digestive system class 10

1. DIGESTIVE SYSTEM RITIMA MANHAS
APS RAKHMUTHI

2. NUTRITION :
All the processes such as respiration, nutrition, circulation,
excretion etc. that are necessary for the survival of the living
organisms are known as life processes.
Modes of Nutrition
The two most common types of nutrition are:
 autotrophic nutrition
heterotrophic nutrition.

3. AUTOTROPHIC NUTRITION
It is a type of nutrition in which inorganic materials such as
carbon dioxide, is used up to synthesise organic food by a
process known as photosynthesis.
For example, green plants use an autotrophic mode of
nutrition.
Organisms that use the autotrophic mode of nutrition are
known as autotrophs.

4. HOW DOES AUTOTROPHIC
NUTRITION OCCUR IN PLANTS
USING PHOTOSYNTHESIS?
For photosynthesis to occur, carbon dioxide, water, sunlight and chlorophyll
are the required as raw materials.
Sunlight provides energy, chlorophyll is used to absorb the sunlight, carbon
dioxide is reduced to carbohydrates and water is oxidised to release the
oxygen.
Water is taken up from the soil through the roots.
The site where photosynthesis occurs is known as chloroplast. They contain
a green colour pigment known as chlorophyll that traps sunlight for
photosynthesis.
The steps of photosynthesis are as follows-
•Absorption of light by chlorophyll.
•Conversion of light energy into chemical energy.
•Splitting of water into hydrogen and oxygen.
•Finally, reduction of carbon dioxide into carbohydrates.

5. STOMATA
Leaves contain small
openings known
as stomata which helps in the
exchange of gases. The
stomata/stoma is surrounded
by a guard cell which guards
the opening and closing of
stomata. Guard cells also
contain chloroplast.

6. THE OVERALL EQUATION OF
PHOTOSYNTHESIS IS:

7. HETEROTROPHIC NUTRITION
In this mode of nutrition, an organism is unable to synthesise
its food. It is of the following types-
1.Holozoic nutrition is a type of nutrition where an organism
takes in whole food and breaks it inside the body. For
example, Amoeba.
2.Saprophytic nutrition is nutrition in which organisms feed on
dead and decaying matter. For example, fungi.
3.Parasitic nutrition is nutrition in which an organism feeds on
a living host. For example, Cuscuta.

8. NUTRITION IN HUMAN BEINGS
Humans consist of the alimentary canal which starts from the
mouth and ends at the anus. The parts of the alimentary
canal are as follows-
1.Mouth
2.Pharynx
3.Oesophagus/food pipe
4.Stomach
5.Small intestine
6.Large intestine
7.Rectum
8.Anus

9. HUMAN DIGESTIVE SYSTEM

10. MOUTH
Mouth is the first portion of the
alimentary canal. The mouth consists
of a muscular tongue and teeth. The
cavity inside the mouth is known as
the oral cavity.
Types of teeth present in mouth:
a. Incisors
b. Molars
c. Premolars
d. canine

11. MECHANISM OF DIGESTION OF
FOOD
•Food digestion process begins in the mouth. Food is complex in nature.
•To break down food and absorb it, we need biological catalysts known
as enzymes.
•The mouth contains salivary glands that secrete saliva. Saliva contains
an important enzyme known as the salivary enzyme that breaks down
starch into simple sugars.
•The food then passes via the oesophagus into the stomach. The
movement of the food inside the oesophagus occurs via rhythmic
contraction of muscles, this is known as peristalsis.
• The stomach contains gastric glands that secrete mucus, hydrochloric
acid and pepsin. Pepsin is a protein-digesting enzyme.
•After the stomach, food then enters the small intestine. The small
intestine is larger in herbivores due to cellulose digestion compared to
carnivores.

12. .
•Complete digestion of carbohydrates, proteins and fats
occurs in the small intestine.
•The small intestine receives secretions from the pancreas
and bile from the liver. Bile helps in the emulsification of
fats whereas the pancreas secretes enzymes such
as trypsin for protein digestion. The intestinal wall also
contains glands that secrete intestinal juice.
•The small intestine has villi that increase the surface area for
the absorption of food.
•The unabsorbed food is then transferred to the large intestine
where water is absorbed.
•Undigested food is then expelled out from the anus.

13. CASE STUDY -1:
Carbon and energy requirements of the autotrophic organism are
fulfilled by photosynthesis. It is the process by which autotrophs
take in substances from the outside and convert them into stored
forms of energy. This material is taken in the form of carbon dioxide
and water which is converted into carbohydrates in the presence of
sunlight and chlorophyll. Carbohydrates are utilised for providing
energy to the plant.
a. Write a chemical reaction which occur during photosynthesis?
b. What is stomata? Write its functions.
c. What is chloroplast ?
d. Draw structure of stomata.

14. CASE STUDY -2:
Heterotrophic nutrition is a mode of nutrition in which
organisms obtain readymade organic food from outside
sources. The organisms that depend upon outside sources for
obtaining organic nutrients are called heterotrophs.
Heterotrophic nutrition is of three types: saprophytic,
parasitic and holozoic nutrition.
(i) In which of the following groups of organisms food material
is broken outside the body and absorbed?
(a) Mushroom, green plants, Amoeba
(b) Yeast, mushroom, bread mould
(c) Paramecium, Amoeba, Cuscuta
(d) Cuscuta, lice, tapeworm

15. .
ii) Which of the following is a parasite?
(a) Yeast (b) Taenia
(c) Amoeba (d) Earthworm
(iii) Which of the following is an example of saprotroph?
(a) Grass (b) Mushroom
(c) Amoeba (d) Paramecium
iv) Heterotrophic nutrition involves
(a) production of simple sugar from inorganic compounds
(b) utilisation of chemical energy to prepare food
(c) utilisation of energy obtained by plants
(d) all of these
(v) In Paramecium, food enters the body through
(a) mouth (b) pseudopodia
(c) cilia (d) cytostomed) all of these.

16. THANKYOU
REGARDS
RITIMA
MANHAS