Lecture 1: Body Fluid Compartments

Question 1

Extracellular fluid makes up what % of body water?

Answer 1

42 L of body water in average person.
14 L = Extracellular fluid (~40% of body water)
-Interstitial fluid= 11 L (75% of extracellular fluid)

     -Blood plasma= 3 L    (25% of extracellular fluid)

Question 2

Intracellular fluid makes up what % of body water?

Answer 2

42L of body water in average person.

28 L = Intracellular fluid (~60% of body water)

Question 3

What makes up the transcellular fluid compartment?

Answer 3

synovial, peritoneal, pericardial, and intraocular spaces, CSF. (combined = 1-2 liters)

All considered aspecialized type of extrcellular fluid.

Question 4

Plasma and interstitial (both extracellular fluids) are similar in what ways?

Answer 4

• Highly permeable capillary membrane

- Protein level > in plasma because of low membrane permeability.

Question 5

Intracellular fluid is different from extracellular fluid in what ways?

Answer 5

• Intracellular fluid is separated by a cell membrane

- Highly permeable to water, not electrolytes (semi-permeable to electrolytes)

Question 6

Which ions are predominently found in extracellular fluid (plasma and interstitial fluids)?

Answer 6

Proteins
HCO3
Cl-
CA++
Na+

Question 7

Which ions are predominently found in intracellular fluid?

Answer 7

K+
Mg++
Phosphate

Cells contain large amounts of protein, almost 4 times as much as in the plasma Guyton Hall p. 287

Question 8

What is the Donnan effect?

Answer 8

Effects the Extracellular fluids.

The concentration of + ions is slightly greater in he plasma than the interstitial fluid because the protein in the plasma has a net negative charge and attracts cations (Na and K).

Negatively charge ions tend to be slightly greater in the interstitial fluid due to repelling of - charged ions from the negatively charged plasma proteins.

For practical purposes, the concentration of ions in the interstitial fluid and plasma are considered about equal.

Question 9

Osmol

Answer 9

1 osmole (osm)= 1 mol (6.02 x 10*23)
Total number of particles in a solution

mole= specific quantity of molecules.

Molecules (mols) which contain more than 1 particle dissociate into separate inos when dissolved in solution (osmol)

1 mol of NaCl=>dissolve into solvent (1 L)=> concentration of 2 osmol/L solution (Na<=>Cl)

Question 10

osmolality:

Answer 10

osmoles/Kg of water

Question 11

osmolarity:

Answer 11

osmoles/Liter of solution

Question 12

Normal body osmolarity:

Answer 12

285 mol/L

Question 13

Osmosis:

Answer 13

-the net diffusion of water across a selective membrane

(High water concentration to low water concentration)

Water follows sodium

Question 14

Osmotic Pressure:

Answer 14

the amount of pressure required to prevent osmosis

pressure applied in opposite direction of osmosis

Question 15

1 mOsm gradient change=

Answer 15

19.3 mmHg osmotic pressure

Osmotic pressure of a solution is proportional to the concentration of osmotically active particles

Question 16

80% of interstitial fluid and plasma osmolarity is due to :

Answer 16

Sodium & Chloride ions

Plasma is 1 mOsm/L >interstitial fluid

(plasma proteins maintain 20mmHg greater pressure in capillaries than surrounding tissues.)

Question 17

50% of Intracellular osmolarity is due to :

Answer 17

Potassium ions

Question 18

The total osmotic pressure at 37*C in plasma, interstitial, and intracellular fluids differ how?

Answer 18

Plasma osmotic pressue (5443) is 20mmHg greater than the osmotic pressue of interstitial and intracellular which are equal (5423).

Question 19

What happens to a red blood cell placed in hypotonic solution?

Answer 19

Swells; takes in water

Question 20

What happens to a red blood cell placed in hypertonic solution?

Answer 20

Shrinks; gives up water

Question 21

Causes of hyponatremia:

Answer 21

• excessive water
• loss of sodium

Conditions:
Diarrhea and vomiting
diuretic abuse
Addison's disease
excessive water retention (ADH)

Question 22

Causes of Hypernatremia:

Answer 22

• Loss of water
• Excess sodium

Conditions:
Lack of ADH
Diabetes insipidus
Dehydration
Aldosterone secretion

Question 23

edema

Answer 23

Excess tissue fluids

Occurs mostly in extracellular fluid compartment

Question 24

Intracellular edema can occur in certain conditions:

Answer 24

• Inflammation has a direct effect on increasing cell membrane permeability
• depression of cellular metabolic function
• lack of nutrition to the cells: decreased blood flow and reduced oxygen & nutrient supply
• ionic pumps of cell membrane require oxidative metabolism (ATP) to remove intracellular sodium

Question 25

Extracellular edema:

Answer 25

-Excess fluid accumulation in extracellular spaces

2 general causes:

1. Abnormal leakage from plasma
   
   • Excessive capillary filtration rate
   • Starling factors: hydrostatic pressure & colloid osmotic pressure
2. Lymphatic failure to return fluids to blood
   
   • lymphatic blockage preventing return of proteins to plasma
   • increased interstitial colloid osmotic pressure
   • CA, surgery, infection (filaria nematodes)

Question 26

Causes of extracellular edema:

Answer 26

• INCREASED CAPILLARY PRESSURE: retention of Na & H2O, high venous pressure (CHF), decreased arterole resistance
• DECREASED PLASMA PROTEINS: loss of proteins, failure to produce proteins
• INCREASED CAPILLARY PERMEABILITY: immune reactions, infection (sepsis) & toxins, burns & ischemia
• BLOCKAGE OF LYMPHATIC RETURN

Question 27

What are the 3 major factors that prevent edema:

Answer 27

1. LOW COMPLIANCE OF THE INTERSTITIUM WHEN INTERSTITIAL FLUID PRESSURE IS IN THE NEGATIVE PRESSURE RANGE.
2. THE ABILITY OF LYMPH FLOW TO INCREASE 10-50 FOLD
3. “WASHDOWN” OF INTERSTITIAL FLUID PROTEIN CONCENTRATION WHICH REDUCES INTERSTITIAL FLUID COLLOID OSMOTIC PRESSURE AS CAPILLARY FILTRATION INCREASES.

Question 28

What are the 3 functions of the kidneys?

Answer 28

1. Regulation of fluid and body fluid composition
2. Excretion of metabolic waste and foreign chemicals
3. Secretion of hormones: Renin (enzyme), erythropoietin, calcitriol

Question 29

What % of cardiac output is dedicated to the kidneys?

Answer 29

11% or 1100ml/min

on a per/gram basis, renal blood flow is the highest of any organ.

Question 30

What is the functional filtration unit of the kidney?

Answer 30

Nephron

Question 31

What are the 2 types of nephrons?

Answer 31

1. CORTICAL NEPHRONS: short loops of henle, extend to outer medulla. Out number Juxtamedullary 7:1
2. JUXTAMEDULLARY NEPHRONS: extend deep into medulla with long loops of Henle. Play a big role in concentrating urine.

Question 32

ADH (Antidiuretic Hormone) Vasopressin:

Answer 32

Function: signals to the kidneys to absorb more water back into the blood. (conservation of water)

Made in the Hypothalamus, Secreted from the Posterior Pituitary gland. It is a hormone.

Question 33

Aldosterone:

Answer 33

Function: acts primarily in renal collecting ducts to stimulate reabsorption of Na+ as well as secretion of K+ and H+.

Made in and secreted by the Adrenal Gland. It is a mineralocorticoid, which is a corticosteroid (made from cholesterol). It is much smaller than ADH.