Revision: Human Physiology >> Digestion and Absorption Biology Science (English Medium) Class 11 CBSE

Key Points: Digestive Glands

Digestive glands associated with the alimentary canal are salivary glands, liver, gall bladder (storage) and pancreas.
Three pairs of salivary glands (parotid, submandibular, sublingual) pour saliva into the buccal cavity; serous cells secrete salivary amylase and mucous cells secrete mucus.
The liver is the largest gland (about 1.2–1.5 kg), located in the upper right abdomen, divided into right and left lobes made of hepatic lobules covered by Glisson’s capsule.
Hepatic cells produce bile (stored in gall bladder), store excess glucose as glycogen, synthesize vitamins A, D, K, B₂, and Kupffer cells remove toxins and worn‑out cells.
The pancreas is a heterocrine gland lying in the C‑shaped curve of the duodenum; its exocrine acini secrete alkaline pancreatic juice with enzymes.
The endocrine islets of Langerhans contain α‑cells (glucagon), β‑cells (insulin) and δ‑cells (somatostatin).
The common hepato‑pancreatic duct opens into the duodenum and is guarded by the sphincter of Oddi.

Key Points: Nutritional and Digestive Tract Disorders

Nutritional disorders are linked to the quality and quantity of food intake (e.g., protein‑energy malnutrition like kwashiorkor and marasmus).
Disorders of the digestive system arise from malfunctioning of digestive organs or glands (e.g., liver, stomach, intestine).
Diarrhoea is defined as abnormally frequent bowel movements with increased liquidity of faeces, leading to poor absorption of nutrients.
Constipation is the prolonged retention of faeces in the rectum, often with irregular or difficult bowel movements.
Other common digestive disorders include jaundice (abnormal bilirubin metabolism), vomiting (forceful expulsion of stomach contents) and indigestion (improper digestion causing discomfort).