{basal nucleus}{}{Nucleus at the base of the cerebrum involved in controlling motor functions.}
{base}{}{Molecule that is a proton acceptor; any substance that binds to hydrogen ions.}
{basement membrane}{}{Specialized extracellular material located at the base of epithelial cells and separating them from the underlying connective tissues.}
{bile}{}{Fluid secreted by liver and stored in gallbladder.}
{binding site}{}{Site on a hormone receptor where the hormone binds.}
{bipolar neuron}{}{One of the three categories of neurons consisting of a neuron with two processesùone dendrite and one axonùarising from opposite poles of the cell body.}
{blastocoel}{}{The space formed in the center of a mass of dividing cells in an embryo at the blastula stage.}
{blastopore}{}{The opening into the archenteron in a gastrula.}
{blastula}{}{Embryonic stage characterized by a hollow ball shape.}
{blood}{}{The primary transport medium of the body for oxygen and carbon dioxide, as well as nutrients, water, ions, and waste products of metabolism.}
{bolus}{}{A mass of food or liquid introduced into the digestive system; can also be a mass of liquid introduced into the circulatory system through a needle.}
{bone}{}{Connective tissue with a protein fiber and ground substance matrix. Bone protects and supports other body structures.}
{brain}{}{The central processing organ of the nervous system. The brain is typically divided into three portions: the cerebrum, the cerebellum, and the brain stem.}
{brain stem}{}{Portion of the brain that includes midbrain, pons, and medulla oblongata.}
{Broca's area}{}{Region of frontal lobe that coordinates complex muscular actions of mouth, tongue, and larynx, making speech possible.}
{bronchial tree}{}{Bronchi and their branches that carry air from trachea to alveoli of lungs.}
{bronchiole}{}{Small branch of a bronchus within lung.}
{bronchus [bronchi]}{}{Branch of trachea that leads to lung.}
{buffer}{}{Mixture of an acid and base that reduces any changes in pH that would otherwise occur in a solution when acid or base is added to the solution.}
{bulbourethral gland}{}{Glands that secrete viscous fluid into male urethra during sexual excitement; Cowper's glands.}
{bursa [bursae]}{}{Closed sac or pocket containing synovial fluid, usually found in areas where friction occurs.}