2. Digestive System – Objectives
Describe and understand the basic
functions of the primary components of
the digestive system.
Compare the functions and locations of
the digestive organs in man and
animals.
Differentiate between and identify
digestive systems of man and animals.
3. Digestion
Digestion is the breakdown
of large, complex organic
molecules into smaller
components that can be
used by the body.
Molecules need to be small
enough to diffuse across
plasma membranes.
5. Four Components of Digestion
Ingestion – this is the consumption of
or taking in of nutrients.
Digestion – the chemical breakdown of
large organic molecules into smaller
components by enzymes.
Absorption – the transport or delivery
of digested nutrients to body tissues.
Egestion – the elimination of food
waste materials from the body.
6. Ingestion
Food enters the
human digestive tract
through the mouth or
oral cavity.
Humans are
considered chunk
feeders because they
consume chunks of
food that are then
mechanically broken
down.
7.
8. Mouth
Teeth
mechanically
break down food
into small pieces.
Tongue mixes
food with saliva
(contains
amylase, which
helps break down
starch).
9. Mouth
Epiglottis is a
flap-like structure
at the back of the
throat that closes
over the trachea
preventing food
from entering it.
10. Esophagus
Approximately 10” long
Functions include:
1. Secrete mucus
2. Moves food from the
throat to the stomach
using muscle movement
called peristalsis
If acid from the stomach
gets in here that’s
heartburn.
11. Esophagus: muscular tube that connects
mouth to stomach
– Peristaltic waves send feed down the
esophagus, (muscle contractions).
– Reverse Peristalsis = blowing chunks
– The cardia, located at the end of the
esophagus prevents feed in the stomach from
coming back into the esophagus. ( non-
ruminants only)
12. Stomach
J-shaped muscular bag that
stores the food you eat,
breaks it down into tiny pieces.
Mixes food with digestive
juices that contain enzymes to
break down proteins and
lipids.
Acid in the stomach kills
bacteria.
Food found in the stomach is
called chyme.
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13. Small Intestine
Small intestines are roughly
7 meters long
Lining of intestine walls has
finger-like projections called
villi, to increase surface
area.
The villi are covered in
microvilli which further
increases surface area for
absorption.
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14. Small Intestine
Nutrients from the food pass
into the bloodstream through
the small intestine walls.
Absorbs:
– 80% ingested water
– Vitamins
– Minerals
– Carbohydrates
– Proteins
– Lipids
* Secretes digestive enzymes
14
15. Large Intestine
About 5 feet long
Accepts what small
intestines don’t
absorb
Rectum (short term
storage which holds
feces before it is
expelled).
16. Large Intestine
Functions
– Bacterial
digestion
• Ferment
carbohydrat
es
• Protein
breakdown
– Absorbs more
water
– Concentrate
wastes
17. Accessory Organs
Not part of the
path of food,
but play a
critical role.
Include: Liver,
gall bladder,
and pancreas
18. Liver
Directly affects
digestion by
producing bile
– Bile helps digest fat
• filters out toxins
and waste
including drugs
and alcohol
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19. Gall Bladder
Stores bile from
the liver,
releases it into
the small
intestine.
Fatty diets can
cause gallstones
20. Pancreas
Produces
digestive enzymes
to digest fats,
carbohydrates and
proteins
Regulates blood
sugar by
producing insulin
22. A RUMINANT ANIMAL
Has four distinctive compartments in its
stomach, which swallows its food essentially
unchewed, regurgitates, and chews it
thoroughly and reswallows it again.
Examples include cattle, sheep, goats, deer,
rhinos, and elk.
23. Rumination (regurgitation)
After rumen if full, it lies down to ruminate
(chew its cud)
Cattle spend from 5-7 hours ruminating,
broken up into 6-8 periods
Regurgitation is the process of forcing the
feed back into the mouth for chewing
Done through a series of muscular
contractions and pressure in the rumen and
reticulum
24. A NONRUMINANT ANIMAL
Has a single compartment in its
stomach, which swallows its food
after chewing and does not
regurgitate its food.
Examples include pigs, humans,
bears, and dogs.
25. Nonruminant Digestion
food is swallowed
directly into the
single stomach
compartment
it is mixed with
digestive juices
26. What do animals need to live?
Animals make energy
using:
– food food
– oxygen
Animals build bodies
using:
– food for raw materials ATP
• amino acids, sugars, O
2
fats, nucleotides mitochondria
– ATP energy for
synthesis
27. How do animals get their food?
filter feeding living in your food
fluid feeding bulk feeding
28. Getting & Using Food
Ingest
– taking in food
Digest
– mechanical digestion
• breaking up food into smaller pieces
intracellular
– chemical digestion digestion
• breaking down food into molecules
small enough to be absorbed into
cells
• enzymes
Absorb
– absorb nutrients across cell membranes
• diffusion
• active transport
Eliminate
– undigested material passes out of body extracellular
digestion
29. Different diets; different bodies
Adaptations of herbivore vs. carnivore
– teeth
– length of digestive system
– number & size of stomachs
31. Herbivores &
Length of digestive
omnivores system
– long digestive
systems
– harder to digest
cellulose (cell
walls)
• bacteria in
intestines help
Carnivores appendix
– short digestive
systems
– protein easier to
digest than
cellulose
32. Fun Facts
• HOW LONG ARE YOUR INTESTINES? At
least 25 feet in an adult. Be glad you're not a
full-grown horse -- their coiled-up intestines
are 89 feet long!
• Food drying up and hanging out in the
large intestine can last 18 hours to 2 days!
• In your lifetime, your digestive system may
handle about 50 tons!!
33.
34. Write the name of each colored
organ:
Green:
Red:
Pink:
Brown:
Purple:
Green:
Yellow:
35. How’d you do?
Green: Esophagus
Red: Stomach
Pink: Small
Intestine
Brown: Large
Intestine
Purple: Liver
Green: Gall Bladder
Yellow: Pancreas
Great Job!