📌 Check out these other AP Biology resources

  • Fiveable+ AP Biology Live Streams (Coming August 2019! 🎉)

Cells communicate with each other and the environment. Especially for multi cellular organisms that contain trillion of cells, the cells must communicate in order to survive. 

Cells communicate primarily in 2 different ways 

  • Direct Contact 
  • Paracrine Signaling

🤝Direct Contact 🤝

There are 2 main examples of direct contact. One is gap junctions in animal cells and one is plasmodesmata in plant cells.

In animal cells, gap junctions directly connect 2 the cytoplasm of 2 adjacent cells. Through the connection materials such as ions and molecules can pass.

👀As you can see in this example, the ions and small molecules can pass through the adjacent cells with the gap junctions. 

For plant cells, the plasmodesmata connect 2 adjacent plant cells to each other. They are the same as gap junctions just in plants.

👀In this example, you can see that the 2 plant cells are connected through the plasmodesmata. This creates a pathway through the cytoplasm that allows transportation of materials between the cells. 

🙌 Paracrine Signaling🙌 

Paracrine signaling is a the release of local signals from one cell to nearby cells. An example of signals that can be released are growth factors. Paracrine signaling is especially important during development. 

In the picture you can see how the secreting cell releases signals that diffuse to the target cells. 

Another example of paracrine signaling is synaptic signaling. Synaptic signaling is how nerve cells communicate. It involves a synapse, which is a connection between nerve cells where the signal travels. As the neuron fires, the signal travels down a fiber-like structure called an axon. When the signal reaches the synapse, it triggers the neurotransmitters. These neurotransmitters cross the gap between the nerve cells to bind with the receptors on the other nerve cell. 

As you can see in the picture, it shows how the signal is transmitted from one nerve cell to the other through synaptic signaling. 

If you have any questions, chat with one of our Fiveable helpers here!!

📌Additional resources on cell communication:

❗️❗️ IMPORTANT: You do not need to know about long distance endocrine signaling because it is not on the AP Biology exam anymore. 

Did this answer your question?