L6-7: Transport Flashcards
How much water and electrolytes are contained in the average male body?
60% water = 42L
Electrolytes ~30kg
What are the components of the extracellular fluid?
Plasma and interstitial fluid separated by a leaky epithelium
What are the major anions and cations?
Anions: Cl-, Proteins (albumins, IgG) and phosphates
Cations: Na+ and K+ (small so travel through membrane)
Why are body compartments in a state of chemical disequilibrium?
Due to active transport and membranes acting as barriers (prevents diffusion)
What molecules is able to move freely between compartments and how?
Water via osmosis from low to high water potential
What is osmolarity?
The number of particles (molecules/ions) per unit volume (litres)
What does the arrangement of molecules in ECF and ICF mean?
They are in a state of chemical disequilibrium but in osmotic equilibrium
How is intracellular osmolarity maintained?
Macromolecules and metabolites can cause problems so inorganic ions can get actively pumped out which compensates for excess organic solutes
What are the 2 main classes of membrane proteins?
Carrier and channel proteins
How do carrier proteins work?
Bind to solute on one side and deliver it to other side by conformational change
How do channel proteins work?
Form hydrophilic pores in membrane which solutes (mainly ions) can diffuse
How does passive transport work?
Concentration gradient across membrane determines direction and rate of transport (no energy)
From high to low conc
e.g. simple diffusion and facilitated diffusion
What is carrier-mediated facilitated diffusion?
Carrier transports one substrate (uniporter)
e.g. GLUT transporters - bind to carrier protein in binding site
What is active transport?
Moving a solute against concentration gradient (energy required)
What are the 2 strategies of active transport?
Primary (ATP hydrolysis required) and secondary (target molecule coupled to downhill transport)
