Bract. A small leaf with relatively undeveloped blade, in axil of which arises a flower or a branch of an inflorescence.

Bracteole. A reduced leaf that arises from the stalk of an individual flower

Bradycardia. An abnormal reduction in heart rate

Bradykinin. A hormone formed a kininogen in the blood plasma that has the effect of rapid vasodilation in the skin.

Brain. The large anterior part of vertebrate central nervous system, present in almost all bilaterally symmetrical animals, with aggregation of sense organs in head region. To a varying degree co-ordinates reactions of whole body.

Bronchus. One of the major air tubes in the tubes in the lung. Each lung has one large bronchus, connecting it to trachea; within the lung the bronchus branches into small and smaller bronchi, and the finally into bronchioles. Has cartilage plates, smooth muscle, and mucus-secreting gland-cells in wall: and lining-cells bear cilia beating towards mouth, which remove dust, etc.
Brunner’s gland. It is the sub-mucosa of duodenum to secrete digestive enzymes.

Bryophyta. The division of simple, green non-vascular plants which are amphibious in nature. They are terrestrial commonly found in moist habitats. Include the liverworts and the mosses. The sex organs are multicellular, and have a jacket of a layer of sterile cells.

The gametophyte is the domination of generations. The sporophyte is always attached to the gametophyte on which it is completely or partially dependent for nutrition.