10. Transport II ppt Flashcards
(23 cards)
What is the driving force of filtration via a semi-permeable membrane?
Hydrostatic pressure gradient between two areas of the membrane.
What substances are penetrated through the membrane pores during filtration?
Water and dissolved small sized substances.
List the four forces that act on capillary walls.
- Blood hydrostatic pressure
- Blood oncotic (colloid-osmotic) pressure
- Interstitial fluid hydrostatic pressure
- Interstitial fluid osmotic pressure
What occurs at the arterial end of capillaries?
Filtration occurs because blood hydrostatic pressure is greater than blood oncotic pressure.
What occurs at the venous end of capillaries?
Reabsorption occurs because blood oncotic pressure is higher than blood hydrostatic pressure.
What happens at mid capillaries regarding fluid movement?
No net movement of fluid occurs due to equal blood hydrostatic and oncotic pressures.
What is the Starling Equation related to?
It relates to the permeability coefficient and reflection coefficient in fluid movement.
What is a physiological process of filtration?
Urine formation in kidney tubules.
What is a pathological process of filtration?
Swelling formation in legs.
What effect does heart failure have on hydrostatic pressure in the kidney glomerulus?
It decreases hydrostatic pressure, leading to ineffective filtration.
What happens when proteins are removed from blood?
Blood oncotic pressure decreases, leading to intensified filtration and swelling.
What is facilitated diffusion?
A transport mechanism that requires carrier proteins.
What is the mechanism of facilitated diffusion?
Molecule + CARRIER PROTEIN, conformational change, molecule detaches.
What types of translocases are there?
- Fixed - Channels
- Mobile - Carriers
What is the saturation phenomenon in facilitated diffusion?
Transport proteins can be saturated if the concentration of molecules is high.
True or False: Facilitated diffusion requires energy.
False.
What is the relationship between facilitated diffusion speed and concentration?
Facilitated diffusion speed is higher than simple diffusion speed but plateaus.
What does chemical affinity refer to?
The tendency of an atom or compound to combine with others in a chemical reaction.
What is K_m in the context of enzymatic reactions?
The Michaelis-Menten constant showing substrate concentration at half maximal velocity.
What characterizes channels in terms of selectivity?
Channels are selective, e.g., sodium channels only carry sodium ions.
What are the two types of ionic channels?
- Voltage-gated
- Ligand-gated
Where are potassium channels found?
In excitable and non-excitable cells.
Where are sodium channels found?
In excitable cells like nerve and muscle cells; they are voltage-gated only.
