cell physiology 2: ion transport, ion signalling Flashcards
What are excitable cells?
- cells that can propagate an action potential
Give examples of excitable cells
- neurons
- muscle cells (myocytes)
What is an action potential?
a specific kind of amplified voltage response
What are non-excitable cells?
cells without action potential
Give examples of non-excitable cells
- anything not muscle or nerve, like skin
- especially epithelial cells (e.g gastric)
How do excitable cells move ions?
- move tiny amounts to make signals
- long term, they maintain a consistent gradient of ions
How do epithelial cells move ions?
they move a lot of them as thats their purpose
What is free calcium?
calcium ions that are ionised and in solution, that are free to activate enzymes
What other forms can calcium take other than free?
- in bone it is part of an insoluble solid that won’t react with enzymes
- bound to proteins
- sequestered
How can free calcium activate enzymes?
- increase amount of free calcium, enzymes are activated
What are the 3 rules of ionic balance?
- conc of +ve and -ve ions must nearly balance
- if ion leaves it must soon be replaced by same type of ion
- energy is used to re-establish ionic gradients across membranes
Which organs correct changes in blood pH?
kidneys and lungs
What is carbonic anhydrase?
- enzyme that catalyses co2 + water to carbonic acid
- carbonic acid dissociates into hydrogen and hydrogen carbonate
How is carbonic anhydrase used in the lungs?
eliminating CO2 source from blood
How is carbonic anhydrase used in RBC?
‘chloride shift’ for removing H+ from muscle
