3. Body Fluid Compartments
Cells contained in watery
internal environment: life-
sustaining exchanges occur
Extracellular fluid (ECF):
Fluid outside the cells
Plasma
Interstitial fluid
Intracellular fluid (ICF): Fluid
contained within the cells
4. Homeostasis
Maintenance of a relatively stable internal
environment
Internal environment is the extracellular fluid
Essential for survival and function of all cells
5. Homeostasis
Factors Homeostatically Regulated:
Concentration of nutrient molecules
Concentration of O2 and CO2
Concentration of waste products
Concentration of water, salt, and other electrolytes
Volume and pressure
pH
Temperature
6. Homeostasis
All the systems of the body work together to
maintain homeostasis:
Gastrointestinal, Respiratory systems Obtaining
nutrients and O2
Circulatory system Transport
Respiratory, Renal systems Removal of waste and
metabolic end products
Nervous and Endocrine systems Regulation
8. Homeostatic Control Systems
Functionally interconnected network of body
components that operate to maintain a given
factor in the internal environment relatively
constant around an optimal level
9. Homeostatic Control Systems
Components:
Sensor: Detects
deviation from set point
Integrating (control)
center: Compares input
with set point &
determines response
Effecter: Produces
response
10. Homeostatic Control Systems
Feedforward:
Term used for responses made in anticipation
of a change
Feedback:
Refers to responses made after change has
been detected
Types of feedback systems
Negative Feedback
Positive Feedback
13. Homeostatic Control Systems
Positive Feedback:
amplifies an initial change
An output is enhanced
A controlled variable moves in the direction
of an initial change
17. Body fluid
On average, body fluids constitute 60% of total
body weight
In the average 70 Kg adult male is about 42 L
18. Body fluid
Variation in water content:
Variation due to age: total body water (TBW) with
increasing age, by age of 60 years it becomes 50 %
Variation between tissues:
Most tissues are water-rich and contain 70-80% water
Plasma contains >90% water
Fat is the driest tissue of all, having only 10% water
content
Variation between individuals:
TBW in a standard male is 60% of his body weight, while
in female, its 55%, due to higher fat content
Obese adults have lower percentage
19. Body Fluid Compartments
TBW represent about 60% of total body weight:
Intracellular fluid (ICF):
fluid within the cells
about 2/3 of TBW (40%)
Extracellular fluid (ECF):
fluid outside the cells
About 1/3 of TBW (20%)
27. Body is in fluid balance
Daily intake of water:
Fluid intake (1.250 mL/day)
Food intake (1000 ml/day)
Metabolically produced H2O
(350mL/day)
Daily loss of body water:
Insensible water loss
(900ml/day)
Fluid loss in sweat
(100ml/day)
Water loss in feces
(100ml/day)
Water loss by kidney (1500
ml/day)
Total intake (2600ml/day) Total output
(2600ml/day)
28.
29.
30.
31. Body is in fluid balance
In a steady state, the osmolarity in ECF is the
same as in ICF
Normally, cells neither shrink or swell because
intracellular and interstitial fluids have the same
osmolarity (280 mmol/L)
Increasing osmolarity of ECF draws water out of
cells and cells shrink
Decreasing osmolarity of ECF draw water inside of
cells and causes cells to swell