1 Body Fluid Compartments

Question 1

What two ways is water added to the body?

Answer 1

• Oral intake (2100 ml/day)
• Synthesized in the body by oxidation of carbs (200 ml/day)

(2300 total/day)

Question 2

How does the body get rid of water?

Answer 2

• insensible loss (350 skin/350 lungs)
• sweat loss (100)
• loss in feces (100)
• loss by kidneys (1400)

Question 3

What is extracellular fluid composed of?

Answer 3

Interstitial fluid and blood plasma

Question 4

What is transcellular fluid?

Answer 4

fluid in the synovial, peritoneal, pericardial, CSF, and intraocular spaces. (1-2 L total)

Question 5

What is the Donnan effect?

Answer 5

The behavior of charged particles near a semi-permeable membrane that sometimes fail to evenly distribute.

Question 6

The concentration of positively charged particles is slightly greater in the ______ than the _______.

Answer 6

Plasma, interstitial fluid.

Question 7

The concentration of negatively charged particles is slightly greater in the ______ than the _______.

Answer 7

Interstitial fluid, plasma.

Question 8

What is the principle of conservation of mass?

Answer 8

The total mass of a substance after dispersion in the fluid compartment will be the same as the total mass injected into the compartment.

If none of the substance leaks out of the compartment, the total mass of substance in the compartment (Volume B × Concentration B) will equal the total mass of the substance injected

Question 9

The rate of diffusion of water is called the _______.

Answer 9

Rate of osmosis.

Question 10

Osmolality vs Osmolarity

Answer 10

Osmolality = osmoles / kg of water
Osmolarity = osmoles / liter of solution

Question 11

What can you calculate using van’t Hoff’s law?

Answer 11

Potential osmotic pressure of a solution assuming the cell membrane is impermeable to the solute.

Question 12

Factors of Interstitial fluid and plasma osmolarity.

Answer 12

• 80% due to Na and Chloride
• plasma is 1 mOsm/L > interstitial fluid
• plasma proteins maintain 20 mmHg greater pressure in capillaries than surrounding tissues.

(300 mOsm/L)

Question 13

Factors of Intracellular fluid

Answer 13

• Almost 50% due to K ions.
• remainder divided among other intracellular substances.

(300 mOsm/L)

Question 14

Conditions that cause hyponatremia

Answer 14

Excess water
Loss of Na
Diarrhea and vomiting
Diuretic abuse
Addison’s disease
Excess water retention (ADH)

Question 15

Conditions that cause Hypernatremia

Answer 15

Loss of water
Excess of Na
Lack of ADH
Diabetes insipidus
Dehydration
Aldosterone secretion

Question 16

Addison’s disease

Answer 16

Decreased secretion of aldosterone which impairs the ability of the kidney’s to reabsorb Na and can cause a modest degree of hyponatremia.

Question 17

__________ is a disorder where the kidneys excrete large amounts of dilute urine.

Answer 17

Central diabetes insipidus.

Question 18

_________ is a disease where the kidneys cannot respond to antidiuretic hormone.

Answer 18

Nephrogenic diabetes insipidus .

Question 19

Excessive secretion of _______ can cause a mild degree of hypernatremia and over-hydration

Answer 19

Aldosterone (Na-retaining hormone)

Question 20

Edema occurs mostly in the _________ compartment of tissue fluid.

Answer 20

Extracellular

Question 21

Intracellular edema occurs in what certain conditions?

Answer 21

• Inflammation (> cell membrane permeability)
• < cellular metabolic function
• < nutrition to the cells
• < blood flow (< O2 and nutrients)

Question 22

What are 2 general causes of extracellular edema?

Answer 22

• Abnormal leakage from plasma

- Lymphatic failure to return fluids to blood

Question 23

More causes of extracellular edema…

Answer 23

> capillary pressure (slide 26)
< plasma proteins (slide 27)
capillary permeability (slide 28)
Blockage of lymph return (slide 29)

Question 24

< blood flow to the kidneys (HF) stimulates the secretion of _____ causing > formation of ______ and > secretion of ______.

Answer 24

Renin, angiotensin II, aldosterone

Question 25

Both aldosterone and angiotensin II cause….

Answer 25

Additional salt and water retention by the kidneys.

Question 26

3 factors that prevent edema:

Answer 26

• low interstitial compliance
• > lymphatic drainage
• “wash down” of interstitial fluid proteins (as lymphatic flow > proteins are washed away)