Neuroscience-Chapter 7 Flashcards
What is paracrine signaling?
A form of chemical communication that acts over a longer range than synaptic transmission and involves the secretion of chemical signals onto a group of nearby target cells.
What is endocrine signaling?
The secretion of hormones into the bloodstream, where they can affect targets throughout the body.
What three components does chemical signalling require?
A signal, receptor, and target.
What is an advantage of chemical signalling?
Signal amplification
Why does signal amplification occur?
Because individual signalling reactions can generate a much larger number of molecular products than the number of molecules that initiate the reaction.
What is an advantage of signal transduction?
Some molecular interactions allow information to be transferred rapidly while other are slower and longer-lasting.
What are the three classes of signaling molecules?
Cell-impermeant, cell-permeant, and cell-associated signalling molecules
What are cell-impermeant molecules?
Molecules that bind to the outside of the cell membrane and are quickly metabolized. Examples: neurotrophic factors, glucagon, insulin, and various reproductive hormones.
What are cell-permeant molecules?
Molecules that cross the plasma membrane to act directly on receptors that are inside the cell. Relatively insoluble in aqueous solutions and may persist in the bloodstream for several hours or days. Examples: steroids, thyroid hormones.
What are cell-associated signalling molecules?
Molecules arrayed on the extracellular surface of the plasma membrane and can only act on other cells that are physically in contact with the cells that carries such signals.
What does binding of the signal molecule to the receptor cause?
A conformation change in the receptor, which then triggers the subsequent signaling cascade within the affected cell.
What are the receptors for impermeant signal molecules?
Membrane spanning proteins. Extracellular domain includes binding site of signal, while the intracellular domain activates intracellular signaling cascades after the signal binds.
What are channel-linked receptors? (Ligand-gated ion channels)
Receptor and transducing functions as part of the same protein molecule. Interaction between the chemical signal and the binding site causes the opening or closing of an ion channel pore in another part of the same molecules. The resulting ion flux changes the membrane potential in the target cell and can lead to the entry of Ca2+ ions that serve as a second messenger signal within the cell.
What are enzyme-linked receptors?
Receptors that have extracellular binding sites for chemical signals and an intracellular domain that is an enzyme whose catalytic activity is regulated by the binding of an extracellular signal. Great majority of these receptors are protein kinases that phosphorylate intracellular target proteins, thereby changing the physiological function of the target cells.
What are G-protein-coupled receptors?
Receptors that regulate the intracellular reactions by an indirect mechanism involving an intermediate transducing molecule, called the GTP-binding proteins (or G-proteins). Cross the plasma membrane seven times.
