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