Introduction to Cell Regulation

Question 1

What are the two types of connections between cells (synapses)?

Answer 1

Electrical- Cells are physically connected and there is a pathway through one cell to the next
Examples include endothelial cells, cardiac myocytes and epithelia
Low resistance pathways formed from proteins called connexins
Chemical synapses- Whatever is going on in one cell causes the release of a transmitter, a chemical which then diffuses a short distance and then interacts with a receptor molecule and that causes a chain of events in the other cell

Question 2

What are the different types of chemical signalling?

Answer 2

Paracrine- intracellular signalling
A chemical is released from the cell which diffuses to neighbouring cells and interacts with a receptor
Endocrine- intercellular signalling
Chemicals released from one cell passes through the blood system and interacts with receptors on another cell
Synaptic signalling- intercellular signalling
Chemicals move through synapses

Question 3

What are ion channels?

Answer 3

They are protoneous pores with a no. of key features:
An aqueous pore- connecting internal and external media
A gating mechanism that opens the pore
High transfer rate- movement of many ions leads to recordable current
Selective permeability- preference of one type of ion over another