nutrition in animals in details for class 7(CBSE)

2. CONTENTS-
 What is nutrition and feeding?
 Processes involved in nutrition in animals
 Nutrition in amoeba, hydra, frog,
paramecium, spider, mosquito
 Human digestive system- digestion in the
mouth, stomach, small intestine, large
intestine, assimilation and egestion
 Ruminants

3. PROCESSES INVOLVED IN NUTRIRION:
 Ingestion
 Digestion
 Absorption
 Assimilation
 Egestion

4. NUTRITION IN AMOEBA
 Unicellular organism
 Engulfs tiny particles of food by false feet
 Pseudopodia joins to form food vacuole
 Food is digested by digestive juices.
 Provides energy
 Wastes are removed by egestion.

5. HYDRA
 Simple, multi-cellular
animal.
 Tentacles around its mouth
for ingestion of food, then
push the insect into the
mouth
 In the body cavity digestive
juices are secreted to digest
the food. Then absorbed
and assimilated in the cell.

6. SPIDER
 Digestion occurs outside the body.
 Weaves sticky web where small animals
get stuck.
 Injects digestive juices on the insect.
 Sucks up the digested food.

7. CONTD..
 Frog - long sticky tongue - catch its prey.
 Paramecium - stiff- hair like projections called
cilia-for ingestion.
 Mosquito - proboscis - sucks blood.
 Housefly - feeding tube - sucks up food in
solution form.
 Butterfly – proboscis - suck nectar from
flowers.

9.  Digestion in the mouth
 Digestion in the stomach
 Digestion in small intestine and absorption
 Assimilation
 Egestion

10. CONTD..
 Our body performs the steps inside a long
tube , coiled structure , called the gut or
alimentary canal.
 Its main parts are – the mouth, food pipe,
stomach, small intestine, large intestine ,
rectum and anus.
 Organs that secrete digestive juices –
salivary glands, liver, gall bladder,
pancreas and inner walls of stomach and
small intestine.

12.  Food is taken in through mouth. The first part of
digestion takes place in mouth when food is chewed.
 Saliva is the digestive liquid found in mouth.
 Saliva is secreted by three pairs of salivary glands (
parotid , sub-mandibular and sub-lingual).
 Chewing food into small pieces and mixes it with saliva
is mastication.
Functions-
 Breakdown starch into sugars.
 Makes food wet and slippery.

14. CONTINUED…
TONGUE:
 Tongue is a muscular organ that helps us to eat , pushes
food towards our teeth.
 Helps to mix the food with saliva and enables us to
swallow it.
 Helps us to speak.
 Taste buds are present. Why?

15.  Food slides down the pharynx into the food pipe.
 Peristalsis – Pushing down of food by muscles in a
wave - like motion.
 Stomach is a J- shaped bag made up of muscles,
hold 2 litres food at a time.
 Food stays in the stomach from a few minutes to a
few hours depending on the type of food eaten.
 Secretes mucous, HCl (kills bacteria that enter along
with food & help indigestion of proteins) and
digestive juices.

17. CONTINUED…
 Stomach muscles squeeze and mix the food with
digestive juices.
 These juices break down proteins into amino
acids.
 Food gets partially digested here.
 Food goes to small intestine where most of the
digestion occurs.

19.  Last steps of digestion takes place here.
 The muscles in the S.I. mix food with more
digestive juices.
 Liver secretes bile juice, stored in gall bladder.
Fats into fatty acids and glycerol.
 Pancreas secretes pancreatic juice. Starch into
simple sugars and proteins into amino acids.

20. ABSORPTION IN THE SMALL INTESTINE:
 Absorption of food occurs – villi
 Villi – increases the surface area of the food
 Each villus has a network of fine blood
capillaries close to the surface.
 Food absorbed on the surface passes into the
blood in the capillaries.

21.  Food absorbed –blood – transported to different
parts of our body, which is used to provide energy
& materials for growth & repair of body tissues.
 Glucose (cells) carbon-dioxide + water+ energy
 Amino acids - building and repairing of body parts.
 Fatty acids & glycerol- under skin- energy reserves.

22.  Undigested food moves from small intestine into a
wide tube called large intestine.
 Most of the water present in wastes are absorbed
here.
 Waste that is solid is stored in the rectum and
passed out of the body through the anus.

23.  Hooved , plant eating animals.
 Examples- cows , buffaloes, goats.
 Digestion occurs in two-steps, (complicated stomach
having 4 chambers).
 Food swallowed goes into the first chamber called
rumen, partially digested & is called cud.
 Then goes to the second chamber where it is returned to
the mouth for thorough chewing, called rumination.
 Food is swallowed for a second time & then digested in
the remaining two chambers.
 Finally sent to the small intestine , for absorption of
nutrients.
RUMINANTS

24. ?

25. Thank you