1. Digestive System

2. Main Functions of the Digestive System
Ingest (take in food)
Digest (breaks down food, both mechanically & chemically)
Absorb (nutrient molecules)
Defecate (eliminates indigestible remains)

3. Alimentary Canal (“The Tube”)
Two Main Groups of Organs in Digestive System
Alimentary Canal (“The Tube”)
Mouth
Pharynx
Esophagus
Stomach
Small intestine
Large intestine
Rectum
Anus

4. Accessory Digestive Organs (helps “The Tube” with digestion)
Salivary glands
Teeth
Tongue
Gall bladder
Pancreas
Liver

5. 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

6. Esophagus
Long tube that pushes food from mouth into stomach using peristalsis
Cardioesophageal sphincter allows food to go from esophagus into stomach

7. 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

8. 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

9. 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.

11. 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

12. 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

13. 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

14. 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.

15. 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
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.
Gallstones

16. 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?

17. 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?