Chapter 27: Fluid, Electrolyte, and Acid-Base Balance

Exam 4

What are electrolytes?

ions released when inorganic compounds diassociate

How are fluid, electrolyte, and acid-base balance related?

all essential for homeostasis

Main fluids in ECF?

interstitial fluid and plasma

Main fluid in ICF?

cytosol

Principal ions in ECF?

Na, Cl, and bicarbonate

Principal ions in ICF?

K, Mg, PO4, and HPO4

Which compartment is monitored for body fluid changes?

ECF

What do receptors monitor for fluid/electrolyte balance?

Plasma and osmotic concetration

Pituitary hormone promoting water retention?

ADH

Effects of increased ADH?

Increased water retention and thirst

Corticosteroid regulating sodium/water balance?

aldosterone

What triggers aldosterone release?

high K or low Na in blood

Hormones released by stretched heart?

ANP and BNP

Effect of natriuretic peptides?

decrease BP and plasma volume

Define diuresis.

fluid loss via kidneys

Water produced during aerobic metabolism?

oxidative phosphorylation in mitochondria

Sensible vs. insensible perspiration?

Sensible – sweat glands; Insensible – skin/lung evaporation.

Define edema.

Swelling from fluid buildup

Define fluid shift.

Rapid water movement between ECF and ICF down the concentration gradient

Hypernatremia vs. hyponatremia?

High vs. low sodium

Principal cation in ECF vs. ICF?

ECF: sodium ICF: potassium

Most common electrolyte imbalance?

sodium

Most dangerous electrolyte imbalance?

potassium

Aldosterone-sensitive pumps reabsorb which ion in exchange for which?

reabsorb Na in exchange for K

Hyperkalemia vs. hypokalemia?

Excess vs. deficient potassium.

Hyperkalemia

Cardiac arrhythmias, muscle spasms.

Effects of hypokalemia?

weakness and paralysis

Normal ECF pH?

7.35 to 7.45

Acidosis vs. alkalosis?

under 7.35 or over 7.45

Mechanisms for acid-base balance?

buffer systems, respiratory and renal

Acid affecting blood pH?

Volatile acids

What acid spontaneously forms CO₂ + H₂O ?

carbonic acid

What is H₂CO₃ , what is HCO₃⁻?

carbonic acid, bicarbonate

Gas most affecting blood pH?

CO₂; inversely proportional to pH.

Buffer function?

Stabilize pH by adding/removing H⁺.

Major buffer systems:

ICF: phosphate + protein; ECF: carbonic acid-bicarbonate + protein

Respiratory compensation?

Adjust respiration to stabilize ECF pH.

Effect of increased respiratory rate?

pH rises

Q: Renal compensation?

Adjust H⁺ and HCO₃⁻ secretion/absorption.

Effect of H⁺ excretion?

Raises blood pH.

Primary molecule in respiratory disorders?

CO2

Primary molecule in metabolic disorders?

bicarbonate (HCO3)

Q: Hypercapnia vs. hypocapnia?

High vs. low PCO2

Hypoventilation → ?

respiratory acidosis

Chronic respiratory acidosis diseases?

Pneumonia, emphysema, CHF.

Compensation for respiratory acidosis?

increased respiration, renal H⁺ secretion, buffer systems.

Q: Hyperventilation → ?

respiratory alkalosis

Compensation for respiratory alkalosis?

decrease respiration, renal H + generation , buffer release 

Metabolic acidosis causes?

lactic acidosis, ketoacidosis, bicarbonate loss via diarrhea/glomerulonephritis

Compensation for metabolic acidosis?

increase respiration + renal H+ secretion

Metabolic alkalosis causes?

alkaline ride, HCO3 excess

Compensation for metabolic alkalosis?

decreased respiration, renal H + generation, bicarbonate secretion

Aging effect on GFR?

decreases, reduced pH regulation

Aging effect on ADH/aldosterone?

reduced, decreased sensitivity leads to less water retention