DIGESTION AND ABSORPTION

Digestion : The process in alimentary canal by which the complex food is converted mechanically and biochemically into simple substances suitable for
absorption and assimilation.
Food : A substance which on taken and digested in the body provides materials for growth, repair, energy, reproduction, resistance from disease or regulation of body processes.
Thecodont : The teeth embedded in the sockets of the jaw bone. e.g., in mammals.
Diphyodont : The teeth formed twice in life time e.g., in mammals 
Peristalsis : The involuntary movement of the gut by which the food bolus is pushed forward.
Degluttition : The process of swallowing of food bolus. It is partly voluntary and partly involuntary.
Ruminants : The herbivours animals (e.g., cow, buffalo etc.) which have symbiotic bacteria in the rumen of their stomach which synthesize enzymes to hydrolyse cellulose into short chains fally acids.
Diarrhoea : The abnormal frequent discharge of semisolid or fluid faecal matter from the bowel.
Vomitting : The ejection of stomach contents through the mouth, caused by antiperistalsis.
Dysentry : Frequent watery stools often with blood and mucus and with pain, fever and causes dehydration.
Chyme : The semifluid mass into which food is converted by gastric secretion and which passes from the stomach into the small intestine.
Goblet cells : The cells of intestinal mucosal epithelium which secrete mucus.
Glissons capsule : The connective tissue sheath which covers the hepatic lobules of liver.
Hepatic lobules : The structural and functional units of liver containing hepatic cells which are arranged in the form of cords.
Sphincter of Oddi : The sphincter which guard the opening of common hepato-pancreatic duct.
Villi : The small finger-like folding in the innermost layer of the alimentary canal which increase the absorption surface area.
PEM : Protein Energy Malnutrition.Basic steps of Holozoic Nutrition :
(1) Ingestion : Intake of food.
(2) Digestion : Breaking down of complex organic food materials into simpler, smaller soluble molecules.
(3) Absorption and assimilation : Absorption of digested food into blood or lymph and its use in the body cells for synthesis of complex components.
(4) Egestion : Elimination of undigested food as faeces.
                                                                   Digestive glands :

(A) Salivary glands (found in mouth). Three types are : (i) Parotid, (ii)
Sublingual, (iii) Submaxillary.
Secrete saliva which contains ptyalin (Salivary amylase)
(B) Pancreas : Secretes pancreatic juice.
(C) Liver : Secretes bile.
(D) Gastric glands : Secretes gastric juice.
(E) Intestinal glands : Secretes intestinal juice or succus entericus

QUESTIONS

Very Short Answer Questions (1 mark each)

1. What do you mean by the term malnutrition ?

2. Name the hardest substance in the body.

3. What is a lacteal ?

4. Name the small projections, found on the upper surface of tongue.

5. Mention the function of epiglottis.

6. Write the names of major parts of stomach.

7. Name the enzyme that digest fats. Mention the end products of fat digestion.

8. In which part of alimentary canal does absorption of water, simple sugars

and alchol takes place ?

9. Why are proteases generally released in inactive form ?

10. Trypsinogen is an inactive enzyme of pancreatic juice. An enzyme, enterokinase,

activates it. Which tissue/cell secrete the enzyme ? How is it activated ?

Short Answer Questions-II (2 marks each)

11. What is emulsification ? Where and how does it occur ?

12. Name three parts of large intestine. Which vestigial organ arises from the

first part of it ?

13. Name the gland which perform/acts as exocrine and endcrine. Also name

the products which are secreted by it.

14. The wall of alimentary canal is made up of four layers. Give the names ofthese four layers.

15. In which part of the digestive enzyme system me, the absorption of

following substances takes place ?(a) Certain drugs (b) Glucose, fructose and fatty acids

(c) Water, some minerals and drugs (d) Simple sugar and alcohol

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