Gas exchange in the lungs happens at _____cells.

During positive selection of a T cell

Air in the thoracic cavity can lead to _____.

The____ defense system is  ____.

Leukocytosis

During emphysema surface-area-to-volume ratio ____

Plasma (Effector) cells make

NK cells _____ and _____

Proliferation and differentiation of a B-cell

If no _____ were present there would be a significantly reduced immune response at both the innate and adaptive levels.