Essential Question What are the structures of the digestive system? 2.07 Remember the structures of...
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Transcript of Essential Question What are the structures of the digestive system? 2.07 Remember the structures of...
Essential Question
What are the structures of the digestive system?
2.07 Remember the structures of the digestive system 2
Structures of the digestive system
Digestive system Also known as:
Alimentary Canal Digestive Tract Gastrointestinal Tract
Upper GI Lower GI
Approximately 30’ in length from mouth to anus
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Primary structures Mouth Esophagus Stomach Small intestines Large intestines
Accessory structures Tongue Teeth Salivary glands Pancreas Liver Gall bladder
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Structures of the digestive system
Structures of the digestive system
Mouth (buccal cavity)
Tongue Teeth Salivary Glands Palate Uvula
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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
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Structures of the digestive system
Teeth Primary (deciduous)
20 “baby teeth” Secondary
(permanent) 32 “adult teeth”
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Deciduous Teeth: baby’s first teeth which eventually fall outAll 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 TEETH1.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.
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
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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 enzymesFunction of saliva: Contains enzymes that begin the chemical breakdown of foodAfter eating, saliva cleans the oral surfaces, reducing the amount of bacteria that grow in the mouth
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
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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 12
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
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digestive system 13
• 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:
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 stomachAfter 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)
Structures of the digestive system
Stomach Upper left quadrant of
the of the abdominal cavity
Fundus Body Pylorus
Cardiac Sphincter Pyloric Sphincter Rugae,
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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
Structures of the digestive system
Accessories… Pancreas
6-9 inches longLocated behind the stomachExtending from duodenum to the spleenIt secretes buffers to neutralize the acids in the chyme saving the intestinal walls from damageReleases enzymes that break down sugars and starches, breaks down fats and proteins
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GallbladderSac shaped organ, 3-4 inches longLocated under the liver’s right lobeIt 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.
LiverLocated in front of the diaphragm
(anterior)Weighs 3.3pounds
Is the largest glandular organ in the bodyLargest 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
FUNCTIONS OF THE LIVERCreates body heat
Detoxifies the body of harmful substances such as certain drugs and alcohols
Destroys old blood cells and recycles their usable partsThe pigment from bilirubin is a waste product and is eliminated in bile
giving feces its distinctive colorForms blood plasma proteins such as albumin and globulins
Produces clotting proteins: fibrinogen and prothrombinManufactures bile, needed for the digestion of fats
Stores and modifies fats for more efficient use by the body’s cellsSynthesizes urea, a by product of protein metabolism, so it can be
eliminated by the bodyStores sugars (when our blood sugar levels fall below normal, the
liver releases glucose into the blood streamStores vitamins A, B12, D, E, and K
Makes cholesterol
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
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Large Intestines are approximately 5 feet long and 25 inches in diameter
FUNCTIONWater absorption
Absorption of vitamins produced by the health bacteria in the large intestine
Compaction of waste products for eliminationLarge intestines contain no villi, so little nutrient
absorption occurs here.
Three Main Regions of Large Intestines Cecum pouch shaped structure that receives any
undigested food and water from the ileumThe appendix is attached to the cecum
The appendix is a 3 “ long, slender hollow, dead ended tube lined with lymphatic tissueThe 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
RECTUMOpens to the anal
canal/anusAnal sphincter opens and
closes to allow the passage of solid waste(feces) from the colon to the outside
world
Essential Question
What are the structures of the digestive system?
2.07 Remember the structures of the digestive system 26