32 terms

Ch 27 Fluid, Electrolyte, and Acid-Base Balance

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interstitial fluid, plasma
What are the primary components of the extracellular fluid:
phosphate and proteins (Pr-)
The principal anions in the ICF are:
ADH
Osmoreceptors in the hypothalamus monitor the osmotic concentration of the ECF and secrete (blank) in response to higher osmotic concentrations
calcium homeostasis
An interplay among reserves in the bone, the rate of absorption, and the rate of excretion describes what?
carbon dioxide
The most important factor affecting the pH of body tissues is the concentration of:
carbonic acid-bicarbonate buffer system, phosphate buffer sytem, changes in the rate and depth of breathing, protein buffers
Changes in the pH of body fluids are compensated for by all of the following:
Respiratory Acidosis
Develops when the plasma pH is decreased due to an elevated plasma Pco2 level
metabolic alkalosis
Occurs when bicarbonate ion concentrations become elevated:
ADH, Aldosterone, ANP, BNP
Identify four hormones that mediate major physiological adjustments affecting fluid and electrolyte balance
Antidiuretic hormone ADH
stimulates water conservation at the kidneys and stimulates the thirst center
Aldosterone
determines the rate of sodium reabsorption and potassium secretion along the DCT and collecting system of the kidney; and the natriuretic peptides
ANP and BNP
reduce thirst, promote the loss Na+ and water at the kidneys, and block the release of ADH and aldosterone
increase in volume and become hypotonic with respect to the ICF
Drinking a hypotonic solution causes the ECF to:
gain of electrolytes
The osmotic concentration of the ECF decreases if an individual gains water without a corresponding
bind a hydrogen at the amino group
When the pH of body fluids begins to fall, fee amino acids and proteins will:
hydrogen ion is released and a carboxyl ion is formed
In a protein buffer system, if the pH rises:
fluid balance
state in which the amount of water gained each day is equal to the amount lost to the environment, it is vital that the water content of the body remain stable, because water is an essential ingredient of cytoplasm and accounts for about 99 percent of ECf volume
Electrolyte balance
exists when there is neither a net gain nor a net loss of any ion in body fluids, it is important that the ionic concentration sin body water remain within normal limits
Acid-base balance
exists when the production of hydrogen ions precisely offsets their loss, the pH of body fluids must remain within a relatively narrow range; variations outside this range can be life threatening
fluid shifts
rapid water movements between the ECF and the ICF that occur in response to increases or decreases in the osmotic concentration of the ECF. such water movements dampen extreme shifts in electrolyte balance
higher fever = higher water loss
Why should a person with a fever drink plenty of fluids?
volatile acid
Acids that can leave solution and enter the atmosphere, such as carbonic acid
fixed acid
Acids that do not leave solution, such as sulfuric acid
organic acid
Acids produced during metabolism, such as lactic acid
volatile acids
What kind of acid represents the greatest threat to acid-base balance?
protein buffer systems, carbonic acid-bicarbonate system, phosphate buffer system
What are the three major buffer systems in body fluids?
Protein buffer systems
These depend on the ability of amino acids to respond to changes in pH by accepting or releasing hydrogen ions, if the pH rises, the carboxyl group of the amino acid dissociates to release a hydrogen ion; if the pH drops, the amino group accepts an additional hydrogen ion to form an NH4+ group.
Carbonic acid-bicarbonate system
most carbon dioxide generated in tissues in converted to carbonic acid which dissociates into a hydrogen ion and a bicarbonate ion. Hydrogen ions released by dissociated of organic or fixed acids combine with bicarbonate ions, elevating the Pco2, additional CO2 is lost at the lungs
Phosphate buffer system
This buffer system consists of H2PO4-, a weak acid that, in solution, reversibly dissociates into a hydrogen ion and HPO42-. The phosphate buffer system plays a relatively small role in regulating the pH of the ECF, b/c the ECF contains far higher concentrations of bicarbonate ions than phosphate ions; however, it is important in buffering the pH of the ICF
secreting or absorbing hydrogen ions, controlling the excretion of acids and bases, and generating additional buffers
How do respiratory and renal mechanisms support the buffer systems?
respiratory compensation
a change in the respiratory rate that helps stabilize the pH of the ECF. Increasing or decreasing the rate of respiration alters pH by lowering or raising the Pco2. When the Pco2 declines, the pH rises; when the Pco2 increases, the pH decreases
Renal Compensation
a change in the rates of hydrogen and bicarbonate ion secretion or reabsorption in response to changes in plasma pH. Tubular hydrogen ion secretion results in the diffusion of bicarbonate ions into the ECF