This slide is based on digestion of animals and humans ect

1. NUTRITION IN ANIMALS

2. INTRODUCTION
• In the previous chapter we learned that plants can prepare their own food
by photosynthesis but animals cannot.
• Animals get their food from plants, either directly by eating plants or indirectly
by eating animals that eat plants. So animals exhibit heterotopic mode of
nutrition.
• Again from previous chapter it is clear that all living organisms (both plants and
animals) need certain nutrients to stay alive and grow and these nutrients are
obtained from food.
• Since this Chapter is about nutrition in animals so in this chapter we will learn
about the process of intake and utilization of food in animals.

3. TYPES OF ANIMALS
 All the animals can be divided into three groups on the basis of their food
habits. These are:
 Herbivores: Those animals which eat only plants are called herbivores.
Examples are Goat, Cow, and Deer etc.
 Carnivores: Those animals which eat only other animals as food are called
carnivores. Examples are Lion, Tiger, and Lizard etc.
 Omnivores: Those animals which eat both, plants and animals are called
omnivores. Examples are Man, Dog and Crow etc.

4. Carnivores animals Herbivores animals
Omnivores animals

5. PROCESS OF NUTRITION
Holozoic nutrition: The method of intake of food is described as holozoic nutrition . It involves different steps
namely, ingestion, digestion, absorption, assimilation and egestion. Human beings exhibit holozoic mode of
nutrition involving five basic steps.
 Ingestion: The process of taking food into the body is called ingestion.
 Digestion : The process of breaking down of complex food molecules into simpler food molecules through
chemical reaction by the action of enzymes is called digestion.
 Absorption: simpler food molecules formed as a result of digestion are absorbed by the cell within the body
of an animal .
 Assimilation: The process in which the absorbed food is used for energy, growth, repair and performing
different life functions is called assimilation.
 Egestion: The process in which the undigested food is removed from the body is called egestion.

6. Nutrition in Amoeba
 Amoeba is a unicellular microscopic organism.
 Amoeba is mostly found in pond water.
 It has no fixed shape.
 It is a mass of protoplasm (the living substance) with a nucleus and some vacuoles (spaces filled with
water) .
 It has pseudopodia (false feet) helps to capture food and in moment.
 Amoeba eats tiny plants and animals as food which floats on water where it lives.
 The mode of nutrition in Amoeba is holozoic.
 The process of obtaining food by Amoeba is called phagocytosis.
 Steps involved in the nutrition of Amoeba:
 Ingestion: Amoeba ingests food by forming temporary finger-like projections called pseudopodia
around it. The food is engulfed with a little surrounding water to form a food vacuole (‘temporary
stomach’) inside the Amoeba.
 Digestion: In Amoeba, food is digested in the food vacuole by digestive enzymes which break down
the food into small and soluble molecules by chemical reactions.
 Absorption: The digested simple and soluble substances pass out of food vacuole into the
surrounding environment.
 Assimilation: the digested food is assimilated into the cytoplasm and is used for growth and life
activity of the animal.
 Egestion: The remaining undigested material is moved to the surface of the cell and thrown out of the
body of Amoeba.

8. AMEOBA

9. NUTRITION IN PARAMECIUM
 Paramecium is also a tiny unicellular animal which lives in water.
 Ingestion: Paramecium uses its hair like structures called cilia to
sweep the food particles from water and put them into mouth.
 Ingestion is followed by other steps such as digestion, absorption,
assimilation and egestion which are same as those we studied in
Amoeba

10. NUTRITION IN HYDRA
 Hydra is a simple multicellular animal.
 It has a number of tentacles around its mouth, which are used for ingestion of
food.
 These tentacles entangle small aquatic animals and kill them with their stinging
cells.
 After this they push them into their mouth. Now inside their body cavity digestive
juices are secreted by the surrounding cells.
 These juices digest the food and the digested food is absorbed through the cavity
walls and assimilated in the cells.

11. NUTRITION IN OTHERS
HYDRA
 The frog uses its long sticky tongue to catch insects. Frogs have well developed
digestion system in which the digestion of food takes place.
SPIDER
 In spiders digestion of food actually takes place outside their body.
 A spider weaves a sticky web in which small insects get stuck.
 It then injects digestive juices into the body of the insect, which digests the body
part of the insects.
 The spider then sucks up the digested food.

12. HUMAN DIGESTIVE SYSTEM
 The mouth and Buccal Cavity.
 The food pipe / oesophagus.
 The stomach
 Absorption in the Small Intestine
 Large Intestine
 Rectum and Anus

14. GLANDS IN HUMANS
 The glands / juices which are associated with human digestive system are:
 Salivary glands- Located in mouth or Buccal Cavity, secretes saliva.
 Stomach walls- secretes gastric juices.
 Liver- It is the largest gland situated in the upper part of abdomen on the right
side, secretes bile juice.
 Pancreas- located just below the stomach, secretes Pancreatic juice.
 Intestinal wall – secretes intestinal juices.

15. THE MOUTH AND THE BUCCAL CAVITY
 Food is taken into the body through the mouth. The process of
taking food in to the body is called ingestion. We chew the food
with the teeth and break it down mechanically into small pieces.
Each tooth is rooted in a separate socket in the gums . Our teeth
vary in appearance and per for different functions. Accordingly they
are given different names. After chewing, food mixes with saliva and
goes into Oesophagus this process is called mastication.

16. THE TOUNGE
 The tongue is a fleshy muscular organ in the mouth which is attached at the back to the floor of the buccal cavity
(mouth cavity).
 The various functions of the tongue are as follows:
 1) The tongue helps in mixing saliva with food during chewing (which is essential for the digestion of food).
 2) The tongue helps in swallowing the food into the food pipe.
 3) The tongue helps in getting the taste of food.
 4) The tongue is essential for talking (or speaking).
 There are four types of tastes : sweet, salty, sour and bitter.

17. TASTE BUDS (TOUNGE)
 The tongue has taste buds which detect different tastes of food. Our tongue has four kind of
taste buds which detect sweet, salty, sour and bitter tastes. The taste buds for each of these tastes are located in
different parts of the tongue.
 Different parts of the tongue are sensitive to different tastes.
 (1) Most taste buds at the front of the tongue detect sweet and salty tastes. The maximum effect of sweet taste is
felt at the tip of the tongue whereas the maximum effect of salty taste is felt just behind the tip of the tongue.
 (2) Most of the taste buds on the sides of the tongue detect sour taste.
 (3) Most of the taste buds at the back of the tongue detect bitter taste.

19. TEETHS
 We chew the food with the teeth and break it down mechanically into small
pieces. There are four types of teeth in our mouth. These are:
 (1) Incisors,
 (2) Canines,
 (3) Premolars and
 (4) Molars.

20. TOOTH
 The upper part of a tooth (which we can see in the mouth) is called crown. The middle part of a tooth (which is
inside the gums) is called neck whereas the lower part of a tooth (which is embedded in the jaw bone) is called
root.
 structure of tooth
 Every tooth is held in a separate socket in the jaw.
 Different types of teeth differ in appearance and perform different functions.

22. TYPES OF TEETHS
 Incisors
 Incisors are the chisel shaped teeth at the front of the mouth. The incisors are for biting and cutting the food. There are
four incisors in the centre of each jaw.
 2) Canines
 Canines are the large, pointed teeth just behind the incisors. The canines are for piercing and tearing the food. There are
two canines in each jaw, one behind the left incisor and the other behind right incisor.
 3) Premolars
 Premolars are the large teeth just behind the canines on each side . Premolars have large, flat surfaces. The premolars are
for chewing and grinding the food. There are four premolars in a jaw, two on each side.
 4) Molars
 Molars are very large teeth which are present just behind the premolars, towards the back of our mouth. Molars are for
chewing and grinding the food. There are six molars in each jaw, three on each side. Molars are present only in the
permanent set of teeth. They are not present in the temporary set of teeth called milk teeth.

24. STAGE OF TEETHS
 Adult men and women have a total of 32 teeth. Of these, 16 are in the upper jaw and 16 are in the lower jaw. The 16
teeth of each jaw consist of 4 incisors, 2 canines, 4 premolars and 6 molar
 Milk Teeth and Permanent Teeth
 In human beings, the teeth grow twice.
 1) First time the teeth grow when one is a small baby (or infant) .This set of teeth is called milk teeth. They are a
temporary set of teeth. The milk teeth loosen and begin to fall off at the age between 6 and 8 years.
 2) When milk teeth fall off in a child, then another set of teeth grow in their place. So, second time the teeth grow
when one is a child. The second set of teeth is called permanent teeth. The permanent teeth grow in place of milk
teeth. The permanent set of teeth remains till the old age . But when old people lose their permanent teeth, then
new teeth do not grow in that place .

25. TOOTH DECAY
 Tooth decay is a process in which the tooth becomes rotten due to the formation of
cavities (holes) inside it leading to toothache.
 If we do not clean our teeth and mouth after eating food, then many harmful bacteria
begin to grow and live on the teeth. These bacteria act on the sugar present in the left-
over food particles sticking to the teeth to form acid. The acid thus formed eats up the
enamel and dentine of the tooth gradually and ultimately makes a cavity (or hole) in the
tooth. When this cavity (or hole) reaches the pulp cavity of the tooth (which contains
nerves), our tooth becomes painful and we get tooth ache.
 In extreme cases, tooth decay can lead to the loss of whole tooth (because it may require
extraction).

27. PREVENT TOOTH DECAY
 We should rinse the mouth thoroughly with clean water after every meal.
 We should clean our teeth with a brush and toothpaste at least twice a day.
 A dental floss should be used to take out food particles trapped between the
teeth.
 We should eat less of sugary foods such as sweets, chocolates, toffees, and ice
cream, etc.
 Too many cold drinks should also be avoided.

28. TEETHS

29. OESOPHAGUS
 Oesophagus/ Food pipe is a long tube starting from throat and connecting mouth to the
stomach.
 food from the mouth reaches the stomach through Oesophagus.
 The moment of the food along Oesophagus and the alimentary canal is helped by automatic
contraction of muscles lining the walls of the food these moments are also called peristalsis or
peristaltic moments.
 During this moment the food is moved by squeezing of muscles from behind pushing the food
forward
 Saliva is little alkaline hence the food from mouth passing through Oesophagus and reaching
stomach is alkaline

30. STOMACH
 Stomach is a muscular bag that receives food from the Oesophagus.
 In the stomach food is mixed with gastric juice and hydrochloric acid given out from the walls of the stomach.
 Gastric juice helps in the digestion of proteins.
 Stomach works like a mixer and a churner. It churns the food into a milky paste called chyme in about 2 to 3
hours.
 Hydrochloric acid (HCI) mixed with food from the mouth provides acidic base to the food and also kills some
of the microorganisms.
 Mucus present along the walls of stomach protects it from any reaction from its own secretion of hydrochloric
acid.

31. STOMACH AND
OESOPHAGUS

32. DIARRHEOA

33. SMALL INTESTINE
The small intestine is a very long tube. It is about 7.5
metres long. Though small intestine is very long it is
called small intestine because it is quite narrow tube.
The small intestine is arranged in the form of a coil in
our belly . The small intestine in human beings is the
site of complete digestion of food. The small intestine
is also the main region for the absorption of digested
food.

34. SMALL INTESTINE (PART A )
 The partially digested food from stomach comes into small intestine. The small intestine receives secretions of digestive
juices from the liver, pancreas and its own walls. All these digestive juices carry out the complete digestion of food.
 Liver secretes a liquid called bile (which is stored temporarily in the sac called gall bladder).
 The bile plays an important part in the digestion of fats. Actually, bile converts fats into tiny droplets so that their
further breakdown becomes easy.
 Pancreas secretes pancreatic juice. Pancreatic juice breaks down fats completely into fatty acids and glycerol. Pancreatic
juice also breaks down starch carbohydrate and proteins into simpler forms.
 The walls of small intestine secrete a digestive juice called intestinal juice. Intestinal juice breaks down the starch
carbohydrate completely into the simplest sugar called glucose, and the proteins into amino acids. Our food breaks
down completely into very small, water soluble substances like glucose, fatty acids, glycerol and amino acids. This is
called digested food.

35. SMALL INTESTINE (PART B)
 The digested food can now pass into the blood vessels in the walls of the small intestine. This process is called absorption.
 The inner surface of the small intestine has millions of tiny, finger-like outgrowths called villi. The presence of villi gives the
inner walls of the small intestine a very large surface area (which helps in the rapid absorption of food). Thus, the role of
villi in the small intestine is to increase the surface area for the rapid absorption of digested food. Each villus has a network
of thin and small blood vessels (called blood capillaries) close to its surface. The surface of villi absorbs the digested food
materials into blood flowing through them.
 Blood carries the absorbed food materials to the cells in all the parts of the body. In the cells, food is used for energy,
growth and repair. This is called assimilation. Glucose breaks down in the cells with the help of oxygen to form carbon
dioxide and water, and releases energy. Fatty acids and glycerol build components of cells and form fats to be stored in
the body as food reserves. Amino acids are used to make proteins required for the growth and repair of the body.
 The food that remains undigested and unabsorbed passes from the small intestine into large intestine

36. LARGE INTESTINE
 The large intestine is about 1.5.metres long. It is called large
intestine because it is a quite wide tube. The undigested and
unabsorbed food from the small intestine enters into large
intestine. The large intestine absorbs most of the water from the
undigested food material. Due to the removal of water, the
undigested food becomes semi-solid. This undigested food (or
waste material) is stored in the last part of large intestine called
rectum for some time. The undigested , semi-solid waste is passed
out from our body through anus in the form of faeces. This is
called egestion.

38. REVISING THE ALIMENTARY CANAL
 A long tube running from mouth to anus of a human being (or other animals) in which digestion and absorption of food takes place is
called alimentary canal. It is also known as gut or digestive tract.
 2) It is about 8 to 9 metres long in humans.
 3)The alimentary canal is a continuous canal which has many parts such as mouth (buccal cavity), oesophagus (food pipe), stomach, small
intestine, large intestine, rectum and anus.
 4)Three glands are also associated with alimentary canal. These are salivary glands, liver and pancreas.
 5)The food enters the alimentary canal at the mouth (or buccal cavity). As the food travels through the various parts of alimentary canal, it
gradually gets digested. During the passage of food through alimentary canal, the various glands (salivary glands, liver, pancreas) and
inner walls of stomach and small intestine, secrete digestive juices. These digestive juices convert the complex substances of food into
simpler substances which can be absorbed by the body.
 6)The undigested part of food is defecated (thrown out) through the last part of alimentary canal called anus.

39. DIARRHOEA
 The condition in which a person passes out watery stools frequently is called diarrhoea. Diarrhoea may be
caused by an infection (due to disease causing micro-organisms), food poisoning or indigestion. Diarrhoea is
very common in children.
 Diarrhoea leads to the loss of water and salts from the body of a person (through frequent watery stools). The
loss of water from the body of a person through watery stools is called dehydration.
 The sudden loss of too much water (or dehydration) makes a person dangerously ill in a very short time .
Excessive dehydration of body caused by diarrhoea can even lead to death
 In order to prevent dehydration, the person suffering from diarrhoea should be given a solution of sugar and
salt in clean water, many times a day. The solution of sugar and salt in water is called Oral Rehydration Solution
(ORS) (because it is given to the person orally, through mouth). ORS makes up the loss of water and salt in the
body . The sugar gives energy which helps in speedy recovery.

40. DIGESTIVE SYSTEM

41. DIGESTION IN GRASS EATING ANIMALS
 The herbivorous animals eat mainly grass and other plant leaves as food. Grass is
rich in a carbohydrate called cellulose (which acts a source of energy).
 The cellulose carbohydrate present in grass can be digested by the action of
certain bacteria which are present only in the stomach of animals called ruminants
like cattle (cows, buffaloes) goat, sheep, deer, antelope, giraffe.

42. RUMINANTS (PART 1)
 The animals (such as cow) which eat grass have a special stomach to digest the tough cellulose carbohydrate
present in grass .
 The stomach of a cow is large and consists of four compartments (or four chambers).The first compartment
of a cow’s stomach is the biggest and it is called rumen.
 When cow eats grass as food while grazing, it does net chew it completely (because it has no time for it).
The cow swallows the grass quickly with little chewing and stores it in the rumen (which is the first
compartment of stomach).
 The rumen contains cellulose digesting bacteria. The bacteria present in the rumen of a cow start to digest
cellulose carbohydrate present in grass food. Thus, the grass is partially digested in the rumen. The partially
digested food (or partially digested grass) in the rumen of a cow is called cud

43. RUMINANTS (PART 2)
 After some time, when the cow is resting, the cud from rumen is brought back to the mouth of cow in small amounts at a
time. The cow now chews the cud thoroughly. This is why many times we see a cow (or buffalo) moving its jaws from side
to side and chewing continuously even when it is not eating grass
 The process by which the cud (partially digested food) is brought back from the stomach to the mouth of the animal and
chewed again is called rumination (or chewing the cud). All the animals which chew the cud are called ruminants.
 When the cud is thoroughly chewed in the mouth of the cow, it is swallowed again. But this chewed cud does not go
back to rumen. The thoroughly chewed cud now goes into the other compartments of the cow’s stomach and then into
the small intestine for complete digestion and absorption.
 The animals called ruminants can survive on grass as food because they have certain bacteria in the rumen part of their
stomach which can digest the cellulose carbohydrate present in grass (and other plant leaves).
 The cellulose digesting bacteria are not present in the body of human beings due to which human beings cannot digest
cellulose carbohydrate present in plant foods.
 We (human beings) cannot survive by eating only grass (or raw leafy vegetables) because these foods contain mainly
cellulose carbohydrate and our body does not have bacteria which can digest cellulose carbohydrate.

45. RUMINATION

46. THE END
SUB TOPICS CLEAR
 Types of animals
 Holozoic nutrition
 Nutrition in amoeba and other animals
 The alimentary canal
 Rumination