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Renin Angiotensin Mechanism.

Cell Signaling

 Cellular level of organization:  Cell Signaling.

Introduction:

  • Cells need to interact with their environment and other cells around them. This is called Cell Signaling. 

    • Single cellular organisms need to detect nutrients in their environment, and cells in multicellular organisms are involved in a complex system of communication with each other.

  • Cells detect signals with Cell Receptors on their plasma membrane, which are usually Glycoproteins or Glycolipids. 

    • The signaling molecule binds to the Receptor because its shape is complementary to it (Lock and Key).

    • This then initiates a chain of reaction within the cell, leading to a response.

Cell Signalling Pathways: 

  • Cell Signalling Pathways can be classified on the basis of distance over which the signalling occurs.

    • Endocrine Signalling.

    • Paracrine Signalling.

    • Autocrine Signalling.

  1. Endocrine Signalling :

    • It involves signalling over large distances.

    • Usually where the signalling molecule is transported in the circulatory system.

    • Hormones are often used as cell signalling molecules in multicellular organisms. 

    • Hormones are produced in special glands called “Endocrine Glands”. 

    • The released hormones bind to receptor sites on a Target Cell, which starts a response.

    • e.g. Use of Insulin to lower blood glucose levels. In response to high glucose levels, Beta-Cells in the pancreas release the hormone Insulin into the blood which causes lowering of elevated blood glucose levels.

2) Paracrine Signalling: 

  • It occurs between cells which are close together, sometimes directly, sometimes via extracellular fluid.

  • Often, cells that are near one another communicate through the release of chemical messengers (ligands that can diffuse through the space between the cells).

3) Autocrine Signaling:

  • Autos meaning self.

  • It is where the cell stimulates a response within itself by releasing signals for its own Receptors.

  • In many cases, a signal may have both autocrine and paracrine effects.

Commonly Asked Questions.

  1. What are different forms of cell signaling?

  2. What is Endocrine signaling? How it works.

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