4: Total Body Water, Body Fluid Compartments, and Disturbances Flashcards
how is total body water (%) related to amount of body fat and age
TBW are inversely proportional with body fat content and age
TBW also varies among species, age, and nutritional state
give the TBW of male and female animals
male: 60%
female: 50%
females are more prone to dehydration
give the TBW (in relation to body weight) of:
newborn animals
lean adult animals
fat adult animals
newborn: 80% (declines sharply then gradually
lean adult: 60-70%
fat adult: 40%
!!! more fat, less TBW
the 2 body fluid compartments
intracellular fluid (ICF) - water inside the cell, 67% of TBW, 40% of body weight
extracellular fluid (ECF) - water outside the cell, 33% of TBW, 20% of body weight
the 3 divisions of ECF separated by the walls of the vascular system
transcellular fluid
plasma
interstitial fluid
- 3/4 of ECF
- 15% of body weight
- fluids of interstitial spaces (b/w the cells and blood vessels)
interstitial fluid
- 1/4 of ECF
- 5% of body weight
- fluid portion & non-cellular part of the blood
plasma
- fluids found in specific parts of the body
- in joints, heart, eye, etc.
- more examples!!
transcellular fluid
plasma has the same composition as interstitial fluid except for ______
protein content
why? because proteins are not permeable to capillary membrane pores where plasma is found
capillary membrane pores are highly permeable to almost all solutes except _______
proteins
identify where these transcellular fluids are found:
- synovial fluid
- pericardial fluid
- aqueous and vitreous humors
- cerebrospinal fluid (CSF)
- urine
- bile
- fluids in lumen of visceral organs
• synovial fluid - joints
• pericardial fluid - pericardial space
• aqueous and vitreous humors - intraocular spaces
• cerebrospinal fluid (CSF) - brain ventricles, subarachnoid of SC
• urine - kidney, urinary bladder
• bile - gall bladder
• fluids in lumen of visceral organs - stomach, intestines
see module!!
formula for body fluid measured using injectable substances
concentration = (amount of substance injected) / (volume of distribution, Vd)
volume of distribution formula
- if injected substance is excreted (via sweat or urine) during the time it should distribute itself in the body compartment of interest
volume distributed (Vd) = (amount injected - amount excreted) / (concentration after equilibrium)
3 IV (intravenous) substances for measuring TBW
heavy H2O - deuterium oxide (D2O)
radioactive H2O - tritium oxide (T2O)
antipyrine - lipid soluble substance
formula for TBW volume
TBW = (quantity injected - quantity excreted) / (concentration in compartment, C)
TBW = ICF + ECF
!!see sample problems in module
3 IV substances used in measuring ECF
radioactive ions or substance - radioactive Na, Cl, or thiosulfate
inulin - polysaccharide excreted by kidney via urine
thiosulfate
substances diffuses through ECF in __-__ minutes; stays in ECF and do not enter the cells or ICF
30-60 minutes
2 IV substances used in measuring plasma
radioactive albumin
dyes that binds to plasma proteins - Evan’s Blue or T-1824
where do injected substances for measuring the plasma remain? not penetrate?
blood plasma, capillary membrane
formula for ECF volume
ECF volume = interstitial fluid + plasma
calculation of interstitial fluid volume
interstitial fluid volume = ECF - plasma
formula for ICF
ICF volume = TBW - ECF volume
refers to gained H2O vs. H2O loss
water balance
!!! total amount of water in the body remains relatively constant from day to day
3 sources of H2O in animals
drinking water - 80-90% of total water intake
water in food - 5% of total water intake
- roughages (high H2O content), concentrates (0% water)
metabolic water - 5-10% of total water intake
- from oxidation of carbs, fats, and amino acid
give the water yield during oxidation of the following substrates:
1 g protein
1 g CHO
1 g fats
1 g protein - 0.4 mL water
1 g CHO - 0.6 mL water
1 g fats - 1.1 mL water
where does 100% of total water intake of dessert-dwelling animals come from?
metabolic water
behavioral and physiologic adjustments of dessert-dwelling animals
avoid daily heat load
minimize water loss (stays in burrows during daytime, very dry feces, low urine volume)
2 types of water loss in animals
sensible and insensible H2O loss
- detectable and measurable H2O loss
- loss of electrolytes
- via urine (12-20 ml/lb/day, normal) and feces
sensible H2O loss
- H2O losses not readily observed and non-measurable
- e.g., sweat and respiratory gases (10-15 ml/lb/day) (hypotonic loss)
nonsensible H2O loss
2 causes of increase in sensible water loss
vomiting, diarrhea
4 causes of increase in insensible H2O loss
high environmental temperature
hyperactivity
fever
hyperventilation
normal urine volume of animals (mL/kg body weight per day)
- cats
- dog
- cattle
- goat
- horse
- sheep
- pig
- cats: 10-20
- dog: 20 - 100
- cattle: 17 - 45
- goat: 10 - 40
- horse: 3 - 18
- sheep: 10 - 40
- pig: 5 - 30
compare the water loss thru feces in dogs, cats, sheep, and cattle
dog and cat: lower water loss
sheep and cattle: higher water loss
compare the water content of inspired (inhaled) and expired (exhaled) air by animals
inspired: lower water content
expired: higher water content
why? air is warmed & saturated with H2O before expiration
!!! increased expiration, increased water loss
what happens to the amount of expired air when animals are exposed to hot environement?
it increases
how is water lost from the skin surface
evaporation as water diffuse through the skin surface from the blood vessels and body fluids
how is water lost in the skin surface in horses, cats, and dogs?
horses: sweating
cats: high amounts of saliva spread over the body surface via grooming or licking
dogs: panting
cats and dogs have no sweat glands
3 causes of pathologic water loss
vomiting
diarrhea
hemorrhage
give the daily water balance in non-lactating and lactating cow (total water intake and loss)
non-lactating cow:
total water intake: 29 L
total water loss: 29 L
lactating cow:
total water intake: 56 L
total water loss: 56 L
2 types of solutes in different body fluid compartments
inorganic molecules
organic molecules
ions that carry an electric charge
inorganic molecules
- ions in solution
- constitutes 90-95% of solutes in the body fluids
electrolytes (cations or anions)
2 types of cations
monovalent cations
divalent cations
- 1 positive charge
- e.g., Na+ (65-70% exchangeable), K+ (all exchangeable)
monovalent cations
exchangeable - can pass through the membrane
- 2 positive charges
- e.g., Mg2+ (in bones or unexchangeable), Ca2+ (98-99% in bones, teeth; 1-2% exchangeable)
divalent cations
give 5 chief anions of the body fluids
Cl-
HCO3-
Phosphates (HPO4-, H2PO4)
Organic phosphates
Polyvalent proteins (negatively charged proteins)
- tendency for the ions to diffuse down their concentration gradient is balanced by an electrical potential that develops across the membrane
- concentration of cations & anions are equal to each other, ELECTRONEUTRALITY is preserved
Gibbs-Donnan Equilibrium
give the total cations and anions in the different body fluid compartments (mEq/L):
- plasma
- interstitial fluid
- intracellular fluid
- plasma: 153 both
- interstitial fluid: 156 both
- intracellular fluid: 198 both
give the total mOsm/L of:
- plasma
- interstitial fluid
- intracellular fluid
plasma: 301.8
interstitial fluid: 300.8
intracellular fluid: 301.8
Concentration of diffusible cations is (greater/lesser)______ in the solution that contains the non-permeable anions or particles.
greater
Concentration of diffusible anions is (greater/lesser)______ in the solution without the non-permeable anions or particles.
greater
The side of membrane facing the solution with the non-diffusible anions is ________ charged compared to the other side of the membrane
negatively
formula for the concentrations of diffusible ions on either side of the membrane
(Na+)1 * (Cl-)1 = (Na+)2 * (Cl-)2
2 major cations in ECF
Na+, Ca2+
2 major anions in ECF
Cl-, HCO3-
2 major cations on ICF
K+, Mg2+
3 major anions in ICF:
H2PO2 -, HPO4 -, charged proteins
substances that do not dissociate & are uncharged
organic molecules or non-electrolytes
5 examples of organic molecules/non-electrolytes
amino acids
ATP
glucose
lactate
urea
- volume contraction
- loss of water and or loss of Na (decrease in ECF volume)
dehydration
type of dehydration: proportional reduction on ECF and ICF volume
simple H2O deficit
type of dehydration: reduction in ECF volume
NaCl deficit
3 types of dehydration
isoosmotic
hyperosmotic
hypoosmotic
describe the changes during isoosmotic dehydration
- ICF volume
- ECF volume
- ICF osmolality
- ECF osmolality
+ etiology
- no change in ICF volume
- !!! decreased ECF VOLUME !!!
- no change in ICF osmolality
- no change in ECF osmolality
- etiology: burns, hemorrhage, GIT fluid loss from vomiting and diarrhea
(see module for visual aid)
describe the changes during hyperosmotic dehydration
- ICF volume
- ECF volume
- ICF osmolality
- ECF osmolality
+ etiology
- decreased ICF volume
- decreased ECF volume
- increased ICF osmolality
- increased ECF osmolality
- etiology: low water intake, excess evaporation from skin, breathe
(see module for visual aid)
describe the changes during hypoosmotic dehydration
- ICF volume
- ECF volume
- ICF osmolality
- ECF osmolality
+ etiology
- !!! increased ICF volume !!!
- decreased ECF volume
- decreased ICF osmolality
- decreased ECF osmolality
- etiology: loss of hypotonic sweat, high renal loss due to adrenal problems
- volume expansion
- gain of water and/or Na (increase in ECF volume)
overhydration
3 types of overhydration
isoosmotic
hyperosmotic
hypoosmotic
describe the changes during isoosmotic overhydration
- ICF volume
- ECF volume
- ICF osmolality
- ECF osmolality
+ etiology
isoosmotic overhydration
- no change in ICF volume
- !!! increased ECF volume !!!
- no change in ICF osmolality
- no change in ECF osmolality
- etiology: excess oral or parenteral of isotonic fluids,
edema
(see module for visual aid)
describe the changes during hyperosmotic overhydration
- ICF volume
- ECF volume
- ICF osmolality
- ECF osmolality
+ etiology
- decreased ICF volume
- increased ECF volume
- increased ICF osmolality
- increased ECF osmolality
- etiology: excess salt intake, IV infusion of NaCl solution
(see module for visual aid)
describe the changes during hypoosmotic overhydration
- ICF volume
- ECF volume
- ICF osmolality
- ECF osmolality
+ etiology
- increased ICF volume
- increased ECF volume
- decreased ICF osmolality
- decreased ECF osmolality
- etiology: excess water intake, water retention in kidneys
(see module for visual aid)