Conducts food from the mouth to the stomach by peristalsis. Muscles at top of esophagus are striated (swallowing is voluntary), but the rest of esophagus is under the influence of involuntary smooth muscles.
Stores food and continues the process of digestion. Stretches to accommodate about 2L. Secretes: Gastric juice, Pepsin, HCl (pH 2).
Materials that must be obtained in preassembled form – can’t be manufactured by body. Example: ascorbic acid (orange juice). Required for metabolic reactions.
Simple inorganic nutrients required in small amounts preventing deficiencies which may result in severe problems.
Ca, P – bone construction, maintenance
Fe – component in cellular respiration and hemoglobin in blood
I – thyroid hormones for metabolism
Na, K, Cl – nerve functioning, maintaining osmotic balance in cells
Body hoards fat – storing fat in-stead of using it for fuel producing an inappropriately high weight to height ratio. Results in: Diabetes, Colon, breast cancer, Cardiovascular disease.