Answer briefly:
(a) Why are villi present in the intestine and not in the stomach?
(b) How does pepsinogen change into its active form ?
(c) What are the basic layers of the wall of alimentary canal?
(d) How does bile help in the digestion of fats ?
(a) The absorptive surface area of small intestine is enormously increased by microvilli and as maximum absorption
of digested food takes place in small intestine as compared to other organs, therefore, villi are present in small intestine and not in stomach. Moreover, stomach is primarily associated with temporary storage of food.
(b) The proenzyme pepsinogen, on exposure to hydrochloric acid, secreted by oxyntic cells of gastric glands gets converted into the active enzyme pepsin, the proteolytic enzyme of the stomach.
(c) The wall of alimentary canal from oesophagus to rectum possesses four layers, namely serosa, muscularis, sub-mucosa and mucosa. Serosa is the outermost layer and is made up of a thin mesothelium with some connective tissues. Muscularis is formed by smooth muscles. The sub-mucosal layer is formed of loose connective tissues containing nerves, blood and lymph vessels. In duodenum, glands are also present in sub-mucosa. The innermost layer lining the lumen of the alimentary canal is the mucosa. This layer forms irregular folds (rugae) in the stomach and small finger ¬like foldings called villi in the small intestine.
(d) Bile has no enzymes but contains bile salts, namely, sodium bicarbonate, sodium glycocholate and sodium taurocholate that reduce the surface tension of large fat droplets and break them into many small droplets by a process known as emulsification. These small fat droplets present large surface area for lipase (fat digesting enzyme) to act upon them. Moreover, bile also activates lipases.
Correct the statement given below by the right option shown in the bracket against them. Absorption of amino acids and glycerol takes place in the (small intestine/ large intestine). The faeces in the rectum initiate a reflex causing an urge for its removal (neural / hormonal). Skin and eyes turn yellow in infection, (liver/stomach). Rennin is a proteolytic enzyme found in gastric juice of (infants / adults). Pancreatic juice and bHe are released through (intestine-pancreatic/hepato ¬pancreatic duct). Oipeptides, disaccharides and glycerides are broken down into simple substances in region of small intestine (jejunum/duodenum).
Discuss the role of hepato – pancreatic complex in digestion of carbohydrate, protein and fat components of food.
The food mixes thoroughly with the acidic gastric juice of the stomach by the churning movements of its muscular wall. What do we call the food then?
What do we call the type of teeth attachment to jaw bones in which each tooth is embedded in a socket of jaw bones?
Stomach is located in upper left portion of the abdominal cavity and has three major parts. Name these three parts.
Match the enzymes with their respective substrates and choose the right one among options given.
Column-I Column-II
A.Lipase (i)Dipeptides
B.Nuclease (ii)Fats
C.Carboxypeptidase (iii)Nucleic acids
D.Dipeptidases (iv)Proteins,peptones and proteoses
(a) A-(ii), B-(iii), C-(i), D-(iv)
(b) A-(iii), B-(iv), C-(ii), D-(i)
(c) A-(iii), B-(i), C-{iv), D-(ii)
(d) A-(ii), B-(iii), C-(iv), D-(i)
Answer briefly:
(a) Why are villi present in the intestine and not in the stomach?
(b) How does pepsinogen change into its active form ?
(c) What are the basic layers of the wall of alimentary canal?
(d) How does bile help in the digestion of fats ?
What is the role of gall bladder? What may happen if it stops functioning or is removed?
In which part of alimentary canal does absorption of water, simple sugars and alcohol takes place?
Choose the correct answer among the following:
(a) Gastric juice contains
(i) pepsin, lipase and rennin
(ii) trypsin, lipase and rennin
(iii) trypsin, pepsin and lipase
(iv) trypsin, pepsin and rennin.
(b) Succus entericus is the name given to
(i) a junction between ileum and large intestine
(ii) intestinal juice
(iii) swelling in the gut
(iv) appendix.
Try psinogen is an inactive enzyme of pancreatic juice. An enzyme, enterokinase, activates it. Which tissue/ cells secrete this enzyme?/ How is it activated?
Describe the digestive role of chymotrypsin. Which two other digestive enzymes of the same category are secreted by its source gland ?
Name the part of the alimentary canal where major absorption of digested food takes place. What are the absorbed forms of different kinds of food materials?
Match the two columns and select the right one among options given.
Column-I Column-ll
A.Duodenum (i) A cartilaginous flap
B.Epiglottis (ii)Small blind sac
C.Glottis (iii)’U’shaped structure emerging from the stomach
D. Caecum (iv)Opening of wind pipe
(a) A-(i), B-(ii), C-(iii), D-(iv)
(b) A-(iv), B-(iii), C-(ii), D-(i)
(c) A-(iii), B-(i), C-(iv), D-(ii)
(d) A-(ii), B-(iv), C-(i), D-(iii)
Match column I with column II.
Column I Column II
(a) Bilirubin and (i)Parotid biliverdin
(b) Hydrolysis of (ii)Bile starch
(c) Digestion of fat (iii)Lipases
(d) Salivary gland (iv) Amylases
A person had roti and dal for his lunch.Trace the changes in those during its passage through the alimentary canal.
What is pancreas? Mention the major secretions of pancreas that are helpful in digestion.
Explain the process of digestion in the buccal cavity with a note on the arrangement of teeth.
Correct the following statements by deleting one of entries (given in italics).
(a) Goblet cells are located in the intestinal mucosal epithelium and secrete chymotrypsin / mucus.
(b) Fats are broken down into di-and monoglycerides with the help of amylase/ lipases.
(c) Gastric glands of stomach mucosa have oxynticcell/chief cells which secrete HCl.
(d) Saliva contains enzymes that digest starch /protein.
What are the various enzymatic types of glandular secretions in our gut helping digestion of food? What is the nature of end products obtained after complete digestion of food?
List the organs of human alimentary canal and name the major digestive glands with their location.
Discuss the main steps in the digestion of proteins as the food passes through different parts of the alimentary canal.