Biology- Topic 8 (Exam 2)

Ligand:

Sends message

What does the signaling cell do?

Releases message

What does target cell do?

Receives message

What are the four common signaling pathways? 

Direct, Paracrine, Endocrine, and Synaptic

Describe structure and function of direct contact (provide example): 

Molecules on the surface of one cell are recognized by receptors on the adjacent cell, without “release” from cell. 

Allows neighbor cells to work as a single unit during response. 

Ex: Gap junctions in cardiac muscle 

Describe structure and function of Paracrine Signaling:

Signal released from a cell affects neighboring cells, less than 20 cells away. 

Coordinates responses among neighboring cells, cells, don’t need to be the same type. 

Ex: Norepinephrine, epinephrine, acetylcholine. 

Describe structure and function of Endocrine signaling:

Hormones released from a cell travel through circulatory system to affect other cells through the body. Greater than 20 cells away. 

Coordinate responses among tissues far away. 

Ex: Insulin and testosterone.

Describe structure and function of Synaptic Signaling:

It is a special type of paracrine signaling where nerve cells release the signal with binds to receptors on nearby cells.

Rapid, short-lived response triggered in target cell.

Ex: Norepinephrine, epinephrine, and acetylcholine. 

Intracellular receptor: 

Located within the cell, more likely to bind with a steroid.

Cell surface receptor/ membrane receptor:

Located on the plasma membrane to bind a ligand outside the cell.

Kinase:

Enzyme that adds phosphate group.

What does a secondary messenger do?

Responds to signal inside cell.