Q.Describe the three principal digestive glands associated with the human alimentary canal — the salivary glands, the liver and the pancreas — with reference to their secretions and the role each secretion plays in digestion.

Intestinal juice (succus entericus), secreted by glands in the small intestine's mucosa, contains several enzymes that complete the digestion of carbohydrates, proteins, and to a lesser extent, fats and nucleic acids.

Enzymes present in intestinal juice include:

• Enterokinase (enteropeptidase): activates pancreatic trypsinogen into active trypsin.
• Disaccharidases: maltase (breaks maltose into glucose), sucrase (breaks sucrose into glucose and fructose), and lactase (breaks lactose into glucose and galactose).
• Peptidases: aminopeptidase and dipeptidase, which break down peptides into free amino acids.
• Nucleosidases and nucleotidases: act on nucleic acid breakdown products.
• Intestinal lipase: assists in the final breakdown of fats (though most fat digestion is carried out by pancreatic lipase). …

The liver secretes bile and carries out storage, detoxification and metabolic regulation.

Main functions of the liver: (1) It secretes bile, which emulsifies fats and helps their digestion. (2) It stores excess glucose as glycogen and releases it when needed, thus regulating blood sugar. (3) It detoxifies harmful substances and converts toxic ammonia into urea. (4) It stores vitamins (A, D, B12) and iron. (5) It helps in metabolism of carbohydrates, proteins and fats, and produces …

The stomach and the small intestine (duodenum) are alimentary-canal organs whose own walls carry exocrine glands, secreting enzymes/mucus straight into the gut lumen.

Most 'digestive glands' people think of first — the liver and the pancreas — are accessory organs: they sit OUTSIDE the alimentary canal and pour their secretions in through ducts. But two organs that are THEMSELVES part of the canal also carry gland tissue built into their own walls, so they double as exocrine glands:

1. Stomach — its mucosa is packed with gastric glands made of three cell types: mucous neck cells (secrete mucus), peptic/chief cells (secrete pepsinogen), and oxyntic/parietal cells (secrete HCl and intrinsic factor). All of this is released straight into the stomach lumen — classic exocrine secretion. …

Three pairs of salivary glands - parotid, sub-mandibular and sublingual - secrete saliva into the buccal cavity to aid digestion.

Human salivary glands are exocrine glands located around the buccal (oral) cavity. There are three pairs:

1. Parotid glands - the largest pair, located just below and in front of each ear, between the skin of the cheek and the masseter muscle. Their secretion (via Stensen's duct) opens near the second upper molar tooth.
2. Sub-mandibular (submaxillary) glands - located in the floor of the mouth, below the mandible (lower jaw), near the angle of the jaw. Their duct (Wharton's duct) opens near the base of the tongue. …

The pancreas is a dual-function (heterocrine) gland: removing it would knock out both its exocrine digestive enzymes and its endocrine hormones (insulin/glucagon), causing severe malabsorption/malnutrition together with uncontrolled high blood sugar (diabetes mellitus).

The pancreas has two distinct functional components, and removing the whole organ affects both:

1. Exocrine (digestive) function: the pancreas normally secretes pancreatic juice containing enzymes such as trypsin (protein digestion), pancreatic amylase (starch digestion), and lipase (fat digestion) into the duodenum. Without the pancreas, these enzymes would be absent, so proteins, carbohydrates and especially fats would be very poorly digested and absorbed, leading to malnutrition, weight loss, and fatty, bulky stools (steatorrhea). …

The liver is the largest gland in the human body, and correspondingly the largest gland attached to the alimentary canal, mainly known digestively for producing bile.

The liver, a large, reddish-brown organ located in the upper right abdomen, is the single largest gland in the human body by weight, performing hundreds of metabolic functions -- among its digestive roles, it continuously produces bile, which is stored and concentrated in the gall bladder before being released into the duodenum to emulsify dietary fats, aiding their digestion by lipase. The pancreas (option d) is also a major digestive gland (producing a wide range of enzymes) but is considerably smaller than th …