Cell to Cell Communication
Cells in multicellular organisms coordinate their activity by communicating with each other.
Analogy of Verbal Communication
In verbal communication, we speak. This means we release words out of our mouths. These words then travel through the air and reach the listener. The listener listens with the ears. Then he/she processes the words and gives a response.
Cells communicate in a similar fashion. To speak, they release chemical messengers. The messengers travel through the blood, and then, other cells listen with help of receptors.
Thus chemical messengers are like spoken words, and the receptors are like ears. The distance of traveling determines the type of communication.
Intracellular signaling is equivalent to the processing of the words by the listener after listening to them.
Also called signal molecules.
Can be of different types as follow:
Peptides or proteins
Other small molecules
Ions like calcium
Gases like nitric oxide.
Type of Communication
Is based on how far the target cells are.
Target cells are far away.
Messenger is released into the blood
Travel along with the blood
Reach the target cell which is far away
Stimulate the receptor
β cells of the pancreas
Travels in the blood
Reaches adipose tissue
Stimulates insulin receptor
Increases glucose uptake
Such messengers are also called hormones.
Target cells are nearby in the same tissue.
One type of cell releases a chemical messenger
Targets a different type of cell in the same tissue.
Enterochromaffin-like cells in the stomach
Acts on parietal cells
Increase acid secretion.
acts on post synaptic neuron
Target cells are of the same type as those released the messenger.
A cell releases messenger
targets the same cell or other cells of the same type.
Some cancer cells
Release growth factors
Stimulate the same cell or other cells of the same type
Stimulate the growth of cancer cells.
Communication by direct physical contact.
Gap junctions between smooth muscle cells
Allow the passage of small ions like sodium and calcium
makes the cells electrically connected
For hydrophilic messengers that cannot cross the lipid bilayer e.g. peptide hormones.
Receptors inside the cell
For hydrophobic messengers that can cross the lipid bilayer e.g. steroid hormones.
Can be located in the cytoplasm or nucleus.