Chapter 29 Digestive System and Pathologies

Liver: Secretion

Bile: greenish-yellow liquid that emulsifies fat -Disperses large globules into small droplets -This allows pancreatic lipase to work more efficiently -Promotes absorption of fatty acids and fat-soluble vitamins (A, D, E, K)

Maltase, sucrase and lactase digest which type of nutrient?

Carbohydrate

The vermiform appendix is suspended from the inferior portion of which structure?

Cecum

Which section of the large intestine is a blind pouch located in the right lower quadrant of the abdomen?

Cecum

Acini Cells

Cells that secrete pancreatic enzymes

Irritable Bowel Syndrome

Characterized by abnormal muscular contractions of the colon.

Mechanical digestion

Chewing with the teeth, churning in the stomach, and localized mixing actions within the oral cavity and in the digestive tube.

Ulcerative Colitis

Chronic inflammation of the colon with the presence of ulcers

Which term means the semiliquid substance churned by the stomach?

Chyme

Small Intestine

Coiled tube between stomach and large intestine -90% of absorption occurs here - Primary function is chemical digestion and absorption of digested food. -Sections: --Duodenum: first/shortest; contains ducts for liver, gallbladder, and pancreas --Jejunum --Ileum: last/longest; contains Peyer patches (lymphatic tissue) -Plicae circulares: circular folds in the intestinal wall -Villi: fingerlike projections containing blood capillary and lacteal (lymph) capillary --Microvilli: projections on villi, giving intestine a velvety appearance (brush border)

Oral Cavity

Contains teeth, tongue, openings for salivary glands - Masticate: chewing -Little absorption occurs here. Exceptions: medication such as nitroglycerin. Administered sublingually (beneath tongue)

Oropharynx

Contains the tonsils

Where can gallstones become lodged?

Cystic duct

Bile

Digestive fat emulsifier that disperses large fat globules into smaller droplets

Teeth

Enamel-coated structures used to bite and chew to help break up large pieces of food into smaller ones. - Adults have 32 secondary teeth -Children have 20 primary, or deciduous, teeth that are usually shed between 6 and 12 years of age. -Teeth are classified according to shape and function: incisors, cuspids (canines), bicuspids (premolars), and multicuspids (molars). -The third molars are also called wisdom teeth because they erupt when a person is old enough to be "wise" (usually between the ages of 17 and 25)

Diarrhea

Frequent passing of unformed, loose, watery stools.

Which structure stores and concentrates bile

Gallbladder

Chief Cells

Gastric cells that secrete pepsinogen which digests proteins

Which section of the peritoneum contains significant amounts of fat, and resembles and apron?

Greater Omentum

Which term refers to the pouches in the large intestine formed by the teaniae coli appearance?

Haustra

Gallbladder

Hollow, pear-shaped sac --Located on inferior surface of liver -Stores/concentrates bile produced by liver --Does not produce bile -Rugae: enabling expansion --Gallbladder contracts; bile moves into duodenum

Hepatitis

Inflammation of the liver

Crohn Disease

Inflammatory bowel disease most commonly affecting the beginning of the large intestine and end of the small intestine.

Consitipation

Infrequent or difficult passing of stools.

Which substance breaks lipids down into glycerol and fatty acids?

Lingual Lipase

Liver

Located inferior to diaphragm; largest organ -Right upper quadrant -Hepatic = liver -Functions: --Metabolize proteins, carbohydrates, and fats --Produce plasma proteins --Store nutrients --Detoxify certain harmful chemicals --Excrete substances --Produce bile --Provide defenses

Gallstones

Masses of solid material or stones that form in the gallbladder

Mastication

Medical term for chewing

Goblet Cells

Mucus-producing cells that are found in the spaces between some of the villi

Gastrointestinal tract

Muscular tube from mouth to anus -Also called alimentary canal or digestive tube

What do the chief cells in the stomach's lining secrete?

Pepsin

Which condition involves damaged areas of the gastrointestinal mucosa that are exposed to acidic gastric juice?

Peptic Ulcer Disease

gastroesophageal reflux disease (GERD)

Periodic regurgitation of gastric contents into the esophagus

Which term refers to the large flat folded serous membrane within the abdominal cavity?

Peritoneum

Pancreas

Pinkish-gray gland located posterior to stomach -Secretes enzymes that break down all categories of digestible foods -Alpha and beta cells: Secrete hormones (glucagon and insulin) -Acini cells: Secrete pancreatic enzymes -Pancreatic duct: runs length of pancreas --Transports digestive enzymes to duodenum

Chemical Digestion

Process by which enzymes, acids, and bases cam break down food into small molecules that the body can use

Cirrhosis

Progressive disease characterized by degeneration and regeneration of liver tissue. Destroyed cells are replaced by scar tissue.

Which nutrients do trypsin and chymotrypsin from the pancreas digest?

Proteins

Stomach

Saclike organ between esophagus and small intestine. - When empty, it is approx the size of a large sausage. When full, it can expand and hold up to 1 gallon of food and liquid (depending on body type). - mixes food with gastric juice until it becomes a semiliquid substance called chyme. - Its lining contains folds called rugae - Gastric juice: stomach secretions - Pyloric sphincter: between the stomach and small intestine - The only substances absorbed by the stomach are water, some minerals, alcohol, and some medications.

Oral Cavity: Secretions

Saliva: watery liquid -Moistens oral mucosa -Helps form/lubricant bolus for easier swallowing -Contains digestive enzymes: salivary amylase and lingual lipase Salivary glands: -Submandibular -Sublingual -Parotid (largest) •The enzymatic breakdown of carbohydrates and lipids is what allows us to taste food. •There is no enzyme in the oral cavity that breaks down protein, which is why high-protein food such as tofu or eggs have little or no flavor.

Peptic Ulcer Disease

Ulcerations of the mucosal lining in parts of the GI tract exposed to acidic gastric juice. - The word peptic refers to the stomach enzyme pepsin, which breaks down proteins.

Which condition involves inflammation of the large intestine?

Ulcerative Colitis

Peritonuem

a large, flat, folded serous membrane within the abdominal cavity. - The serous fluid lubricates the viscera and allows peritoneal layers to slide across each other - Mesentery: membranes behind organs and intestines - Greater/lessor omentum: membranes in front of organs and intestines - Retroperitoneal space: behind peritoneum. Contains pancreas, kidneys, and part of intestines

Ileocecal sphincter

between small and large intestines

Pyloric sphincter

between the stomach and small intestine

Chyme

blend of food and gastric juice - The process of moving chyme into the small intestine may take up to 4 hours; food with higher fat content will stay in the stomach longer.

Digestion

breaking down materials into simple molecules -has both mechanical and chemical digestion

Defecation

indigestible/unabsorbed materials are eliminated from the body through the anus.

Mucosa

innermost layer; mucous membrane

Peristalsis

mixing/propulsion movements -in the small intestine is distinct and not only contracts to propel its contents forward but also contracts in a localized mixing motion to move nutrient-rich materials back and forth over the villi, maximizing the rate of nutrient absorption.

Layers of Gastrointestinal Tract

mucosa, submucosa, muscle, serosa.

Sphincter

ring of muscle; remains contracted to close an opening

Parietal Cells

secrete hydrochloric acid and intrinsic factor

Absorption

simple molecules from GI tract move into blood and lymph vessels, then into body cells

Bolus

small round mass of food; formed as food is chewed and mixed with saliva

What substances does the large intestine absorb?

water and electrolytes

Esophagus

Transports food/liquids from pharynx to stomach - the base of the esophagus contains the lower esophageal sphincter LES. Also called the cardiac sphincter or the gastroesophageal sphincter. - Located behind the trachea - Secretion: mucus

Pharnyx (throat)

-Deglutition: swallowing. Occurs via peristalsis •Contraction begins behind the bolus -Secretion: mucus

Hepatic Portal System and Biliary Tract

-Hepatic portal system: transports blood from GI tract, spleen, gallbladder, and pancreas to liver -Biliary tract: transports bile to gallbladder or duodenum --Common hepatic duct: transports bile from liver •Merges with cystic duct --Cyst duct joins the common bile duct •Merges with pancreatic duct --Major duodenal papilla: entrance into duodenum

Stomach: Secretions

-Pepsin: digests proteins; secreted by chief cells -Hydrochloric acid: assist protein digestion, activates enzymes, kills pathogenic bacteria; secreted by parietal cells -Intrinsic factor: assist vitamin B12 absorption; secreted by parietal cells -Gastrin: hormone stimulating secretions -Mucus: secreted by goblet cells that protect the gastric lining from enzymes and acids.

Small Intestine: Secretions

-Peptidase and enterokinase: protein digestion -Disaccharidase, maltase, sucrose, and lactase: carbohydrate digestion -Lipase: fat digestion -Cholecystokinin: hormone stimulating gallbladder contraction and pancreatic secretions -Secretin: hormone releasing alkaline liquid from pancreas; facilitates digestion

Large Intestine: Features

-Taeniae coli: thick, longitudinal bands resembling thread-gathering fabric -Haustra: pouches formed by taenia coli --Contents move by peristaltic waves that push contents of one haustrum to next -Water is continually absorbed from the feces through the intestinal lining, changing it from a semiliquid to a semisolid mass before it is removed during defecation.

Pancreas: Secretions

-Trypsinogen and chymotrypsin: protein digestion -Pancreatic amylase: carbohydrate digestion -Pancreatic lipase: fat digestion -Bicarbonates: neutralize acidic chyme released from stomach into duodenum

Large Intestine: Sections

1. Cecum: blind pouch - Vermiform appendix: lymphatic tissue 2. Colon: subdivisions are ascending, transverse, descending, and sigmoid -hepatic flexure: curve on right side -splenic flexure: curve on left side -sigmoid flexure: curve at top of (left) iliac crest -the S-shaped sigmoid joins the rectum. 3. Rectum: expands when filled with feces 4. Anus: contains external anal sphincter -releases feces during defecation

What percentage of absorption occurs in the length of the small intestine?

90%

Large Intestine

A large bowel, or colon, begins at the ileocecal sphincter and ends at the anus. Primary functions: Absorption of water/electrolytes, Vitamin production (K/some Bs), and Formation and elimination of feces (stools) -Secretion: mucus

Which part of the colon connects to the rectum?

Sigmoid

Ingestion

The process of taking materials into the mouth by eating and drinking

Gastroenterology

The study of the digestive system

Salivary amylase (ptyalin)

carbohydrate digestion

Enzyme

catalyst in chemical reactions

Secretion

cells or glands that secrete mucus, chemicals, and enzymes for chemical digestion. - Example: salivary glands, stomach, liver, gallbladder, pancreas, and the intestines

Submucosa

contains loose connective tissue, blood/lymph vessels, nerves, and glands

Muscle

contains smooth muscle -responsible for mixing or propulsion movements called peristalsis, as well as actions of swallowing and defecation

Which term means swallowing?

deglutition

Serosa

extends and attaches to peritoneum

Lingual lipase

fat digestion

Villi

fingerlike projections containing blood capillary and lacteal (lymph) capillary

Duodenum

first section of the small intestine

Rugae

folds in lining enabling it to enlarge - expanding structures, such as the stomach, gallbladder, urinary bladder, and vagina