Lec 4- Intercellular Comm and Membrane Potentials Flashcards
Direct cell-cell interactions
Direct link up via surface markers = cell signaling via proteins.
Gap junctions - ephaptic
Cells linked together by connexons which allow the passage of ions and small molecules.
Create coordinated contractions.
Autocrine
Do not travel through the bloodstream.
Move through interstitial fluid.
Paracrine
Do not travel through the bloodstream.
Move through interstitial fluid.
Ex: Neuron and its target cell.
Endocrine
Performed by hormones which travels through the bloodstream.
Hormones
Long range chemical messengers specifically secreted into the blood by endocrine glands in response to an appropriate signal.
Ligand Specificity
Which ligands are bound.
This is similar to the specificity of an enzyme for its substrate.
Due to the receptor.
Effector Specificity
The response to ligand binding.
Due to the molecules in the cell that interact with the receptor that produce the signal inside the cell.
Second Messengers
Ca++, cAMP, cGMP, DAG, IP3
Allows the cell the amplify the message within the cell, so that a cell can respond to a small amount of first messengers binding to the outside.
Found inside the cell.
Membrane potential
The separation of opposite charges across the membrane or to a difference in the relative number of cations and anions in the ICF and ECF.
Potential energy
the energy possessed by a body by virtue of its position relative to others, stresses within itself, electric charge, and other factors.
Kinetic energy
energy which a body possesses by virtue of being in motion.
Semi-permeable membrane
Membrane that allows some substance to cross but won’t allow others to cross.
Electro-chemical gradient
Both an electrical and a concentration (chemical) gradient may be acting on a particular ion at the same time. The net effect of simultaneous electrical and concentration gradients on this ion.
Fixed anions
The cytoplasm of the cell contains negatively charged organic ions (anions) that cannot leave the cell.
