Digestion of Food

1. BY- NIHARIKA VERMA
DIGESTIVE SYSTEM

2. DIGESTIVE SYSTEM
 The digestive system is a group of organs working
together to convert food into energy and basic passes,
through along tube inside the body known as the
Alimentary canal or the Gastro intestinal tract (GIT Tract).
Parts of Digestive System  Salivary Glands, Pharynx,
Esophagus, Stomach, Small Intestine, Large Intestine,
Rectum, Liver, Gall bladder, Pancreas (pancreatic juice).
Accessory Digestive Organs- Liver(produce gastric
juice/bile), Gall bladder (store gastric juice/bile).
• Digestion time varies between individuals and between
men and women.
• After you eat, it takes about six to eight hours for food to
pass through your stomach and small intestine.
• Food then enter your large intestine (colon) for further
digestion, absorption of water and finally elimination of
undigested food.

3. FUNCTIONS OF DIGESTIVE
SYSTEM
 ESOPHAGUS- Carries food from the mouth to the
stomach.
 STOMACH- The organ where digestion of protein
begins.
 SMALL INTESTINE- The organ where most digestion
occur.
 LARGE INTESTINE- Also called colon. It absorbs
water and sodium from stool.
 APPENDIX- A pouch attached to the first part of the
large intestine. No one can know its function.
 LIVER- The largest organ inside the body. Makes bile
(fluid that helps break down fats and gets rid of
wastes in the body). Changes food into energy and
cleans alcohol, some medicines and poisons from the
blood.
 GALL BLADDER- Stores the bile made in the liver,
then empty it to help digest fats.

4.  PANCREAS- A gland that makes enzymes for
digestion and the hormone insulin (which helps
the body) turn food into energy.
 RECTUM- The lower end of large intestine
leading to the anus.
 ANUS- The opening at the end of the digestive
tract where bowel movements leave the body.

6. THE DIGESTIVE PROCESS
1. The start of the process The Mouth- The digestive
process begins in the mouth. Food is partly broken
down by the process of chewing and by the
chemical action of salivary enzymes (these
enzymes are produced by the salivary glands and
break down the starches into smaller molecules).
2. On the way to the stomach  The Esophagus- After
being chewed and swallowed, the food enters the
esophagus, the esophagus is a long tube that runs
from the mouth to the stomach. It uses rhythmic,
wave like muscle movement (called Peristalsis) to
force food from the throat into the stomach. This
muscle movement gives us the ability to eat or drink
even when we are upside down.

7. 3. In the stomach  The stomach is a large, like organ that churns
the food and bathes it in a very strong acid (gastric acid). Food in
the stomach that is partly digested and mixed with stomach acids
is called Chyme.
After being in the stomach, food enters the duodenum, the first part
of the small intestine. It then enters the jejunum, and then the
ileum (the final part of the small intestine).
In the small intestine, bile (produced in the liver and stored in the
gall bladder), pancreatic enzymes and other digestive enzymes
produced by the inner wall of the small intestine help in the
breakdown of food.
4. In the large intestine  After passing through the small intestine,
food passes into the large intestine. In large intestine, some of
the water and electrolytic (chemical, like sodium are removed
from the food). Many microbes (bactericides, lactobacillus,
acidophilus, E coli) in the large intestine help in digestive
process. The first part of the large intestine is called the Cecum (
the appendix is connected to the cecum). Food then travels
upward in the ascending colon.

8. FUNCTION OF DIGESTIVE
SYSTEM
 LIVER (ACCESSORY ORGANS)
 GALL BLADDER (ACCESSORY ORGANS)
 PANCREAS
 LARGE INTESTINE
 APPENDIX
 ESOPHAGUS
 STOMACH
 SMALL INTESTINE
 RECTUM
 ANUS

9. QNA
 Carbohydrates turned into  GLUCOSE
 Protein turns into  AMINO ACIDS
 Fats and oils are turned into  FATTY ACIDS AND
GLYCEROL
 Salivary _GLANDS_ begins digestion of starch.
 Is bile is an enzyme?  NO
 The Gastrointestinal Tract  ORGANIZATION:
MOUTH – ANUS
 Accessory Organs  SALIVARY GLANDS, LIVER,
PANCREAS, GALL BLADDER
 Overview of Digestion  PHYSICAL MOVEMENT-
Peristalsis, Segmentation
 CHEMICAL REACTION-
Enzymes, Other Secretions.

10. Physical Digestion
 The food we eat consists of large lumps of
material.
 We must bite off small pieces and chew them up
into even smaller ones before swallowing them.
 Once it gets to the stomach the food is further
broken down by the stomach muscular walls.
 This is Physical Digestion.

11. Chemical Digestion
 But the substances which our body needs cannot
be absorbed into our blood until they have been
broken down further- converted into small soluble
chemicals.
 This is done with the aid of enzymes and other
chemicals in our gut, and is called Chemical
Reaction.

12. DIGESTIVE ENZYMES
 The enzymes in our digestive system break down
complex substances into simpler ones which can
be absorbed.
 Enzymes work best at their optimum PH, so if the
stomach, for example, does not have enough
acid, its enzyme, pepsin, will not work properly.
DIGESTION AND ABSORPTION
 Small intestine sections of small intestine –
Duodenum, Jejunum, Ileum.

13. DIGESTION
- Bicarbonate neutralizes stomach acid.
- Pancreatic and intestinal enzymes – Carbohydrates, Fat, Protein
DIGESTION AND ABSORPTION
 Small Intestine – ABSORPTION
- Folds, villi, microvilli expand absorptive surface.
- Most nutrients absorbed here.
- Fat soluble nutrients go into lymph.
- Other nutrients into blood.
 Large Intestine – DIGESTION
- Nutrient Digestion already complete.
- Some digestion of fiber by bacteria.
- ABSORPTION
-Water
- Sodium, potassium, chloride
- Vitamin K (produced by bacteria)

14. SALIVARY GLANDS
 Salivary glands are a group of organ present in
our mouth that secrets saliva.
 It is found in mammals only.
 It is an exocrine gland that secrets substances
outside the body or within a body cavity.
 Saliva contains various chemicals with water
including mucus, salts, anti bacterial substances,
enzymes and chemicals that control Ph in the
mouth.

15. FUNCTIONS OF SALIVARY
GLANDS
 Saliva is a mixture of water, mucus, anti bacterial
substances, and digestive enzymes.
 Therefore, saliva has many uses. One of the digestive
enzyme alpha- amylase helps to break down the
starch present in our food into a simpler one like
glucose and maltose.
 Whenever we chew, we attractive these glands to
secrete an enzyme to breakdown the food.
 Saliva has lubricating properties- It protects the inside
cavity of our mouth, teeth, and throats as we begin to
swallow the food bolus.
 It also cleanses the mouth after the meal and
dissolves it into chemicals that we perceive as taste.
 Parotid gland is the largest salivary gland.