Patho Fluids and Electrolytes playposit

functions of body fluids

- transport gases, nutrients, wastes

- help generate the electrical activity needed for body functions

- take part in transformation of food into energy

- maintain overall function of the body

environmental stresses and disease affect the

balance

most of the water is

inside the cell

distribution of body fluids

intracellular (2/3rds)

extracellular (1/3)

- intrastitial , intravascular, transcellular

intravascular fluid ?

plasma and lymph fluid

- part of extracellular

transcellular fluid ?

its in various body spaces:

- synovial, intestinal, csf, sweat, urine, pleural, peritoneal, pericardial and intraocular fluids

- part of extracellular

most of the fluid in the body is in

intracellular compartment (40% of body weight)

from extracellular water, the largest compartment is

interstitial fluid (around the cells)

how are fluids distributed by age? pediatrics

75%-80% of body weight

- susceptible to significant changes in body fluids

- dehydration in newborns

how does the body fluid change with aging

decreased percent of total body water

- decreased muscle mass and free fat mass

- renal decline

- diminished thirst perception

consists of fluid contained within all of the cells

- high concentration of K+

- larger of the two components

intracellular compartment

contains 1/3 body water

- all fluids outside the cells

- high concentration of Na+

the osmolarity of the extracellular fluid is almost entirely due to ?

- tells us osmolarity in the compartment

sodium (Na+)

different osmolarity between compartments causes,

liquid to move between compartments until equilibrium is achieved

organs involved in fluid balance

kidneys, lungs, heart, adrenal glands, parathyroid glands, pituitary gland

adrenal glands secrete?

aldosterone (important for water and sodium balance)

- retains sodium and water and excretes potassium

parathyroid glands secrete

parathyroid hormone - to increase concentration of calcium in the blood and decrease concentration of phosphate in the blood

pituitary gland secretes

antidiuretic hormone - retains water

- secreted by posterior pituitary

- increases water reabsorption into the plasma

the tension or effect that the osmotic pressure of a solution exerts on a cell size because of water movement across the cell membrane

tonicity

isotonic is?

- equilibrium

- cell remains the same

hpotonic

- less osmolarity outside the cell, more inside

- this causes water to move from low osmolarity to high , inside the cell

- cell swells

hypertonic solution

-osmolarity outside of the cell is higher

-water leaves the cell, shrinks

water channels that allow water to go in and out of the cell

aquaporins

forces favoring filtration minus forces opposing filtration

net filtration

why do cells need oxygen

for energy and to stay alive (cellular respiration makes ATP)

at capillary system, there is exchange of

water, oxygen, nutrients (glucose), CO2, wastes

- waste and co2 goes back to get oxygenated

why is water leaving the capillaries and returning to venule site?

sterling forces

- hydrostatic pressure is caused by water (direct relationship)

- oncotic pressure retains water

- fight between hydrostatic and oncotic pressure

oncotic pressure

retains water

-hydrostatic pushes the water

high oncotic/colloid pressure in interstitial space=

water is retained

forces that favor filtration

capillary hydrostatic pressure (bp)

interstitial oncotic pressure (water-pulling)

forces favoring reabsorption back into vessel

plasma oncotic pressure (water pulling)

interstitial hydrostatic pressure

accumulation of fluid within the interstitial spaces

edema

causes of edema

- increase capillary hydrostatic pressure

- decrease capillary oncotic pressure

- increase in capillary permeability

- lymph obstruction

what causes decrease of capillary oncotic pressure?

low protein levels in the blood (cirrhosis, malnutrition)

increased capillary permeability is from

burns, inflammation

increased tissue oncotic pressure

- interstitial

edema

increased capillary hydrostatic pressure is from

retention of fluid, heart failure

how to assess edema?

- weight

- visual

- measure affected part

- apply finger pressure to assess for pitting edema

natriuretic peptide (ANP, BNP)

tells the kidneys: increase excretion of sodium by the kidneys

- secreted by the heart when its too full (like in heart failure)

renin angiotensin aldosterone system (RAAS)

aldosterone leads to sodium and water reabsorption back into the circulation and excretion of potassium

when ADH is secreted:

low fluid in the body is sensed; posterior pituitary will secrete adh for water retention in the kidneys;

- this will increase number of aquaporins

- less urine, more concentrated

- plasma osmolarity increases and plasma volume decreases

atrial natriuretic peptides are released:

- high plasma volume like in heart failure

- secreted when atrial stretching of heart cells occurs

-tells the kidneys to increase glomeral filtration rate to excrete more water and sodium

RAAS system (renin angiotensin aldosterone)

- low extracellular fluid and low blood pressure = low volume in arteries

- kidneys sense that fluids are low, which causes them to secrete renin by juxtaglomerular cells

- renin transforms angiotensinogen into angiotensin 1

- angiotensin 1 goes to lungs and is converted into angiotensin 2

- angiotensin 2 travels to adrenal cortex and induces the secretion of aldosterone

- aldosterone increases sodium reabsorption by kidney and water, decreases potassium

- this helps with increasing blood pressure and vascular volume

- this is done to help recover lost water

angiotensin 2 also helps vasoconstriction of arterials to increase blood pressure since with fluid loss, the volume of blood is low

alterations osmolarity occur in

interstitial compartment

isotonic alterations

losing same amount of volume and electrolytes

- no change in concentration

hypertonic alterations

losing more water than electrolytes

- water moves from inside of the cell to outside

- intracellular dehydration

hypotonic alterations

- decreased osmolality

- water moves into the cell, causes expansion due to osmosis

normal osmolarity in the blood is

2.75-2.95

isotonic dehydration

inadequate intake of fluids

- excessive loss of isotonic body fluids

hypertonic dehydration

- condition that increases fluid loss, such as excessive perspiration/hyperventilation/ketoacidosis/fevers/diarrhea/diabetes insipidus

hypotonic dehydration

chronic illness, renal failure, chronic malnutrition

isotonic overhydration

- hypervolemia

- excessive fluid in extracellular compartment

hypertonic overhydration

- rare, from excess Na intake

- fluid is drawn from the intracellular fluid compartment

hypotonic overhydration

- water intoxication

- fluid moves into the intracellular space and all body fluid compartment expands

loss of sodium or gain of water

hyponatremia (low sodium)

gain of sodium or loss of water

hypernatremia

major cation in extracellular compartment

- primary determinant of plasma osmolality***

- influence water distribution with Cl-

sodium

essential for nerve impulse transmission, muscle contraction and the movement of glucose and aminoacids

sodium

normal serum level for sodium

135-145 mEq/L

hyponatremia

causes of hyponatremia

pure sodium loss

low intake

dilutional hyponatremia

diuretics, diaphoresis, GI loss

symptoms of hyponatremia

- nervous system problems (lethargy, disorientation, confusion, seizures, coma ***

- cellular swelling

- muscle cramps, weakness, fatigue

hypernatremia

sodium concentration >145

- decrease in sodium excretion (cushing syndrome: too much cortisol in the body; renal failure, hyperaldosteronism)

- increase sodium intake

- decrease water intake (NPO)

- increase water loss ( severe burns, fever, diabetes insipidus which is too little ADH)

too much ADH causes (with diabetes insipidus)

hypernatremia

symptoms of hypernatremia

thirst

decreased urine output

increased urine osmolality

increased serum osmolality

dry skin and mouth, seizures

tachycardia

major intracellular cation

- concentration maintained by Na/K pump

- transmission and conduction of nerve impulses

- regulated by the kidneys and transcellular buffer system

potassium (normal serum level 3.5-5

potassium levels are changed by

pH

aldosterone, insulin, epinephrine

kidney is the most efficient regulator of

potassium

with metabolic acidosis, potassium moves

out of the cell

with metabolic alkalosis potassium moves

inside the cell

hypokalemia

potassium lower than 3.5 mEq/L

caused by:

- reduced intake, cushing syndrome, increased entry of potassium into cells, diuretics

symptoms of hypokalemia

- decrease in neuromuscular excitability (cell is more depolarized)

-EKG changes (more flat, shallow T wave; prominent U wave)

hyperkalemia

potassium >5 mEq/L

- rare because of efficient renal excretion

causes:

- increased intake

- shift from K+ in acidosis

- addison's disease (opposite of cushings; accumulation of potassium, excreting too much sodium and water)

hyperkalemia causes

changes in EKG (peak T waves)

- membrane cell depolarization: initially increased neuromuscular irritability

calcium and phosphate are controlled by

parathyroid hormone

vitamin d acts to control the levels of ??? by increasing their absorption from the intestine

calcium and phosphate

acts on the kidney and bone to remove calcium from the extracellular circulation

calcitonin

necessary for structure of bones, teeth, clotting, hormone secretion, muscle contraction

calcium (8.5-10.5 ng/dl)

calcium 3 forms

- protein bound (albumin)

- complexed (attached to other molecules)

- ionized

maintain calcium concentration of extracellular fluid

- goal is to increase levels of calcium to normal

parathyroid hormone

if calcium level is high pth will

be inhibited and calcium gets stored in the bones

if calcium level is low pth

will increase and calcium is mobilized from the bone

hypoparathyroidism

low levels of parathyroid hormone

- low calcium

-can occur following thyroidectomy

hypocalcemia

less than 8.5 mg/dl calcium level

- low calcium absorption by GI tract

- too much renal excretion

symptoms of hypocalcemia

chvostek's sign (twitching of facial nerve in response to a tap on the nerve)

- trousseau's sign (spasm of forearm on obstruction of its blood supply)

- tetany (laryngospasm)

hypercalcemia

calcium >10.5

-decrease in calcium excretion

- increase intestinal absorption

- increase in bone resorption of calcium

normal value of phosphate

2.5-4.5 mg/dl

hypophosphatemia

caused by increased renal excretion of phosphate associated with hyperparathyroidism

- malabsorption of vitamin d`

hyperphosphatemia `

phosphorus level that is over 4.5 mg/dl

- hypocalcemia is the problem

caused by decrease renal excretion (renal failure)

normal magneisum level

1.5-2.5

- increases neuromuscular excitability

hypomagnesemia

- causes: alcoholism, diuretics, malnutrition, gastric suction

hypermagnesemia

caused by:

- renal failure

- excessive intake of antiacids

- decreased renal excretion

causes bradycardia, lethargy, drowsiness, hypotension

- check deep tendon reflexes

anecdote for hypermagnesia

calcium carbonate