The human digestive system is approximately 10 meters long and breaks down food through mechanical and chemical digestion. Along the pathway from ingestion to egestion, food is broken down into nutrients that can be absorbed and used by the body. The major organs that make up the digestive system include the mouth, esophagus, stomach, small intestine, large intestine, and anus. Accessory organs like the liver, gallbladder and pancreas also aid in digestion.

1. Digestive System
( Also called Gastrointestinal or Alimentary system )

2. • The food we consume will be broken down into
nutrient which later can be absorbed by the
body
• There are 6 nutrients that are needed to keep
healthy ;
1. Carbohydrates
2. Fat
3. Protein
4. Vitamins
5. Minerals
6. Water
Created By Alfi Msk _ A biology Teacher of GIS JH

3. 1. Carbohydrates
• Are a source of energy
• Excess carbohydrates will be stored in the liver and
muscles
• Sources of carbohydrates are rice, corn, sweet potatoes,
potatoes, cassavas, etc
• 1 gr of carbohydtares provides 4,1 cal.
• In the digestion process, carbohydrates are brokendown
into simple saccharides or monosaccharides
• The body will then absorb these monosaccharides
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4. • If we consume more carbohydrates more than
our body needs, the excess will be converted
to glycogen or fat
• Glycogen will be stored in the liver or muscles
• Fat will be stored in areas around the waist,
around the kidneys, and under the skin
• Lack of carbohydrates will cause the body to
be thin and weak, and it will cause a lack of
energy, anxiety, and reduced body immunity
Created By Alfi Msk _ A biology Teacher of GIS JH

5. There are 3 kinds of carbohydrates, they are ;
1. Monosaccharides
 carbohydrates that consist of 1 simple sugar
 they are glucose, fructose, galactose
2. Disaccharides
 carbohydrates that consist of 2 simple sugars
 they are ;
a. Maltose = glucose + glucose
b. Sucrose = glucose + fructose
c. Lactose = glucose + galactose
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6. 3. Polisaccharides
 carbohydrates that consist of many simple
sugars
 for example, rice, bread, potatoes, etc
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7. 2. Fat
• Its function as a source of energy
• 1 gr of fat provides 9,3 cal
• Fat is acquired from both animals and plants
• Fat that is acquired from animals is called animal
fat, for ex. Butter, milk, meat, eggs, etc
• Fat that is acquired from plants is called
vegetable oil, coconuts, candlenuts, peanuts,
avocado, etc
Created By Alfi Msk _ A biology Teacher of GIS JH

8. • In the digestion process, fat is broken down
into fatty acids and glycerol with the help of
the enzymes
• Fat also has other function ;
a. As a food store, that is stored under the
skin
b. Protect vital organs
c. As an insulator and prevents the loss of
body heat
d. Helps to dissolve vitamin A, D, E, and K so
that they can be easily absorbed.
Created By Alfi Msk _ A biology Teacher of GIS JH

9. 3. Protein
• The main function of protein is for the formation
of the body’s main structure, cell regeneration,
and coordination of biological processes in the
body
• 1 gr of protein provides 5,3 cal.
• Proteins are acquired from both animals and
plants, that are acquired from animals are called
animal proteins (meat, fish, egg, etc) and that
are acquired from plants are called vegetable
proteins (soybeans, peanuts, green beans, etc)
Created By Alfi Msk _ A biology Teacher of GIS JH

10. 4. Vitamins
• Vitamins are needed only in small amounts, but lack of one
of vitamins can cause avitaminosis.
• Vitamins act as coenzymes (biocatalysts), substances that
help accelerate chemical reactions in the body.
• Based on their solubility, vitamins are classified into water-
soluble and fat-soluble vitamins.
a. Water-soluble vitamins are vitamin B and C.
These vitamins can not be stored in the body, which
means that the body will only use as much as it needs
and excretes the rest.
b. Fat-soluble vitamins are vitamin A, D, E and K
Created By Alfi Msk _ A biology Teacher of GIS JH

11. 5. Dietary Minerals
• Minerals are needed only in small amounts
• Each mineral has certain functions in the body, and lack
of a mineral is called mineral deficiency
• Examples of dietary minerals needed by the body are as
follows ;
1. Calcium (Ca)
2. Iron (Fe)
3. Iodine (I)
4. Phosporus (P)
5. Potassium (K)
6. Sodium (Na)
7. Fluorine (F)
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12. 6. Water
• Water is the main component of protoplasm
• The human body contains 60% of water
• In the body, water has the role of ;
a. Dissolving nutrients and accelerating chemical
reactions
b. Carrying metabolic waste
c. Carrying other bodily substances
d. Forming body fluids
e. Regulating body heat
Created By Alfi Msk _ A biology Teacher of GIS JH

13.  The human body’s “gastrointestinal tract” or “alimentary canal”
is up to 10m long
 Along this pathway:
Ingestion  Digestion  Absorption  Egestion
 About 95% of ingested food is absorbed and made available to our
body, the rest is egested
 Digestion is the breakdown of substances (other organisms!) into
small molecules that can be absorbed by cells
 There are two ways of digestion ;
 Physical/Mechanical
 Chemical
Created By Alfi Msk _ A biology Teacher of
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14. The 2 ways of digestion
Mechanical Chemical
 Changes the physical form of food  Changes the chemical composition
 Chew of food with the aid of digestive
 Tear enzymes
 Grind • Lipids to fatty acids
 Mash • Proteins to individual amino
 Mix acids
 The breakdown of food into small • Carbohydrates into simple sugars
pieces without chemically changing
them into different substances
 Helps facilitate chemical digestion by  Digestive enzymes are special
increasing surface area proteins that help break up large
 Increased surface area exposes food molecules of food into very tiny
pieces to enzymes and other
substrate molecules and increases molecules that can be absorbed
the rate of metabolic reactions and used by the cells in the form of
 Examples: teeth, stomach (HCl), nutrition.
intestines (bile) Created By Alfi Msk _ A biology Teacher of
GIS JH

15. 6 Functions of the Digestive System
1. Ingestion:
occurs when materials enter digestive tract via the mouth
2. Mechanical processing:
crushing and shearing
makes materials easier to propel along digestive tract
3. Digestion:
is the chemical breakdown of food
into small organic fragments
for absorption by digestive epithelium
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16. 4. Secretion
is the release of water, acids, enzymes, buffers, and
salts
by epithelium of digestive tract
by glandular organs
5. Absorption
 movement of organic substrates, electrolytes,
vitamins, and water
 across digestive epithelium
 into interstitial fluid of digestive tract
6. Excretion
removal of waste products from body fluids
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17. Components of the Digestive System
Digestive Tract
Gastrointestinal (GI)
tract divided into:
 Alimentary canal.
 Accessory digestive
organs.
Is a muscular tube
Extends from oral
cavity to anus
Created By Alfi Msk _ A biology Teacher of
GIS JH

18. • Your digestive tracts or food tube consist of the
following:
(1) mouth
(2) esophagus
(3) stomach
(4) small intestine
(5) large intestine
(6) Anus
• The accessory organs are :
(1) salivary glands
(2) pancreas
(3) liver
(4) gallbladder
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19. The Organs of Digestive System movie
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20. Digestion from the Mouth
• Saliva – lubricates the food and secretes an
enzyme, ptyalin or salivary amylase, that
convert starch to maltose
• 3 Salivary Glands
• Parotid glands
• Submaxillary glands
• Sublingual glands
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21. • Tongue – pushes
the food to the
back of your
mouth
• Bolus – a soft,
mass of rounded
ball of food that
is being chewed
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22. Digestion from the Esophagus
• Pharynx – an alimentary canal where food
goes down after the digestion in the mouth
• Epiglottis- a flap of tissue that closes over
the trachea to prevent the food from
entering
• Esophagus – carries the food down the
stomach
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23. Digestion from the Stomach
Stomach
 a large J-shape organ found at the end of the
esophagus
 contraction of the muscles of the stomach causes
the churning, squeezing and twisting effect
 it where partial digestion of food happens
Cardiac spincter – closes and opens to allow the
flow of food from the esophagus to the stomach
Pepsin – enzymes secreted in the stomach that
breaks down the protein
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24. • Pyloric valve or spincter – opens and
closes to allow the food getting in the small
intestine
• Chyme – partial product retained in the
stomach before transferring into the small
intestine
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25. Digestion from the Small Intestine
• 3 Major Parts
1.duodenum – upper 20 cm
2. jejunum – 2.5 meters long
3. ileum – longest half coiled into the abdominal cavity
• It is where the final digestion and absorption of food
take place
• Villi – small finger-like projection in the lining of the
small intestine that is used in absorption
• Maltase – enzymes that break down maltose into
glucose
Created By Alfi Msk _ A biology Teacher of
GIS JH

26. PANCREAS
• Pancreas – a digestive
gland that serves 2
functions:
1. secrete hormones
that regulate blood
glucose
2. secretes pancreatic
juice that netralizes
the acid in the
stomach
Created By Alfi Msk _ A biology Teacher of
GIS JH

27. LIVER
• The liver is the
largest gland in
our body that
carries the gall
bladder
Created By Alfi Msk _ A biology Teacher of
GIS JH

28. GALL BLADDER
• Gall bladder –
Produces a blue
green fluid
called bile
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29. The Gallbladder Movie
Created By Alfi Msk _ A biology Teacher of GIS JH

30. LARGE INTESTINE
• Undigested food goes
down into the large
intestine
• It is where the
absorption of water is
happen
• It is also called as colon
FECES – remaining food
material
Created By Alfi Msk _ A biology Teacher of
GIS JH

31. RECTUM AND ANUS
Rectum
• 20 to 30 cm
• a muscular cavity
where feces is
temporarily stored
Anus – end of the
alimentary canal
Created By Alfi Msk _ A biology Teacher of
GIS JH

32. The Digestive System movie
Created By Alfi Msk _ A biology Teacher of GIS JH

33. The Digestive System Diseases
 Appendicitis
the inflammation of the appendix
may cause inflammation of the diaphragm
membrane
the basic treatment of appendicitis is surgical
removal of the appendix  appendectomy
 Constipation
the delayed passage of waste
continuous constipation may be a symptom of
other diseases
will cause irregular defecation and headache
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GIS JH

34.  Parotitis or Mumps
is a feverish cold caused by virus, soon followed by
swelling and stiffening in the region of the parotid
salivary glands in front of the ear
if you suffer mumps, take a vitamin C supplement
and consult a doctor
 Xerostomia
is a disease that infects the oral cavity
It may cause dry mouth due to the distrubed
production of saliva, which will later affect the food
processing in the mouth
Created By Alfi Msk _ A biology Teacher of GIS JH