Download File digestive system

Digestive System
Main Functions of the Digestive System
•Ingest (take in food)
•Digest (breaks down food, both mechanically & chemically)
•Absorb (nutrient molecules)
•Defecate (eliminates indigestible remains)
Two Main Groups of Organs in Digestive System
Alimentary Canal
Mouth
Pharynx
Esophagus
Stomach
Small intestine
Large intestine
Rectum
Anus
(“The Tube”)
Accessory Digestive Organs (helps “The Tube” with
digestion)
Salivary glands
Teeth
Tongue
Gall bladder
Pancreas
Liver
The Mouth
• Mechanical digestion occurs here (mastication)
• Salivary amylase is an enzyme in the saliva that
breaks down starches into sugars. This is what
starts the digestive process. Amylase is also made
in the pancreas
• Swallowing pushes the food bolus down
esophagus
Esophagus
• Long tube that pushes food from mouth into
stomach using peristalsis
• Cardioesophageal sphincter allows food to go
from esophagus into stomach
Stomach
• “C shaped organ”, approx. 10” long
• Can hold 1 gallon of food
• Folds in stomach (rugae) help with further mechanical
digestion
• Stomach secretes gastric juices which contain digestive
enzymes that are highly acidic
• Stomach itself is protected by a mucus layer
• Food is broken down into a creamy, liquidy substance
(chyme)
• Protein digestion occurs here
• Sphincter at bottom (pyloric sphincter)
only allows small amounts of chyme
to enter small intestine
Small Intestine
• Coiled muscular tube, that is 6-13 feet long
• Chemical digestion of fats, proteins, and carbs occur here with
help of specific enzymes released from accessory organs (pancreas
& liver)
• Absorption of small molecules (glucose, amino acids, etc.) occurs here
through microvilli
• Microvilli are tiny projections which increase surface area
allowing for more absorption
• The small intestine is made up of the duodenum, jejunum, and
the ileum.
Small intestine
Microvilli
F.Y.I
• The duodenum is the first section of the small intestine, the shortest,
and where most chemical digestion takes place.
• The jejunum is the middle section of the small intestine. The lining of
the jejunum is specialized for the absorption of small nutrient particles
which were previously digested by enzymes in the duodenum. If the
jejunum is impacted by blunt force, the emesis (vomiting) will be
initiated.
• The ileum is the final section. It’s function is to absorb vitamin B12
and bile salts and any other products not absorbed by the jejunum.
Large Intestine
• Reabsorption of water as well as vitamin
absorption occurs here
• Undigested wastes collect & compact here
(until expelled/excreted)
• Sections of Large Intestine: Cecum, Ascending,
Transverse, and Descending Colon, Rectum, Anus
Accessory Digestive Organs
•Salivary glands in mouth secrete saliva (essential for taste and
forming bolus) & salivary amylase
•Teeth carry out mechanical digestion of food
•Tongue helps move food around in mouth to start digestion &
helps form bolus and push it down esophagus
Liver
• Largest gland in body and is located under
diaphragm in the RUQ
• Humans have 4 lobes
• One of the most important organs in body
• Detoxifies blood (i.e. drug detoxification)
• Produces bile
Bile
Bile is a yellow-green watery solution containing bile salts,
bilirubin, cholesterol, and other substances. It is made in the
liver but is stored in the gall bladder. It does not contain
enzymes but the bile salts help to emulsify fat, breaking it
down from large fat globules into smaller fat droplets which
help with fat digestion in small intestine.
Gall Bladder
•Small, thin, green sac
•Located near (inferior to) liver
•Stores and concentrates bile
•Release bile into small intestine for fat
digestion through bile duct
Gallstones
FYI: Gallstones are hard, pebble-like deposits
that form inside the gallbladder. Gallstones
may be as small as a grain of sand or as large
as a golf ball. The two main causes are an
increase of bilirubin in the blood due to the
breakdown of RBC’s and a build-up of
cholesterol in the blood.
Pancreas
•Soft, long, pink, triangular gland that extends horizontally in
abdominal cavity
•Produces enzymes that break down all categories of food (fats,
proteins, and carbohydrates)
•Produces hormones such as insulin and glucagons
– What disorder is associated with the lack of insulin in the pancreas?
So altogether, the digestive system allows us to ingest and digest
food so that we may obtain necessary nutrients and energy. Who
can label our Digestive System?