A polypeptide hormone secreted by the thyroid; it causes the deposition of calcium and phosphate in bones and thus lowers their concentrations in the blood.

A firm, elastic, translucent connective tissue produced by cells called chondrocytes.

The chemical breakdown of complex substances (macromolecules) to yield simpler substances and energy.

A substance that speeds up a chemical reaction by lowering the activation energy without being altered or consumed during the reaction.

A cavity open at one end, such as the blind pouch (diverticulum) at the junction of the small and large intestines.

The brain and spinal cord.

A small organelle in the cytoplasm of animal cells; it organizes the spindle apparatus during mitosis or meiosis.

The area of a chromosome at which sister chromatids are joined; it is also the point of attachment to the spindle fiber during mitosis or meiosis.

The section of the mammalian hindbrain that controls muscle coordination and equilibrium.

The outer layer of the forebrain, consisting of gray matter; it is the site of higher cognitive function in humans. Neurons of the cerebral cortex initiate voluntary muscle action and constitute the final reception area for sensory impulses.

Site at which crossing over occurs between homologous chromosomes during meiosis.

A differentiated cartilage cell that synthesizes cartilage matrix.