Receptors › Overview

Cellular Communication

Cellular Communication

Sections

CELLULAR COMMUNICATION

Receptor

Molecule allowing a cell to recognize a message and respond to it

Ligand

Molecule that specifically binds to another molecule

Cell Junctions

  • Local signaling
  • Use gap junctions
  • Signals can bypass cell membrane

Direct Contact

  • Local signaling
  • Requires cell to cell contact
  • Signal molecule bound on cell membrane
  • Signal molecule on one cell binds to receptor molecule on another cell

Paracrine

  • Local signaling
  • Cell releases soluble signal molecules into the extracellular space
  • Signals diffuse from releasing cell and reach target cell

Synaptic

  • Local signaling
  • Allows neurons to pass signals to other cells
  • Use neurotransmitters as signal molecules

Endocrine

  • Long distance signaling
  • Signals travel through blood vessels before reaching target cell
  • Insulin released by pancreas into bloodstream causes cells all over the body to absorb glucose from the bloodstream

Full-Length Text

  • In this tutorial, we will learn about methods cells use to communicate with one another.
  • To begin, start a table to learn some key concepts about cellular communication.
  • Denote that a receptor is a molecule that allows cells to recognize (hear) a message and respond to it.
  • Denote that a ligand is a molecule that specifically binds another molecule, a signal molecule in the case of this tutorial.

Next, let's address some key terminology.

  • Write that when we refer to distance, we mean that cells send and receive signals over both: local (short) and long distance.
    • Long distance signals originate in one part of the body and reach a target cell in another part of the body.
  • Write that the target cell is the cell that receives the signal.

Now we will explore the local and long-distance methods of signaling.

  • Label the first box cell junctions, which is local signaling.
  • Draw two cells in contact, with channels in their shared plasma membrane.
  • Label these gap junctions, which connect the cytoplasm of cells in contact
    • Write that they allow cells to signal directly with one another, bypassing the plasma membrane.
  • Draw two different signal molecules, one in each cell.
  • Indicate that they travel through the gap junctions to the other cell.
  • Write that each cell is the target of the other.
  • Label the next box direct contact, which is also local signaling.
  • Write that, as the name suggests, direct contact signaling requires cell to cell contact.
  • Write that these signaling molecules are bound to cell membranes (unlike the previous example in which the signaling molecules were solutes).
  • Draw two cells slightly separated from one another.
    • On one, draw a signal molecule attached to the cell membrane.
    • On the other, the target cell, draw the receptor binding the signal and attached to the cell membrane.
  • This binding creates a response in the target cell.
  • Label the third box, paracrine, which is also local signaling.
  • Write that cells release soluble signals that diffuse close, within reach of nearby cells.
  • Draw two cells – the secreting cell with a vesicle fused to its membrane and the target cell.
  • Draw the secreting cell releasing soluble signal molecules.
  • Indicate that these signals diffuse away from the secreting cell and reach the target cell.
  • Label the fourth box, synaptic, which is also local signaling.
  • Write that synapses allow neurons to pass signals to other cells; they are the areas of highest cortical activity.
    • Although neuronal signaling can occur over a long-distance (the electrical signal can travel far along the nerve itself), synaptic transmission is local.
  • Draw a neuronal axon coming from the top of the box.
  • For simplicity's sake, draw a neuron without dendrites along the bottom of the box.
  • Indicate with an arrow that the electrical signal travels down the axon of the top neuron.
  • Now draw signaling molecules being released due to the electrical signal.
  • Label them neurotransmitters and indicate with an arrow that they diffuse towards the bottom neuron.
  • Now indicate, with an arrow, that after the target cell receives the signal, it is stimulated.
    • In this case, an electrical signal is produced which travels along the axon.
  • Label the final box, endocrine, which is long distance signaling.
  • In the upper left part of the box, draw an endocrine cell.
  • In the lower right part of the box, draw the target cell.
  • Now draw a small blood vessel next to the endocrine cell.
  • Then, draw another blood vessel next to the target cell.
  • Draw signal molecules being released from the endocrine cell, passing into the blood vessel, and traveling through it until they reach the target cell.
  • As a clinical correlation, denote that insulin is produced in the pancreas and is released into the bloodstream, which causes cells all over the body to absorb glucose from the bloodstream.

This concludes our diagram of cellular communication.

UNIT CITATIONS:

  1. Campbell, N. A. & Reece, J. B. Biology, 7th ed. (Pearson Benjamin Cummings, 2005).
  1. Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K. & Walter, P. Molecular Biology of the Cell, 5th ed. (Garland Science, 2008).
  1. Alberts, B., Bray, D., Hopkin, K., Johnson, A., Lewis, J., Raff, M., Roberts, K. & Walter, P. Essential Cell Biology, 3rd ed. (Garland Science, 2010).
  1. Marieb, E. N. & Hoehn, K. Human Anatomy & Physiology, 10th ed. (Pearson, 2016).
  1. Lodish, H., Berk, A., Kaiser, C. A., Krieger, M., Scott, M. P., Bretscher, A., Ploegh, H. & Matsudaira, P. Molecular Cell Biology, 6th ed. (W. H. Freeman and Company, 2008).