Page 287 - Biology_F5

Biology for Advanced Level Secondary Schools

into the body. The digested materials, 5.3.2 The process of digestion
which are absorbed into the blood, are Digestion in mammals, such as human
carried by the blood stream to the body beings occurs throughout the alimentary
cells and tissues for use in life processes canal. The alimentary canal in humans
such as respiration, growth, repairing comprises the mouth, oesophagus,
body tissues and maintaining good health. stomach, small intestine, large intestine
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In addition, excess of such food materials (colon), caecum, rectum and anus (Figure
may be stored in the liver, muscles and 5.10). The alimentary canal is also
adipose tissues for future use. associated with the accessory organs such
as the liver, salivary glands, and pancreas,
(e) Egestion which assist in digestion. The wall of the
Egestion is the process of eliminating alimentary canal has almost the same
undigested food materials from the gut basic structure throughout its length. The
through the anus. This is the final stage wall is lined by the simple epithelium or
in holozoic nutrition in mammals, during stratified epithelium tissue, and all parts of
which the undigested food materials or the gut contain circular and longitudinal
faeces are removed from the alimentary
canal. muscles.

Mouth Parotid gland
Tongue Submandibular gland
Sublingual gland Pharynx

Eusophagus

Liver

Gallbladder Stomach
Spleen
Duodenum Pancreas
Transverse colon

Ascending colon
Jejunum

Ileum Descending colon
Cecum
Appendix Sigmoid colon
Rectum
Anus Anal canal

Figure 5.10: The human alimentary canal

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