Glossary of Biological Terms



joule (J)

A unit of energy: 1 J = 0.239 cal; 1 cal = 4.184 J.

juvenile hormone (JH)

A hormone in arthropods, secreted by the corpora allata glands, that promotes the retention of larval characteristics.

juxtaglomerular apparatus (JGA)

Specialized tissue located near the afferent arteriole that supplies blood to the kidney glomerulus; the JGA raises blood pressure by producing renin, which activates angiotensin.