O

oligosaccharides
A small chain of carbohydrate monomers.
omasum
One of the ruminant forestomachs.
omentum
Sections of peritoneum that extend from the stomach to other abdominal organs and to the abdominal wall.
omnivore
An animal that eats both plants and other animals. Examples include humans, pigs and chickens.
ontogeny
Developmental biology. The ontogeny of the brain refers to the events and processes by which the brain develops to attain its mature form and function.
orexigenic
Capable of stimulating or increasing appetite.
osmolarity
A measure of solute concentration in aqueous solution. A 1 M solution of a single non-dissociating solute has an osmolarity of 1 osmol. A physiologic osmolarity is about 300 mOs, roughly equivalent to 150 mM NaCl (NaCl dissociates into Na+ and Cl-, both of which contibute to osmolarity).
osmosis and osmotic pressure
Osmosis is the movement of water across a selectively permiable membrane (a membrane through which water but not solutes can flow) caused by a difference in concentration of water on the two sides of the membrane. Water flows into the compartment having higher concentration of solute and in the process generates "osmotic pressure".
osteostatin
A peptide hormone derived from parathyroid hormone-related protein.
ovine
Pertaining to sheep.
oxidation
Loss of electrons (or electron density) from an atom, most commonly due to addition of oxygen or removal of hydrogen from a molecule. The opposite of reduction.
oxyntomodulin
A peptide generated in the small intestine from proglucagon; probably not of physiological significance.
oxytocin
A peptide hormone secreted from the posterior pituitary that plays an important role in birth, lactation and maternal behavior.

Last updated on 1/17/2005