5+6

Bulk flow requires a  

  = equal,   = consistent state, not necessarily equal

Rate of diffusion depends on
1.  
2.  
3. 

Permeability coefficent includes   and 

Rate of diffusion is proportional to concentration
difference:  

In simple diffusion, Vmax increases with
increased  

In carrier mediated transport, Vmax is
reached when all channels are in use,
so a rise in extracellular concentration
make   in Vmax

Carrier mediated (Facilitated) diffusion is  

Molecules that mix well with lipids in
the plasma have a high  therefore   and cross the
membrane easily and are  

 is controlling the opening/closing of an ion channel based on
membrane potential

  is controlling the opening/closing of an ion channel based on ligand
binding (i.e. nicotinic acetylcholine receptor)

  a channel opens or close with events happening at
other locations in the cell (i.e. cGMP sodium channel in rod cells)

  allows for the transport of hydrophillic molecules and reaches saturation with structural  . There can be   if structure is similar (i.e. D-galactose, D-glucose).

General mechanism of carrier diffusion: molecule enters and creates   change to exit.

What are the 3 examples of facilitated diffusion?
1.   -  
2.   -  
3.   -  

Active transport moves
solutes  a
concentration gradient

What is an example of active transport found in all cells?

What is an example of active transport found in intracellular organelles SERCA?

What is an example of active transport found in Parietal cells (stomach), alpha
intercalated cells collecting duct
(kidney)?

What is an example of active transport found in Golgi and lysosomes, keeps the
inside more acidic , osteoclasts
(bone breakdown)?

What is an example of active transport found in mitochondria?

A   (AKA  ) is involved in the transport of two different molecules across the cell membrane in the same direction (One transporter is  transport and the symporter is  transport )

An  (AKA  ) is involved in the transport of two different molecules across the cell membrane in opposite directions (One transporter is  transport and the antiporter is   transport)

SECONDARY ACTIVE TRANSPORT: A uniport (passive) transporter involves one transporter that is   and another that is a  

Symporters, antiporters, and uniports DO NOT USE ATP. They harnest the energy generated from  .

Examples of an Na+/Glucose symporter can be found in the  .

  = general mechanism by which region of plasma membrane pinched off

  endocytosis (nonspecific uptake of extracellular fluid).  endocytosis (more efficient process where recepted accumulate coated pits)

Continuous secretion “  pathway”

 pathway: molecules are stored inside a cell until a signal stimulates
their release- this pathway is responsible for   release of hormones,
digestive enzymes, etc.

The difference between paracellular and trancellular transport is based on the physiology of the  

In the Gastrointestinal System,
*  side is the side facing the Interstitial fluid
* : facing the tubular fluid/lumen

Transport of Glucose in Epithelial Cells: TQ
An   transporter brings in   and   on the apical side of cell. Sodium potassium pump allows the formation of a gradient that allows amino acids to enter into blood on basolateral side. The same mechanism is used by   to move sodium and glucose in on the apical end, which causes   to be released at   end.

When a cell is referred to as " ", it means that one side has one set of transporters and the other side has a   set of transporters.

Cystic fibrosis: Involves a defect in  

Cytstic Fibrosis: Transport of “ ” is necessary for
maintaining a hydrated mucus layer.
Mucus layer is protective in the
respiratory tract and GI system
In the lungs, defect in the   reduced the
hydration of the mucus layer,
creating a thick layer creating the
 of the disease

Bacteria cause diarrhea by secreting  that bind to receptor apical end. Causes the permanent activation of cAMP, and maximal secretion is stimulated

Epithelial cells maintain equilibrium through   which is unidirectional transport from one side of the cell to
the opposite side of the cell

  is in contact with
external environment or  (membrane type?)

 : faces
extracellular fluid compartment (membrane type?)

 : separates apical &
basolateral membranes

 : link
epithelial cells to the cytoskeleton, also
contains cadherins (adhesion molecules)

  are Mechanical adhesion by linking together the
  of cells

  Mechanical adhesion by linking   of   cells

  Cytoplasmic   to share molecules
between cells, Reduce resistance across
cells, important physiologically in spread of
action potential

 
1) Divides the cell into  and
 domains
2)   transport

 Functional unit of the gap junction

Epithelial cells are capable of  
transport (AKA  ) because of its structure

Tight junctions are also known as “ ". Consists of several  membrane proteins and 

The most important of the epithelial junctions are the   because they serve as barriers

Movement through tight junctions makes the
 pathway depended on the  
pathway

  is an important determinant
in ionic movement, which in turn is regulated based
on the function of the cell

The   is always more positive compared to the   side

  and  both move in a paracellular fashion down electrical gradient with   moving towards basolateral membrane and  moving towards apical membrane.

Capillaries are also lined by endothelial cells with  and  surface. Some capillaries have  .