A person had roti and dal for his lunch.Trace the changes in those during its passage through the alimentary canal.
Roti contains starch while dal contains proteins. When the food is taken into the buccal cavity the teeth and tongue with the help of saliva masticate and mix up the food thoroughly. Mucus in saliva helps in lubricating and adhering the masticated particles into a bolus. By swallowing, the bolus is then passed into the pharynx and then into the oesophagus. In the oral cavity, about 30% of the starch present in roti is hydrolysed by salivary amylase present in saliva into maltose.
The food then moves into the stomach. In the stomach, the food mixes thoroughly with the acidic gastric juice by the churning movements of its muscular wall and is called chyme. A proteolytic enzyme pepsin present in the gastric juice converts proteins into proteoses and peptones. Gastric juice does not contain any starch digesting enzyme. Proteins, proteoses and peptones in the chyme reaching the intestine are acted upon by the proteolytic enzymes of pancreatic juice as follows:
Carbohydrates in the chyme are hydrolysed by pancreatic amylase into disaccharides.
The enzymes in the intestinal juice act on dipeptides and maltose to form the respective simple absorbable forms.
Finally, the amino acids and glucose are absorbed through the mucosa of the small intestine into the blood stream. The absorbed substances finally reach the tissues which utilise them for their activities. This process is called assimilation.
The undigested and unabsorbed substances of roti and dal are passed on to the large intestine for defecation (egestion of faeces).
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)
What is the role of gall bladder? What may happen if it stops functioning or is removed?
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 ?
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.