ANIMALS OBTAIN NUTRITION FROM PLANTS .

2. DIGESTION
 The breakdown of complex components of food into simpler substances is
called digestion.

3. FUNCTION
 Produces various chemicals to breakdown the food.
 Filters out harmful substances.
 Gets rid of solid wastes.

4. DIGESTION
 MECHANICAL
Changes the physical
form of food
1. Chew
2. Tear
3. Grind
4. Mash
5. Mix
Digestion
Mechanical
Chemical

5.  CHEMICAL
Changes the chemical composition of food with the aid of
digestive enzymes
1. Amylase
2. lipase
3. pepsin

6. THE DIGESTIVE TRACT
 A Long muscular tube with many
sections and areas.
 Begins with the mouth and ends
with the anus.
 Parts of the digestive tract.
 Accessory parts ( organs that are
not in the digestive tract but helps
in the digestion)

7. Mouth
 FUNCTIONS
1) Food enters in the mouth or oral cavity
2) Mechanical breakdown of food
3) Secretion of salivary glands ( Salivary amylase)

8.  STRUCTURE
1)Teeth- cut, tear, crush and grind food.
2) Salivary glands- Produce and secrete saliva
into the oral cavity.
 Parotid ( beneath the cheeks)
 Submandibular ( below the jaw bone)
 Sublingual ( below the tongue)
 Saliva moistens the food and contains
enzymes that begins digestion for starch into
simpler substance.
3) Tongue- Pushes the bolus towards the
pharynx and into the esophagus when
swallowing.

9. ESOPHAGUS
 A Straight muscular tube that is about 10 inches (25 cm) long which
connects the mouth with the stomach.
 Food takes about 4to 8 seconds as it passes through to the stomach.
 Its wall contain smooth muscles that contracts in wavy motion
( peristalsis)
 Cardiac sphincter ( ring –like valve relaxes to allow food the stomach.

11. STOMACH
 J – Shaped muscular sac.
 Has inner folds ( Rugae) that increases the surface area of the stomach.
 Churns and grinds together the bolus into smaller pieces.
 Food is mixed with gastric juices (HCL & enzymes) secreted by the stomach walls.
 HCL helps break down food and kills bacteria that came along with the food.

12. SMALL INTESTINE
 Long (20ft) ,coiled tube beneath the stomach.
 Has three parts-
1. Duodenum
2. Jejunum
3. lleum

13. SMALL INTESTINE
 Site of greatest amount of digestion and absorption.
 Takes about 4-8 hrs. to complete its journey.
 Mucosa ( inner wall) – secretes several enzymes that acts on the
food.
 Where the pancreatic enzymes are emptied into.
 Digested nutrients are absorbed through intestinal walls.
 Absorbed materials cross the mucosa into the blood then other parts
of the body for storage or further chemical change.

15.  Has folded inner walls covered
with fingerlike projections
(villi)
 Each villus has tinier
projections called microvilli
that absorbs digested food.
 Villi and microvilli increases
the surface area of the small
intestine for greater
absorption
 Peristalsis moves the
undigested food to the large
intestine.

16. LARGE INTESTINE
 Also known the large bowel or colon,
 Larger diameter, but shorter (5ft)
 Water is absorbed from the undigested food making the waste harder until it
becomes solid.
 Waste stays for 10-12 hours.

17. LARGE INTESTINE
 Waste is pushed into the expanded portion (rectum) of the large intestine.
 Solid waste stays in the rectum until it is excreted through the anus as
feces.
 Appendix hands on the right side of the large intestine.

18. Accessory organs
 Produce or store enzymes that helps in digestion.
1) Liver
- Largest gland of the body
- Stores vitamins A,D,E,K
- Stores sugar and glycogen
- Produces bile ( watery, greenish substance)
- Secretes bile to the gall bladder via the hepatic
duct and cystic duct.

19. 2) Gall bladder
- Stores bile in between meals
- Secretes bile to the duodenum through the bile duct during mealtime.
3)Pancreas
- Produces a juice that contains enzymes ( amylase and insulin) to break
down carbohydrates , fats and protein.
- Secretes the juice into the duodenum through the pancreatic duct.

20. Digestion in grass eating animals and amoeba
 Have you noticed something special about grass eating animals?

21.  They quickly swallow the grass and store it in a part of the stomach called
rumen.
 Food gets partially digested is called cud.
 Later the cud returns to the mouth in small lumps and the animal chews it. This
process is called rumination

22.  AMOEBA
Amoeba is microscopic single –celled organism found in pond water.
Amoeba has a cell membrane, a rounded, dense nucleus and many small
bubble-like vacuoles in its cytoplasm.
Amoeba constantly changes its shape and position.
It pushes out one, or more finger-like projection, called pseudopodia or
false feet for movement and capture of food.