O Flashcards
Obliquely Striated Muscle
A muscle where striations run obliquely to the axis of shortening.
Odorant
Molecules that can be detected by the sense of smell.
Odorant-Binding Protein
Proteins found in the mucus of the nasal epithelium that bind to odorants and transfer them to odorant receptors.
Odorant Receptor Protein
A G protein–coupled receptor involved in the detection of odorants and thus the sense of smell.
Olfaction
Detection of environmental chemicals from outside the body: the sense of smell.
Olfactory Bulb
A part of the vertebrate forebrain that is involved in processing olfactory sensations.
Oligodendrocyte
A vertebrate glial cell that forms the myelin sheath of a neuron in the central nervous system.
Ommatidium
plural: ommatidia
The functional unit of the arthropod compound eye.
Oncotic Pressure
The osmotic pressure of blood that is due to the concentration of large macromolecules, primarily protein.
Oocyte
One of the intermediate stages in the process of producing an ovum during meiosis.
Oogenesis
The production of an ovum.
Oogonia
singular: oogonium
After the primordial germ cell enters the ovary, it differentiates into an oogonium, which undergoes multiple rounds of mitosis before entering meiosis.
Open Circulatory System
A circulatory system in which the blood passes through one or more unbounded spaces called sinuses.
Operculum
The stiffened flaplike cover of the gills of bony fishes.
Opsin
A family of G proteins that is involved in visual phototransduction.
Opsonins
Proteins that bind to pathogens, enabling them to be better recognized by
immune cells.
Opsonization
The addition of opsonins to pathogens.
Optic Chiasm
Area in the vertebrate brain where the optic nerves cross.
Optic Lobe
Either of the two lobes of the vertebrate midbrain that are involved in visual processing; also, in arthropods the regions of the brain involved in processing signals from the compound eyes.
Organ of Corti
Located in the cochlea of the inner ear; contains the hair cells that are involved in the sense of hearing.
Ornithine-Urea Cycle
A pathway by which urea is produced from nitrogen arising from ammonia or glutamine.
Orphan Receptors
Receptors whose ligand and function is not known; identified based on structural similarity to known receptors.
Orthologs
Genes in different species that are related by direct descent as a result of a speciation event.
Osmoconformer
An animal that exhibits an internal osmolarity that parallels that of the external environment.
Osmolarity (OsM)
Analogous to molarity, it is the concentration of osmolytes in a solution (osmoles per liter).
Osmole
One mole of osmotically active solutes.
Osmolyte
An osmotically active solute; any solute that has a significant effect on osmotic pressure.
Osmoregulator
An animal that exhibits an internal osmolarity that is controlled independently of the osmolarity of the external environment.
Osmosis
The movement of water across a membrane from an area with a high activity of water to an area with low activity of water.
Osmotic Pressure
A force arising due to the tendency of water to move by osmosis.
Osteoblast
A bone precursor cell.
Osteoclast
A type of cell that dissolves and reabsorbs bone.
Ostia
singular: ostium
An anatomical term for a small opening.
Otolith
A small mineralized granule (usually calcium carbonate) in the inner ear of vertebrates. Involved in the sense of balance.
Outer Ear
External portion of the vertebrate ear (consisting of the pinna and auditory canal in mammals).
Outer Hair Cells
One of two types of hair cells found in the organ of Corti in the inner ear of mammals; involved in amplifying sound and protecting the inner hair cells from loud sounds.
Oval
A structure that is used in gas reabsorption from the swim bladder of a fish back into the blood.
Oval Window
Membrane between the middle ear and the inner ear of vertebrates. Vibrates to transmit sound to the inner ear.
Oviparous
An animal that produces eggs that hatch outside the body.
Ovoviviparous
An animal that holds its eggs inside the body until the eggs hatch, and then releases active young.
Ovulation
The release of an ovum following the rupture of a follicle.
Ovum
The larger of the two gametes of a sexually reproducing species. Although an ovum is often defined as the gamete produced by a female, in reality this definition is backward: an individual is a female if it has gonads that can produce an ovum.
Oxidant
A molecule that accepts an electron from another molecule (the reductant). In doing so, the oxidant becomes reduced.
Oxidation
A chemical reaction whereby a molecule donates an electron to another molecule, becoming oxidized.
Oxidative Phosphorylation (OXPHOS)
The process by which mitochondria produce ATP from the oxidation of reducing equivalents (NADH, FADH2). The electron transport chain expels protons from the mitochondria to produce a proton motive force, which is then used by the F_1F_0 ATPase to produce ATP.
Oxyconformer
An animal that exhibits a respiratory rate that declines when oxygen pressure declines.
Oxygen Carrying Capacity
The maximum amount of oxygen that can be carried by blood. Includes both dissolved oxygen and oxygen bound to respiratory pigments.
Oxygen- and Capacity-Limitation of Thermal Tolerance
The hypothesis that an organism’s thermal tolerance is limited by its ability to supply and utilize oxygen at extreme temperatures.
Oxygen Equilibrium Curve
A curve showing the relationship between PO2 and the oxygen saturation of blood containing a respiratory pigment.
Oxyregulator
An animal that exhibits a constant respiratory rate despite a decline in oxygen pressure.
Oxytocin
A peptide hormone produced by the anterior pituitary; induces the contraction of smooth muscle during parturition.
