Unit 4: Renal Physiology Pt 2 Flashcards
What two things must inputs and outputs be adjusted to maintain?
- maintain ECF
- maintain osmolality
What is a typical daily fluid intake? How much of that is from ingestion of food and fluid? What about from carbohydrate oxidation?
2300 ml/day (2.3L/day)
food/fluid--> 2100 ml carbohydrate oxidation (metabolic water)--> 200 ml
What are the ways we lose body water?
- insensible water loss –> breathing and through skin
- Sweating
- feces
- via kidneys (major contributor)
What percentage of the body is fluid weight? What of that is intracellular and extracellular?
60%
- 40% intracellular fluid
- 20% extracellular fluid
“60-40-20 rule”
What ions is intracellular fluid low in? high in?
low in–> Na+, Ca++, Cl-
high in–> K+ and Phosphate
What does the extracellular fluid consist of? What ions is it high in? low in?
all fluid outside cells–> plasma and interstitial fluid
low in–> K+, phosphates, and proteins
high in–> Na+, Cl- and bicarbonate
What is the net diffusion of water across a selectively permeable membrane from a region of high water concentration to one that has a lower water concentration?
Osmosis
What is Osmotic Pressure?
the equilibrium pressure b/w:
- hydrostatic pressure (due to increase in water in a compartment–pushing water into solute free compartment)
AND
- the osmotic forces generated by the addition of a solute
What is the Osmotic Pressure proportional to?
the number of active or dissociable solute/particles in the solution (ones that cannot pass membrane)
What is the total number of particles in a solution called?
Osmoles
1 Osmole = 1 mole of solute particle
Ex: 1 mole of glucose/liter = 1osm/L
What is the difference b/w Osmolality and Osmolarity?
Osmolality = Osmoles per kilogram of water
Osmolarity = Osmoles per liter of water
in dilute body fluids the terms can be used interchangeably
What is the equation for Plasma Osmolarity? What three things do you need?
Plasma Na+, Glucose, Blood Urea Nitrogen (BUN)
Plasma Osmolarity = 2 x Plasma Na+ + (Glucose/18) + (BUN/2.8)
What is normal plasma osmolarity? What occurs if it is above this?
~290-300 mOsm/L
plasma osmolarity is too high–> and stimulate ADH and keep more water
T/F. Plasma Osmolarity (ECF) = intracellular osmolarity (ICF)
true, must be balance
If a cell is placed in an Isotonic Solution, what happens? What are two examples of an isotonic solution?
the cell won’t shrink or swell
290 mOsm/L
0.9% NaCl solution
5% glucose solution
What does it mean when intercellular and extracellular fluids are in osmotic equilibrium?
Isotonic solution
What is a solution called that has a lower concentration of impermeant solutes than the cell? What happens to the cell? What are examples of this?
Hypotonic solution (so less than 290 mOsm/L)
water will move INTO the cell –> cell swells and may rupture
Ex: less than 0.9% NaCl solution
Ex: less than 5% glucose solution
Ex: Freshwater
What is a solution with a higher concentration of impermeant solutes than the cell? What happens to the cell? What are examples of this?
Hypertonic fluid (greater than 290 mOsm/L)
water will move OUT of cell–> cell will shrink
Ex: more than 0.9% NaCl solution
Ex: more than 5% glucose solution
Ex: salt water
In the following, how does osmolarity compare?
- Isomotic solutions
- Hyperosmotic solution
- Hyposmotic solution
- osmolarity = cell
- osmolarity > normal ECF
- osmolarity < normal ECF
What will cause an increase in the cellular volume? What will decrease it?
increase:
- ingestion of fluid (water)
- intravenous infusion
decrease:
- not ingesting adequate fluids
- loss of fluids from GI tract
- sweating
- fluid loss from kidneys
What is the most common electrolyte disorder? What can this result in?
Hyponatremia (now plasma Na+)
edema, brain swelling, brain damage, death
(rapid correction can also cause damage)
What does Hyponatremia mean?
plasma sodium is low
What are normal levels of plasma Na+? How can one get Hyponatremia?
Normal levels of Na+ = 135-145 meq/L
via:
- dehydration (via loss of sodium chloride)
- overhydration (over retention of water)
How can dehydration or over-hydration cause Hyponatremia?
dehydration–> via diarrhea, vomiting, overuse of diuretics
over-hydration–> abnormally high secretion of antidiuretic hormone (ADH)
What is the term for plasma sodium being too high? Do these effects tend to be more or less severe than hyponatremia?
Hypernatremia; less severe
What two ways can one get Hypernatremia?
dehydration (via water loss)–> excessive sweating, lack ADH production/sensitivity
over-hydration (via excess NaCl) –> abnormally high secretion of aldosterone (which stimulates Na+ being pulled back)
What is the term for presence of excess fluid in body tissues?
edema
What is Intracelluar Edema due to? What is Extracellular Edema due to?
Intracellular due to–> hyponatremia, metabolic depression, lack of adequate nutrition
Extracellular due to–> fluid leakage, lymphatic failure (lymphedema)
What is the breakdown for the total body water and the percentage of our body weight?
60% of total body weight
- 2/3 ICF (40%)
- 1/3 (ECF (20%)
- — 3/4 of ECF is interstitial fluid
- – 1/4 if ECF is plasma
What is the equation for measuring volumes of body fluid?
V = injected marker / diluted concentration
What can be used to measure Total Body water?
Isotopic water (D2O) or Titrated water, or antipyrine
What can be used to measure ECF volume?
Sulfate; Mannitol or Inulin (larger molecular weight sugars)
What can be used to measure ICF?
always determine ICF by subtraction
ICF vol = TBW - ECF
What can be used to measure plasma volume?
radioactive albumen (with RISA or Evans blue)
What does the volume of a body fluid compartment depend on?
the amount of SOLUTE it contains
What is the major cation in ECF?
What are the major anions in ECF?
cations–> Na+
anions–> Cl- and HCO3-
What is the concentration of osmotically active particles?
Osmolarity
What is the normal value for Osmolarity? What is the equation used to get it?
normal–> ~290-300 mOsm/L
Plasma Osmolarity = 2 x Plasma Na+ + (gucose/18) + (BUN/2.8)
What are the three situations we can have for ECF Volume Contraction?
- Diarrhea–> (loss of isomotic fluid)
- Water Deprivation (sweating)–> (hyperosmotic)
- Adrenal Insufficiency (Addison’s Disease) –> (hyposmotic)
What are the three situations we can have for ECF Volume Expansion?
- Infusion of Isotonic Saline–> (isotonic vol. expansion)
- High NaCl intake–> (Hyperosmotic vol. expansion)
- Syndrome of inappropriate ADH (SIADH)–> (Hyposmotic vol. expansion)
T/F. Anytime it is an isotonic situation, there is no change in fluid shift.
True
What type of situation is Diarrhea? What volume will be decreasing? How does the ECF and ICF water shift?
isosmotic volume contraction
–loss of sig. amount of isomotic fluid from GI tract, results in a decrease in ECF volume
– NO fluid shift b/w ECF and ICF
What type of situation is sweating? How does the ECF and ICF water shift? What happens to plasma protein conc.? What happens to Hematocrit?
Hyperosmotic Volume Contraction
– sweat is more water, less solute than body fluids –> therefore pull fluid from ICF to ECF
– both ICF and ECF osmolarities increase
–plasma protein conc. increases
– Hematocrit unchanged
What type of situation is Adrenal Insufficiency (Addison’s Disease)? How does the ECF and ICF water shift? What happens to the ECF and ICF volumes? What happens to the Plasma protein conc. and Hematocrit?
Hyposmotic volume contraction
– shift ECF–> ICF due to decrease in aldosterone creating an increase in excretion of NaCl in urine (do not hold onto it anymore) and have decrease is ECF osmolarity
- ECF vol decreases
- ICF vol increases
– BOTH increase
What type of situation does infusion of isotonic saline create? What happens to ECF volume? What does the water shift b/w ECF and ICF? What happens to plasma protein conc. and Hematocrit?
Isosmotic Volume expansion
– increase ECF volume (no change is osmolarity)
– NO shift in fluid b/w ECF and ICF
– decrease in BOTH (b/c diluting everything)
What type of situation will a High NaCl intake create? What happens to ECF osmolarity? How does fluid shift b/w ECF and ICF? What happens to ECF and ICF volumes? What happens to plasma protein conc. and Hematocrit?
Hyperosmotic volume expansion
- increase ECF osmolarity
- fluid shift from ICF–> ECF to rebalance osmolarity
- ECF vol increases
- ICF vol decreases
– decrease in BOTH plasma protein conc. and Hematocrit
What type of situation does Syndrome of inappropriate ADH create? How will the fluid shift b/w ECF and ICF?
Hyposmotic volume expansion
– fluid shift from ECF–> ICF (cells swell) due to too much water reabsorbed by kidney and diluting ECF fluid; therefore decreasing ECF osmolarity
Will the water retained from Syndrome of inapparopriate ADH be added in proportion in body compartments?
yes:
1/3 to ECF (20%)
2/3 to ICF (40%)
For the following tell me how the fluid shift is b/w ICF and ECF.
- Diarrhea
- Sweating
- Adrenal Insufficiency
- Infusion of Isotonic NaCl
- High NaCl intake
- Syndrome of inappropriate ADH
- none (isosmotic vol. cont.)
- ICF–> ECF (hyperosmotic vol. cont.)
- ECF–> ICF (hyposmotic vol. cont)
- none (isosmotic vol. expansion)
- ICF–> ECF (hyperosmotic vol. expansion)
- ECF–>ICF (hyposmotic vol. expansion)
What is occurring if we have volume contraction taking place? What about if we have volume expansion taking place?
contraction–> LOSS of fluid
expansion–> gain of something
For all volume contraction situations what is happening to ECF volume and Plasma protein conc.? What about for all volume expansion situations?
Vol. contraction:
- ECF volume decreases
- Plasma protein conc. increases
Vol. expansion:
- ECF volume increases
- plasma protein conc. decreases
What happens during Diarrhea for ECF osmolarity, ECF vol, and ICF vol?
Isosmotic Volume Contraction
- No change in ECF osmolarity
- decrease ECF vol
- no change in ICF vol
What happens during H2O Deprivation (sweating) to ECF osmolarity, ECF vol, and ICF vol?
Hyperosmotic Volume Contraction
- increase ECF osmolarity
- decrease ECF vol
- decrease ICF vol
What happens during Adrenal insufficiency to ECF osmolarity, ECF vol, and ICF vol?
Hyposmotic Volume Contraction
- increase ECF osmolarity
- decrease ECF vol
- increase ECF vol
What happens during Infusion of isotonic NaCl to ECF osmolarity, ECF vol, and ICF vol?
Isosmotic Volume Expansion
- no change in ECF osmolarity
- increase ECF vol
- no change in ICF
What hpapens during High NaCl intake to ECF osmolarity, ECF vol, and ICF vol?
Hyperosmotic Volume Expansion
- increase ECF osmolarity
- increase ECF vol
- decrease ICF vol
What happens during syndrome of inappropriate ADH to ECF osmolarity, ECF vol, and ICF vol?
Hyposmotic Volume expansion
- decrease ECF osmolarity
- increase ECF vol
- increase ICF vol
What makes up the ECF?
plamsa + intersitial fluid
How do we find the volume of intersitial fluid?
ECF - plasma
