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digestion of food in the elementary canal


DIGESTION OF FOOD AND THE ELEMENTARY CANAL IN MAN

Alimentary canal, also called digestive tract, pathway by which food enters the body and solid wastes are expelled. The alimentary canal includes the mouth, pharynx, oesophagus, stomach, small intestine, large intestine, and anus.

What is the elementary canal?

This is the digestive system in man through which food substances are taken in and by which also nutrients are taken into the blood steam. The elementary canal in man includes the following









i. Mouth
ii. Oesophagus
iii. Stomach
iv. Duodenum
v. Small intestine
vi. Large intestine or colon
vii. Rectum
viii. Anus

Importance of the parts of the elementary canal are as follows

1. Functions of the teeth
i. The teeth are used to cut, grind and chew food into tiny particles
ii. The teeth exposes large area of food for the action of enzymes

2.

Functions of the tongue

i. The tongue helps to roll the food into bolus
ii. The tongue aids the movement of food in the mouth
iii. The tongue allows the mixing of food in the mouth with saliva or ptyalin-enzyme
iv. The tongue aids in swallowing of food into the Oesophagus or gullet

3.

Functions of the salivary gland

i. The salivary gland is part of the digestive system which secretes saliva which in turn contains an enzyme called ptyalin.
ii. The ptyalin as an enzyme that breaks down starch into maltose which is later swallowed into the gullet in form of bolus
iii. It allows for the easy chewing or movement of food in the mouth for swallowing
iv. It also serves as solvent for food







4. h2>Functions of the Oesophagus/Gullet:The Oesophagus connects the mouth to the stomach. The food swallowed is passed down into through the Oesophagus by a movement called peristaltic movement.


5.

Functions of the stomach:

i. The stomach is a temporary storage for food which takes just a few hours which is then released through the opening of the pyloric sphincter at regular intervals.
ii. In the stomach, the gastric gland secretes gastric juice which contains two enzymes, the RENIN and PEPSIN
iii. The renin acts on milk. It helps to curdle milk.
iv. The pepsin breaks down protein to peptones
v. The gastric gland also secretes hydrochloric acid (HCL) which creates an acid medium for two enzymes to act.
vi. The HCL also helps to kill bacteria in the stomach.
vii. The food is churned by muscular contraction of the stomach wall which enables the mixing of food with digestive juice-enzymes
viii. The churning movement then converts the food in semi-liquid state called chyme





6.

Functions of the DUODENUM

I. The digestion of food takes place in this region of the elementary.
II. The Duodenum contains pancreas which secretes pancreatic juice that contains three enzymes. These enzymes are
1. Amylase: this enzyme converts starch to maltose
2. Lipase: lipase converts fats and oil to fatty acid and glycerol
3. Trypsin: trypsin converts proteins and peptones to polypeptides
iii. The pancreatic juice is alkaline and provides that medium for enzymes
iv. The digestion of fats and oil is aided a green alkaline liquid called BILE which is secreted by the liver and stored in the gall bladder.
v.

The bile helps in the emulsification of fats-meaning breaking down fats into tiny droplets

vi. At the end of the digestion in the Duodenum, the food which is now in liquid form called chyme, passes into the ileum or small intestine

7.

The functions of the small intestine

i. The small intestine also known as ileum is found between the Duodenum and large intestine
ii. Two major events takes place in the small intestine
iii. These events are 1. Digestion and 2. Absorption of the digested food
iv.

DIGESTION of food also takes place in the small intestine or ileum

v. The intestinal wall secretes intestinal juice which contains the following enzymes, lipase, erepsin, maltase, sucrose and lactase
vi.

The lipase converts fats and oil to fatty acid and glycerol

vii.

Erepsin converts polypeptides to amino acid

viii.

Maltase converts maltose to two units of glucose

ix. Sucrose

converts sucrose to glucose and fructose

x.

Lactase converts lactose to glucose and galactose











In man, the final digestion of food ends in the small intestine.
The end product in the
digestion of protein are amino acids, fats and oil, fatty acid and glycerol while that of starch ends in glucose


ABSORPTION OF FOOD

The end product of digestion of food, which are amino-acids, glucose, fatty acids and glycerol are absorbed in the small intestine by a tiny finger-like structures called villi, Villus for singular.
The folding of the small intestine and the numerous villi presence creates a large surface area for the absorption of digested food nutrients.
The inner surface layer or epithelium of each villus is thin.
This allows the end product by either diffusion or by active transport through it.
The glucose and amino acids are easily absorbed by blood capillaries through the epithelium while the fatty acid and glycerol enter the lacteal where they are carried through the lymph vessels which eventually empty their contents into the blood vessels near the heart.
The blood then carries the fats and other food materials to various parts of the body where they are needed.


8.

THE FUNCTIONS OF THE CEACUM AND APPENDIX

The functions of the caecum and appendix are not well defined or known in man but are well known to contain some bacteria which aid minor digestion of cellulose.
Some vitamins such as K and B-complex are partially synthesized in this region


9.

THE FUNCTIONS OF THE LARGE INTESTINE

i. The undigested food particles passes into the colon or large intestine.
ii. Here in the large intestine, water is absorbed
iii. This absorption of water, concentrates the waste products and turn them into faeces.
iv. These faeces is finally passed into the rectum and then eventually pushed out of the body through the anus.










FUNCTIONS OF THE DIGESTIVE ENZYMES

Enzymes performs the following function within the body. They are
1. Enzymes helps in breaking down proteins in food into amino acid
2. The help to break down fats and oil into fatty acids and glycerol
3. Enzymes helps to break down carbohydrates into glucose, fructose and galactose
4. The digestive enzymes aids in the absorption of digested food through the addition of water to the food

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Agricultural biology topics


HERE YOU WILL FIND EVERY AVAILABLE TOPICS ABOUT AGRICULTURAL SCIENCE AND BIOLOGY. AND THE LINKS TO THEIR VARIOUS SOURCES.
1. DEVELOPMENT OF AGRICULTURE
2. IMPORTANCE OF AGRICULTURE
3. SUBSISTENCE AGRICULTURE
4. COMMERCIAL AGRICULTURE
5. PROBLEM OF AGRICULTURAL DEVELOPMENT
6. SOLUTIONS TO POOR AGRICULTURAL DEVELOPMENT
7. AGRICULTURAL LAWS AND REFORMS
8. ROLES OF GOVERNMENT IN AGRICULTURAL DEVELOPMENT
9. AGRICULTURAL POLICIES
10. PROGRAM PLANNING IN AGRICULTURE
34. FORESTRY
35. WILDLIFE CONSERVATION
36. FACTORS AFFECTING LAND AVAILABILITY
37. TOPOGRAPHY
38. SOIL
39. BIOLOGICAL FACTORS
40. SOCIAL-ECONOMIC FACTORS
41. ENVIRONMENTAL FACTORS AFFECTING AGRICULTURAL PRODUCTION
42. CLIMATIC FACTORS AFFECTING AGRICULTURAL PRODUCTION
43. TEMPERATURE
44. RAINFALL
45. WIND
46. SUNLIGHT
47. SOLAR RADIATION
48. BIOTIC FACTOR AND AGRICULTURAL PRODUCTION
49. PESTS
50. BIRDS
51. DISEASES
52. SOIL MICRO-ORGANISMS
53. SOIL PH
54. ROCK FORMATION
55. IGNEOUS ROCK
56. SEDIMENTARY ROCKS
57. METAMORPHIC
58. SOIL AND ITS FORMATION
59. FACTORS OF SOIL FORMATION
60. LIVING ORGANISM
61. PARENT MATERIALS
62. SOIL FORMATION TOPOGRAPHY
63. PROCESS OF SOIL FORMATION
64. WEATHERING
65. PHYSICAL WEATHERING
66. CHEMICAL WEATHERING
67. PRESSURE
68. WATER
73. BIOLOGICAL WEATHERING
74. CHEMICAL AND BIOLOGICAL COMPOSITION OF THE SOIL
75. SOIL WATER
76. MICRO AND MACRO NUTRIENTS
77. SOIL MICRO ORGANISM
78. PROPERTIES OF SOIL
79. SOIL STRUCTURE
80. SANDY SOIL
81. CLAY SOIL
82. LOAMY SOIL

83. SOIL TEXTURE
84. IDENTIFICATION OF SOIL TYPES THROUGH EXPERIMENTS
85. RETENTION OF WATER BY VARIOUS SOIL TYPES
86. DETERMINATION OF SOIL PH REACTION







87. COLORIMETRIC DETERMINATION OF SOIL PH LEVEL
88. PH SOIL TEST
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118. FARMING PRACTICES
119. BUSH BURNING CLEARING
121. FERTILIZER APPLICATION
122. ORGANIC MANURING FARM YARD MANURE
124. HUMUS
125. COMPOST
126. CROP ROTATION
133. FARM POWER AND MACHINERY
134. SOURCES OF FARM POWER
135. HUMAN SOURCE
149. PLOUGHS
142. FIELD MACHINES
157. PLANTERS
164. SIMPLE FARM TOOLS
165. AGRICULTURAL MECHANIZATION
166. THE CONCEPT OF MECHANIZATION

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