Digestive System Anatomy and Physiology Notes (HAP) B.Pharm 2nd Semester
BP201T
Unit-II
Digestive System
Dr. Amit Bhargava
Digestion
• Phases Include
1. Ingestion
2. Movement
3. Mechanical and Chemical Digestion 4. Absorption
5. Elimination
Digestion
• Types
– Mechanical (physical)
• Chew
• Tear
• Grind
• Mash
• Mix
– Chemical
• Enzymatic reactions to improve digestion of
– Carbohydrates
– Proteins
– Lipids
Digestive System Organization
• Gastrointestinal (Gl) tract
– Tube within a tube
– Direct link/path between organs
– Structures
• Mouth
• Pharynx
• Esophagus
• Stomach
• Small intestine
• Large Intestine
• Rectum
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Mouth
• Teeth mechanically
• Epiglottis is a flap-like break down food into
structure at the back of
small pieces. Tongue
the throat that closes
mixes food with saliva
over the trachea
(contains amylase,
preventing food from
which helps break down
entering it. It is located
starch).
in the Pharynx.
Esophagus
• Approximately 20 cm 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.
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 (HCl) in the stomach Kills Bacteria.
• Food found in the stomach is called Chyme.
• Formation of HCL has already explained in the class
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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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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 9
Large Intestine
• About 1.5 meters long
• Accepts what small intestines don’t absorb
• Rectum (short term storage which holds feces before it is expelled).
Large Intestine
• Functions
– Bacterial digestion
• Ferment carbohydrates
– Absorbs more water
– Concentrate wastes
Accessory Organs The Glands
• Not part of the path
of food, but play a
critical role.
• Include: Liver, gall
bladder, and
pancreas
Liver
• Directly affects digestion by producing bile
– Bile helps digest fat
• filters out toxins and waste including drugs and alcohol and poisons.
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Gall Bladder
• Stores bile from the
liver, releases it into the small intestine.
• Fatty diets can cause
gallstones
Pancreas
• Produces digestive
enzymes to digest fats,
carbohydrates and
proteins
• Regulates blood sugar
by producing insulin