Question

How can a signaling molecule be interpreted in different ways by cells in the body?

Answer 1

the signalling molecules are interpreted in different ways by the following ways

there are 4 types of cell signalling on the basis of distances

• paracrine signaling
• endocrine signaling
• autocrine signaling
• direct signaling across gap junctions

1. paracrine signaling

• here the signalling molecules from the source cell are transported towards the target cells which are neighbouring cells.
• these signals move by diffusion through the extracellular matrix.
• this type of signals give quick responses and take only short time
• eg;transfer of signals across synapses between nerve cells.

1. endocrine signaling

• here the signalling molecules from the source cell are transported to the target cells which are little distant from the source cells and molecules need to travel here little bit.
• these signals originate from endocrine cells.the endocrine cells are located in endocrine glands.(thyroid gland)
• these types of signals produce slower response compared to paracrine but are not for a short peroid of time
• eg:hormones travelling in blood stream

1. autocrine signalling

• here the target and source cell are the same which means the ligand produced by the source cell bind on the receptors of the source cell.
• this type of signalling occurs during the early development of an organism.to ensure cells develop on respective tissues and take proper functions.
• this regulates pain sensation and inflammatory responses.
• eg:embryo development

1. DIRECT SIGNALLING ACROSS GAP JUNCTIONS-

• GAP JUNCTION IN ANIMALS
• PLASMODESMATA IN PLANTS
• these two are connections between the plasma membrane of neighboring cells.
• here small molecules such as calcium ions(Ca⁺ ) will move between cells, but larger molecules will not fit through it(like DNA,and proteins)