Question

KE feat 4. In the small intestines what type(s) of digestion are occurring? What, if any, enzymes and/or chemicals might participate in the digestion of the greasy meal based on the macronutrients typically found in them?

Answer 1

QUESTION 4

Small intestine is the major site of digestion and absorption of carbohydates, proteins and fats. Chyme (food in intestine) are mixed with a) intestainal juice b) pancreatic juice and c) bile.

Enzymes of intestinal juice (succus entericus)

1.Enzyme for carbohydarte digestion

( a) Invertase

(b) Maltase

(c) Lactase

(d) alpha limiting dextrinase

2. Proteolytic enzyme -protein digestion

(a) Erepsin ( mixture of several peptidases)

(b) Nuclease (nucleotidase, nucleosidade)

3. Intestinal lipase -fat digestion

4. Enterokinase - activates trypsin

5. Cholestrol esterase - convert cholestro esters to free cholestrol

6. Lecithinase-convert lecithin into simpler phospholipid

7. Alkaline phosphatase-organic phosphate into free phosphate

Types of Digestion

carbohyderate digestion : dissaccharids are converted into monasaccharides in the intestine

( end product each reaction along with the enzymes involved)

invertase

I) sucrose ------------------------> glucose and fructose

maltase

II) maltose  ---------------------> 2 molucules of glucose

lactase

III) lactose ----------------------> glucose and galactose

alpha limiting dexterinse

IV) alpha limiting dexterins -------------------------------------> glucose

  Fat Digestion

Lipase hydrolyses fat to monoglycerides.Majority of fat digestion occurs in the small intestine.

• Lipase and bile salts enter at the second part of duodenum(part of small intestine).
• pancreatic juice: The pH of panceriatic juice is 7.8-8.4 ,convert acidic chyme
  (food) to pH of 7.0 optimal pH for lipase action.
• Bile salts: Enzyme Lipase cannot act directly on fat droplets, fat has to undergo a process called "Emulsification" for the lipase to act on them. Bile salts lower the surface tension by its hydrophobic action on the fat molecules and breaks down largen fat globules into smaller uniform particles (micelles), this is called as Emulsification of fat. This provides greater surface area for the lipase to act on the resultant emulsified fat.  

lipase lipase lipase

• Fat -------------------> triglycerides ---------------> diglyceride ----------------> monoglyceride

Thus, enzyme lipase, bile salts, panceratic juice are all involved in the fat digestion.

Protein

All proteolytice enzynmes are produced in inactive frorms and they are later activated in the stomach and small intestine duing the time of digestion . This is kind of bodys precaution to prevent the lysis of the intestinal walls by the proteolytic enzymes. Enzyme entrokinase( present in interstinal juice) activates trypsinogen which is later activated into trypsin.

trypsin and chymotrypisin   

peptones -------------------------------------->  small polypeptides

carboxy peptidases

polypetides ------------------------------------> peptides

erepsin

peptides ------------------------------------> free amino acids

nuclease nucleotides and nucleosides

nucleic acid --------------------------> nucleotides and nucleosides -----------------------------------> purine and pyrimidine

Greasy meal is the one that contain high amount of oil. It contains high amount of fat as macronutrient. Digestion of fat occurs in the intestin. Steps of digestion, enzymes and process involved are listed above