Question

What is the role of digestive enzymes in the human digestive process?

Answer 1

lingual lipase: Lipid digestion initiates in the mouth. Lingual lipase starts the digestion of the lipids/fats.Salivary amylase: Carbohydrate digestion also initiates in the mouth. Amylase, produced by the salivary glands, breaks complex carbohydrates to smaller chains, or even simple sugars. It is sometimes referred to as ptyalin.lysozyme: Considering that food contains more than just essential nutrients, e.g. bacteria or viruses, the lysozome offers a limited and non-specific, yet beneficial antiseptic function in digestion.Haptocorrin (also known as R-factor): Helps with the absorption of vitamin B12. After Vitamin B12 is released from its original carrier protein in the stomach, it gets bound to haptocorrin. Haptocorrin protects it from acidic conditions of the stomach but is cleaved in the duodenum by pancreatic proteases. Vitamin B12 can then bind to intrinsic factor (IF) that has been produced by parietal cells. Finally, the IF-Vitamin B12 complex is taken up by in ileum via the cubam receptor.

Of note is the diversity of the salivary glands. There are two types of salivary glands:

serous glands: These glands produce a secretion rich in water, electrolytes, and enzymes. A great example of a serous oral gland is the parotid gland.Mixed glands: These glands have both serous cells and mucous cells, and include sublingual and submandibular glands. Their secretion is mucinous and high in viscosity.
Pepsin is the main gastric enzyme. It is produced by the stomach cells called "chief cells" in its inactive form pepsinogen, which is a zymogen. Pepsinogen is then activated by the stomach acid into its active form, pepsin. Pepsin breaks down the protein in the food into smaller particles, such as peptide fragments and amino acids. Protein digestion, therefore, first starts in the stomach, unlike carbohydrate and lipids, which start their digestion in the mouth.Hydrochloric acid (HCl): This is in essence positively charged hydrogen atoms (H+), or in lay-terms stomach acid, and is produced by the cells of the stomach called parietal cells. HCl mainly functions to denature the proteins ingested, to destroy any bacteria or virus that remains in the food, and also to activate pepsinogen into pepsin.Intrinsic factor (IF): Intrinsic factor is produced by the parietal cells of the stomach. Vitamin B12 (Vit. B12) is an important vitamin that requires assistance for absorption in terminal ileum. Initially in the saliva, haptocorrin secreted by salivary glands binds Vit. B, creating a Vit. B12-Haptocorrin complex. The purpose of this complex is to protect Vitamin B12 from hydrochloric acid produced in the stomach. Once the stomach content exits the stomach into the duodenum, haptocorrin is cleaved with pancreatic enzymes, releasing the intact vitamin B12. Intrinsic factor (IF) produced by the parietal cells then binds Vitamin B12, creating a Vit. B12-IF complex. This complex is then absorbed at the terminal portion of the ileum.Mucin: The stomach has a priority to destroy the bacteria and viruses using its highly acidic environment but also has a duty to protect its own lining from its acid. The way that the stomach achieves this is by secreting mucin and bicarbonate via its mucous cells, and also by having a rapid cell turn-over.Gastrin: This is an important hormone produced by the "G cells" of the stomach. G cells produce gastrin in response to stomach stretching occurring after food enters it, and also after stomach exposure to protein. Gastrin is an endocrine hormone and therefore enters the bloodstream and eventually returns to the stomach where it stimulates parietal cells to produce hydrochloric acid (HCl) and Intrinsic factor (IF).Gastric lipase: Gastric lipase is an acidic lipase secreted by the gastric chief cells in the fundic mucosa in the stomach. It has a pH optimum of 3–6. Gastric lipase, together with lingual lipase, comprise the two acidic lipases. These lipases, unlike alkaline lipases (such as pancreatic lipase), do not require bile acid or colipase for optimal enzymatic activity. Acidic lipases make up 30% of lipid hydrolysis occurring during digestion in the human adult, with gastric lipase contributing the most of the two acidic lipases. In neonates, acidic lipases are much more important, providing up to 50% of total lipolytic activity.

Answer 2

■ MOUTH:-

♤ FLUID CALLED SALIVA SECRETED BY THE SALIVARY GLANDS.

♤ THE SALIVA CONTAINS AN ENZYME CALLED SALIVARY AMYLASE.

♤ FUNCTION :- BREAK DOWN STARCH INTO COMPLEX MOLECULE TO GIVE SUGAR.

HELP IN MOISTENS THE FOOD EASY FOR CHEWING AND SWALLOWING

■ OESOPHAGUS:-

♤ THE CANAL HAS MUSCLES THAT CONTRACT RHYTHMICALLY TO PUSH THE FOOD FORWARD & THIS MOVEMENT OF FOOD IS CALLED PERISTALTIC MOVEMENT WHICH OCCURS ALONG THE G.UT.

■ STOMACH:-

♤ GASTRIC GLANDS ARE PRESENT IN STOMACH.

♤ IT RELEASE HYDROCHLORIC ACID (HCL).

♤ FUNCTION:- KILL HARMFUL BACTERIA THAT ENTERS WITH THE FOOD.

MAKES THE MEDIUM ALKALINE.

♤ PEPSIN:- THEY ARE PROTEIN DIGESTED ENZYME.

♤ MUCUS:- PROTECTS THE INNER LINING OF THE STOMACH FROM THE ACTION OF HYDROCHLORIC ACID.

■ SMALL INTESTINE:-

♤ THE EXIT OF FOOD FROM THE STOMACH IS REGULATED BY A SPHINCTER MUSCLE.

♤ IT HELPS IN DIGESTION OF CARBOHYDRATES, PROTEINS AND FATS.

■ LIVER :- IT SECRETE BILE JUICE IN GALL BLADDER.

♤ FUNCTION:- TURN ACIDIC MEDIUM TO ALKALINE.

EMULSIFY THE ACTION OF FAT.

♤ PANCREAS:- IT SECRETE PANCREATIC JUICE IT CONTAIN ENZYME LIKE:-

♤ TRYPSIN :- HELPS IN BREAK DOWN OF PROTEINS.

♤ LIPASE :- CONVERT FAT INTO FATTY ACID AND GLYCEROL.

■ INTESTINAL JUICE:- THE WALL OF SMALL INTESTINE CONTAIN GLAND WHICH SECRETE INTESTINAL JUICE.

♤ FUNCTION :- CONVERT PROTEINS TO AMINO ACIDS.

♤ COMPLEX CARBOHYDRATES INTO GLUCOSE.

♤ FATS INRO FATTY ACIDS AND GLYCEROL.

■ VILLI:- THE INNER LINING OF THE SMALL INTESTINE HAS NUMEROUS FINGER LIKE PROJECTIONS CALLED VILLI.

♤ FUNCTION:- INCREASE THE SURFACE AREA FOR ABSORPTION.

THEY ARE RICHLY SUPPLIED WITH BLOOD VESSELS WHICH TAKE THE ABSORBED FOOD TO EACH AND EVERY CELL OF THE BODY

■ LARGE INTESTINE:-

THE EXIT OF WASTE MATERIAL FROM THE BODY IS REGULATED BY THE ANAL SPHINCTER.