Blood-brain barrier
A specialized capillary arrangement in the brain that restricts the passage of most
substances into the brain, thereby preventing dramatic fluctuations in the brain's
environment.
Blood pressure
The hydrostatic force that blood exerts against the wall of a vessel.
Blood vascular system
When blood vessels connect to form a region of diffuse vascular supply it is
called an anastomosis
Biology
The scientific study of life and of living organisms. Botany, zoology, and ecology are all
branches of biology.
Bond energy
The quantity of energy that must be absorbed to break a particular kind of chemical bond;
equal to the quantity of energy the bond releases when it forms.
Bond strength
The strength with which a chemical bond holds two atoms together; conventionally
measured in terms of the amount of energy, in kilocalories per mole, required to break the
bond.
Bony
Having a internal skeleton of bones.
Book lungs
Organs of gas exchange in spiders, consisting of stacked plates contained in an internal
chamber.
Botany
The study of plants.
Bottleneck effect
Genetic drift resulting from the reduction of a population, typically by a natural disaster,
such that the surviving population is no longer genetically representative of the original
population.
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