Structures and functions of human digestive system
2. • The food contains necessary
nutrients needed by the
body for its growth, repair or
replacement of damaged
tissues, and other physical
activities.
3. Major food
groups
Common sources building blocks
carbohydrat
es
Rice, bread,
noodles, corn,
wheat
Simple sugar
(glucose,fructose,
galactose
proteins Meat, chicken,
egg, tofu, soya,
milk
Amino acids
Fats/ lipids Butter,
margarine, lard
Fatty acids and
glycerol
4. Physical/mechanical digestion
includes processes like chewing or
mastication, cutting, and tearing of
food to make food particles smaller
in size, which makes digestion
easier.
Chemical digestion involves
enzymes which chemically break
down the food into simpler form.
6. • The main part of the digestive
system is the alimentary canal/
digestive tract which include
the mouth, esophagus, stomach,
small intestine, large intestine,
and anus.
• The alimentary canal is about 30
ft long from mouth to anus.
7. • There are accessory organs
glands which include the salivary
glands, the pancreas, liver, and
the gallbladder.
• These accessory parts secrete
digestive enzymes or juices
necessary for chemical digestion.
8. • Digestion process begins in the
mouth. It is the site of ingesting
food. Foods enters the body
through the mouth, with teeth,
tongue, and salivary glands. The
sharp-edged teeth help to tear,
rip, and cut the food while the
flat- surfaced pre- molars grind
and chew the food into smaller
sizes thus increase surface area.
9. • There are 3 pairs of salivary glands in the
mouth: parotid, the sublingual, and the
submandibular salivary glands
• Saliva consist of
1. Water, which moisten and soften the
food
2. Mucus, which binds the food particles
into a slippery bolus that can pass easily
to the esophagus
3. Salivary amylase, which is an enzyme
that specifically digest food rich in starch,
a complex carbohydrate
10. • After swallowing bolus passes from
the pharynx down to the
esophagus, which is a tube leading
to the stomach.
• Peristaltic muscular contraction in
the pharynx propels the bolus into
esophagus.
• The esophagus is also coated with
slippery mucus, making bolus pass
easily along the tube.
11. • From esophagus, food moves into
the stomach.
• Stomach is a J-shaped muscular
organ which stores food, it has a
capacity of about one to two liters
in adults.
• It is made up of three layers of
muscular which are very important
in creating grinding motion.
12. • Both mechanical and chemical
digestion occurs in the stomach.
• The churning or contraction of the
stomach is mechanical, and gastric
juice secretions is chemical
digestion.
• The epithelial lining of the stomach
secretes fundamental substances
which aid in the digestion process.
13. 1. Mucous cell, which secrete
alkaline mucus that protects the
lining of the stomach against
acid
2. Parietal cells, which secrete
hydrochloric acid that destroys
ingested bacteria or
microorganisms
14. • 3. Chief cells, which secrete
protein- digesting enzymes pepsin
and rennin
• 4. G-cells. Which secrete hormone
gastrin, a protein that controls
acid secretion.
• These substances are called gastric
juices, a combination of
hydrochloric acid, mucus,
hormones, and enzymes.
15. • The small intestine is the longest
part of the alimentary canal which is
about 23 ft long. It is divided into 3
sections.
1. Duodenum, receives all secretions
from the liver via the common bile
duct and pancreas via the
pancreatic duct.
2. jejunum is the middle part and
3. ileum, the longest, most coiled and
very near the large intestine.
16. • The food chyme is push along by
the peristalsis and the food will
undergo complete digestion in
the small intestine. In the small
intestine, intestinal glands
secretes enzymes for complete
digestion of carbohydrates.
• The mixture of enzymes in the
intestine is called intestinal
juice.
17. • It is also site of absorption, where
nutrients are absorbed into the
blood vessels of the circulatory
system.
• The lining of the small intestine
have finger like projection called
villi which contain blood vessels
that absorbs nutrients.
18. • After absorption of nutrients, it
becomes mostly undigested food
and water. It passes through the
large intestine.
• The large intestines is divided into
3 regions, namely: Caecum, Colon
and Rectum
19. 1. Caecum, which is a blind-ended
pouch connected to the
appendix
2. Colon, which is the longest in
the organ, and is divided into:
ascending, transverse and
descending colon
3. Rectum, which is a short
segment that stores feces.
20. • Salivary gland pour their secretions
called salivary amylase to the
mouth.
• Liver, the largest gland in the body
located to the right of the mouth.
• Liver plays important role in the
assimilation of absorbed food
• Assimilation is a process where
food nutrients become part of the
body tissues.
21. 1. Redistribution of glucose to all cells for cellular
respiration through the hepatic vein
2. Storage of excess glucose forming glycogen
3. Working together with the islets of Langerhans
in the pancreas to regulate glucose level
4. Redistribution of amino acid through the
hepatic vein
5. Conversion of fats to forms that can be easily
oxidized by other tissues or be stored in adipose
tissue if they are in excess.
22. • Digestive enzymes are proteins
that serve as biological catalyst,
which speed up the chemical
reactions.
• Enzymes are specifics, their action is
described by the “lock and key”
hypothesis which means that each
enzymes has an active site with a
specific shape which will fit only at a
specific substrate.
23. • The inner surface of the small
intestine is covered by microscopic
finger-like projections called villi
(villus-singular).
• The villi of the small intestine are
responsible for distributing the
nutrients that has been processed
through the digestive system into
the circulatory and lymphatic
systems for delivery to all cells of our
body.
25. • Human body needs nutrients to be
healthy.
6 nutrients classes of essential
nutrients are:
1. Carbohydrates
2. Proteins
3. Lipids/fats
4. Vitamins
5. Minerals
6. Water
26. • Carbohydrates- the main source of
energy
• Proteins- is for growth, repair and
replacement of cells and tissue
• Fats- provide much energy than
carbohydrates but they are needed
only in small amount
• Vitamins and Minerals contain no
energy but they help maintain a
healthy body specifically for growth
and repair.
• Water- carries nutrients and wastes
throughout the body in the
bloodstream.
28. 1. Gastroesophageal Reflux
Disease (GERD), caused by acids
that leak up into the esophagus
2. Peptic ulcer, characterized by
painful sores in the lining of the
stomach or the first segment of
the small intestines, the
duodenum.
3. Gastritis- an inflammation of the
stomach lining
29. 4. Colitis, an inflammation of the
inner lining of the colon
5. Diarrhea, the condition that is
classified as the appearance of
loose, watery stool
6. Constipation, the condition in
which a person has fewer than three
bowel movement a week or with
bowel movement with hard stool
that is painful to eliminate.
7. Appendicitis, the inflammation
of the appendix, and usually needs
surgical treatment.
30. 8. Obesity, the condition in which
the body mass index (BMI) of a
person is 30 kg/m³ or higher,
characterized by high accumulation
of body fats that might have
negative effect on his health.
9. Colon cancer/colorectal cancer,
a cancer from the uncontrolled cell
growth in the colon or rectum; a
malignant tumor originating from the
inner lining of the colon
10. Cirrhosis of the liver, an
abnormal liver condition in which
there is irreversible scarring of the
liver.
31. • Gastroenterology- the branch of
medicine which deals with the
study of the digestive system and
associated disease.
• Magnetic Resonance Imaging
(MRI)
-The magnetic resonance imaging is
a medical test that causes magnetic
field and pulses of radio wave energy
to make pictures of internal body
organs.
33. • Endoscopy is a nonsurgical procedure
used to examine or study the digestive
tract.
• An instrument called endoscope, a
flexible tube with a light and camera
attached to it is being used.
• Upper endoscopy- the endoscope
passed through the mouth, throat,
esophagus, stomach and upper part of
the small intestine.
• Colonoscopy- the endoscope passes
into the large intestine (colon) through
the rectum or anus.
34. • Laparoscopy is a surgery that
uses thin, lighted tube through a
cut/ incision in the abdomen or
belly to examine the abdominal
organs or pelvic organs