It includes alimentary canal and digestive glands.
Alimentary canal starts from mouth and ends into anus.
• Mouth or Buccal Cavity : An adult has 16 teeth on each jaw.
In each half of jaws starting from middle to backward these are, incisors - 2, canine - 1, premolar - 2, molars - 3 (2 + 1 + 2 + 3).
Dental formula is 2123/2123.
Last molars are called wisdom teeth.
Milk teeth start erupting after 6 months of birth and appear between 6 to 24 months.
Dental formula of milk teeth is 2102/2102.
• Stomach : Inner mucosa of stomach is raised into larger number of longitudinal folds called gastric rugae.
NUTRITION
It helps in mechanical churning and chemical digestion of food.
The stomach of ruminant (cud chewing) animals have compound stomach and consists of 4 chambers rumen, reticulum; omasum and abomasum.
Rumen and reticulum harbour numerous bacteria and Protozoa which help in digestion of cellulose called symbiotic digestion.
Abomasum is true stomach as it secretes gastric juice containing HCl and pepsin.
• Small Intestine : Villi and microvilli increase the surface area of digestion and absorption of food.
Pancreatic duct release few enzymes which act on carbohydrates, fats and proteins.
• Large Intestine : In some herbivores (like horse and ass), caecum is large and is a site of microbial digestion of cellulose.
In man caecum very small vestigial organ and is called appendix.
Table : Vitamins Necessary for Normal Cell Functioning
Deficiency Disease Deficient Nutrient Deficiency Disease Deficient Nutrient
1. Xerophthalmia Vitam in A / Retinol 10. Megaloblastic
anaemia Folic acid and Vitam in B12
2. Night-blindness Vitam in A 11. Pernicious
anaemia Vitam in B12 (Cyanocobalam ine) 3. Rickets (in children) Vitam in D/ Sun-Shine Vitam in 12. Scurvy Vitam in C/ As corbic acid
4. Osteomalacia (adults) Vitam in D 13. Tetany Calcium
5. Sterility Vitam in E (Tocopherol) 14. Anaemia Iron 6. Bleeding disease Vitam in K (Phylloquinone) 15. Goitre Iodine
7. Beri beri Vitam in B1 (Thiam ine) 16. Fluorosis Exces s of fluorine 8. Cheilosis Vitam in B2 (Riboflavin) 17. Kw ashiorkor Proteins
9. Pellagra Vitam in B3 (Niacin) 18. Marasm us Proteins and food calories
• Knowledge Boosters :
(1) Salivary Glands : It produces saliva. In man only three pairs of salivary glands are present.
(a) Parotid glands : largest glands present just below the external ear. In this glands, virus causes mumps disease.
(b) Submaxillary glands : these lie beneath the jaw-angles.
(c) Sublingual glands : smallest glands which lie beneath the tongue and open at the floor of buccal cavity.
(2) Gastric Glands: Present in the mucosa of the stomach. These are of 3 types :
(a) Cardiac glands : secrete an alkaline mucus.
(b) Pyloric glands : secrete an alkaline mucus.
(c) Fundic glands : each gland has 4 types of cells.
1. Peptic / Zymogen cells - secrete pepsinogen, prorennin
2. Oxyntic cells - secrete HCI 3. Goblet cells - secrete mucus
4. Argentaffin cells - produces serotonin, somatostatin and histamine
(3) Liver :It is the largest gland and consists of a large right lobe, a small left lobe and two small lobes.
On the right lobe lies gall bladder, which, stores bile juice secreted by the liver.
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Bile juice contains no enzyme but possesses bile salts and bile pigments (bilirubin-yellow and biliverdin-green).
Formation of glucose from excess organic acids.
• Storage of vitamins : A, D, E, K
• Synthesis of vitamin A from carotene.
• Secretions of blood anticoagulant named heparin.
• Synthesis of blood or plasma proteins, (fibrinogen and prothrombin)
• Secretion of bile, detoxification of harmful chemicals.
• Elimination of pathogens and foreign particles through phagocytic cells called Kupffer’s cells.
Table : Various Enzymes Involved in Digestion
E X E R C I S E
1. In human digestion is :
(A) Intercellular (B) Intracellular (C) Extracellular (D) Both A & B 2. The enzyme rennin converts
(A) Proteins to proteoses (B) Fats to fatty acids (C) Casein to paracasein (D) Proteins to peptones 3. Digestion in Amoeba is :
(A) Intercellular (B) Intracellular (C) Both of these (D) None of these 4. Statements true or false is:
(i) No absorption of food takes place in mouth and oesophagus
(ii) Absorption of H
2O, alcohol, simple salts, glucose and chloride takes place in the stomach to slight extent.
(iii) Whole protein particles can be absorbed by pinocytosis.
(A) (i) and (ii) true (iii) rarely true (B) All true
(C) (i) and (iii) true B false (D) (i) and (ii) true (iii) false
5. Stomach is protected from HCl and gastric juice because :
(A) The two are dilute
(B) Epithelial lining is resistant to them (C) Wall has neutralizing agents (D) Stomach lining is covered by mucus
6. In a villus, some of the glycerol and fatty acids are combined to form fats, coated with proteins, and then transported to the :
(A) Lacteal (B) Capillaries
(C) Lumen of the small intestine (D) Lumen of the large intestine 7. Among mammals, an herbivore has :
(A) More teeth than a carnivore (B) Fewer teeth than a carnivore (C) Flatter teeth than a carnivore
(D) Teeth that are more pointed than a carnivore 8. Gastric juice has a pH of about :
(A) 1 (B) 2
(C) 6 (D) 10
9. Softness and deformities of bones like bowlegs and pigeon-chest are symptoms of the disease :
(A) Rickets (B) Osteomalacia
(C) Goitre (D) Beri-Beri
10. In rabbit when a dilute solution of glucose reaches small intestine is :
(A) Absorbed rapidly by the active transport with sodium ions
(B) Absorbed by facilitated diffusion (C) Lost to outside with undigested food
(D) Absorbed rapidly by active transport independent of sodium ions
11. Chymotrypsin acts on :
(A) Carbohydrates (B) Proteins
(C) Fats (D) Starch
12. The vermiform appendix is made up of : (A) Striated muscles (B) Excretory tissue (C) Lymphatic tissue (D) Stem cells 13. Digestion is completed in :
(A) Ileum (B) Duodenum
(C) Stomach (D) Rectum
14. One of the following is not an enzyme of digestive system :
(A) Trypsin (B) Amylase
(C) Enterogastrone (D) Enterokinase 15. Fat soluble vitamins are :
(A) A, D and E (B) B, C and D (C) B,D and E (D) A, B and C 16. Sunshine vitamin is :
(A) Vitamin A (B) Vitamin D (C) Vitamin K (D) Vitamin E
17. Which of the vitamins is essential for normal vision : (A) Folic acid (B) Biotin
(C) Riboflavin (D) Retinol
18. B.M.R. for a normal human adult is : (A) 1600 Kcal/day (B) 2000 Kcal/day (C) 2500 Kcal/day (D) 3000 Kcal/day 19. Cholesterol rich diet is undesirable because it :
(A) Makes person obese (B) Causes heart ailments
(C) Is difficult to remove it from body (D) All of the above
20. If all bacteria of intestine die, then what will be the effect on body:
(A) Man will feel tired all the body (B) It will cause blindness
(C) There will be no synthesis of vitamin -B Complex (D) Excretion will be effected
21. The gall bladder is involved in [KVPY 2011]
(A) synthesizing bile
(B) storing and secreting bile (C) degrading bile
(D) producing insulin
22. In the 16th century, sailors who travelled long distances had diseases related to malnutrition, because they were not able to eat fresh vegetables and fruits for months at a time scurvy is a result of deficiency of [KVPY 2011]
(A) carbohydrates (B) proteins (C) vitamin C (D) vitamin D
23. Several mineral such as iron, iodine, calcium and phosphorous are important nutrients. Iodine is
found in [KVPY 2011]
(A) thyroxine (B) adrenaline (C) insulin (D) testosterone