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28 Cards in this Set

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What are the 3 types of movement?
1. Bulk Flow
2. Diffusion
3. Transport
What are some examples of Bulk Flow?
*CONVENTION*
1. blood/artery
2. air/bronchiole
3.chyme/intestine
What are some examples of Diffuision?
*WITHIN COMPARTMENTS*
1. passive/random thermal action
2. concentration gradients
What are some examples of Transport?
*ACROSS BARRIER*
1. solubility + Diffusion/ lipid bilayer
2. Carrier mediated transport
3. Endo/Exo-cytosis
What does FICK'S LAW of diffusion depend on?
1. Concentration gradient
2. Area
Why are cells no further than 100um from thier energy source?
Distances greater than 100um increase the time of diffusion by a lot!
Why are cells no bigger than 10um?
Because a cell that is greater in size will be less efficient in moving things around the cell..by ALOT!
So what do diffusional distances tell us about the function?
If we need diffusion to be slow then distances should be greater like in dermis which provide a protection function vs. a mitcondria that has small distance across b/c it needs to produce energy fast!
What does the partition coefficient tell us?
measure of a solute lipophilicity and an indication of its ability to cross cell membranes.
What does a Partition coefficient greater than 1 tell us (1>K)?
Lipophilic i.e can cross easily across lipid bilayer
What does a Partition coefficient Less than 1 tell us (1<K)?
Lipophobic i.e cannot cross easily acoss lipid bilayer
What can DIFFUSE across the lipid bilayer?
1. Gases
2. Small,uncharged, POLAR molecules (ethanol)
What can DIFFUSE across the lipid bilayer very little?
1. Water
2. UREA
Why does Asprin get absorbed in the stomach quickly?
1. pKa of aspirin is low
2. pH of stomach is low
=therefore, Asprin in stomach exist as non ionized form and is able to diffuse through lipid layer
Why do you get drunk faster w/alcohol when you dont eat?
1. The Deudunem has a huge surface area w/huge absorption potential
2.food breakdown slows digestion and therefore, maintains alcohol in stomach longer where surface area for absorption is smaller
Do glucose, adenosine, urea, alanine diffuse through lipd membrane?
No, these molecules are TRANSPORTED by membrane proteins b/c they are essential for energy
Which membrane transit pathway has the highest selectivity for its substrate?
Ion channels<pumps/transporters
Does each monomer of a homotetramer aquaporin conduct water?
Yes
How many pores exist in a homotetramer aquaporin?
5
Which aquaporins also transport glycerol and urea?
AQP:
3(epithelial basolateral membrane),
7(proximal tuble),
9 (epithelial basolateral membrane),
10(small intestine)
Are these poisons, vinblastin and vincristine transported across the lipid bilayer?
yes
During SECONDARY ACTIVE TRANSPORT glucose taps into the sodium gradient energy gradient. Does water follow sodium?
Yes
What is an example of a Transporter?
Glucose comes in
What is an example of a Cotransporter
Na+ and glucose come in together
What is an example of an Exchanger
Na+ in
H+ out
Which have higher specificities: transporters/pumps or channels?
Transporters and pumps since they require molecular conformation
Which pass more stuff through them per second: transporters/pumps or channels?
channels: millions per second
Which are saturable: transporters/pumps or channels?
transporters and pumps