Body Fluid Compartments Flashcards
What does blood contain?
Extracellular (plasma) and intracellular (in RBC) fluid
Why is blood considered as a separate fluid compartment?
Contained within its own chamber - circulatory system
How much extracellular fluid?
14 litres
Plasma = 3L
Interstitial fluid = 11L
Composition in plasma and interstitial fluid:
Almost same composition - apart from proteins
Most proteins too big to permeate so higher conc in plasma
How much intracellular fluid?
28 litres
How is intracellular fluid separated from extracellular fluid?
Membranes highly permeable to water but not permeable to most electrolytes
Potassium conc. in intracellular fluid?
140 mM
Potassium conc. in extracellular fluid?
5 mM
Sodium conc. in intracellular fluid?
15 mM
Sodium conc. in extracellular fluid?
140 mM
Chloride conc. in intracellular fluid?
5 mM
Chloride conc. in extracellular fluid?
110 mM
What ions are critical for action potential initiation?
Potassium and chloride
What structures define each cell and control substance movement?
Lipid bilayer membranes
What do cells determine?
Basic biological function
What does the cell membrane do?
Give structure
Physical barrier - separates intracellular fluids from extracellular fluids
Why is the cell membrane dynamic?
To allow controlled movement of water and solutes across membrane
What may membrane proteins be?
Integral
Peripheral
Lipid anchored
What may transport through the membrane be?
Restricted
Free
Permitted under certain conditions
Composition of protein in cell membrane:
55%
Composition of phospholipid in cell membrane:
25%
Composition of cholesterol in cell membrane:
13%
Composition of other lipids4% in cell membrane:
4%
Composition of carbohydrate in cell membrane:
3%
What are the different membrane lipids?
Phospholipids
Spingolipids
Cholesterol
What do phospholipids form?
Basic hydrophobic-hydrophilic bilayer
What are spingolipids?
Contain amino alcohols + have hydrophilic-hydrophobic characters
What is cholesterol?
Dissolved in membrane + contributes to fluidity
What are membrane proteins like?
Mainly glycoproteins
Transporters - move substances against conc. gradient
Receptors for water soluble chemicals
Channels
What are channel proteins?
Watery spaces through molecule - allow free movement of water + molecules + ions
What are carrier proteins?
Bind to molecules/ions and move them through protein to cross bilateral
Characteristics of channel and carrier proteins:
Selective
What does passive membrane transport involve?
Down conc. gradient
No energy
What does active membrane transport involve?
Against conc. gradient
Requires energy
What’s primary active transport?
Uses energy source directly
What is secondary active transport?
Indirect use of energy source
What can rate of transport be influenced by?
Concentration
Electrical potential
Pressure
How does concentration influence rate of transport?
Net diffusion rate into cell is proportional to concentration on outside minus concentration on inside
How does electrode potential effect rate of transport?
Electrode potential drives movement of ions to opposite poles, even against concentration gradient
E.g. negative ions move to more positive side
How does pressure difference effect rate of transport?
Pressure differences increase forces of molecular motion + diffusion
Increased energy causes net increase in movement from high pressure to low pressure
What is the permeability co-efficient of a solute?
The rate of movement calculated in cm/sec
Affects rate of diffusion
Where does water diffuse?
Diffuses from low solute conc. to high solute conc.
What is osmotic pressure measured in?
mmHg
What is the membrane like in osmosis?
Selectively permeable
What’s tonicity?
Mechanical effects on cell caused by placing in solution of impermeant osmotically active particles
