Body fluid compartments, osmolality & tonicity of physiologic solutions

Question 1

Total body luid consists of..

Answer 1

ICF
ECF-Interstitial fluid and plasma

Question 2

What is in ICF?

Answer 2

• Lage amount of K+ &Phosphate ions
• Moderate quantities of Mg2+ and sulphate ions
• small quantities of Na+ and Cl-
  -almost no Ca2+
• large amount of intracellular protei
  -total osmolarity:300 mOsm/L(due to K+)

Question 3

• Plasma&interstitialfluid
• It exchanges substances continuously with the interstitial fluid.
• Plasma have higher protein concentration; because the capillaries have a low permeability to the plasma proteins

Answer 3

ECF compartment

Question 4

-has a net negative charge and tend to attract more cations such as Na+ and K+
-repel negatively charge ions

Answer 4

Plasma

Question 5

Measurement of Total Body Water by?

Answer 5

-radioactiv water
-Antipyrine

Question 6

Measurement of ECF?

Answer 6

-Radioactivesodium,radioactivechloride,radioactive iothalamate, thiosulfate ion, and inulin

-Disperse in the plasma and interstitial fluid but do not readily permeate the cell membrane

Question 7

Estimation of ICF?

Answer 7

Intracellular volume
= Total body water – Extracellular volume

Question 8

Estimation of Intracellular Volume?

Answer 8

Intracellular volume
= Total body water – Extracellular volume

Question 9

-Albumin labeled with radioactive iodine(125 I-albumin) &Evans blue dye
- does not readily penetrate capillary membrane but remains in vascular system.

Answer 9

Plasma volume

Question 10

Measurement of blood volume

Answer 10

Total blood volume = Plasma volume /1 – Hematocrit

• Hematocrit: fraction of blood composed of RBCs

• In healthy men, ~0.40; women, ~0.36

OR

• labeling the red blood cells with radioactive
chromium (51Cr), which binds tightly with the red blood cells
• Inject the labeled RBCs into the circulation
• After these mix in the circulation, the radioactivity of a mixed blood sample can be measured and the total blood volume can be calculated using the indicator-dilution principle

Question 11

Difference between osmolality and osmolarity

Answer 11

Osmolality
• Number of osmoles/kg of solution

Osmolarity
• Number of osmoles/L of solutions

Question 12

Tonicity is..

Answer 12

Osmolality of a solution relative to plasma

Question 13

Solutions that have the same osmolality as plasma :

Answer 13

-isotonic
-282 mOsm/L

Question 14

Solutions that have greater osmolality as plasma:

Answer 14

-hypertonic
->282 mOsm/L

Question 15

Solutions that have lesser osmolality as plasma:

Answer 15

-hypotonic
-<282 mOsm/L

Question 16

Hyponatremia

Answer 16

• excess water retention
• Excess water retention results in hyponatremia—overhydration
• Excess ADH : excess water retention  dilutes the sodium in ECF
• ↑ECFvolume

Question 17

Hyponatremia:

Answer 17

• loss of sodium
• LossofNaClresultsinhyponatremia&dehydration
• Diarrhea;vomiting;overuseofdiuretics;Addison’sdisease(↓
aldosterone)
• ↓ECFvolume

Question 18

Hypernatremia:

Answer 18

water loss

• Water loss results in hypernatremia & dehydration
• Excessive sweating, diabetes insipidus (↓ADH)
• ↓ ECF volume

Question 19

Hypernatremia:

Answer 19

excesssodium
• Excessive NaCl results in hypernatremia—overhydration
• Primaryaldosteronism(↑aldosterone)
• ↑ECFvolume