Chapter 3 Flashcards, Fluids and Electrolytes, Acids and Bases
(56 cards)
How are body fluids classified?
Body fluids are classified as intracellular fluid (ICF) or extracellular fluid (ECF).
What is total body water (TBW)?
TBW is the sum of all fluids in the body, varying with age and body fat, and is higher in infants due to less body fat.
How does water move between ICF and ECF?
Water moves between the ICF and ECF compartments principally by osmosis.
What facilitates water movement between plasma and interstitial fluid?
Water moves between plasma and interstitial fluid by osmosis and hydrostatic pressure across the capillary membrane.
What is net filtration?
Movement across the capillary wall is called net filtration, described by the Starling law (forces favoring filtration minus forces opposing filtration).
What is edema?
Edema is a problem of fluid distribution resulting in fluid accumulation within interstitial spaces.
What causes edema?
Edema is caused by venous or lymphatic obstruction, plasma protein losses, increased capillary permeability, and increased vascular volume.
What pathophysiologic process leads to edema?
The process leading to edema is related to an increase in forces favoring fluid filtration from capillaries into tissues.
What are the symptoms of edema?
Edema may be localized or generalized, associated with swelling, tighter-fitting clothes, limited movement, and in severe cases, weight gain.
How are sodium and water balance related?
Sodium balance and water balance are intimately related; chloride levels generally change proportionally with sodium levels.
How is sodium balance regulated?
Sodium balance is regulated by aldosterone, which increases sodium reabsorption in the distal tubule of the kidney.
What role do renin and angiotensin play in sodium balance?
Renin and angiotensin are enzymes that promote or inhibit aldosterone secretion, regulating sodium and water balance.
What is the role of atrial natriuretic hormone?
Atrial natriuretic hormone decreases renal tubular resorption and promotes urinary excretion of sodium.
How is water balance regulated?
Water balance is regulated by thirst sensation and antidiuretic hormone levels, initiated by increased plasma osmolality or decreased blood volume.
How can alterations in water balance be classified?
Alterations in water balance may be classified as isotonic, hypertonic, or hypotonic.
What occurs during isotonic alterations?
Isotonic alterations occur when changes in total body water (TBW) are accompanied by proportional changes in concentrations of electrolytes.
What characterizes hypertonic alterations?
Hypertonic alterations develop when the osmolality of the extracellular fluid (ECF) is elevated above normal, usually due to increased ECF sodium concentration or a deficit of ECF water.
What is hypernatremia?
Hypernatremia is defined as sodium levels greater than 145 mEq/L and may be caused by an acute increase in sodium level or a loss of water.
What can cause water deficit or hypertonic dehydration?
Water deficit can be caused by lack of access to water, pure water losses, hyperventilation, arid climates, or increased renal clearance.
What causes hyperchloremia?
Hyperchloremia is caused by an excess of sodium or a deficit of bicarbonate.
What occurs during hypotonic alterations?
Hypotonic alterations occur when the osmolality of the ECF is less than normal.
What is hyponatremia?
Hyponatremia occurs when the serum sodium concentration decreases to less than 135 mEq/L, and may be caused by inadequate intake of sodium or dilution of the body’s sodium level.
What can cause water excess?
Water excess is rare but can be caused by compulsive water drinking, decreased urine formation, or the syndrome of inappropriate secretion of ADH.
What is the effect of hyponatremia on cells?
Hyponatremia usually causes movement of water into cells.
