1. 2.07 Remember the structures of the digestive system

2. What are the structures of the digestive system?
Essential Question
What are the structures of the digestive system?
2.07 Remember the structures of the
digestive system

3. Structures of the digestive system
Also known as:
Alimentary Canal
Digestive Tract
Gastrointestinal Tract
Upper GI
Lower GI
Approximately 30’ in length from mouth to anus
2.07 Remember the structures of the
digestive system

4. Structures of the digestive system
Primary structures
Mouth
Esophagus
Stomach
Small intestines
Large intestines
Accessory structures
Tongue
Teeth
Salivary glands
Pancreas
Liver
Gall bladder
2.07 Remember the structures of the
digestive system

5. Structures of the digestive system
Mouth
(buccal cavity)
Tongue
Teeth
Salivary Glands
Palate
Uvula
2.07 Remember the structures of the
digestive system

6. Structures of the digestive system
Tongue
Attached to floor of mouth
Made of skeletal muscle attached to four bones
Taste buds on the surface
Sweet
Sour
Bitter
Salty
2.07 Remember the structures of the
digestive system

7. Structures of the digestive system
Teeth
Primary (deciduous)
20 “baby teeth”
Secondary (permanent)
32 “adult teeth”
Did you know???
Canine teeth are also
known as cuspids and
eye teeth.
2.07 Remember the structures of the
digestive system

8. Deciduous Teeth: baby’s first teeth which eventually fall out
All deciduous teeth are in place by 2 ½ years.
Between 6 and 12 years, deciduous teeth begin to fall out and are replaced by 32 larger permanent teeth
TYPES OF TEETH
Incisors: located at the front of the mouth, they are blade sharp and are used to cut food
2. Canine teeth: located next to incisors, used for holding, tearing or slashing food
3. Bicuspids, or premolars: crush and grind food
4. Molars: Located in the very back of the mouth, have flattened tops, crush and grind food.
Structure of Teeth
All teeth have a cow, neck and root
Crown: The visible portion of the tooth covered by enamel (which is the hardest biologically manufactured substance)
Neck is the transitional section that leads to the root
Root: the portion of the tooth that anchors it to its bony socket. It’s held in place by fibers.
MOST Teeth are made up of dentin, a mineralized bone like substance.
Inside teeth there’s a layer of connective tissue called pulp located inside the pulp cavity.
Pulp cavity contains blood vessels that provide nutrients to the tooth and nerves which provide sensation to the tooth. Gums hold your teeth in place.

9. Structures of the digestive system
Salivary glands
Parotid glands:
located anterior and inferior to each ear.
Swell when you get mumps
Largest salivary gland
Submandibular gland
located along the inner surface of the lower jaw
Sublingual gland
Located under tongue
2.07 Remember the structures of the
digestive system

10. Salivary glands produce 1-1.5 liters of saliva daily.
Small amounts are continuously secreted to keep the mouth moist.
Saliva is 99.4% water and contains antibodies, buffers, ions, waste products and enzymes
Function of saliva: Contains enzymes that begin the chemical breakdown of food
After eating, saliva cleans the oral surfaces, reducing the amount of bacteria that grow in the mouth

11. Structures of the digestive system
Palate
Hard
Soft
Uvula
Flap of skin
hanging in the
back of the throat
Aids in swallowing by directing food toward the pharnyx
Uvula blocks food from entering your nose.
2.07 Remember the structures of the
digestive system

12. Structures of the digestive system
Pharynx (throat)
Nasopharynx
Connects to the nose
Oropharynx
Connects to the mouth
Located at the back of the
Tongue
Laryngopharynx
A passageway for food,
Water, and air into the
Internal parts of the body. ]
2.07 Remember the structures of the
digestive system

13. Structures of the digestive system
Esophagus
Muscular tube, 10” long
Transports food from the pharynx to the stomach
Is a collapsed tube until a bolus of food is eaten.
Esophageal wall layers
Mucosa
Submucosa
Muscular
External serous
Rhythmic contractions called peristalsis push food down the esophagus.
2.07 Remember the structures of the
digestive system

14. 4 layers make up the alimentary tract
Mucosa: innermost layer, lines the canal, contains cells that secrete enzymes to break down food, contains goblet cells that secrete mucus for lubrication
Submucosa: the next layer
Composed of soft connective tissue
Contains blood vessels, lymph vessels, lymph nodes and nerve endings.
Musculara Externa the next layer
Innermost layer of muscle encircles the canal
Outer most layer is longitudinal so it lies in the direction of the canal
Serosa: the outermost layer makes up visceral peritoneum
Peritoneum is a serous membrane in the abdominopelvic cavity. It has two layers:
Visceral layer covers the organs and the parietal peritoneum lines the walls of theabdominopelvic cavity

15. At the end of the esophagus is a muscular “Door” called the lower esophageal sphincter . The LES is also known as the cardiac sphincter.
It must open to allow food to move into the stomach
After food passes through, it must close to prevent stomach acids from splashing back up into the esophagus.
If the sphincter opens, it will cause heartburn (pyrosis)

16. Structures of the digestive system
Stomach
Upper left quadrant of the of the abdominal cavity
Fundus
Body
Pylorus
Cardiac Sphincter
Pyloric Sphincter
Rugae,
The stomach is under the diaphragm and almost completely covered by the liver. It is approx. 10 inches long and can hold up to 4 liters of food when filled. Rugae are the folds in the stomach that help the stomach expand and contract.
2.07 Remember the structures of the
digestive system

17. Serves as a temporary holding area for received food
STOMACH FUNCTIONS:
Serves as a temporary holding area for received food
Secretes gastric acids and enzymes that mix with food, performing chemical digestion
Regulates the rate partially digested food (chyme) enters the intestines
Absorbs small amounts of water on a limited basis
It takes about 4 hours for the stomach to empty following a meal.
Liquids and CHO’s pass through quickly
Proteins take more time
Fats take the longest usually between 4-6 hours

18. Structures of the digestive system
Accessories…
Pancreas
6-9 inches long
Located behind the stomach
Extending from duodenum to the spleen
It secretes buffers to neutralize the acids in the chyme saving the intestinal walls from damage
Releases enzymes that break down sugars and starches, breaks down fats and proteins
2.07 Remember the structures of the
digestive system

19. Gallbladder Sac shaped organ, 3-4 inches long
Located under the liver’s right lobe
It stores bile produced by the liver
If the bile becomes over concentrated, bile salts may solidify forming gallstones
Fatty foods in the duodenum (first section of small intestines)
Cause the gallbladder to contract releasing bile into the common bile duct and this leads to the duodenum.

20. Liver Located in front of the diaphragm (anterior) Weighs 3.3pounds
Is the largest glandular organ in the body
Largest organ in the abdomen
Is divided into a large right lobe and a smaller left lobe.
Receives about 1 ½ quarts of blood every minute from the hepatic portal vein
And hepatic artery.
The blood provides oxygen rich blood that keeps the liver tissue alive

21. Destroys old blood cells and recycles their usable parts
FUNCTIONS OF THE LIVER
Creates body heat
Detoxifies the body of harmful substances such as certain drugs and alcohols
Destroys old blood cells and recycles their usable parts
The pigment from bilirubin is a waste product and is eliminated in bile giving feces its distinctive color
Forms blood plasma proteins such as albumin and globulins
Produces clotting proteins: fibrinogen and prothrombin
Manufactures bile, needed for the digestion of fats
Stores and modifies fats for more efficient use by the body’s cells
Synthesizes urea, a by product of protein metabolism, so it can be eliminated by the body
Stores sugars (when our blood sugar levels fall below normal, the liver releases glucose into the blood stream
Stores vitamins A, B12, D, E, and K
Makes cholesterol

22. Structures of the digestive system
Large intestines
Approximately 2” in diameter
5’ long
Begin at the junction of the ileum (last portion of small intestine) and extends to the anus
2.07 Remember the structures of the
digestive system

23. Compaction of waste products for elimination
Large Intestines are approximately 5 feet long and 25 inches in diameter
FUNCTION
Water absorption
Absorption of vitamins produced by the health bacteria in the large intestine
Compaction of waste products for elimination
Large intestines contain no villi, so little nutrient absorption occurs here.

24. Three Main Regions of Large Intestines
Cecum pouch shaped structure that receives any undigested food and water from the ileum
The appendix is attached to the cecum
The appendix is a 3 “ long, slender hollow, dead ended tube lined with lymphatic tissue
The appendix has no current purpose
If it becomes blocked or inflamed it causes appendicitis
Colon has 4 secions:
ascending colon, transverse colon, descending colon, and sigmoid colon(the S shape portion that extends from the left side to the rectum

25. Opens to the anal canal/anus
RECTUM
Opens to the anal canal/anus
Anal sphincter opens and closes to allow the passage of solid waste(feces) from the colon to the outside world

26. What are the structures of the digestive system?
Essential Question
What are the structures of the digestive system?
2.07 Remember the structures of the
digestive system