B2.2 - Key Words

Alveoli

Air sac in the lung which increases the surface area

Artery

Blood vessel that carries blood away from the heart

Atria

Upper chamber of the heart (singular - atrium)

Capillary

Small blood vessels that carry blood close to all cells in the body. They link arterioles and venules

Diffusion distance

Distance over which a molecule diffuses

Double circulatory system

A system in which blood travels through the heart twice in each circuit of the body

Exchange surface

An area where materials are interchanged

Heart

Muscular organ which pumps blood around the body

Lumen

The open channel within a tube

Phloem

Tissue that transports dissolved sugar around a plant

Potometer

Apparatus used to measure rate of water uptake in a plant

Semipermeable membrane

A membrane which only allows certain molecules to pass through it

Stomata

Small openings (pores) in a plant’s epidermis used to exchange gases (singular - stoma)

Translocation

Movement of sugars from the leaf to stores in the roots, or to growing areas of a olant

Transpiration

Loss of water form the leaves of a plant

Transpiration stream

The flow of water through a plant caused by the loss of water from a plant’s leaves

Valve

Structure that controls the direction of flow

Vein

Blood vessel that carries blood towards the heart

Ventricle

Lower chamber of the heart

Villi

Finger-like projections on the intestine wall, which increase the surface area

Xylem

Tissue that transports water around a plant