2. • In average young adult male:
Body composition % of body weight
Protein, & related substances 18%
Fat 15%
Mineral 7%
Water 60%
Body composition
Body
Fluids
3. The Body fluids
Total body water (TBW):
consititutes 55-60% of the body weight in
young men and 45-50% in young women.
Why the percentage is lower in women?
Infants have low body fat, low bone mass, and are
73% or more water.
Total water content declines throughout life.
Healthy males are about 60% water; healthy
females are around 50%
This difference reflects females’:
Higher body fat
Smaller amount of skeletal muscle
In old age, only about 45% of body weight is water.
3
4. Body Fluid Compartments
Total Body Water
varies depending on body fat:
infant: 73%
male adult: 60%
female adult: 40-50%
effects of obesity
Old age 45%
6. • Water content in body is divided into 2
compartments:
1. Extracellular fluid (ECF):(internal environment or the milieu intérieur)
- fluid outside the cells.
1/3 volume of fluids in body ( 33% of total body
water).
- contains ions & nutrients needed for cellular life.
Extracellular fluid is further dividedinto
A.Interstitial Fluid: Fluid between thecells
B.Plasma: Fluid portion of blood
1. Intracellular fluid (ICF):
- fluid inside the cells.
2/3 volume of fluids in body ( 67% of total body
water).
Body
Fluids
7. Fluid Compartments
60%of bodyweight
Extracellularfluid
( 1/3)
33% of TBW
20% of body wt
Intracellularfluid
( 2/3)
67% of TBW
40% of body wt
Interstitialfluid
75% of ECF
15% of body wt
Plasma
25%of ECF
5% of body wt
Transcellularfluid
CSF
Intraocular
Pleural
Peritoneal
Pericardial
Synovial
Digestive
secretions
Fluid
Compartments
8. VOLUME OF BODY FLUIDS IN 70 kg MAN
TOTAL VOLUME
42 L
INTRA CELLUAR FLUID
28 L(ROUGHLY 2/3 OF TBW)
EXTRA CELLULAR FLUID
14 L(ROUGHLY 1/3 OF TBW)
PLASMA
4 L (ROUGHLY ¼ OF ECF)
13. Q. Calculate TBW for a 70 kgman.
TBW =60%of body weight
TBW =60%X70 =42 Lof
water
• 28 liters intracellular fluid (ICF)–
(2/3rd)
• 14 liters extracellular fluid (ECF)-
(1/3rd)
-3 liters plasma
-11 liters interstitial fluid (ISF)
Example: How to calculate total body water
(TBW)?
14. Solute Overview:
Intracellular vs. Extracellular
Ionic composition very
different
Total ionic concentration
very similar
Total osmotic
concentrations virtually
identical
14
16. Sodium Na+
Most abundant ion in ECF
90% of extracellular cations
Plays pivotal role in fluid and electrolyte balance as it accounts for half of the osmolarity of
ECF
Chloride Cl-
Most prevalent anion in ECF
Moves easily between ECF and ICF because most plasma membranes contain Cl-
leakage channels and transporters
Can help balance levels of anions in different fluids
Bicarbonate HCO3-
Second most prevalent extracellular anion
Concentration increases in blood passing through systemic capillaries picking
up carbon dioxide
Chloride shift helps maintain correct balance of anions in ECF and ICF.
Potassium K+
Most abundant cation in ICF
Establish resting membrane potential in neurons and muscle fibers
Maintains normal ICF fluid volume
Helps regulate pH of body fluids when exchanged for H+
17. Regulation of fluids and electrolytes:
17
• Antidiuretic hormone (ADH)
–Stimulates water conservation and the thirst center
–Regulates the concentration of body fluid
• Aldosterone
–Controls Na+ absorption and K+ loss along the DCT
–Regulates the volume of body fluid compartment
• Natriuretic peptides
–Reduce thirst and block the release of ADH and
aldosterone
18. Sodium balance
Rate of sodium uptake across
digestive tract directly
proportional to dietary intake
Sodium losses occur through
urine and perspiration
Shifts in sodium balance result in
expansion or contraction of ECF
Large variations corrected by
homeostatic mechanisms
Too low, ADH / aldosterone
secreted
Too high, ANP secreted
18
Potassium balance
• Potassium ion
concentrations in ECF are
low
– Not as closely regulated
as sodium
– Potassium ion excretion
increases as
• ECF concentrations
rise
• Aldosterone secreted
• pH rises
– Potassium retention
occurs when pH falls
19. Specialized Fluids of the
Body
Milk
Secreted by mammary glands
Complete natural food
83-87% water and 13-17% solids: (Vitamins except Vit – C, Lactose, Triacylglyerols, Caesin (80%),
Lactalbumin and immunoglobulins.
Function: Milk sugar provides galactose, a structural unit for growing infant.
In intestine, it gets metabolized to lactic acid which eliminates harmful bacteria.
Cerebrospinal fluid (CSF)
Clear, colorless liquid formed within the cavities of brain and around spinal cord
At any given time, there is 120-150ml CSF in the system
Function: Hydrolic shock absorber
Regulation of intracranial pressure
Amniotic Fluid
Liquid produced by membranes and fetus
Volume of fluid increases with gestational age
Clear with some desquamated fetal cell and a little lipid.
20. Aqueous Humor
Fluid that fills the interior chamber of eye
Secreted by ciliary body, enters anterior chamber
Blockade in the flow of aqueous humor causes glaucoma due to increased
intraocular pressure.
Posterior chamber of eye is filled with vitrous humor which contains a gel
(vitrous body of hyaluronic acid secreted by retina)
Sweat
Secretion of sweat gland
Regulates body temperature by cooling and evaporation
Sweat glands controlled by ANS, Adrenal cortical steroid - which affect the quantity
of electrolyte present.
Tears
Produced by lacrimal glands
Lysozyme protects eye from infectious agents
Lubricate the surface of the cornea
Fill the irregularities of the corneal surface to improve optical properties
Protects eyes from injury
21. Carry Home Message
1. Physiology is a science dealing with the way a
normal organism and their body parts function.
2. There are four types of body tissues.
3. There are four branches for studying human
physiology.
22. Fluid Compartments
60%of bodyweight
Extracellularfluid
( 1/3)
33% of TBW
20% of body wt
Intracellularfluid
( 2/3)
67% of TBW
40% of body wt
Interstitialfluid
75% of ECF
15% of body wt
Plasma
25%of ECF
5% of body wt
Transcellularfluid
CSF
Intraocular
Pleural
Peritoneal
Pericardial
Synovial
Digestive
secretions
Carry Home Message
