1. Tortora, Ebaa M Alzayadneh, DDS, PhD
Body Fluids & Blood
Tortora,
Ebaa M Alzayadneh, DDS, PhD
University of Jordan

2. Body Fluid Compartments
Barriers
1-plasma membrane
2- blood vessel wall
1L- has a mass of 1kg
40%
20%

3. Q? Calculate volume of blood plasma in a lean 60 kg female?
University of Jordan

4. Source of daily water normal conditions
University of Jordan

5. Renal excretion of water is regulated
Route
ml/day
Water intake
Fluid
In food
Metabolic product
Total
Water output
Insensible
Sweat
Feces
Urine
1200
1000
300
2500
700
100
200
1500
Water loss
Normal temp.
Hot weather
Prolonged exercise
Insensible loss
Skin
Lungs
Sweat
Feces
Urine
Total loss
Intake
350
100
200
1500
2500
250
1400
1200
3400
650
5000
500
6700

6. Regulation of water gain (Intake)
Metabolic water volume : depends on level of aerobic cellular respiration (ATP demand).
Mainly; water intake (drinking):
Thirst center in the hypothalamus is stimulated by
Blood high osmolality (Osmoreceptors)
neurons in the mouth
Baroreceptors in the heart and blood vessels
Dehydration occurs when water loss is greater than water intake.
Decline in blood pressure stimulates RAS (Renin Angiotensin System)
Angiotensin II
RAS: Renin Angiotensin System
University of Jordan

7. Regulation of water and solute loss
Although loss of water by sweat and exhalation is increased during exercise, elimination of excess water and solutes is mainly controlled by urine output.
The main factor that determines body fluids volume is the extent of urinary NaCl loss (Water follows solutes).
Variable NaCl intake- variable urinary NaCl loss to maintain homeostasis.
University of Jordan

8. Regulation of water and solute loss
increased NaCl intake leads to increased blood volume by increased water movement from intracellular to ICF.
The three most important hormones that regulate Na and Cl excretion are Angiotensin II, Aldosterone and ANP.
Ang II : increases NaCl reabsorption in the kidney, water follows.
Aldosterone: increases NaCl reabsorption in the kidney, water follows.
Atrial Natruitic PeptideANP: decreases NaCl and water reabsorption; thus decrease blood volume. (Natriuresis)
The main hormone that regulate water loss is antidiuretic hormone (ADH) which decreases water loss from kidney.
University of Jordan

9. Effective Osmoles
#Na concentration and it’s attendants (such as Cl-) is the major determinant of the osmolality of the ECF. You can estimate ECF osmolality by doubling the concentration of Na+.
#Na and Cl in the ECF are considered effective osmoles as they can cause water to move into or out of the cells.
#Glucose and urea can move freely through the cellular membrane so they don’t cause water to move in or out so they are considered ineffective osmoles.
# In contrast to the ECF, content of Na+ in the ICF is very low and K is the predominant cation of the ICF.
#This difference between the 2 compartments in Na and K content is due to Na+-K+ ATPase channel.
University of Jordan

10. Osmole
Measure of solution’s ability to create osmotic pressure & thus affect movement of water
Proportional to the number of osmotic particles formed in solution
1 mole of nonionizable substance= 1 osmole.
1mole of glucose forms a 1 osmolar solution in 1L water
1mole of NaCl forms a 2 osmolar solution in 1L water
1mole of CaCl2 forms a 3 osmolar solution in 1L water
Osmolality
When the concentration of a solution is expressed in osmoles per kilogram of water, the osmolar concentration of a solution is referred to as its osmolality.
1 osmoles/kg H2O=1 osmoles/L = 1000 milliosmoles/L= 1000 mOSM =1000mmol/L

11. hypotonic isotonic hypertonic
Particle concentration compared with intracellular fluid
fewer same more
Osmolality (mmol/L)
< >310
Representative solution
0.45% NaCl % NaCl % NaCl
Distilled water 5% glucose % glucose
Response of cell placed in solution
Swell & burst no alteration wrinkle or shrivel

12. Distribution of some cations and anions in extracellular and intracellular fluid
ECF
mOsm/kgH2O
ICF
Na+
145 mEq/L
12 mEq/L K+ 4
150
Ca++ 5
0.001
Cl-
105
HCO3- 25 12
Inorganic phosphate (Pi)+ 2
100 pH
7.4
7.1
#Na concentration and it’s attendants (such as Cl-) is the major determinant of the osmolality of the ECF. You can estimate ECF osmolality by doubling the Concentration of Na+.
#Na and Cl in the ECF are considered effective osmoles as they can cause water to move into or out of the cells.
#Glucose and urea can move freely through the cellular membrane so they don’t cause water to move in or out so they are considered ineffective osmoles.
# In contrast to the ECF, content of Na+ in the ICF is very low and K is the predominant cation of the ICF.
#This difference between the 2 compartments in Na and K content is due to Na+-K+ ATPase channel.

13. University of Jordan

14. University of Jordan

15. Movement of water between compartments
Normally, cells neither shrink or swell because intracellular and interstitial fluids have the same osmolarity.
Increasing osmolarity of interstitial fluid draws water out of cells and cells shrink
Decreasing osmolarity of interstitial fluid causes cells to swell
Changes in osmolarity most often result from changes in Na+ concentration
Water intoxication – drinking water faster than the kidneys can excrete it
Can lead to convulsions, coma or death
University of Jordan

16. Electrolytes in body fluids
Ions form when electrolytes dissolve and dissociate
To compare the charge carried by ions in different solutions, the conc. of ions(cations or anions) is expressed in milliequivalents per liter (mEq/L); one thousandth of amount of charge in one mole of H+.
for single positive or negative charge = mEq/L = number in mmol/L
Na+ or Cl- number of mEq/liter = mmol/liter
Ca2+ or HPO42- number of mEq/liter = 2 x mmol/liter
Functions of electrolytes
Control osmosis of water between body fluid compartments
Help maintain the acid-base balance
Carry electrical current
Serve as cofactors
University of Jordan

17. Concentrations in body fluids
Concentration of ions typically expressed in milliequivalents per liter (mEq/liter)
Na+ or Cl- number of mEq/liter = mmol/liter
Ca2+ or HPO42- number of mEq/liter = 2 x mmol/liter
Chief difference between 2 ECF compartments (plasma and interstitial fluid) is plasma contains many more protein anions
Largely responsible for blood colloid osmotic pressure
University of Jordan

18. Differences between plasma and interstitial fluids
Chief difference between the two ECF compartments (plasma and interstitial fluid) is that plasma contains many more protein anions.
Largely responsible for blood colloid osmotic (oncotic) pressure
University of Jordan

19. ICF differs considerably from ECF
ECF most abundant cation is Na+, anion is Cl-
ICF most abundant cation is K+, anions are mostly proteins and phosphates (HPO42-)
Na+ /K+ ATPase pumps play major role in keeping K+ high inside cells and Na+ high outside cell
University of Jordan

20. Sodium Na+ Most abundant ion in ECF 90% of extracellular cations
Plays key role in fluid and electrolytes balance because it account for almost half of the osmolarity of ECF.
Hypernatremia, hyponatremia and natriuresis ( urinary excretion of Na).
Level in blood controlled by
AngII
Aldosternone – increases renal reabsorption of Sodium (Na+ )
ADH – low sodium, inhibits ADH release
Atrial natriuretic peptide – increases renal excretion of Sodium (Na+) natriuresis
University of Jordan

21. Chloride Cl- Gastric juice Most prevalent anions in ECF
Moves relatively easily between ECF and ICF because most plasma membranes contain Cl- leakage channels and antiporters.
Can help balance levels of anions in different fluids
Chloride shift in RBCs
Gastric juice
Regulated by
ADH – governs extent of water loss in urine
Processes that increase or decrease renal reabsorption of Na+ also affect reabsorption of Cl-
University of Jordan

22. Potassium K+ Most abundant cations in ICF
Key role in establishing resting membrane potential in neurons and muscle fibers and repolarization.
Also helps maintain normal ICF fluid volume
Helps regulate pH of body fluids when exchanged for H+
Controlled by aldosterone – ( under high K+ plasma conc) aldosterone stimulates principal cells in renal collecting ducts to secrete excess K+ .
abnormal K levels can be lethal.
hyperkalemia – ventricular fibrillation and death.
University of Jordan

23. Bicarbonate HCO3- Second most prevalent extracellular anion
Concentration increases in blood passing through systemic capillaries picking up carbon dioxide
Carbon dioxide combines with water to form carbonic acid which dissociates
Drops in pulmonary capillaries when carbon dioxide exhaled
Chloride shift helps maintain correct balance of anions in ECF and ICF
Kidneys are main regulators of blood HCO3-
Can form and release HCO3- when low or excrete excess
University of Jordan

24. Calcium Ca2+ Most abundant mineral in body
98% of calcium in adults in skeleton and teeth
In body fluids mainly an extracellular cation
Contributes to hardness of teeth and bones
Plays important roles in blood clotting, neurotransmitter release, muscle tone, and excitability of nervous and muscle tissue
Regulated by parathyroid hormone
Stimulates osteoclasts to release calcium from bone – resorption
Also enhances reabsorption from glomerular filtrate
Increases production of calcitrol to increase absorption for GI tract
Calcitonin lowers blood calcium levels
University of Jordan

25. Phosphate
About 85% in adults present as calcium phosphate salts in bone and teeth
Remaining 15% ionized – H2PO4-, HPO42-, and PO43- are important intracellular anions
HPO42- important buffer of H+ in body fluids and urine
Same hormones governing calcium homeostasis also regulate HPO42- in blood
Parathyroid hormone – stimulates resorption of bone by osteoclasts releasing calcium and phosphate but inhibits reabsorption of phosphate ions in kidneys
Calcitrol promotes absorption of phosphates and calcium from GI tract
University of Jordan

26. Magnesium
In adults, about 54% of total body magnesium is part of bone as magnesium salts
Remaining 46% as Mg2+ in ICF (45%) or ECF (1%)
Second most common intracellular cation
Cofactor for certain enzymes and sodium-potassium pump
Essential for normal neuromuscular activity, synaptic transmission, and myocardial function
Secretion of parathyroid hormone depends on Mg2+
Regulated in blood plasma by varying rate excreted in urine
University of Jordan