After reading this chapter I was confused about which cells had sodium pumps, which cells had voltage drops across their membrane, and which had voltage gated ligand channels. The giant axon of the squid is used when introducing this topic, and is the cell in which the values in table 11.1 come from. Because a nerve cell was used as the example, I wasn’t sure if the topics discussed are specific to a nerve cell or to cells in general. So I took to the internet.
First of all, all cells have sodium-potassium pumps. This makes sense, as all cells need to osmoregulate. According to Wikipedia, the sodium-potassium pump in a normal cell expends a third of the cell’s energy.
All cells do have a membrane potential, around that of the resting potential of a neuron. It is used to power some of the molecular devices in the membrane. However, not all cells can use it for signalling like neurons.
Voltage-gated ion channels are necessary in neurons, but again, according to Wikipedia, can be found in many kinds of cell. I had trouble finding examples other than muscle and neuronal cells, but I found one example. The Transient Receptor Potential Channels are voltage triggered. An example of a protein in this family is the capsaicin receptor, which responds to the chemicals which make chilli taste hot. Voltage gated ion channel are not found in every cell.
So everything that I found out here is pretty much what I expected. But I am glad I found out for sure, and I hope this helps confirm things for you too.
P.S. I can’t remember if I was taught this last year in BIPH2000, but in case I wasn’t, I thought I’d share: The research done on squid giant axons was not performed on the axons of a giant squid, but the giant axon of a regular sized squid. You probably already know this, but I didn’t realise this until it was pointed out to me.