Prerrogativas del Ayuntamiento

1. What keeps fluid in our blood vessels? Albumin, and this is called oncotic pressure. 80% of our oncotic pressure is related to the serum albumin levels. Anytime there is

hypoalbuminemia then we will have a leaking of a transudate (protein of less than 3 g/dL) leaking into interstial space via capillaries and venules (pitting edema);

2. Normally, hydrostatic pressure is trying to push fluid out. Therefore, in a normal person, oncotic pressure is winning. Therefore, a decrease in oncotic pressure and an increase in hydrostatic pressure will lead to transudate (pitting edema).

3. Albumin is made in the liver. With chronic liver dz (cirrhosis), have a decreased albumin level. Can you vomit it out? No. Can crap it out (malabsorption syndrome), or can pee it out (nephrotic syndrome), can come off our skin (3rd _{degree burn b/c losing plasma),}

another possibility of low protein ct (low-intake) is seen in kids – Kwashiorkor – kid has fatty liver and decreased protein intake, leading to low albumin level.

4. Examples:

a. Person with MI 24 hrs ago and he died and he has fluid coming out– transudate b/c increased hydrostatic pressure and left HF due to MI so things backed up into the lungs. B/c the CO decreased, the EDV increases and pressure on left ventricle increases, and the pressure is transmitted into the left atrium, to the pul vein, keeps backing up, and the hydrostatic pressure in the lung approaches the oncotic pressure, and a transudate starts leaking into the interstitial space, which leads to activation of the J receptor, which will cause dyspnea. Leads to full blown in alveoli and pulmonary edema, which is what this is.

b. venom from bee sting on arm leads to exudate due to anaphylactic rxn (face swelled), with histamine being the propagator, and type one HPY, causing tissue swelling. Rx – airway, 1:1000 aqueous epinephrine subcutaneously

c. cirrhosis of liver, with swelling of the legs: transudate, mechanism: decreased oncotic pressure b/c cannot syn albumin, and increased hydrostatic pressure b/c portal HTN; there is cirrhosis of the liver, and the portal vein empties into the liver; in this case, it cannot, and there is an increase in hydrostatic pressure, pushing the fluid out into the peripheral cavities (so there are 2 mech for acites). Pitting edema in legs: decreased in oncotic pressure

d. Pt with dependent pitting edema: pt has right heart failure, and therefore an increase in hydrostatic pressure; with right heart failure, the blood behind the failed right heart is in the venous system; cirrhosis of liver is due to decrease in oncotic pressure.

e. modified radical mastectomy of that breast, with nonpitting edema: lymphedema. Other causes – w. bancrofti, lymphogranulomon venarium (subtype of chylamdia

trachomata– scarring tissure and lymphatics, leading to lymphedema of scrotum

lymphatic). Inflammation carcinoma of breast (p’eau de orange of the breast) deals with dermal lymphatics plug with tumor; excess leads to dimpling, and looks like the surface of an orange. MCC lymphedema = postradical mastectomy; can also run risk of

lymphangiosarcoma. II. Renal Physio

A. ECF/ICF

ECF (1/3) = extracellular fluid of two compartments – vascular (1/3) and interstitial (2/3) ICF (2/3) = intracellular fluid compartment

Example: how many liters of isotonic saline do you have to infuse to get 1 liter into the plasma? 3 Liters (2/3:1/3 relationship); 2 liters in interstial space, and 1 L would go to the vascular space; it equilibrates with interstial/vascular compartments.

B. Osmolality = measure of solutes in a fluid; due to three things: Na, glucose, and blood urea nitrogen (BUN) – urea cycle is located in the liver, partly in the cytosol and partly in the mitochondria; usually multiply Na times 2 (b/c one Na and one Cl).

Audio file 6: Fluid and hemodyn 2

Normal Na is 135-140 range, times that by 2 that 280. For glucose, normal is 100 divide that by 18, let’s say it’s roughly 5, so that’s not contributing much. BUN: located in the liver, part of the cycle is in the cytosol and part of it is in mitochondria. The urea comes from ammonia, that’s ammonia is gotten rid of, by urea. B/c the end product of the urea cycle is urea. The normal is about 12; divide that by 3, so we have 4. Therefore, in a normal person Na is controlling the plasma osmolality. To measure serum osmolality: double the serum Na and add 10.

C. Osmosis

2 of these 3 are limited to the ECF compartment; one can equilibrate between ECF and ICF across the cell membranes – urea; therefore, with an increased urea, it can equilibrate equally on both sides to it will be equal on both sides; this is due to osmosis. B/c Na and glucose are limited to the ECF compartment, then changes in its concentration will result in the movement of WATER from low to high concentration (opposite of diffusion – ie in lungs, 100 mmHg in alveoli of O2, and returning from the tissue is 40 mmHg pO2; 100 vs. 40, which is bigger, 100 is bigger, so via diffusion, O2 moves through the interspace into the plasma to increase O2 to about

95mmHb). Therefore, in diffusion, it goes from high to low, while in osmosis, it goes from low to high concentration.

1. Example: In the case with hyponatremia – water goes from ECF into the ICF, b/c the lower part is in the ECF (hence HYPOnatremia); water goes into the ICF, and therefore is expanded by osmosis. Now make believe that the brain is a single cell, what will we see? cerebral edema and mental status abnormalities via law of osmosis (the intracellular compartment of all the cells in the brain would be expanded)

2. Example: hypernatremia – water goes out of the ICF into the ECF, therefore the ICF will be contracted. So in the brain, it will lead to contracted cells, therefore mental status abnormalities; therefore, with hypo and hypernatremia, will get mental status abnormalities of the brain.

3. Example: DKA – have (1000mg) large amount blood sugar. Remember that both Na and glucose are limited to the ECF compartment. You would think that glucose is in the ICF but it’s not. You think that since glycolysis occurs in the cytosol therefore glucose in the ICF (again its not) b/c to order to get into the cell (intracellular), glucose must bind to phosphorus, generating G6P, which is metabolized (it’s the same with fructose and

galactose, which are also metabolized immediately, therefore, there is no glucose, fructose, or galactose, per se, intracellularly). So, with hyperglycemia, there is high glucose in the ECF, so water will move from ICF to ECF. Therefore, the serum Na concentration will go down – this is called dilutional hyponatremia (which is what happens to the serum sodium with hyperglycemia).

Therefore the two things that control water in the ECF are Na and glucose; but a normal situation, Na controls. Urea does not control water movements b/c its permeable, and can get through both compartments to have equal concentrations on both sides.