Fluid, Electrolyte, and Acid-Base Balance

Predict the effect of hypertonic fluid on a cell.

Hypertonic fluids cause water to move out of the cytosol and the cell shrinks.

What happens during compensation for alkalosis?

Renal compensation for alkalosis includes secretion of bicarbonate ions and reabsorption of hydrogen ions; respiratory is hypoventilation

If the Pco2 in the plasma increases, what effect will this have on plasma pH?

The pH will decrease; An increase in Pco2 is caused by hypoventilation and will result in acidosis.

The normal hydrogen ion concentration of body fluids is equal to a pH range of about 7.35-7.45.

True

PCO2 normal range

alkaline 35-45 acid

Identify the hormones responsible for increasing sodium ion retention.

angiotensin-II and aldosterone

Hyperventilation is the compensation for an acid-base imbalance known as

metabolic acidosis

Total body water

60% of body weight (average man) cytosol - 60% about 26L Plasma - 8% about 3L Interstitial fluid - 32% about 13L

Dehydration

A condition characterized by a decreased volume and increased concentration of the extracellular fluid

Hyperventilation causes __________, and hypoventilation causes __________.

respiratory alkalosis; respiratory acidosis

composition of hydroxyapatite

Calcium ions and phosphate ions (PO43−)

bicarbonate ion

most common base in the human body and is part of the major extracellular buffer system.

Hypercalcemia

most common cause is hyperthyroidism; muscle weakness, lack of coordination, abdominal pain, confusion, shallow respirations, excess urination

Hyponatremia

most common cause is overhydration; administer isotonic saline; muscle weakness and spasms; irritability; headache; nausea and vomiting

hypokalemia

most common cause is use of diuretics; cells are hyperpolarized and difficult to stimulate; muscle weakness, mental changes, decreased heart rate

Hyperkalemia

most dangerous imbalance; high doses of K+ cause immediate death; cells are no longer excitable and they shut down

Increased water volume causes the hydrostatic pressure in plasma to increase and the osmotic pressure to decrease; as a result, water will

move from ECF to ICF

The concentrations of sodium, chloride, calcium, and bicarbonate ions are

much higher in the ECF than in the cytosol (ICF).

osmostic pressure

net movement of water into or out of a cell; moves from hypotonic (low concentration) to hypertonic (high concentration)

sensible water loss

noticeable water loss; through urine and feces (1500ml from urine and 100ml from feces)

uncompensated

pH and one other value is abnormal

compensated

pH is normal and other two values are abnormal

hypotonic hydration

-water intoxication -ECF is diluted, hyponatremia (low ECF Na+) -noted after renal insufficiency or drinking too much water too quickly (hikers or athletes overdoing water intake or X) b. symptoms: nausea, vomiting, muscle cramps, cerebral edema, severe: disorientation, convulsions, coma, death

Anion

A negatively charged ion

Cation

A positively charged ion

electrolyte

A substance that dissolves in water to give a solution that conducts electric current (ionizes in water)

4 main hormones that regulate fluid balance

ADH, aldosterone, angiotensin-II, and ANP

Partially compensated

All 3 values will be abnormal.

CO2 + H2O ↔ H2CO3 ↔

H+ + HCO3- (The most important chemical buffer system in the blood is the carbonic acid-bicarbonate ion buffer system, which consists of the weak acid carbonic acid and its weak conjugate base, the bicarbonate ion. When carbonic acid dissociates, it yields a hydrogen ion and a bicarbonate ion.)

Calcium ion reabsorption in the kidneys is stimulated by the hormone

PTH

hypernatremia

S (Skin flushed) A (agitation) L (low grade fever ) T (thirst) most common cause is dehydration water moves out of cell to ECF (crenation)

most abundant ECF ion

Sodium

HCO3 normal range

acid 22-26 alkaline

What accounts for about 60% of our total body water?

cytosol

When fewer hydrogen ions are secreted into the filtrate, how is blood pH affected?

decreases

What triggers the release of parathyroid hormone (PTH)?

decreasing calcium ion concentration of the blood

What do the kidneys to maintain proper pH

excretes/retains H+ or HCO3- to maintain blood pH

appropriate compensation for metabolic acidosis

first response is hyperventilation; retention of bicarbonate ions in the kidneys; bicarbonate ions will then be used by the carbonic acid bicarbonate buffer system to neutralize the extra acid

metabolic alkalosis

high pH, high HCO3; caused chronic diarrhea, overuse of antacids (TUMS), overuse of diuretics (laxatives)

respiratory alkalosis

high pH, low CO2; hyperventilation, stress, anxiety, fear, high atmosphere, stroke

Mrs. Frykholm is experiencing diabetic ketoacidosis, which causes metabolic acidosis. She has experienced damage to her kidneys from diabetes mellitus. Predict how her body compensates to return her blood pH to normal.

hyperventilation

A patient present with severe metabolic alkalosis. The appropriate respiratory compensation would be

hypoventilation

Importance of Magnesium

involved in activation of many enzymes; important component of bone

respiratory acidosis

low pH, high CO2; caused by hypoventilation, emphysema, pneumonia

metabolic acidosis

low pH, low HCO3; caused by chronic diarrhea, diabetic ketoacidosis (production of metabolic acids), ingestion of acidic drugs and toxins (alcohol, caffeine, aspirin), renal failure, dehydration and starvation

A patient has been experiencing prolonged vomiting. Since she has lost many hydrogen ions, you predict her acid-base imbalance to be:

metabolic alkalosis

The following has been determined from an arterial blood gas (ABG) sample: an elevated blood pH and an elevated bicarbonate ion level. Determine the acid-base imbalance.

metabolic alkalosis

most abundant ICF ion

potassium

What leads to metabolic alkalosis?

prolonged vomiting and the loss of acidic stomach contents

The following has been determined from an arterial blood gas (ABG) sample: elevated arterial PCO2 level and a low blood pH. Determine the acid-base imbalance.

respiratory acidosis

Sarah was so upset and nervous that a snake was in her house that she began hyperventilating. Predict the acid-base imbalance created by her psychological state.

respiratory alkalosis

obligatory water loss

the amount of urine that must be produced daily to excrete wastes and other solutes; 500ml

hydrostatic pressure

the pressure within a blood vessel that tends to push water out of the vessel; moves from high to low concentration

metabolic water

the water formed as a by-product of our body's metabolic reactions; 250ml/day

insensible water loss

unnoticed water loss; through sweat and expiration (600ml from sweat and 300ml from expiration)

Hypocalcemia

usually due to decreased PTH or vitamin D deficiency; CATS Convulsions, Arrythmias, Tetany, spasms

buffers

weak acids and weak bases to minimize pH changes in the ECF and the ICF

principle of mass balance

what is gained by the body must equal what is lost by the body