Page 39 - EM BIOLOGY NOTES 10TH CLASS PSR DIGITAL BOOKS

7. CO-ORDINATION IN LIFE PROCESSES

 Different systems in living organisms like Respiratory System, Lesson related 1, 2, 4 marks
Activities Question and
Digestive System, Blood Circulatory System, Excretory System, videos Answers PDF
Nervous System, Endocrine System etc ... are inbuilt in our body pl.scan QR pl.scan QR
at their specific places and carry out their specific functions in a
co-ordinated manner.
 Every process is dependent on others to keep the body in good condition.
 Ex :- Digestive System, Circulatory System, Muscular System, Endocrine System and Ner-
vous System are involved in the ‘process of digestion’.
 Hunger Pangs :-
 Hunger pangs are nothing but hunger generating signals that reach the brain from the
stomach due to the secretion of a hormone called Ghrelin.
 When glucose levels in the blood fall or stomach go empty the hormone Ghrelin secreted
by the cells of the stomach then hunger pangs start in the stomach.
 Increase in ghrelin levels results in sensation of hunger and motivation to consume food.
 When we feel our stomach is full and there is no need of food, another hormone leptin is
secreted that suppresses hunger.
 Taste and smell are closely related :-
 Taste and smell are closely related. For example when we suffer from severe cough and
cold can’t make out the difference in tastes of certain food items.
 Smell also increases appetite. So there is a close relation present between taste and
smell.
 Taste buds :-
 We can taste the food materials with the help of taste buds which are present on the
tongue.
 When we place any food materials on the tongue, gets dissolved in the saliva secreted by
salivary glands in the oral cavity.
 When food substance dissolved in saliva taste buds open and recognise the taste with the
help of taste cells which are present in the taste buds.
 If we press the tongue against the palate. We can recognise the taste easily. Why because
the food substance is pressed against the opening of the taste buds. Then letting it to
reach the taste cells. Then triggering taste signals finally the taste recognised in the brain.
 We can’t identify taste when food is very hot because the taste buds become paralyzed
due to the overheat.
 Mastication :-
 Before swallowing the food materials we are grind, chew and shred them with the help of
teeth and tongue in oral cavity is called mastication. Thus mouth acts as a munching ma-
chine.
 During mastication food size becomes small and sticky due to chew and mixing with saliva.
 Masticated food materials forms into a slurry mass called bolus.
 The 5th cranial nerve has been found to control the movement of muscles in the jaw for
mastication.
 Types of teeth and Dental formula :-
 An adult human has 32 teeth.
 There are 4 types of teeth in man.

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