IMPORTANT TERMS:
v Absorption: Passing of diffusible food through small intestine into blood or lymph.
v Appendicitis: Inflammation and abnormal elongation of vermiform appendix.
v Deglutition: Swallowing of food bolus into the oesophagus.
v Enamel: The hardest material which covers the exposed part of the tooth.
v Splenchnology: It is the study of viscera.
v Dyspepsia: Indigestion due to defective diet.
v Modified Teeth: Vomerine teeth of frog kill prey, fangs of a poisonous snake are maxillary teeth, elephant tusks are modified incisors and tusks of walrus are modified canines.
v Dental Formula: Number and arrangement of teeth in one-half of each jaw.
v Digestion: Conversion of non-diffusible food into diffusible food by the process of hydrolysis.
v Egestion: Expelling out of undigested food as faeces.
v Emulsification: Breaking of large fat droplets into a fine emulsion by bile juice of the liver.
v Extracellular Digestion: Digestion occurring outside the cells.
v Fluorosis: Disease caused by the excess of fluorine in the diet.
v Heterodont: Presence of different types of teeth, e.g., in mammals.
v Heterotrophic Nutrition: Intaking readymade organic food by consuming plants or animals.
v Holozoic Nutrition: Obtaining food like animals, i.e., solid food through mouth.
v Homodont: When all the teeth are similar, e.g., in frog.
v Intracellular Digestion: Digestion of food inside the cells.
v Microvilli: Electron microscopic processes on free surface of intestinal cells to increase the surface area for absorption of food.
v Milk Teeth: Which appear earlier in the life and are replaced by the permanent teeth.
v Night-blindness: Inability to see at night, caused due to deficiency of vitamin A.
v Osteomalacia: A disease of bones in adults caused due to deficiency of vitamin D.
v Peristalsis: Involuntary movements of gut wall which moves food backward.
v Protein Energy Malnutrition (PEM):Deficiency of proteins as well as food calories.
v Regurgitation: Back flow of food from stomach to oesophagus. It is found in ruminants.
v Rickets: A disease of bones in children caused due to the deficiency of vitamin D.
v Ruminants: Cud-chewing mammals, e.g., cattle.
v Scurvy: A disease caused by deficiency of vitamin C.
v Villi: Finger- like of intestinal mucosa to increase the surface area for absorption of food.
ADDITIONAL INFORMATION
v Dentition: (i) Many fossil reptiles and Archeopteryx had thecodont dentition.
(ii) Thecodont condition also occurs in crocodilians.
(iii) Pleurodont dentition occurs in lizards and Acrodont in frog.
A natural space between two types of teeth is called diastema.
In rabbit which lacks canine teeth, a diastema is present between the incisor and premolar on each side.
v Carnasial teeth in dog are (last upper premolar and first lower molar) used for tearing flesh.
v Dental Formula of other Animals
Rabbit=2023 ⁄1023 = 28
Dog =3142 ⁄3143 = 42
Cat=3131 ⁄ 3121= 30
Rat =1003 ⁄1003 = 16 *
Horse = 3143 ⁄3143=44*
*Maximum and minimum number of teeth in mammals.
(i) Spiny ant-eater. Scaly ant- eater and Whales are Toothless mammals.
(ii) Bats, Guinea pig loose milk teeth before birth.
(iii) Platypus, toothed whales, sloths (bear) and sirenians (sea-crow) are Monophyodont.
v The Ruminant Stomach
Rumen is the largest chamber.
v Gastritis: Inflammation of the stomach generally due to excessive consumption of alcohol.
v Peptic Ulcer: Inflammation of mucosa of stomach and duodenum due to acidic gastric juice.
v Constipation is infrequent passage of dry, hardened faeces.
v Ulcerative Colitis: Mucosal lining of the colon becomes ulcerated.
v Bad Breath is usually due to cavities in the teeth, infection of throat and nose.
v Poison Glands of a snake are modified labial glands homologous to parotid salivary glands. Tongue of Whale is not movable.
v Pigeon’s Milk is produced by its crop glands.
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