digestive system

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breaks down the food you eat into nutrients needed for metabolic processes, such as making ATP, and rids the body of materials that cannot be used such as fiber.

The digestive system

ANATOMY OF THE DIGESTIVE SYSTEM

Organs of the Alimentary Canal Accessory organs

Also called the "gastrointestinal (GI) tract" or gut, is a continuous, coiled, hollow muscular tube that winds through the ventral body cavity from the mouth to anus. It is approx. 9 meters (about 30 ft long), but in a living person, it is considerable shorter because of its muscle tone.

ALIMENTARY CANAL

ORGANS OF THE ALIMENTARY CANAL

1. Mouth 2. Pharynx 3. Esophagus 4. Stomach 5. Small Intestine 6. Large Intestine

Food enters the digestive tract through the __, a mucous membrane-ined cavity.

Mouth or oral cavity

protect its anterior opening, the cheeks form its lateral walls, the hard palata forms its anterior root, and the soft palate forms the its posterior root

lips

is a fleshy finger-like projection of the soft palate, which dangles from the posterior edge of the soft palate

uvula

The space hetween the lips and cheaks externally and the teath and gums internally is the .

vestibule

occupies the floor of the mouth. The tongue has several bony attachments-two of these are to the hyoid bone and the styloid processes of the skull.

tounge

fold of mucvus membrane that secures the tongue to the floor of the mouth and limits its posterior movements

Lingual frenuluma

a small round mass of a substance, especially food that has been chewed to make it soft before it is swallowed

Bolus

Masses of lymphatic tissue which are part of the body's defense. system. They become inflamed and enlarge, they partially block the entrance into the throat (pharynx), making swallowing difficult and painful

tonsils

two types of tonsils

Palatine tonsils Lingual Tonsils

Food passes posteriorly into the oropharynx and laryngopharynx, both of which are common passageways for food, fluids, and air.

pharynx

The walls of the pharynx contain two (2) skeletal muscle layers; Alternating contractions of these two (2) muscle layers propel food through the pharynx inferiorly into the esophagus

Longitudinal muscles Circular/constrictor mascles

Also known as the "gullet", runs from the pharynx through the diaphragm to the stomach (approx. 25 meters or 10 inches long) It is an essential passageway that conducts food (by peristalsis) to the stomach (spprox. 25m or 10in long) It is an essential passageway that conducts food (by peristalsis) to the stomach

ESOPHAGUS

valve praventing backflow of food to esophagus

Esophageal sphincter

It is a digestive disorder that occurs when acidic stomach juices, or food and fluids back up from the stomach into the esophagus due to weakness or unusual relaxation of the esophageal sphincter

GASTROESOPHAGDAL RELUX DISEASE (GERD)

The main symptom of GERD is acid reflux which can cause an uncomfortable burning feeling in your chest often known as

heartburn

The walls of the alimentary canal organs from the esophagus to the large intestine are made up of the same four (4) tissue layers, or tinica

Mucosa Submucosa Muscularis externa

-innermest layer; moist mucous mambrane lining the hallow cavities of the organ

Mucosa

soft connective tissue containing blood vessels, narve endings, and lymphatis vessels

Submucosa

muscle layer (circular and longitudinal smooth muscles

Muscularis externa

-outermost layer

Serosa

SEROSA

Visceral peritoneum- 2. Parietal peritoneum 3. Mesentery

-organs

Visceral peritoneum

. interior wall of the abdominal cavity

Parietal peritoneum

-fold of membrane that attaches the intestine to the abdominal wall and holds it in place

Mesentery

The alimentary canal wall contains two (2) important intrinsic nerve plexuses

Submucosal nerve plexus. 2. Myenteric ("intestinal muscle") nerve plexus

These networks of nerve fibers are actual parts of the autonomic nervous system. They helps regulate the mobility and secretory activity of Gl tract organs.

Submucosal nerve plexus. Myenteric ("intestinal muscle") nerve plexus

-double layer of peritoneum from the liver to the lesser curvature of the stomach

Lesser Omentum

another extension of the peritoneum. which covers the abdominal organs; contains macrophages and defensive cells

Greater Omentum

C-shaped and is located on the left side of the abdominal cavity, nearly hidden by the liver and diaphragm.

stomach

region of the stomach

1. Cardial region 2. Fundus 3. Body- 4. Pyloric antrum 5. Pylorus

-food enters from the esophagus

Cardial region or cardia

expanded part of the stomach

Fundus

-midportion of the stomach

Body

. -terminal part continuous with the small intestine

Pylorus

-prevents backflow of food to the esophagus

Cardioesophageal sphincter

- controls the outflow of gastric contents into the duodenum

Pyloric sphincter or pyloric valve

The stomach varies from

15 to 25cm (6-10in)

-series of ridges produced by folding of the walls of the stomach

Rugae

Storage, mixing and breakdown of food (chemical breakdown of proteins)

stomach

-variable mixture of water, hydrochloric acid, electrolytes (sodium, calcium, phosphate, sulfate, and bicarbonate), and organic substances (mucus, pepsins, and protein)

Gastric juice

-openings leading to gastric glands that secrete gastric juice

Gastric pits

-hormone produced by "G"cells in the lining of the stomach, stimulates secretion of gastric juice

Gastrin

It is a condition that inflames the stomach lining (the mucosa), causing belly pain, indigestion (dyspepsia), bloating and nausea. It is often caused by bacterial infection. (Helicobacter pylori), excessive drinking or smoking, unhealthy diet or nutrient deficiencies, excessive spicy or acidic. food, prolonged use of Non-Steroidal Anti- Inflammatory Drugs (NSAIDs).

GASTRITIS

It can progress into an ulcer or an open sore in the lining of the stomach

gastritis

treatment for gastritis

Treatment: Antacids, Antibiotics, Proton pump inhibitors

The body's "Major Digestive Organ" Longest section of the alimentary canal; It is a muscular tube hanging in sausage-like coils extending from the pyloric sphincter to the large intestine

small intestine

Three (3) subdivisions: of small intestine

1. Duodenum 2. Jejunum 3. Ileum

-semifluid mass of partly digested food expelled by the stomach into the duodenum

Chyme

-contains digestive enzymes

Pancreatic Juice

-openings at the duodenum that lead into the pancreas

Pancreatic ducts

-fluid that breaks down fats into fatty acids

Bile

-opening at the duodenum leading into the liver

Bile duct

SMALL INTESTINE DIGESTION organs

chyme pancreatic juice pancreatic ducts bile bile ducts

Nearly all nutrient absorption occurs in the small intestine (water and electrolytes

SMALL INTESTINE -ABSORPTION

Three (3) structures absorption

Circular Folds-deep folds on the mucosa and submucosa layer Villi-fingerlike projections of the mucosa with abundant capillaries Microvilli - "brush border"; tiny projections of the plasma membrane containing enzymes that complete digestion of proteins and carbohydrates

-deep folds on the mucosa and submucosa layer

Circular Folds

-fingerlike projections of the mucosa with abundant capillaries

Villi

- "brush border"; tiny projections of the plasma membrane containing enzymes that complete digestion of proteins and carbohydrates

Microvilli

-collections of lymphatic tissue in the submucosa Important part of the immune system by monitoring intestinal bacteria populations and preventing the growth of pathogenic bacteria in the intestines

Peyer's Patches

Also known as the "large bowel" - largest part of the digestive system Water absorption; elimination of residues

large intestine

Three (3) subdivisions of large intestine

1. Cecum 2. Colon- 3. Rectum

-first part of the large intestine

CECUM

- narrow, finger-shaped pouchthat projects out from the cecum No known function It is an ideal location for bacteria to accumulate and multiply which can lead toAppendicitis.

appendix

hast two valves that opens and closes the anus

anal canal

parts of large intestine

anal canal External Anal Sphincter Internal Anal Sphincter

voluntaryskeletal muscle

External Anal Sphincter -

-involuntary smooth muscle of parge intestine

Internal Anal Sphincter

ACESSORY DIGESTIVE ORGANS

TEETH SALIVARYGLANDS PANCREAS LIVER ANDGALL BLADDER

chewing by openingand closing of jaws and moving fromside to side while using our tongueand cheek muscles to keep food inbetween

mastification

baby or milk teeth)begin to erupt around 6mos until ababy has a full set (20 teeth) by thee of 2 years

Deciduous teeth

developsbetween the ages of 6-12 yearsold

Permanent teeth

(wisdom teeth)usually erupt between 17-25years

Third molars

Overall, there are ___permanentfull set of teeth but there aretimes that wisdom teeth fail toerupt or sometimes completelyabsent

thick ceramic-like substance; hardestsubstance in the body which bears the force ofchewing

enamel

bone-like material underlies the enameland forms the bulk of the tooth

dentin

- contains pulp (connective tissue,blood vessels, and nerve fibers)

Pulp cavity

- extension of the pulp cavitywhich provides a route for blood vessels, nervesand the other pulp structures

Root/Root Canal

mixture of mucus and serous fluids whichmoistens and helps to bind food together into a mass called a bolus

saliva

- enzyme that begins theprocess of starch digestion in the mouth Lysozyme and IgA antibodies that inhibit bacteria

Salivary amylase

Three (3) pairs of salivary glands:

Parotid glands Submandibular glands Sublingual glands

Soft, pink, triangular gland thatextends across the abdomen fromthe spleen to the duodenum Only the pancreas producesenzymes that break down alcategories of digestible food

PANCREAS

- neutralizes theacidic chyme coming in from thestomach

Pancreatic juice

Largest gland in the body Located under the diaphragm at the rightside of the body and overlies the stomach

liver

produces bile

liver

liver has four (4) lobes and is suspended from the diaphragm and abdominal wall by delicate mesentery

Falciformligament

detoxify drugs and alcohol and degrade hormones

liver

- a yellow-to-green, watery solution bilepigments (bilirubin), cholesterol,phospholipids, ad electrolytes

Bile

salts physically break large fat globules into smaller ones

bile

Bile exits the liver via the

common hepatic duct

Bile exits the liver via the

common hepatic duct

an inflammation of the liver resulting from drinking contaminatedwater or transmitted in blood via transfusion or contaminated

hepatitis

- chronic inflammatory condition in which ther is severely damagedand becomes hard and fibrous; caused by excess alcoholic beverageconsumption for many years

Cirrhosis

Small-walled green sac in thnferionsurface of the liver Live Bile enters the gall bladder via the cystic ductwhere it is stored when food digestion doesnot occur Common While in the gallbladder, bile is concentrated by the removal of water

gall bladder

- crystalize cholesterol formedwhen bile is stored in the gall bladder fortoo long or when too much water is removed

gall stones

The major functions of the digestive tract are usually summarized in two words

digestion and absorption

100

The essential activities of the GI tract include the ff. six (6) processes:

1. Ingestion 2Propulsion 3. Food Breakdown: Mechanical breakdown 4. Food Breakdown: Digestion 5. Absorption 6Defecation

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Conan Clint · 100問 · 2年前

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