Final answer:
The stomach absorbs water, salt, and simple sugars directly into the bloodstream, also absorbing some substances like alcohol and aspirin, but most nutrient absorption occurs in the small intestine.
Step-by-step explanation:
Substances absorbed in the stomach include water, salt, and simple sugars. These substances can be absorbed directly into the bloodstream from the stomach lining. However, this organ is primarily involved in the initial stages of digestion, especially protein breakdown. The stomach secretes gastric juices that contain hydrochloric acid to create an acidic environment for the enzyme pepsin to begin protein digestion. Although an important digestive organ, the stomach is involved in minimal absorption of nutrients, with major absorption occurring in the small intestine. Substances like alcohol and aspirin are exceptions as they can be readily absorbed through the stomach lining. The small intestine is equipped with structural adaptations, such as villi and microvilli, that significantly increase its surface area for efficient nutrient absorption.