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Caffeine ingestion Why caffeine ingestion leads to heightened alertness and sleeplessness? Networks of communication between cells can be even more complicated than the World Wide Web. In humans, caffeine acts as a central nervous system stimulant, temporarily warding off drowsiness and restoring alertness. It is the world's most widely consumed psychoactive drug. The result of caffeine ingestion is increased release of norepinephrine (noradrenaline) from sympathetic nerves, elevated adrenaline release from the adrenal medulla and higher dopamine signaling in the basal ganglia. All in all, your body ends up more alert and primed for action. All this process is nothing but cell to cell communication. What does a “talking” cell say to a “listening” cell? Let's try to resolve these questions by studying this topic.

Learning Objectives

After completing the topic, the student will be able to:

  • Predict what happens if cells does not communicate with each other and appreciate the importance of this phenomenon.
  • Discuss and illustrate how cell communication acts as a cellular internet in our body.
  • Define cell signaling and understand the molecular events of this phenomenon.
  • Analyze how external signals are converted into responses within the cell.
  • List the different types of cell signaling mechanisms.
  • Define and distinguish local and long distance cell signaling.
  • Define and co–relate the terms paracrine, synaptic and endocrine signaling.
  • Explore and illustrate the molecular details involved in the three stages of cell signaling.
  • Define signal transduction pathway and understand the basic principles behind this phenomenon.
Communication in day-to-day life Communication in day-to-day life Cell communication, like our day-to-day communication, is possible with sending and receiving signals.
Introduction

Communication plays a key role in every one's life in the form of mobile phones, internet, e-mails etc., and no one would deny the importance of communication in day-to-day life. The role of communication at cellular level is equally critical as it is absolutely an essential part in multicellular organisms (humans).

It is known that trillions of cells together communicate each other to coordinate their activities. There are many examples of cell to cell signaling in our human body. For example; the ability of cells to perceive and correctly respond to their microenvironment is the basis of development, tissue repair, and immunity as well as normal tissue homeostasis. Errors in cellular information processing are responsible for diseases such as cancer, autoimmunity, and diabetes.

The interactions between organisms may range from cooperative to antagonistic, which is true for single-celled organisms as well as individual cells that make up multicellular organisms. This cooperation among individuals cell is more likely due to the genetic similarity of the cells.

Molecular model of Serotonin Molecular model of Serotonin Serotonin molecule is a nerve signaling chemical (serotonin: 5-hydroxytryptamine). Serotonin is an important brain signaling molecule and lack of it results in depression and other mood disorders.
Types of cell communication

Most cell-to-cell communication involves a kind of chemical signaling, that includes

  • Chemicals that allow easy diffusion between cells,
  • Chemicals that are received by a cell through cell-to-cell contact, and
  • Chemicals that freely diffuse from one cell's cytoplasm to another's via junctions that directly link the cytoplasm of adjacent cells.

A local regulator is a chemical signal that influences only the neighboring cells whereas hormones are chemical signals that diffuse systemically (diffusion through and are carried by blood and lymph as well as the intercellular space/extracellular matrix) and influence the long distance cells.