Brief Cell Communication:

- one way cells communicate with each other is through direct contact

- microphage: a white blood cell that is part of your immune system 

- microphages ingest foreign invaders like bacteria or viruses 

   - once ingested, they then break it down and display an antigen of the invader on the surface of the cell 

   -this antigen is the message that is passed on and maybe a helper T-cell comes and takes the antigen which is how the cells communicated

       -the T-cell then decides if it produces an immune response

           -can encourage B cells to attack or they may do nothing 

- cells communicate over short distances ( paracrine communication) 

   - when a message travels from the end of a neuron, and the message diffuses over the synaptic cleft, where it then binds to another dendrite of a neuron

- neural communication 

   - long distance cell communication (endocrine signaling ) 

   - ligands: signaling molecules, molecules that bind specifically to other molecules 

       -the pathway goes from the ligand attaching itself to the receptor, where the message gets sent to the chemical messengers that relay the signal and then lastly there is a response.

- PARACRINE SIGNALING 

   - when cells communicate over fairly short distances 

   - paracrine signaling allows cells to locally communicate 

   - paracrine signals are especially important for development

- SYNAPTIC SIGNALING

   -when nerve cells transmit signals 

   - synapse: the junction between two nerve cells where signal transmission occurs 

- AUTOCRINE SIGNALING

   - a cell signals itself and a ligand binds to receptors on its own surface 

   - autocrine signaling is important during development,  helping cells take on and reinforce their correct identities 

   -important in signaling cancer and plays a key role in metastasis.