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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