from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A path.
- n. Physiology A course usually followed by a body part or process.
- n. Physiology A chain of nerve fibers along which impulses normally travel.
- n. Physiology A sequence of enzymatic or other reactions by which one biological material is converted to another.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A footpath or other path or track
- n. A sequence of biochemical compounds, and the reactions linking them, that describe a process in metabolism or catabolism
from the GNU version of the Collaborative International Dictionary of English
- n. A footpath; a beaten track; any path or course. Also used figuratively.
from The Century Dictionary and Cyclopedia
- n. A path; usually, a narrow way to be passed on foot; also, a way or a course of life.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a trodden path
- n. a bundle of myelinated nerve fibers following a path through the brain
Sorry, no etymologies found.
And even more than the qualifiers it already gives, the page reminds us that "The carbohydrate - tryptophan - serotonin pathway is simply a hypothesis at this point."
Your use of the term pathway is much too generous.
Obama says people who are here illegally should be given what he calls pathway to legalization.
How you design a mutant hunt, isolate additional mutations in a known gene, define a null phenotype, and order genes into a pathway is the same, whatever the problem being addressed.
Yes, but that doesn't salvage your suggestion that a posited evolutionary pathway is a notion that works best when one doesn't think about it too closely.
If experiments conducted in the here and now are to shed light on the there and then, they must meet two conditions: They must demonstrate in the first place the existence of a detailed chemical pathway between RNA precursors and a form of self-replicating RNA; and they must provide in the second place a demonstration that the spontaneous appearance of this pathway is plausible under pre-biotic conditions.
You obviously mean "No". but that doesn't salvage your suggestion that a posited evolutionary pathway is a notion that works best when one doesn't think about it too closely.
As for a pathway from a simple notochord to a human brain, you need only study the developing human embryo.
Second, there is a narrowing of the pathway from the right ventricle to the pulmonary artery, or what we call pulmonary stenosis.
One pathway is a mid-line pathway, very akin to what is called a default mode, that seems to be functioning when nothing else is supposed to be happening -- like being or mind wandering, or something like that, which is what they call the narrative network for self.