Inner lining of the digestive tube

Which is NOT a way that venous blood gets back to the heart?

The _______ pumps blood into the aorta.

The surfactant secreted by special cells in pulmonary alveoli _____.

The true stomach of the ruminant

Using the symbols +, −, and 0 to indicate interspecific species interactions, where the first symbol refers to the first organism mentioned, what interactions exist between cellulose-digesting organisms in the gut of a termite and the termite?

A species population’s size (N) may vary depending on a number of factors including crowding and resource limitation. As N approaches K (carrying capacity) for a certain population, which of the following outcomes is predicted by the logistic growth model?

Which chamber of the heart receives blood with the LOWEST oxygen concentration?

T- helper cells act in immune pathways by ______.

What organs are involved in swallowing and are just passageways that are not involved in mechanical nor chemical digestion?