DLA #2: Membrane and Gas Transport (Note Cards + Sheet on CFTR SECRETION AND ABSORPTION) Flashcards
In general terms, a partition coefficient tell us:
The degree of ease with which a substance wants to cross a membrane (diffuse)
In mathematical terms, the partition coefficient is expressed as:
[Substance in oil] / [Substance in water]
If their is a pc = 1, we say that
The substance equally exists as a solute in water and oil
If pc > 1
The substance is “lipophillic”
AKA Substance prefers to be in the oil/lipid phase and will readily cross the membrane.
If pc < 1
- The substance is unable to enter the oil/lipid phase.
- The substance is unable to pass through the cell membrane.
The partition coefficient of O2 and CO2 is generally
- HIGH (greater than 1)
- Gasses can readily diffuse through the pm
The partition coefficient of sugars and electrolytes are generally
- Low (less than 1)
- They are polar and therefore cannot readily pass the pm
Flux is defined as
The rate of diffusion or flow of substances b/w two compartments
What is the relationship b/w pc and delta G (concentration gradient)
What is Fick’s First Law of Diffusion and write out the equation
- Fick’s First Law is an equation that explains the Flux between to compartment and the paramters governing that behavior.
- J => Flux
- P => Permeability Coefficient
- Dc => Diffusion Coefficient
- Pc => Partition Coefficient
- A => Area
- x => Distance the flux needs to take place (spans the membrane)
- Delta C => Concentration Gradient
Permeability Coefficient is defined as
The degree to which a substance can pass through the membrane.
On a scale b/w 0 to 1
0 => no permeability through pm
1 => complete permeability through pm
Reflection Coefficient is defined as:
How easily a substance can cross the membrane based on its reflection.
- If the substance is reflected, its RC is 1
- If the substance is not reflected, its RC is 0
Lumen is basically
The inside space of an organ
Lumen of organ and the blood are divided by
Epithelial cells
The apical membrane is in contact w/
The luminal space
The basolateral membrane is in contact w/
Interstitium and blood
Transporters and pumps on the apical and basolateral membrane are important on epthelial cell b/c they give rise to differences in
Polarity
Transport across the cells that line the hollow organs or tubes is called
Epithelial Transport
The Sodium-Atpase Pump is always found at the
Basolateral Membrane
Epithelial cells allow for solutes/fluid to be _______ and ______ in the body
Absorbed and Secreted.
Absorption is when solutes/fluid move from the :
LUMEN => BLOOD
Secretion is when solutes/fluid move from the:
BLOOD => LUMEN
Tight junctions b/w epithelial cells are important because they allow for the flow of
Water, solutes, ions (ex Na+, Cl-)
