Body Fluids Flashcards
What makes the majority of the body’s composition?
Water, which makes up 45% to 75% of the body.
What is the “Milieu Interieur”?
The “Milieu Interieur” refers to the internal
environment of the body, which includes various
body fluids.
What is the fundamental principle that directs
functional activities in the body?
The fundamental principle is maintaining
homeostasis, which is the relative constancy of the
internal environment.
What are the aspects of body fluids? (4)
The aspects of body fluids include :
volume,
distribution,
characteristics,
functions
What is the medium in which solutes are dissolved
and metabolic reactions take place?
Body water
What are body water functions? (8)
-Regulates body temperature
-Lubricates joints
-Lessens the burden on the kidneys and liver by flushing out waste products
-Carries nutrients and oxygen to cells
-Helps dissolve minerals and other nutrients to make them accessible to the body
-Helps prevent constipation
-Protects the body organs and tissues
-Moistens tissues such as those in the mouth, eyes and nose
What accounts for the large variation in water
content in different individuals?
The percentage of water in various tissues, such as
skin, muscle, heart, liver, brain, kidney, bone, and
adipose tissue. The difference in adipose tissue leads to the difference of body water.
What is the percentage of water in skin, muscle,
heart, liver, brain, kidney, bone, and adipose
tissue?
Skin: 70%, Muscle: 75%, Heart/Liver/Brain/Kidney:
70-80%, Bone: 25%, Adipose tissue: 10%.
True of False: If body water content is computed as a fraction of lean body mass (excluding fat), the differences between individuals becomes significant.
False
If body water content is computed as a fraction of lean body mass (excluding fat), the differences between individuals becomes insignificant.
How do variations in body water with age and sex
differ?
Infants have the highest percentage of body water regardless of sex.
By puberty, the oestrogen creates a fat deposit for women, reducing their body water.
As we age, body water continues to reduce because the lean body mass is reducing.
What are the standard values for a physiological
reference individual in terms of body water
percentage?
60%
How do you calculate the absolute amount of water in a 70-kg male with a body water percentage of 60%?
70 x 60% = 42 kg = ~42L.
What must be adjusted for when calculating body
water percentage in individuals? (3)
Age, sex, and weight.
What is the final concentration of a 100 mg
medication administered to a 70-kg male with 42L
of water?
(dosing : 10mg/7kg)
100 mg/42,000 mL
(0.0024mg/mL)
What is the importance of knowing the amount of
body water when administering water-soluble
medication?
It helps in determining the appropriate dose of
medication based on the concentration in the body
How does the percentage of body water affect the
final concentration of medication in the body?
A lower percentage of body water results in a higher
final concentration of medication in the body.
What is the final concentration in the body when
administering 100 mg medication to a 70-kg female
with 35 L of water in their body?
(Dosing: 10mg/7kg)
100/35 000 = 0.0029mg/mL
What is the mechanism of water intake in the body? (3)
Fluid
Food
Oxidative water from metabolism
What is the mechanism of water output in the body?
kidneys
stool
lungs
skin.
What is the dynamic steady state of body water?
Body water remains constant in health, both
internally between different compartments and
externally with the environment.
What are the obligatory losses of water per day?
Obligatory losses of water per day are (~1.5 L), which
includes insensible losses from lungs and skin, and
sensible losses from urine and stool.
What are the facultative losses of water per day?
Urine
What is the major homeostatic organ for water
balance?
The kidney is the major homeostatic organ for water
balance.
What is the difference between obligatory and
facultative losses of water?
Obligatory losses will happen no matter what. Facultative losses will vary with water intake.
What is the normal water turnover for an adult over
24 hours?
The normal water turnover for an adult over 24
hours is 3-4% of total body weight.
What is the normal water turnover for an infant over
24 hours?
The normal water turnover for an infant over 24
hours is ~10% of total body weight.
What are the different ways in which water is lost
from the body?
urine, stool,
insensible losses from lungs and skin, perspiration, sweating.
What is the difference between insensible perspiration and sweating? (4 each)
Insensible perspiration is pure water, involves passive evaporation (affected by ambient temperature and relative humidity), involves the entire skin surface and is continous (day and night).
Sweating is an electrolyte solution, is an active secretion (requires energy), produced only where sweat glands are located and is activated by heavy work or high temp.
Why is body water volume remarkably constant
under conditions of health?
Body water volume is remarkably constant under
conditions of health to help maintain homeostasis.
What are the benefits of body water volume
remaining constant?
It helps maintain normal solute concentrations,
normal blood volume and pressure, which allows an
adequate supply of O2 to tissues.
What is a negative water balance?
Water loss is greater than water intake
What are the five ways excessive water loss can
occur?
Excessive loss from gut (excess vomiting),
excessive sweating,
excessive loss in expired air (e.g., dry air at high altitudes),
reduced intake,
and excessive loss in urine.
What is water intoxication?
Water intake is greater than water loss
What are the two causes of water intoxication?
Excessive intake
Renal system failure
What is body water in a “dynamic steady state”?
It is in a constant state of flux between different
compartments internally and between the individual and the external environment.
What are the two major subcompartments of the
major body water compartment?
Intracellular fluid (ICF) and extracellular fluid (ECF).
What is the composition of ICF and ECF (% of total body water and/or body mass) ?
ICF is 2/3 of body water and ECF is 1/3 of body water.
ICF is 40% of body mass and ECF is 20% of body mass.
What is the total body water as a percentage of
body mass?
60%
What are the two major subcompartments and two
minor subcompartments of ECF?
Major subcompartments:
plasma
interstitial fluid (ISF)
Minor subcompartments :
lymph
transcellular fluid
What is plasma?
Plasma is the fluid medium in which blood cells are
suspended.
What is the normal value of hematocrit (Ht)?
~45%.
What is hematocrit (Ht)?
The percentage of Blood Volume that is occupied by Red Blood Cells (erythrocytes)
( packed cell volume (PCV))
What is the fluid that percolates between individual
cells called?
interstitial fluid (ISF).
What is the equation to calculate hematocrite (Ht) ?
height of erythrocyte column/height of the whole blood column
What is the percentage of body mass that the
interstitial fluid (ISF) occupies?
The interstitial fluid (ISF) occupies 15% of body
mass.
What is the percentage of body mass that the
plasma occupies?
The plasma occupies 5% of body mass.
What is the volume of intracellular fluid (ICF) in a 70
kg male?
The volume of intracellular fluid (ICF) in a 70 kg
male is approximately 28 L
What is the lymphatic system? (4points)
The lymphatic system is a network of
-blind-ended terminal tubules
-that coalesce to form larger lymphatic vessels, which
-converge to form large lymphatic ducts that
-drain into the large veins in the chest.
What is the volume of lymph in the body?
The volume of lymph in the body is approximately
1-2% of the extracellular fluid (ECF).
Who am i :an aggregate of small fluid volumes secreted by specific epithelial cells that line
some body cavities and have specialized functions.
transcellular fluid
What is the function of transcellular fluid? In water body
Locally, transcellular fluid plays an important role in
function, but it does not contribute significantly to
overall water exchanges, and local changes do not
affect body fluid balance.
What is the state of compartments in the body?
Dynamic equilibrium
What are the two methods to determine
compartment volumes?
Direct and Indirect.
What are the steps involved in the indicator dilution
method? (5)
1-Introduce known quantity of indicator into vein
2-allow time to equilibrate
3-remove known volume of blood
4-measure concentration in unit volume of plasma
5-calculate.
What is the indicator choice for the indicator dilution
method? (4)
*Non-toxic
*Diffuse readily, distribute evenly throughout compartment(s) to be measured
* Induce no changes in distribution of water between compartments
*Easy to measure
What is the formula for calculating the volume of a compartment using the indicator dilution method?
V= Q/c
where V is the volume, Q is the amount of
indicator used, and c is the concentration of the
indicator in plasma
What needs to be known to calculate the volume of
a compartment using the indicator dilution method?
The total quantity of test substance introduced
the concentration of the substance/unit volume of
fluid, after dispersion.
What should we change about the indicator if we want to measure ECF volume?
indicator that crosses capillary wall but doesn’t cross cell membrane
ex: inulin, sucrose, mannitol
What should we change about the indicator if we want to measure plasma volume?
indicator that doesn’t cross capillary wall and doesn’t cross cell membrane
ex: Evan’s Blue
What is the normal Plasma Volume value?
Approximately 3.5 L.
How to measure ICF volume?
Total body water - ECF = ICF
How to measure ISF volume?
ECF - Plasma = ISF
What is the difference in ionic composition between
ECF and ICF?
ECF is high in Na+ and Cl- but low in K+,
while ICF is high in K+ (and Mg++) but low in Na+ and Cl-.
What is the purpose of Ringer’s Solution?
It is an artificial substitute for plasma/ISF
What is the composition of Physiological Saline?
0.9% NaCl
