Secretion from the salivary glands is driven by osmosis following the establishment of osmotic gradients between the lumen, the cell and the interstitium by active ion transport.
The major pathway into saliva for most steroid hormones and other small, neutral molecules is by passive diffusion. The salivary glands are surrounded by dense beds of capillaries, and many blood components pass easily through the capillary walls, bathing the saliva glands.
