CBSE CLASS 12 - Biology - Digestion - Five Digestive Juices (#cbsenotes)(#eduvictors)

Digestion - FIVE DIGESTIVE JUICES

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There are five digestive juices i.e.

① Saliva,

② Gastric juice

③ Pancreatic juice

④ Intestinal juice (succus entericus)

⑤ Bile juice




The composition and functions of each are described below:

① Saliva,
Its composition is:
- Water (99.5%)
- Solids (0.5%)
- Inorganic and organic salts, mucus (Ptyalin and Mucin)

Enzymes: Amylase

Functions:
- Keeps the mouth moist.
- Helps in the formation of bolus.
- Salivary Amylase digests (breaks down) startch into maltose.

② Gastric juice

Composition:
- Water (99.45%)
- Solids (0.55%)
- HCl (0.4% - 0.5%) makes medium acidic
- Inorganic and oragnic salts, mucus (mucin)

Enzymes: pepsionogen, renin, lipase

Functions:
- Protein digestion (upto peptone and peptoses)
- Acidic medium kills harmful germs
- helps in the absorption of Vitamin B12
- Iron absorption

③ Pancreatic juice

Composition:
- Inorganic and organic constituents
- alkaline in nature due to the high concentration of bicarbonate ions

Enzymes:
- Trypsinogen
- Chymotrypsinogen
- Procarboxy peptidase,
- nucleases
- Lipase

Functions:
- Digestion of carbohydrates, proteins and fats

④ Bile juice

Composition:
- Inorganic salts,
- bile salts,
- bile pigment (Bilirubin, Biliverdin)
- Cholesterol

Functions:
- Helpful in digestion of lipids (coagulation)
- Removes the acidity.

⑤ Intestinal juice (succus entericus)

Composition:
- Water (98.5%)
- Solids (1.5%)

Activator:
- Enterokinase

Enzymes:
- Erepsin,
- Nucleotidases
- Sucrase
- Maltase
- Lactase
- Lipase

Function:
- Digestion of all types of food.