the immature free-living form of most invertebrates and amphibians and fish which at hatching from the egg is fundamentally unlike its parent and must metamorphose
a major part of the central nervous system which conducts sensory and motor nerve impulses to and from the brain; a long tubelike structure extending from the base of the brain through the vertebral canal to the upper lumbar region
the junction between two neurons (axon-to-dendrite) or between a neuron and a muscle; "nerve impulses cross a synapse through the action of neurotransmitters"
(biology) the field of science concerned with processes of communication and control (especially the comparison of these processes in biological and artificial systems)
colorless watery fluid of blood and lymph containing no cells and in which erythrocytes and leukocytes and platelets are suspended
(physical chemistry) a fourth state of matter distinct from solid or liquid or gas and present in stars and fusion reactors; a gas becomes a plasma when it is heated until the atoms lose all their electrons, leaving a highly electrified collection of nuclei and free electrons; "particles in space exist in the form of a plasma"
a green slightly translucent variety of chalcedony used as a gemstone
any of a large group of nitrogenous organic compounds that are essential constituents of living cells; consist of polymers of amino acids; essential in the diet of animals for growth and for repair of tissues; can be obtained from meat and eggs and milk and legumes; "a diet high in protein"
a part of the cell containing DNA and RNA and responsible for growth and reproduction
any histologically identifiable mass of neural cell bodies in the brain or spinal cord
the positively charged dense center of an atom
(astronomy) the center of the head of a comet; consists of small solid particles of ice and frozen gas that vaporizes on approaching the sun to form the coma and tail