4: Total Body Water, Body Fluid Compartments, and Disturbances Flashcards by John Rhayan Habana

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

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give the TBW of male and female animals

male: 60%
female: 50%

females are more prone to dehydration

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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

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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

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the 3 divisions of ECF separated by the walls of the vascular system

transcellular fluid
plasma
interstitial fluid

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3/4 of ECF
15% of body weight
fluids of interstitial spaces (b/w the cells and blood vessels)

interstitial fluid

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1/4 of ECF
5% of body weight
fluid portion & non-cellular part of the blood

plasma

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fluids found in specific parts of the body
in joints, heart, eye, etc.
more examples!!

transcellular fluid

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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

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capillary membrane pores are highly permeable to almost all solutes except _______

proteins

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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!!

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formula for body fluid measured using injectable substances

concentration = (amount of substance injected) / (volume of distribution, Vd)

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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)

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3 IV (intravenous) substances for measuring TBW

heavy H2O - deuterium oxide (D2O)
radioactive H2O - tritium oxide (T2O)
antipyrine - lipid soluble substance

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formula for TBW volume

TBW = (quantity injected - quantity excreted) / (concentration in compartment, C)

TBW = ICF + ECF

!!see sample problems in module

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3 IV substances used in measuring ECF

radioactive ions or substance - radioactive Na, Cl, or thiosulfate

inulin - polysaccharide excreted by kidney via urine

thiosulfate

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substances diffuses through ECF in __-__ minutes; stays in ECF and do not enter the cells or ICF

30-60 minutes

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2 IV substances used in measuring plasma

radioactive albumin
dyes that binds to plasma proteins - Evan’s Blue or T-1824

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where do injected substances for measuring the plasma remain? not penetrate?

blood plasma, capillary membrane

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formula for ECF volume

ECF volume = interstitial fluid + plasma

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calculation of interstitial fluid volume

interstitial fluid volume = ECF - plasma

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formula for ICF

ICF volume = TBW - ECF volume

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refers to gained H2O vs. H2O loss

water balance

!!! total amount of water in the body remains relatively constant from day to day

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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

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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)