UNIT 8 - FLUIDS & ELECTROLYTES Flashcards
p
Potential
H
Hydrogen
pH ranges
Acidic solutions have pH below 7, basic solutions have pH above 7, neutral solutions have pH 7
pH units
Each pH unit is 10 times as larger as the previous one (eg. Change of 2 pH units = 100x more acidic/basic)
pH
Scale from 0-14 that specifies the acidity/basicity of a solution (measure of hydrogen ions present per litre of solution in g)
Electrolytes
Compound that releases ions in water and conducts electric current and are found in all bodily fluids (eg. Cations, anions)
Strong electrolytes
Compound that dissociate in water and produces positive and negative ions and conduct an electric current (eg. NaCl = Na+ Cl- (100% ions)
Non-electrolytes
Compounds that dissolve as molecules in water and do not produce ions or conduct electric current
Functions of electrolytes (4)
- Act a co-factors for enzymes
- Maintenance of fluid balance osmosis)
- Maintenance of acid-base balance (pH)
- Neuromuscular activity and synaptic transmission (electrical currents)
The electrolyte trio
Sodium, magnesium, potassium
Extracellular fluid
Body fluid outside cells
Extracellular fluid characteristics (3)
- Na+ & Cl-
- Cation concentrations similar in both plasma and interstitial fluid (ions can move easily between them)
- Anion concentrations similar in both plasma and interstitial fluid, except for protein anion concentration = higher in plasma
Sodium (Na) functions
Impulse transmission, muscle contraction, fluid & electrolyte balance
Chloride (Cl) functions
Osmotic pressure, HCl formation in gastric acid controlled by hormones
Intracellular fluid
Fluid inside cells
Intracellular fluid characteristics (3)
- K+ & PO43-
- Mg2+ major cation for activating enzymes
- Larger concentration of protein anions here
Potassium (K) function
Resting membrane potential, action potential for nerves/muscles, intracellular volume, pH regulation
Acid
Solution with excess H+ ions, the more H+ ions then the more acidic
Base
Solution with excess OH- ions, and are substances that can accept hydrogen ions
Sources of acids in body (4)
- CO2 from total combustion of carbohydrates
- Metabolic processes: Breakdown of protein, glucose, fat, organic molecules
- Nitrogenous waste: uric acid
- HCl gastric acid
Sources of bases in body (3)
- Bile salts
- Pancreatic juice
- Alkaline drugs
Mechanisms by which the body regulates pH (3)
- First line defense: Blood buffer (bicarbonate-carbonic, phosphate, protein)
- Second line defense: Respiratory system
- Third line defense: Renal regulation (excretory)
Blood buffer
Immediate, short-term mechanism for maintaining pH
Bicarbonate-carbonic acid buffer system
Buffer system for maintaining pH in blood and most effective in extracellular fluid. Carbonic acid act as weak acid, and sodium bicarbonate act as weak base
Phosphate buffer system
Buffer system for maintaining pH in renal tubular fluid (urine) and most effective in intracellular fluid. Phosphate ions act has weak acids and bases
Protein buffer system
Buffer system for maintaining pH by proteins and most abundant in intracellular fluid & blood plasma. Carboxyl group are weak acids, amino groups are weak baes (eg. Hemoglobin)
Respiratory system
: Regulates how much CO2 stays/leaves body and works within 1-3 min to affect pH
Respiratory regulation in increase of acidity of blood (4)
- Results in increase of hydrogen ions
- Hydrogen ions combine with bicarbonate to form carbonic acid
- Carbonic acid forms CO2 and H2O
- Excess CO2 removed from system
Respiratory regulation in decrease of acidity of blood (3)
- Results in decrease of hydrogen ions
- Lungs need to retain CO2 and form more carbonic acid
- Carbonic acid breaks down to form more hydrogen ions and bicarbonate
Renal regulation
Controls acid-base balance by excreting or secreting various ions and requires hours or days to affect pH
Acidosis
Condition in decrease in pH below 7.35; kidneys generate bicarbonate and add to blood to equal out the amount of hydrogen ions to urine
Respiratory acidosis
Most common cause of blood pH imbalance caused by anything that interferes with CO2 leaving the blood to alveoli (eg. Emphysema, edema, damage to respiratory muscles or breathing centers in brain)
Metabolic acidosis
Caused by buildup of acid metabolic products or loss of bicarbonate ions from body best indicated by low blood pH + low blood bicarbonate
Alkalosis
Condition in increase in pH above 7.45; kidneys secrete bicarbonate ions and absorb hydrogen ions
Respiratory alkalosis
Can be caused by hyperventilation due to loss of CO2 from stress/pain
Causes of hyperventilation (3)
- High altitudes
- Anxiety
- Aspirin overdose
Metabolic alkalosis
Caused by excessive loss of acids from body (vomiting) best indicated by rising blood pH and bicarbonate levels
ROME (2)
- Respiratory = Opposite: pH is high PCO2 is low (alkalosis), pH is low PCO2 is up (acidosis)
- Metabolic = Equal: pH is high HCO3 is high (alkalosis, pH is low HCO3 is low (acidosis)
