Human digestion process

Introduction• Cephalic phase - This phase occurs before food enters

the stomach and involves preparation of the body for eating and digestion

• Gastric phase - This phase takes 3 to 4 hours. It is stimulated by distention of the stomach and alkaline pH.

• Intestinal phase - This phase has 2 parts, the excitatory and the inhibitory. Partially-digested food fills the

duodenum. This triggers intestinal gastrin to be released.

ORAL CAVITY In humans, digestion

begins in the oral cavity where food is chewed. Saliva is secreted in large amounts (1-1.5 litre/day) by three pairs of exocrine salivary glands (parotid, submandibular, and sublingual) in the oral cavity. Swallowing transports the chewed food into the esophagus.

ESOPHAGUS

The esophagus, a narrow, muscular tube about 20 centimeters, long and ends at the cardiac orifice of the stomach. The chewed food is pushed down the esophagus to the stomach through peristaltic contraction of these muscles

STOMACH In the stomach, food is

further broken apart thoroughly mixed with a gastric acid and digestive enzymes that denature proteins. The acid itself

does not break down food molecules

PANCREAS• The pancreas is an organ that

releases hormones and enzymes to help digestion.

• It releases substances through special cells called the Islets of Langerhans.

• Amazingly, the pancreas is the only organ in the human body to belong to two systems of function (the digestive system due to its role in breaking down nutrients and the endocrine system for its role in hormone production).

LIVERThe liver is an organ

present in vertebrates and some other animals. It plays a major role in metabolism and has a number of functions in the body, including glycogen storage, decomposition of red blood cells, plasma protein synthesis, and detoxification. This organ also is the largest gland in the human body.

Small intestineAfter being processed in

the stomach, food is passed to the small intestine via the pyloric sphincter. The majority of digestion and absorption occur here as chyme enters the

duodenum.

Large intestine After the food has been

passed through the small intestine, the food enters the large intestine. The large intestine is roughly 1.5 meters long, with three parts: the cecum at the junction with the small intestine, the colon, and the rectum.

By…

• Araceli Carmona Ayora

• Cristina Alcaide Cabello

• Mª Aurora Carmona Muñoz

• Ana Belén Fernández Marín

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