Ion Flux Flashcards
Which molecules can travel by way of simple diffusion?
Small nonpolar and and uncharged polar
Facilitated diffusion is needed by who?
large and in charge need proteins to function as transporters
water, Na, Cl, K , gluc
What is the structure of a channel?
polar tube to allow latge charged molecules through
How do transporters work?
bind to molecule on one side change conformation and spit them out on the other side
Cystinuria is what?
Think CALO
autosomal recessive disease which causes a defect in the channels responsible for transporting cystine arginine, lysine, and ornathine
What pathology happens in Cystinuria?
too much CALO so cystine crystals form in the kidney tubules and become stones patients present with renal colic
Hartnup disease
autosomal recessive disorder where transporters for nonpolar or neutral amino acids like trp is defective (found primarily in kidney and intestines
S/S of Hartnup disease
Failure to thrive, nystagimus, tremors, ataxia because aa balance is off
2 kinds of gated ion channels
Ligand and voltage gated ion channels
What is primary active transport?
protein assisted movement of something across a membrane up its concentration gradient using ATP hydrolysis
2 Examples of primary active transport
Na/K (3NA our and 2 K in) atpase pump and Ca++ atpase punp
2 inhibitors of Na/K atpase pump
Ouabain and digoxin, in people having a cardiac episode these drugs are given to inhibit the pump and increase intracellular Ca++ to increase contracton
What is secondary active transport?
NO ATP is used here. It’s just coupling energy of moving something down a graadient with moving something else up a gradient
2 examples of secondary active transport
Na/Glucose transporter
Na linked Ca++ antiporter (linked with Na/Ca++ exchanger)
Where is the sodium glucose transporter?
SGLT1 is present in epithelial cells that line the small intestine and renal tubule
What does SGLT1 do?
mediated the unidirectional movement of Na and glucose across the membrane, Na goes down its gradient and gluc goes up
What other transporter allows the SGLT system to work?
Na/K atpase pump which resets the sodium balance by pumping Na back out into the intestinal lumen
What is the NA/Ca++ exchanger (NCX)
its an antiporter that functions to maintain low levels of intracellular Ca++ (3Na in and 1 Ca++ out) maintained by Na/K pump
how are monosaccharies (from polysaccharides from food) carried across the enterocyte lumen of the intestines?
facilitated diffusion and active transport
