%) [extracellular intravascular (plasma) = 6%, extracellular extravascular (interstitial fluid) = 26%]
True or False:
ECF is quite similar to ICF
False; plasma and interstitial fluid are similar because they are both outside the cell - ICF in inside the cell, which is vastly different from outside the cell, which has much more negatively charged electrolytes
Movement of water through a semipermeable membrane toward an area of greater solute concentration is due to ___________.
Osmotic pressure
What accounts for the osmotic pressure in tissues and cells?
Osmotic pressure
Number of molecules of a substance in a kg of water
Osmolarity
What is the osmolarity of normal serum?
285-295 mOsm/kg
Water moves from an area of high pressure to an area of low pressure.
Hydrostatic pressure
Is BP higher or lower in an arteriole than tissue pressure? A venule?
Higher; lower
Affects osmotic pressure and can regulate how much fluid moves into the tissue and move it back into the capillary bed and out the venules
Capillary fluid dynamics
ECF is filtered through the renal _____.
Glomeruli
Selective reabsorption and excretion of water and solutes occur in renal _____.
Tubules
The mechanism that brings glucose and other nutrients back into the body after they are filtered out
Selective reabsorption
Severe hydration; decreases renal perfusion; causes release of aldosterone from the renal cortex
Hypovolemic state
What hormone directly conserves water and is released by the pituitary gland?
Antidiuretic hormone (ADH) aka Vasopressin
What hormone indirectly conserves water and is released by the adrenal cortex?
Aldosterone
Name the 3 steroidal hormone types that bind to intracellular receptors, all work to conserve water and all come from the adrenal gland?
- Gonadal
- Glucocorticoids
- Mineralocorticoids
Formed in the hypothalamus; stored in the post. pituitary; area of storage and relate may overlap with the thirst center
ADH
What are the major stimuli for release of ADH?
- Increased osmolarity
- Decreased volume of ECF
- Stress of trauma, surgery, pain, and some anesthetics and drugs
A significant decrease in ADH from lesions or trauma of the hydrophyseal tract causes __________.
Diabetes insipidus (massive increase in urine output)
Secreted by the adrenal gland; acts on renal tubules to increase Na+ uptake
Aldosterone
What are the stimuli for the release of aldosterone?
- K+ concentration
- Na+ concentration
- Renin-angiotensin system
Naturally occurring fatty acids, fxns in the inflammatory response, BP control, uterine contractions, and GI mobility; causes vasodilation in kidneys, promoting Na+ excretion
Prostaglandins
Secreted by the adrenal cortex; weak activity for reabsorption of Na+ and water; increases blood volume and Na+ retention
Glucocorticoids
Causes increased kidney excretion of water and Na+; improved glomerular filtration rate; inhibits renin secretion; inhibits release of ADH
ANP
Extracellular volume depletion; abrupt decrease in fluid intake or extracellular volume decrease (hemorrhage, diarrhea,etc.); decreased extracellular space and circulatory collapse
Hypovolemia
Often from sodium retention due to excess ingestion or excess ADH secretion
Water excess
Extracellular volume excess; serum Na+ level is normal; excessive administration of isotonic solutions or adrenal glucocorticoids; may occur with diseases; expansion of extracellular space and vascular overload
Hypervolemia
Conscious desire for water; happens when osmolarity reaches 295 mOsm/kg
Thirst
What is thirst stimulated by?
- Decreased renal perfusion
- Osmoreceptors in the hypothalamus detect elevation of osmotic pressure
- Local dry mouth from reduced salivation
Caused by loss of blood, loss of plasma, loss of body fluids; burns, vomiting, diarrhea
Fluid deficit
Expansion or accumulation of interstitial fluid; localized or general; pitting or non-pitting
Edema
Caused by not moving blood from body back into heart, so increased venous pressure and edema in the body
Right side CHF
Caused by pulmonary edema because blood is not being moved back into the heart from the lungs
Left side CHF
What is the most common cause of CHF?
Increase capillary hydrostatic pressure
What causes increased capillary permeability?
Think more fluid will be out in the tissue
- Blood vessel damage (trauma, burns)
- Localized edema from an allergen
- Inflammation
What does the obstruction of lymphatics cause?
Excess fluid in the tissue; more water goes in than goes out; lymphs remove excess fluid from tissue
Edema from hypoproteinemia is usually generalized, but pronounced in ______ and ______ from recumbent positioning
Eyelids; face
Fluid shift:
From vascular to extracellular - similar to fluid volume _______
From extracellular to vascular - similar to fluid volume _______
deficit; excess
Electrolyte function:
Membrane potential; affects osmolarity of the blood
Sodium
Electrolyte function:
Membrane potential; muscle activity (heart, intestines, respiratory tract, and neural stem of skeletal m.)
Potassium
Electrolyte function:
Permeability of cell membranes; imbalances affect bones, kidneys, and GI tract
Calcium
Electrolyte function:
Neuromuscular integration and parathyroid hormone stim; imbalances cause irritability of nervous system
Magnesium
Signs and symptoms are paresthesias muscle weakness, muscle wasting, muscle tetany, and bone pain
Electrolyte imbalance
Normal range of sodium
135-145 mEg/L
Na+ deficit; Losses may be caused by nausea, vomiting, accumulation of fluid in the peritoneal cavity, sequestration of secretions in an obstructed GI tract, excessive sweating in conjunction with excessive water intake, and sequestration of sodium and fluid in burned skin
Hyponatremia
How would you treat hyponatremia?
Involves Na+ replacement, Na+ containing IV fluids, Lactated ringer’s or .9% NaCl solution
Na+ excess; due to Na+ gain or water loss; occurs in individuals who are unable to respond to the sensation of thirst, which includes, infants, elderly, people who are mentally ill, and individuals who are immobile
Hypernatremia
How would you treat hypernatremia?
involves fluid replacement either orally or through an IV of 5% dextrose (isotonic) in water or hypotonic saline solution
What is the normal serum value for potassium?
3.5-5.0 mEg/L
K+ deficit; losses related to GI losses and renal losses
Hypokalemia
K+ excess; may rest from an increased intake of K+, or decreased output or a shift of K+ out of the cells; inadequate renal secretion; trauma that destroys cells and releases excess K+
Hyperkalemia
What is the normal adult levels of calcium?
9.0-10.5 mg/dL
When calcium levels increase, phosphate levels _____
decrease
Electrolyte function:
Works with calcium to support bone formation; primary intracellular ion; 85% in bones; works to keep Ca levels more in the blood
Phosphate
Calcium deficit; results from poor intake or absorption in GI tract; overcorrection of acidosis
Hypocalcemia
Calcium excess; due to hyperparathyroidism, hyperthyroidism, adrenal insufficiency, tumors, multiple fractures, excess intake
Hypercalcemia
What is the normal serum levels for chloride?
90-110 mEg/L
Electrolyte function:
Important in maintaining (along with Na+) osmolarity, body water balance, and acid-base balance
Chloride
Cl- deficit; result from gastric fluid loss, diarrhea, hypokalemia, hyponatremia, continuous IV infusion of 5% dextrose in water, etc.
Hypochloremia
Cl- excess; result from dehydration, hypernatremia, stomach cancer, adrenal gland hyperactivity, head injuries, and kidney dysfunctions
Hyperchloremia
What are normal adult magnesium levels?
1.2-2.0 mEg/L
Magnesium deficit
Hypomagnesemia
Magnesium excess; chronic renal and adrenal insufficiency, overuse of antacids and laxatives, severe dehydration, near drowning in sea water
Hypermagnesemia
Normal pH level of the body; limits of pH level?
7.35 - 7.45; 7.2-7.55
