The Body Fluids And Kidneys Flashcards
This compartment includes fluid in the synovial, peritoneal, pericardial, and intraocular spaces, as well as the cerebrospinal fluid
transcellular fluid.
it is usually considered to be a specialized type of extracel lular fluid, although in some cases its composition may differ markedly from that of the plasma or interstitial f luid.
cerebrospinal fluid
All the transcellular fluids together constitute about
1 to 2 liters.
the intracellular fluid constitutes about 40 percent of the total body weight in an “average” person.
True or False
True
the noncellular part of the blood; it exchanges substances continuously with the interstitial fluid through the pores of the capillary membranes.
Plasma
the pores of the capillary membranes are highly permeable to all solutes in the extracellular fluid.
True or False
False. Except proteins
The two largest compartments of the extracellular fluid are the
interstitial fluid-three fourths
plasma, which makes up almost one fourth
The most important difference between these two compartments is
higher concentration of protein in the plasma
Cations and Anions in the ECF and ICF
ECF ANiONS - Cl, HCO3
ECF CATIONS- Na, Ca
ICF CATIONS- K,Mg
ICF ANIONS- PO4 and lther organic ions, Protein
substance that has been used to measure total body water
Radioactive water (tritium, 3H2O) or heavy water (deuterium, 2H2O)
antipyrine
several substances that disperse in the plasma and interstitial fluid but do not readily permeate the cell membrane.
radioactive sodium, radioactive chloride, radioactive iothalamate, thiosulfate ion, and inulin.
distribution of fluid between intracellular and extracellular compartments, in contrast, is determined mainly by
osmotic effect of the smaller solute
water diffuses across the membrane toward the region of higher solute concentration
True or False
True
Where sodium goes, water follows
corrected osmolar activities of plasma, interstitial fluid, and intracellular f luid
reason for these corrections
cations and anions exert interionic attraction, which can cause a slight decrease in the osmotic “activity” of the dissolved substance.
for each milliosmole concentration gradient of an impermeant solute, about ________ of osmotic pressure is exerted across the cell membrane.
19.3 mm Hg
Solutions with an osmolarity the same as the cell are called
isosmotic
One can calculate both the changes in intracellular and extracellular fluid volumes and the types of therapy that should be instituted if the following basic principles are kept in mind:
- Water moves rapidly across cell membranes
2. Cell membranes are almost completely impermeable to many solutes
If a hypertonic solution is added to the extracellular f luid,
The net effect is an increase in extracellular volume
a decrease in intracellular volume, and
a rise in osmolarity in both compartments.
Calculation of Fluid Shifts and Osmolarities After Infusion of Hypertonic Saline Solution
first step is to calculate the initial conditions, including the volume, concentration, and total millios moles in each compartment.
Next, we calculate the total milliosmoles added to the extracellular fluid in
we calculate the instantaneous effect of adding 2051 milliosmoles of sodium chloride to the extra cellular fluid
In the third step, we calculate the volumes and con centrations that would occur within a few minutes after osmotic equilibrium develops
Because glucose in the solution is rapidly transported into the cells and metabolized, infusion of a 5 percent glucose solution reduces extracellular fluid osmolarity and therefore helps correct the increase in extracellular fluid osmolarity associated with dehydration.
True or False
True
This osmoticmediated demyelin ation of neurons can be avoided by limiting the correction of chronic hyponatremia to
less than 10 to 12 mmol/L in 24 hours and
to less than 18 mmol/L in 48 hours.
CAUSES OF HYPERNATREMIA:
WATER LOSS
EXCESS SODIUM
Correction of hypernatremia can be achieved by
hypoosmotic sodium chloride or dextrose solutions.
T hree conditions are especially prone to cause intracel lular swelling:
1) hyponatremia
2) depression of the metabolic systems of the tissues
3) lack of adequate nutrition to the cells.
Inflammation does not increase cell membrane permea bility,
True or False
False.. increases
two general causes of extracellular edema:
1) abnormal leakage of f luid from the plasma to the interstitial spaces across the capillaries
2) failure of the lymphatics to return f luid from the interstitium back into the blood
Failure to produce proteins
- Liver disease (e.g., cirrhosis) 2. Serious protein or caloric malnutrition
Serious generalized edema occurs when the plasma protein concentration falls below
2.5g/100mL
three major safety factors prevent excessive fluid accumulation in the interstitial spaces:
1) low compliance of the interstitium when interstitial fluid pressure is in the negative pressure range
2) the ability of lymph flow to increase 10 to 50fold
3) “washdown” of interstitial f luid protein concentration, which reduces interstitial f luid colloid osmotic pressure as capillary filtration increases.
CAUSES OF HYPONATREMIA:
EXCESS WATER OR LOSS OF SODIUM
CAUSES OF HYPERNATREMIA:
WATER LOSS OR EXCESS SODIUM
