Body Fluid Compartments Flashcards
What percentage of the adult body is fluid ?
Approx 60%
How much fluid is found intracellularly ?
Approx 70% - approx 28L
How much fluid is found extracellularly ?
Approx 30% - approx 14L
What does extracellular fluid include ?
Interstitial fluid (mostly)
Plasma
Also transcellular fluid - synovial, peritoneal, pericardial, intraocular, cerebrospinal fluid
How are the body compartments separated ?
By membranes
What is the approximate volume of blood in the body ?
5L (7% total body weight)
What does blood contain ?
ECF - plasma
ICF - fluid in the RBC’s
What is the difference in composition between plasma and interstitial fluids ?
Plasma has a higher concentration of proteins
Why does plasma have a higher concentration of proteins ?
Both plasma and interstitial fluid exchange substances through highly permeable capillary membranes, but most proteins are too big to permeate and so are maintained in higher concentration plasma than in interstitial spaces.
What is the intracellular concentration of potassium ?
140 mM
What is the intracellular concentration of sodium ?
15 mM
What is the intracellular concentration of chloride ?
5 mM
What is the extracellular concentration of potassium ?
5 mM
What is the extracellular concentration of sodium ?
140 mM
What is the extracellular concentration of chloride ?
110 mM
Which 2 ions have similar ICF and ECF concentrations ?
Sodium and Chloride
What anions have high ICF concentrations ?
Protein
PO4 and organic anions
What cations have high ICF concentrations ?
Potassium
What anions have high ECF concentrations ?
Bicarbonate (HCO3)
Chloride
What cations have high ECF concentrations ?
Sodium
Function of the cell membrane
Provides structure and is a physical barrier separating intracellular from extracellular fluids.
The barrier is dynamic with specialised proteins to allow controlled movement of water and solutes across the membrane.
Amphipathic
Has both hydrophobic and hydrophilic properties
Name the parts of the lipid bilayer
Phosphate
Glycerol
Fatty acids
Membrane proteins - integral, peripheral, lipid anchored
Describe the phospholipid bilayer
Hydrophobic interior
Hydrophilic exterior
Describe the cell membrane composition
55% Protein
25% Phospholipid
13% Cholesterol
4% Other lipids
3% Carbohydrates
Phospholipids
Form the basic hydrophobic/hydrophilic bilayer
Spingolipids
Contain amino alcohols and have hydrophilic-hydrophobic characters.
Are in most cell membranes especially NERVE CELLS.
Cholesterol
Dissolved in the membrane and contributes to fluidity
Channel proteins
Have watery spaces through the molecule allowing free movement of water and some other molecules and ions
Carrier proteins
Bind to molecules or ions and move them through the protein to cross the bilayer.
What word is used to describe channel and carrier proteins ?
Selective
Types of membrane transport
Active
Passive
Passive transport
Down the concentration gradient
Doesn’t require energy
Active transport
Up the concentration gradient
Requires energy
Difference between Primary and Secondary active transport
Primary - uses the energy source directly
Secondary - indirect use of the energy source
Name the 3 factors which influence the rate of transport
Concentration
Electrical potential
Pressure
Describe how concentration influences the rate of transport
The net diffusion is proportional to the concentration difference across a membrane .
Concentration outside - concentration inside
Describe how the electrical potential influences the rate of transport
Electrical potential drives the movement of ions to the opposite pole.
Movement occurs even against a concentration gradient.
Describe how pressure influences the rate of transport
Pressure differences across membranes increases the forces of molecular motion and diffusion increases.
The increased energy causes a net increase in movement from high pressure to low pressure.
What is meant by permeability co-efficient ?
The rate of movement of a solute calculated in cm/s
What is the rate of diffusion affected by ?
Permeability coefficient
What is meant by tonicity ?
Mechanical effects on a cell in terms of shrinkage or swelling caused by placing cell in solution of impermeant osmotically active particles
Isotonic
The water concentration in the ICF and ECF are equal, solutes can’t leave or enter, so the cell volume stays the same.
Hypotonic
CELL SWELLS
Cell in solution with high water concentration and lower concentration of impermeant particles.
Water diffuses in
Cell swells (bursts)
Hypertonic
CELL SHRINKS
Cell in solution with low water concentration, high concentration of impermeant particles.
Water diffuses out
Cell shrinks
