2. Permeability Barriers & ATP Pumps/Ion Gates Flashcards
In a normal cell what is the extracellular concentration of Na+?
145mM
In a normal cell what is the intracellular concentration of Na+?
12mM
In a normal cell what is the intracellular concentration of K+?
155mM
In a normal cell what is the extracellular concentration of K+?
4mM
In a normal cell what is the intracellular concentration of Cl-?
4.2mM
In a normal cell what is the extracellular concentration of Cl-?
123mM
In a normal cell what is the distribution of Ca2+ intracellularly and extracellularly?
Intracellular 100nM
Extracellular 1.5mM
In the small intestine, name a protein that allows the entry of glucose and explain how it works?
Na+glucose co transporter, the energy from sodium moving in is used to allow the uptake of glucose also.
Name a protein that involves Ca2+ and Na+ movement?
Na+Ca2+ exchanger. Inward flow of 3 Na+ drives outward flow of 1 Ca2+. (This is electrogenic)
Name a protein that leads to internal alkalinisation of the cell.
Na+H+ exchange, inward flow of Na+, outward flow of H+
How many subunits make up the Na+K+ATPase and what are their functions?
2, alpha unit is phosphorylated and allows the movement of the ions, beta directs the protein into the membrane
Name four proteins that control resting Ca2+ concentration.
PMCA - Plasma Membrane Calcium ATPase
SERCA - Sarco Endoplasmic Reticulum Calcium ATPase
NCX - Na+Ca2+exchanger
Ca2+ uniports - in mitochondria, remove H+ take in Ca2+
Explain the significance that the NCX protein is membrane potential dependant?
When polarised (negative inside) the protein removes a calcium ion for every 3 sodium ions that enter When depolarised (positive inside) the protein reverses and removes 3 sodium ions for every calcium ion that enters
In ischaemia why does the membrane become more permeable to calcium ions?
No oxygen therefore ATP depleted, the Na+K+ATPase therefore doesn’t transport any Na+ out of the cell, the NCX then reverses, removing Na+ but causing an influx of Ca2+
How would a decrease in intracellular pH be corrected?
Increase activity of NHE
How would an increase in intracellular pH be corrected?
Increased activity of AE, anion exchange, (Cl- in, HCO3- out)
How does a cell resist swelling?
Removes ions (K+/Na+/Cl-), water follows
How does a cell resist shrinking?
Ions taken in, water follows
How much of bicarbonate does the kidney reabsorb and what does it use it for?
Under normal circumstances, all of it, it is retained for use in pH buffers.
Name the part of the kidney that loop diuretics work on?
Thick ascending limb
What part of the kidney do Thiazides work at?
Distal convoluted tubule
What part of the kidney does ADH work at?
Cortical collecting duct
What part of the kidney does amiloride work at?
Distal convoluted tubule
What part of the kidney does aldosterone work at?
Cortical collecting duct
