Chapter 3 - Fluids, Electrolytes and acid-base Flashcards
What percentage of body weight does total body water (TBW) represent in adult horses?
60%
What percentage of body weight does total body water (TBW) represent in foals?
70%
What proportion of TBW does the extracellular fluid (ECF) volume represent in adult horses?
One third (20% of the BW)
Which component forms the largest part of the ECF?
Interstitial fluid (two thirds, 40% of BW)
What is the normal volume of gastrointestinal secretion in a 500-kg horse?
About 100 L every 24 hours
What is the blood volume in fit horses as a percentage of body weight?
14%
What is the normalblood volume as a percentage of body weight in sedentary horses?
8% in sedentary and 14% in sport horses
In neonates, blood volume represents what percentage of body weight?
15%
What is the osmotic pressure generated mainly by proteins in the plasma called?
Colloid osmotic pressure (COP)
The ECF is composed by what?
interstitial fluid (75%),
plasma (25%) lymph, and transcellular fluids such as synovial, pleural, abdominal, and cerebrospinal fluids (<1%).
The overall concentrations of anions and cations have to be ____________ in all fluids
The overall concentrations of anions and cations have to be equal in all fluids, including plasma (sum of all anions = sum of all cations)
In plasma what is the main anion and the main cation
In plasma, sodium is the main** cation**
n plasma what is the main anion and the main anion
bicarbonate and chloride are the main anions
Proteins have positve or negative charge?
Proteins have a negative charge and contribute
to the anions.
The interstitial fluid accounts for ___% of the ECF
The interstitial fluid accounts for about 75%
of the ECF, and the components with significant concentrations
are sodium, bicarbonate, and chloride
The composition of the ICF
the important cations are potassium and magnesium, and the important anions are** phosphates and proteins**
Definitation of osmolality
Osmolality is defined as
the concentration of osmotically active particles in solution per
kilogram of solvent (mOsm/kg)
definition of osmolarity
is the number
of particles of solute per liter of solvent (mOsm/L)
Normal plasma
osmolality
from 275 to 312 mOsm/kg
what is the Starling’s equation?
**Kf **is the filtration coefficient, which varies depending on the surface available for filtration and the permeability of the capillary wall; **Pcap and Pint **represent the hydrostatic pressures in the capillary bed and in the interstitial compartment, respectively;
πp and πint represent the oncotic pressure in the plasma and interstitial fluid, respectively; and σ is the reflection coefficient of proteins across the capillary wall
**Kf **is the filtration coefficient, which varies depending on the
depending on the surface available for filtration and the permeability of the capillary wall
what Pcap and Pint
**Pcap and Pint **represent the hydrostatic pressures in the capillary bed and in the interstitial compartment, respectively;
Colloid osmotic pressure
(COP) is generated mainly by
proteins, albumin
What is the normal COP for foals and adults?
Normal values of 15.0 to 22.6 mm Hg for foals
Normal values of 19.2 to 31.3 mm Hgfor adults
Henderson-Hasselbalch equation - What does the traditional approach to determine acid-base and electrolyte status focus on?
Bicarbonate and hydrogen ions
Stewart’s definition what is the definition of base?
a substance that can accept H (Bronsted)
result in a decrease of H+in the fluid (Stewart),
Stewart’s definition what is the definition of acid
a substance that can donate H (Bronsted)
result in an H+ increase in a fluid (Stewart)
which voltatile acid exist?
volatile acid (CO2)
what other acids exist beside the CO2?
lactate
acetate
pyruvate
citrate
Henderson-Hasselbalch approach centers on what to determine if it is metabolic or respiratory?
centers on pH, bicarbonate and HCO3-
What is the formula of law of mass with dissociation of carbonic acid?
Name the Henderson-Hasselbalch equation
Name causes of metabolic acidosis and what does it mean
Metabolic acidosis is present when there is a decrease in HCO3− caused by either loss or buffering of nonvolatile acids
what does it mean to have metabolic alkalosis
Metabolic alkalosis is present when there is an increased concentration of HCO3
what are the reasons of respiratory acidosis
what are the reasons of respiratory alkalosis
The major route for return of fluid to the circulation is
lymph
Why focusing only on pH as sole determinant of acid-base homeostasis is not sufficient?
because pH can be normal and electrolytes are ignored using traditional approach
What challenge did Peter Stewart present to the traditional approach to acid-base balance?
Emphasized the role of strong ions and weak electrolytes (Quantative Strong ion approach)
3 parameters PCO2, SID and total proteins (Atot)
What is an increase in the strong ion difference (SID) indicative of?
Metabolic alkalosis
What does Atot represent in the quantitative strong ion approach?
Total mass of nonvolatile weak acids (proteins)
What is the effect of a significant increase in Atot?
Metabolic acidosis
What are the strong cations mentioned in the Stewart quantative strong ion approach?
Na+, K+, Mg++, and Ca++
What is the primary buffer system of the extracellular fluid (ECF)?
Bicarbonate
What is considered the primary respiratory component in the quantitative strong ion approach?
Carbon dioxide partial pressure (pCO2)
What happens when the strong ion difference (SID) decreases?
Metabolic acidosis