Body Fluid Compartments

Question 1

What percentage of men’s body weight is water? Women?

Answer 1

60% 50%

Question 2

What is the normal molarity of human plasma?

Answer 2

300 mOsm

Question 3

What is Albumin responsible for?

Answer 3

Anion Gap!

-HUGE NEGATIVE CHARGE

Question 4

What is the normal anion gap and how do you calculate it?

Answer 4

8-12 = normal

Na+ - [Cl- + HCO3-]

Question 5

What is an example of an anion gap?

Answer 5

Lactic acidosis

• Extra negative charges present
• Anion gap = 12-30

Question 6

What type of wall exists between the tissue and vascular areas?

Answer 6

Fenestrated capillary wall

Question 7

Where does Albumin exist?

Answer 7

In the vascular system.

Not in the tissue!

Question 8

What do we call hydrostatic pressure in the vascular space?

Answer 8

BLOOD PRESSURE

Question 9

What is the Gibbs-Donan Paradox?

Answer 9

Opposition of forces make the state still.

Question 10

What is the equation for Filtration?

Answer 10

Kf [(Pc+pii) - (Pi+pic)] = mmHg

-Usually equal and opposite (balanced, no filtration)

Question 11

What differential do you have between the intracellular and extracellular space to generate electrical activity?

Answer 11

• High sodium extracellular, low sodium intracellular.
• High potassium intracellular, low potassium extracellular
• Phosphorus and anions on both sides

Question 12

What is important to remember about the composition of the Intracellular space?

Answer 12

High K+, Low Na+, Impermeable protein, some PO4-, some Cl-, some Mg+, some SO4-

Question 13

Where does Digitalis act?

Answer 13

Shuts off the Na+-K+ ATPase –> cell swells, bursts and dies!

Question 14

What is the composition of Normal Saline (0.9%)?

Answer 14

Osmolality 308 mmol/L
Sodium 154 mmol/L
Chloride 154 mmol/L
No K+
No Bicarb.
No Glucose

Question 15

What is the composition of half Normal Saline (0.45%)?

Answer 15

Osmolality 150 mmol/L
Sodium 75 mmol/L
Chloride 75 mmol/L
No K+
No bicarb. 
No Glucose

Question 16

What is the composition of D5?

Answer 16

Osmolality 300 mmol/L

280 mmol/L Glucose

Question 17

How is the body’s water divided?

Answer 17

60% water = males
50% water = females
2/3 of total water = Intracellular
1/3 of total water = Extracellular
1/4 of Extracellular = Plasma
3/4 of Extracellular = Interstitial

Question 18

How does a liter of water disperse?

Answer 18

Evenly, like body water is divided. 666 mL in Intracellular, 261 mL Interstitial and 71 mL in plasma

Question 19

How does a liter of NS disperse?

Answer 19

300 mM Intracellular
300 mM Interstitial
301 mM Plasma

Question 20

What does the Na+-K+ pump prevent when NS is given?

Answer 20

Na+-K+ pump makes it so that Na+ and plasma cannot go into the cells.

Question 21

What would you use NS to treat?

Answer 21

• Sepsis, DKA, Secretory Diarrhea (loss of Na+ and Cl-)

- Used to bouy blood pressure

Question 22

How does a liter of 1/2 NS disperse?

Answer 22

Half like NS, Half like H2O

Question 23

What would you use 1/2 NS to treat?

Answer 23

• Athletes (sweat losses)

- Febrile (Hospitalizations)

Question 24

How does a liter of D5W disperse?

Answer 24

Like water!

• 666 mL and 2/3 glucose in Intracellular space
• 261 mL + glucose in Interstitial space
• 71 mL + glucose in plasma space

Question 25

When is D5W used?

Answer 25

To replete water if the patient cannot drink!

Question 26

What conditions is D5W used for?

Answer 26

• DI (nephrogenic or central)

- Severe hypoglycemia

Question 27

What does serum Na+ concentration NOT TELL YOU?

Answer 27

Volume status!

Question 28

What does Blood pressure and Edema tell you?

Answer 28

Na+ status

Question 29

What cannot flow into the cell by diffusion?

Answer 29

Na+

Question 30

What happens to the extra and intra cellular spaces when you add Normal Saline?

Answer 30

• No change in Na+ Extracellularly
• Volume increases Extracellularly
• Osmoles stay the same

Question 31

What happens to the extra and intra cellular spaces when you add Water (H2O)?

Answer 31

• Water inc. Extracellularly
• Water inc. Intracellularly
• Volume inc. Extracellularly
• Volume inc. Intracellularly
• Sodium dec. Extracellularly
• Osmolality dec. Extracellularly
• BOTH COMPARTMENTS EXPAND!!

Question 32

What happens to the extra and intra cellular spaces when you add NaCl (Pure Salt)?

Answer 32

• Na+ increases in Extracellular space
• Osmolarity increases in Extracellular space
• Water rushes from Intracellular to extracellular space –> Water increases in Extracellular space
• EXTRACELLULAR VOLUME INCREASED AT INTRACELLULAR VOLUME’S EXPENSE

Question 33

Why is Hypernatremia life threatening?

Answer 33

Due to the Extracellular space expanding at the expense of the intracellular space.
-Cell could shrink and die!!