This document summarizes the human digestive system. It describes how digestion involves both mechanical and chemical breakdown of food. Mechanical digestion begins in the mouth through chewing, while chemical digestion occurs through enzymes secreted in the mouth, stomach, pancreas, and intestines. The digestive system is made up of the digestive tract, which includes the mouth, esophagus, stomach, small intestine, large intestine, and anus. Food moves through this tract as it is broken down and nutrients are absorbed for use by the body.

1. DIGESTIVDIGESTIV
EE
SYSTEMSYSTEM

2. -This group of organs that break down-This group of organs that break down
food into smaller particles or moleculesfood into smaller particles or molecules
-This breakdown makes it possible for-This breakdown makes it possible for
the smaller digestive particles to passthe smaller digestive particles to pass
through the intestinal wall into thethrough the intestinal wall into the
bloodstreambloodstream

3. DigestionDigestion
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WhatWhat
isis

4. The chemical breakdown of complexThe chemical breakdown of complex
biological molecules into their componentbiological molecules into their component
parts.parts.
•Lipids to fatty acidsLipids to fatty acids
•Proteins to individual amino acidsProteins to individual amino acids
•Carbohydrates into simple sugarsCarbohydrates into simple sugars
DigestionDigestion

5. •Produces various chemicals to breakProduces various chemicals to break
down the food.down the food.
•Filters out harmful substances.Filters out harmful substances.
•Gets rid of solid wastes.Gets rid of solid wastes.
FunctionsFunctions

6. TYPESTYPES
OFOF
DIGESTIODIGESTIO
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7. •Changes the chemical composition of food withChanges the chemical composition of food with
the aid of digestive enzymesthe aid of digestive enzymes
CarbohydrateCarbohydrate
ProteinProtein
LipidLipid
•Digestive enzymes are special proteins that helpDigestive enzymes are special proteins that help
break up large molecules of food into very tinybreak up large molecules of food into very tiny
molecules that can be absorbed and used by themolecules that can be absorbed and used by the
cells in the form of nutrition.cells in the form of nutrition.
Chemical DigestionChemical Digestion

8. 1. Liver
• Largest gland in the body
• Aids in chemical digestion by producing bile.
• Occupies much of the space in the upper portion of the
abdomen
2. Gall bladder
• A small organ found on the surface of the liver which
stores the bile.
3. Pancreas
• Large glandular organ lying just below the stomach
Secretes different enzymes and pour these into the small
intestines via the common bile duct
Chemical DigestionChemical Digestion

9. 4. Intestinal Glands
Completes the digestion of food.
1. Peptidase – peptides to amino acids
2. Sucrase – sucrose to glucose
3. Maltase – Maltose to glucose and
fructose
4. Lactase – lactose to galactose and
glucose

10. Enzymes secreted by Pancreas
Lipase – enzyme that digest fats or
splits fat into soluble glycerol and fatty acids
Pancreatic amylase – acts like salivary
amylase, splitting starch into a double sugar
maltose
Trypsin and chymotrypsin – breaks
proteins toamino acids.
Chemical DigestionChemical Digestion

11. Mechanical DigestionMechanical Digestion
•Changes the physical form ofChanges the physical form of
foodfood
>Chew>Chew
>Tear>Tear
>Grind>Grind
>Mash>Mash
>Mix>Mix

12. 1.1.IngestionIngestion
2.2.MovementMovement
3.3.DigestionDigestion
4.4.AbsorptionAbsorption
5.5.Further digestionFurther digestion
Phases of DigestionPhases of Digestion

13. •A long muscularA long muscular
tube with manytube with many
sections and areas.sections and areas.
•Begins with theBegins with the
mouth and endsmouth and ends
with the anus.with the anus.
The DigestiveThe Digestive
TractTract

14. Path of DigestionPath of Digestion
>Mouth>Mouth
>Pharynx>Pharynx
>Esophagus>Esophagus
>Stomach>Stomach
>Small Intestine>Small Intestine
>Large Intestine>Large Intestine
>Anus>Anus

15. - this is where food is mixed
with the saliva secreted by several
sets of salivary glands
- Saliva dissolves and
softens food and acts as a
lubricant, facilitating swallowing
and passage through the next
portions of the digestive tract.
MoutMout
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16. Teeth
- This is where food is
broken into smaller pieces by
both biting and chewing.
Tongue
- manipulates the food
during chewing and forms it into a
mass called bolus, in
preparation for swallowing.
-Pushes the bolus
through a cavity called the
pharynx and into esophagus.
MouthMouth

17. - a long tube running
through the throat and thorax
and connecting to stomach in the
upper portion of the abdominal
cavity.
-Food takes about 4 to 8 seconds as it
passes through to the stomach.
Peristalsis – contraction
movement of esophagus muscle
Sphincter – special ring of
muscle found on the junction
between esophagus and
stomach, which when contracted
EsophagusEsophagus

18. >This is a large muscular sac, which functions as a
storage organ, making discontinuous feeding possible.
Rugae –>folds of the stomach that increases its surface
area.
>churns the food, mixing it with the gastric juice
Gastric Juice –> contains enzymes that break down
protein
Chyme ->soupy mixture that leaves the stomach and
passes through the pyloric sphincter into the small
intestines.
StomachStomach

19. StomachStomach

20. >This is where final digestion and absorption takes place
Measures 23 ft long in an adult
Small IntestineSmall Intestine
>>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.

21. Site of greatest amount of digestion and absorptionSite of greatest amount of digestion and absorption
Small IntestineSmall Intestine

22. Duodenum – first section of the small
intestines attached to the stomach
Jejunum – middle portion of the
intestine
Ileum – very long coiled section lying
lower in the abdominal cavity
Villi – Finger-like projections in the
inner wall of the small intestine that
increases absorptive surface area.
Small IntestineSmall Intestine

23. - also known as colon
- Reabsorbs much of the
water used in the digestive process
and excretes certain salts, such as
those of calcium and iron.
Waste stays for 10 – 12 hours.Waste stays for 10 – 12 hours.
Caecum – this is a small and functionally
unimportant for human
Appendix – finger-like process found at
the tip of the caecum
Feces – undigested food excreted into
the colon and eliminated from the body.
Rectum – Last portion of the large
intestines that functions as a storage
chamber for the feces until defecation
Large IntestinesLarge Intestines

24. AnusAnus
>opening for the
elimination of feces.