What are disadvantage of incomplete alimentary canal ? And also discuss the advantage of complete alimentary canal.

Complete alimentary cycle : In this, mouth and anus or clocal aperture are present. E.g. from Nematodes to Chordates

Incomplete alimentary cycle : In this, only ore opening i.e. mouth is present. E.g. flatworms

Disadvantage of incomplete alimentary canal.

1. Waste food must be expelled before taking the next food, otherwise there would be mixing of both.

2. The incomplete digestive tract cannot store the food.

3. It is less efficient because it serves as the function of circulatory system.

Advantage of complete alimentary canal.

1. There is no chance of mixing in digested food and waste food, because the opening for ingestion and egestion are separate.

2. For circulation of absorbed food there is circulatory system.

3. It is more efficient. 

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Give the process of digestion of fat.

Or Describe digestion of butter. (NCERT)


Butter is a type of fat . The digestion of fats takes place in the following way :

In the buccal cavity and stomach. : Fats are not digested in buccal cavity and stomach. In stomach gastric juice has very weak gastric lipase which converts some fats into fatty acids and glycerol. This reaction is, however, negligible.

Digestion in duodenum : In duodenum the food is mixed in bile and pancreatic juice.

Role of bile : Bile emulsifies the fats and increases solubility of fatty products. The bile salts helps in the absorption of fats and fat soluble vitamins (A, D, E, K). 

Pancreatic juice : Fats are broken down by lipases present in the pancreatic juice and with the help of bile into di-and monoglycerides.

Digestion in Jejunum-ileum : In jejunum-ileum food is mixed with intestinal juice or succus entericus which has intestinal lipase which converts remaining fat into fatty acids and glycerol.

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 Describe various Nutritional disorders.

Nutritional disorders are :

1. Marasmus : is a form of severe malnutrition characterized by energy deficiency. It is caused due to undernourishment causing a child's weight to be significantly low for their age. It is a disorder caused by deficiency of food or protein energy malnutrition .

2. Kwashiorkar : is a form of severe protein energy malnutrition characterised by edema, irritability , anorexia  and an enlarged liver with fatty infiltrates. 

3. Obesity :  It is the condition in which excess body fat has accumulated to the extent that it may have a negative effect on health It is quite common in persons having higher intake of sweets, carbohydrate rich food, fried edibles, fat rich food and absence of roughage in food.

4. Hyper-cholesterolemia : It is characterized by high blood cholesterol due to higher intake of cholesterol rich eggs, red meat, butter and ghee of reduced biotin intake. Cholesterol gets deposited on, the walls of blood vessels making their lumen narrow and walls stiffer.

5. Rickets : It occurs in children due to the deficiency of vitamin D, calcium or phosphorus.

6. Osteomalacia :The disorder occurs in adults when their food is deficient in vitamin D, calcium or phosphorus due to which the bones become weak and brittle. 

7. Night Blindness : It is due to the dietary deficiency of vitamin A results in deficiency of rhodopsin or visual purple pigment. It is the inability to see things in the dim light. 

8. Beri-Beri : Beriberi is a disbility produced by deficiency of thiamine.It is caused due to the deficiency of Vit B1.

9. Scurvy - It is caused due to the deficiency of Vitamin C. It is characterised by bleeding gums 

10. Anaemia : It is disorder in which haemoglobin content of the blood is low due to either few red blood corpuscles or their haemoglobin content. 

 

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Describe digestion of proteins.

Digestion of proteins :

Proteins do not get any justice in buccal cavity. The digestion pf proteins takes place in the stomach . The gastric juice has HCl, propepsin, prorennin and weak gastric lipase. The HCl converts the enzyme pepsinogen into pepsin. The pepsin is an proteolitic enzyme which converts proteins to peptones converts casein of milk into paracasein.

In duodenum :The pancreatic juice has many enzymes like trypsinogen, amylases, lipases, chymotrypsinogen, procarboxypeptidase and nucleases..

Functions of Trypsin and Chymotrypsin :

1. Converts proteins to peptides.

2. Trypsin acts on keratin present in exoskeleton and converts that to peptones.

Functions of carboxy-peptides : It separates amino acids present adjacent to carboxylic acid group in peptides.

Digestion of proteins in jejunum-ileum :  The intestinal juice contains following protein digesting enzyme.

Aminopeptidase : It separates amino acids adjacent to amino group.

Describe digestion of proteins.

Dipeptidase converts dipeptides to amino acids.

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Describe the digestion of carbohydrates.

Digestion of carbohydrates :

Carbohydrates are a major part of our food. They include polysaccharides, disaccharides and monosaccharides. 

1. Digestion in buccal cavity : In buccal cavity food is mixed with saliva secreted by salivary glands. The saliva contains ptyalin. Ptyalin converts starch into sugar (maltose, isomaltose and limit dextrin)

2. Digestion in stomach : In stomach the saliva continues to act on food for about 30 minutes but the action of HCl stops the action of saliva.

3. Digestion in duodenum : As the food called chyme comes from stomach into duodenum immediately pancreatic juice secreated by pancreas under the influence of secretin hormone (secreated by enteric epithelium of duodenum) comes into duodenum. The pancreatic juice contains pancreatic amylase whcih converts starch into maltose, isomaltose and limit dextrin.

Digestion of carbohydrates in jejunum-ileum : As chyle comes from duodenum into ileum the intestinal juice secreted by intestinal glands gets mixed with the food. The intestinal juice carry out the reactions :

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