The document discusses the anatomy and physiology of the digestive system. It describes the four basic digestive processes of digestion, motility, secretion, and absorption. It then explains how the digestive system is regulated by both the autonomic nervous system and hormones. Finally, it details the major components of the digestive tract including the mouth, esophagus, stomach, small intestine, accessory organs like the liver and pancreas, and large intestine.

1. ANATOMY AND PHYSIOLOGY
OF THE DIGESTIVE SYSTEM
COLON THERAPY INSTITUTE
ANATOMY AND PHYSIOLOGY OF THE DIGESTIVE SYSTEM © COLON THERAPY INSTITUTE

2. Agenda
A. Basic digestive processes
A. Regulation of the digestive tract
A. Components of the digestive
system
ANATOMY AND PHYSIOLOGY OF THE DIGESTIVE SYSTEM © COLON THERAPY INSTITUTE

3. There are four basic digestive
processes…
1. Digestion: mechanical and
chemical breakdown of food
1. Motility: movement of
material along the digestive
tract
1. Secretion: release of
enzymes into the digestive
tract
1. Absorption: active or passive
transfer of substances from
the lumen of the digestive
tract to ECF
ANATOMY AND PHYSIOLOGY OF THE DIGESTIVE SYSTEM © COLON THERAPY INSTITUTE

4. 1 Digestion is the breakdown of food
• What’s digestion?
• Digestion refers to the breakdown of food structure by enzymes produced
within the digestive system so that the nutrients locked in the complex foods
become available for absorption and use
• How does it work?
• Say a carbohydrate molecule is too large to be able to be absorbed into the
circulation…
• Enzymes will first break down this large molecule into smaller molecules called
monosaccharides
• The monosaccharides are then able to be absorbed across the cells and into
circulation
• Similarly, proteins are degraded into amino acids and small polypeptides, and
fats are degraded into monoglycerides and free fatty acids
ANATOMY AND PHYSIOLOGY OF THE DIGESTIVE SYSTEM © COLON THERAPY INSTITUTE

5. 2 Motility is muscle contraction
• What’s motility?
• Motility is a term used to describe the
contraction of the muscles that mix
and propel contents in the digestive
tract
• How does it work?
• Muscle contraction causes motility in
two ways:
1. Peristalsis: progressive waves of
contraction that move from one
section to the next
2. Segmentation: short segments of the
small and large intestines alternately
contracting and relaxing which mixes
contents and keeps them in contact
with absorptive epithelium
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6. 3 Secretion involves the release of
fluids
• What’s secretion?
• Secretion involves the release of
digestive juices (e.g., hydrochloric
acid, enzymes) into the the digestive
tract
• These juices aid in digestion and
absorption of food
• How does it work?
• This process is under neural and/or
hormonal regulation
• How much secretion occurs daily?
• About 9 liters of fluid pass through the
digestive system each day, and only
about 2 liters are ingested, the rest
represent secretions from the system
itself
ANATOMY AND PHYSIOLOGY OF THE DIGESTIVE SYSTEM © COLON THERAPY INSTITUTE

7. 4 Absorption occurs when materials
enter the blood or lymph
• What’s absorption?
• Absorption refers to the process
whereby the products that result
from digestion are transferred
from the digestive track into the
blood or lymph
• How does it work?
• Digested molecules of food, as
well as water and minerals from
the diet, are absorbed from the
cavity of the upper small
intestine
• The absorbed materials cross the
mucosa into the blood, mainly,
and are carried off in the
bloodstream to other parts of
the body for storage or further
chemical change
ANATOMY AND PHYSIOLOGY OF THE DIGESTIVE SYSTEM © COLON THERAPY INSTITUTE

8. Agenda
A. Basic digestive processes
A. Regulation of the digestive tract
A. Components of the digestive
system
ANATOMY AND PHYSIOLOGY OF THE DIGESTIVE SYSTEM © COLON THERAPY INSTITUTE

9. The digestive system is controlled by
both nerves and hormones
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10. The nerves that control digestion are
in the submucosa layer of the tissue
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11. These nerves are part of the
Autonomic Nervous System (ANS)
• What’s the Autonomic Nervous System (ANS)?
• The ANS sends messages from the central nervous system to the internal
organs and triggers automatic bodily functions without conscious effort
• It helps control the heart rate, blood pressure, digestion, respiration, blood
pH and other bodily functions
ANATOMY AND PHYSIOLOGY OF THE DIGESTIVE SYSTEM © COLON THERAPY INSTITUTE

12. The ANS consists of two branches:
the parasympathetic nervous system
and the sympathetic nervous system
Note: The activity of
the digestive system
increases if the
parasympathetic
nervous system is
aroused and decreases
if the sympathetic
nervous system is
aroused
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13. Too much arousal of either branch
can lead to problems
• If the sympathetic nervous system is too aroused:
• Food will not move through the digestive tract and
mucus will not be released
• If the parasympathetic nervous system is too aroused:
• Food will move through the digestive tract too fast
• Not enough nutrients may be absorbed into the
body
• Thus, both branches work together to attain the
correct balance so that food moves through the tract
at a suitable pace
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14. The hormones that control digestion
are produced and secreted by various
organs along the digestive tract
These hormones cause the various chemicals that aid in digestion to
be released or prevented from being released
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15. Nerves and hormones work together
to ensure that food moves at an
appropriate pace and is digested
ANATOMY AND PHYSIOLOGY OF THE DIGESTIVE SYSTEM © COLON THERAPY INSTITUTE

16. Agenda
A. Basic digestive processes
A. Regulation of the digestive tract
A. Components of the digestive
system
ANATOMY AND PHYSIOLOGY OF THE DIGESTIVE SYSTEM © COLON THERAPY INSTITUTE

17. The digestive tract is a series of
hollow organs joined in a long tube
running from the mouth to the anus
Components of the digestive
tract:
1. Mouth
2. Pharynx
3. Esophagus
4. Stomach
5. Small intestine
6. Accessory organs
7. Large intestine (colon)
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18. 1 Food is ingested by the mouth
• What does it do?
• Ingests food
• Chews and mixes food
• Begins chemical
breakdown of
carbohydrates
• Moves food into the
pharynx
• Begins breakdown of
lipids via lingual lipase
• Moistens and dissolves
food, allowing you to
taste it
• Cleans and lubricates
the teeth and oral
cavity
• Has some
antimicrobial activity
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19. 2 The pharynx moves food from the
oral cavity to the esophagus
• What does it do?
• Propels food from the oral cavity to the esophagus
• Lubricates food and passageways
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20. 3 The esophagus sends food to the
stomach
• What does it do?
• Propels food to the stomach
• Lubricates food and passageways
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21. 4 The stomach mixes and churns
food to form chyme
• What does it do?
• Mixes and churns food
with gastric juices to
form chyme
• Begins chemical
breakdown of proteins
• Releases food into the
duodenum as chyme
• Absorbs some fat-soluble
substances (for example,
alcohol, aspirin)
• Possesses antimicrobial
functions
• Stimulates protein-digesting
enzymes
• Secretes intrinsic factor
required for vitamin B12
absorption in small
intestine
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22. 5 The small intestine absorbs and
digests
• What does it do?
• Mixes chyme with
digestive juices
• Propels food at a rate
slow enough for
digestion and absorption
• Absorbs breakdown
products of
carbohydrates, proteins,
lipids, and nucleic acids,
along with vitamins,
minerals, and water
• Performs physical
digestion via
segmentation
• Provides optimal medium
for enzymatic activity
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23. 6 Accessory organs secrete digestive
fluids
• Liver: produces bile
salts, which emulsify
lipids, aiding their
digestion and absorption
• Gallbladder: stores,
concentrates, and
releases bile
• Pancreas: produces
digestive enzymes and
bicarbonate
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24. 7 The large intestine (colon) absorbs
water; stores and eliminates stool
• What does it do?
• Further breaks down
food residues
• Absorbs most residual
water, electrolytes,
and vitamins produced
by enteric bacteria
• Temporarily stores
stool
• Propels stool toward
rectum
• Eliminates stool
• Mucus eases
passage of stool
through colon
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