Digestion & Absorption is one of the steady, low-risk scorers in NEET's Human Physiology unit — in recent papers it gives about 2 questions, and almost all of them are direct NCERT recall. The marks cluster in three places: the enzyme → substrate → product → pH table, where and how each nutrient is absorbed, and the gastrointestinal hormones with a few disorders. Nothing here is numerical, so it rewards a clean enzyme chart and the small finite set of NCERT facts over problem practice — which is why it is a high marks-per-hour chapter.

How to Study Digestion & Absorption — In Order

1. Alimentary canal and glands. The layout mouth → oesophagus → stomach (cardiac/fundic/pyloric) → small intestine (duodenum/jejunum/ileum) → large intestine, plus the four layers of the gut wall (serosa, muscularis, sub-mucosa, mucosa). Anatomy and labelling questions come straight from this.
2. The enzyme table. The spine of the chapter. For each region learn enzyme → substrate → product → optimum pH. Most direct questions are a single row of this table read back to you.
3. Absorption mechanisms by nutrient. Glucose and amino acids by active transport into blood; fructose by facilitated transport; fatty acids and glycerol re-formed into chylomicrons that enter the lacteals (lymph), not blood. The "enters blood vs lymph" point is a NEET favourite.
4. GI hormones and the nutrient-digestion summary. Gastrin (→ HCl), secretin (→ bicarbonate), CCK (→ bile + pancreatic enzymes); then a one-line summary of where carbohydrate, protein and fat digestion start and finish.
5. Disorders. Jaundice, vomiting, diarrhoea, constipation, indigestion, and protein-energy malnutrition (kwashiorkor vs marasmus). A short recall add-on, frequently a single MCQ.

High-Yield Sub-Topics (most-asked first)

1. Enzyme → substrate → product → pH map. Salivary amylase (starch → maltose, pH ~6.8), pepsin (proteins → peptides, acidic pH ~1.8), trypsin/chymotrypsin (proteins → peptides, alkaline pH ~8), pancreatic amylase (starch → maltose), pancreatic lipase (fats → fatty acids + glycerol), intestinal maltase/sucrase/lactase. The single most-asked block in the chapter.
2. Where each nutrient is absorbed and how. Most absorption is in the small intestine (mainly ileum): glucose and amino acids by active transport into blood; fatty acids → chylomicrons → lacteals (lymph). The large intestine absorbs water and some minerals; the mouth and stomach absorb almost nothing (a little water, alcohol, certain drugs).
3. Gastrointestinal hormones. Gastrin (from stomach → stimulates HCl), secretin (from duodenum → stimulates bicarbonate-rich pancreatic juice and damps gastric secretion), cholecystokinin/CCK (→ bile release from the gall bladder + pancreatic enzymes). Match-the-hormone questions recur most years.
4. Bile and emulsification. Bile is made by the liver and stored in the gall bladder and contains NO enzymes; bile salts emulsify fat into tiny micelles to give lipase a larger surface to act on. "Bile contains digestive enzymes" is a deliberate NEET trap.

Mistakes Students Repeatedly Make

• Thinking bile digests fat. Bile has no enzymes — bile salts only emulsify fat; pancreatic lipase does the actual chemical digestion. The most common error in this chapter.
• Mixing up the optimum pH of stomach vs intestinal enzymes. Pepsin needs an acidic pH (~1.8); trypsin needs an alkaline one (~8). Reversing them is a classic slip.
• Assuming digested fat enters the blood directly like glucose. Fatty acids and glycerol are re-formed into triglycerides, packaged as chylomicrons, and enter the lacteals (lymph) first — only glucose and amino acids go straight into blood capillaries.
• Confusing the gastrin / secretin / CCK jobs — gastrin → HCl, secretin → bicarbonate, CCK → bile + pancreatic enzymes.