Module 8 Flashcards
- balance and constancy
- keeping the internal environment compatible with life (pH 6.8-8.0)
Homeostasis
Body Fluid Compartments
60% Body weight is Water
40% Body weight is Intracellular Fluid
20% Body weight is Extracellular Fluid
15% Body weight (75% ICF) Interstitial Fluid
5% Body weight Plasma
Babies are made up of __ water
75%
- fluid inside the normal body cavities
- includes intraocular fluid, synovial fluid, water in gallbladder and water in urinary bladder
Transcellular Fluid
Extracellular Fluid is divided into
- Transcellular Fluid
- Insterstitial Fluid
- Plasma
Constituents of ECF and ICF
• Made up of Ions and Proteins
– CATIONS: Positively-charged molecules
– ANIONS: Negatively-charged molecules
- Number 1 Cation in the ECF
- main determinant of plasma osmolarity (where sodium goes, water follows)
Sodium
- Number 1 Cation in the Intracellular Fluid (ICF)
Potassium
Number 1 Anion in the ECF
Chloride
Number 1 Anion in the ICF
Phosphate and organic Anions
• Flow of water from a solution of low solute concentration to a solution of high solute concentration across a semi-permeable membrane
Osmosis
Transport of Water
- Movement of water is via OSMOSIS (utilize water channels)
- It is based on concentration gradient
Movement of Solute and Solvent
Solute - move from high concentration to low concentration
Solvent - move from low concentration to high; hypertonic to hypotonic
– Number of osmotically active particles in a solution
– One osmole = 6.02 x 10^23 of solute particles
OSMOLE (Osm)
Normal value of Osmolarity
300
– Osmoles per kilogram of water (according to weight of water)
– more accurate because it doesn’t vary according to temperature
OSMOLALITY
– Osmoles per liter of water (according to volume)
– “Pogi Points”
– Equal to molar solute concentration x number of particles that the solute dissociates into once dissolved
– Approximately 300mOsm/L in the body compartments
– PLASMA OSMOLARITY: Mainly determined by Sodium
concentration
OSMOLARITY
The higher the osmolarity, the __ the ability to attract water
higher
Osmolarity vary according to temperature. Water tends to expand in high temperature. The higher the temperature, the __ the serum osmolarity
lower
At human body temperature (37.5C), the difference between the osmolarity and osmolality is __
Less than 1%
– Not completely semi-permeable membrane
– Takes into account effect of solute permeability
Effective Osmolarity or Tonicity
TYPES OF SOLUTIONS
– Hypertonic solution
– Isotonic solution
– Hypotonic solution
What is the difference between:
Isotonic, Hypotonic, Hypertonic
Isoosmotic, Hypoosmotic, Hyperosmotic
“…TONIC”: impermeant solutes; may cause change in cell
volume.
“…OSMOTIC”: permeant solutes; may NOT cause change in
cell volume
What will happen if you have a RBC that is 300 mOsm/L when you place in hypotonic solution (209mOsm/L)?
Water will move from outside to inside. The cell will swell.