Digestive System Chapter 26 Flashcards
What are the 6 functions of the digestive system?
- Ingestion
- Motility
- Secretion
- Digestion
- Absorption
- Defecation
What are the organs of the GI Tract?
- Oral cavity
- Pharynx
- Esophagus
- Stomach
- Small Intestine
- Large Intestine
- Anus
What are the accessory digestive organs?
- Teeth
- Tongue
- Salivary Glands
- liver
- Gall Bladder
- Pancreas
Define Ingestion
eating food and liquid
define Motility
Mixing and peristalsis
The capability of smooth muscles to mix and move the food contents
Define secretion
DS secretes acids, bile mucus, enzymes 7L/day
Define Digestion
Mechanical and chemical breakdown of CHO, Lipids and Proteins
Define Absorption
Absorption of nutrients, ions and fluids into blood stream
Define defecation
Removal of metabolic wastes
What is the overall function of the oral cavity?
Mechanical and chemical digestion
What is the overall function of the digestive system?
Ingest, mix, transport and break down food mechanically/chemically. Absorb digested nutrients and expels wastes
What is the overall function of the pharynx?
Passageway for food and liquid
What is the overall function of the esophagus?
secrete mucus and transports food to the stomach
What is the overall function of the stomach?
mixing area and holding reservoir
What is the overall function of the anus?
discharge feces form body
What is the overall function of the small intestine?
completion of digestion and absorption
What is the overall function of the large intestine?
absorb most water remaining in digested material and forms faces
What is the overall function of the teeth?
Mechanically digest
Responsible for Mastication
What is the overall function of the tongue?
movement of food and assisting swallowing
What is the overall function of the salivary glands?
produce and secrete saliva
what is the overall function of the liver?
Produce bile
What is the overall function of the gallbladder?
Store and concentrate bile
What is the overall function of the pancreas?
produce enzymes to digest food (exocrine)
What are mesenteries?
Folds of peritoneum that support and stabilise intraperitoneal GI tract organs
What are the types of mesenteries?
- Greater Omentum
- Lesser Omentum
- Mesentery proper
- Mesocolon
What is the Greater omentum?
Longest peritoneal fold
Covers most abdominal organs
fatty apron
What is the lesser omentum?
secures stomach and duodenum from the liver
What is the mesentery proper?
suspends small int. from posterior abdominal wall
what is the mesocolon?
attaches large int. to the posterior abdominal wall
What are retroperitoneal organs?
Ascending and descending colon, duodenum and pancreas
situated behind the peritoneum
What are peritoneal ligaments?
Folds of the peritoneal that connect structures
What are 3 examples of peritoneal ligaments?
- Coronary ligament (liver to diaphragm)
- Falciform ligament (liver to abdominal wall)
- Lienorenal ligament (Spleen to kidney)
What are the four tunics of the GI Wall?
(deep to superficial)
1. Mucosa
2. Submucosa
3. Muscularis
4. Adventital/serosa
What is the mucosa?
Innermost lining of GI Tract
What are the 3 layers of the mucosa?
- Epithelium
- Lamina propria
- Muscular mucosa
What is the epithelium of the mucosa?
Absorbs nutrients and contains enteroendocrine cells
What is the lamina propria of the mucosa?
Connective tissue, blood vessels and lymphatic vessels.
Contains muscle-associated lymphatic tissue MALT
What is the muscular mucosa?
Smooth muscle fibres increase surface area
What is the Submuscosa?
Second deepest layer
Meshwork of collagenous fibres, nerves, blood vessels and lymphatic vessels
Contains submucosal glands
What plexus does the submucosa contain?
Submucosal nerve plexus
ENS
regulates movements of the mucosa and vasoconstriction of blood vessels
innervates mucosal glands
What is the muscularis?
Smooth muscle layer
What are the two types of smooth muscle within the muscularis?
Inner layer= Circular fibers
Outer layer= Longitudinal fibers
What plexus is within the muscularis?
myenteric nerve plexus
controls GI tract motility
What is the adventitia/serosa?
superficial layer
serous membrane
secretes serous fluid
aka visceral peritoneum
What are the functions of the saliva?
Moistened ingested stuff to form bolus
moisten/lubricate oral cavity structures
chemical digestion (amylase)
Antibacterial (lysozyme)
dissolve food for taste receptors
What are the three pairs of salivary glands?
- Parotid glands
- Submandibular glands
- Sublingual glands
How much saliva is produced by the parotid glands?
25-30%
How much saliva is produced by the submandibular glands?
60-70%
How much saliva is produced by the sublingual glands?
3-5%
What enzyme is secreted by lingual glands?
Lingual lipase
What are the teeth composed of?
Crown
Neck
Dentin
Enamel
Pulp cavity
Root canal
Apical foramen
periodontal ligaments
What are the specific functions of the stomach?
Connect esophagus to the duodenum
Mixing area and holding reservoir
Site for mechanical and chemical digestion
Starts digestion of proteins
Converts bolus to chyme
What does the stomach secrete?
Gastric juice containing HCL and pepsin
Gastrin
What are the four main regions of the stomach?
- cardia
- fundus
- body
- pyloric part
What is the cardia of the stomach?
Initial part
What is the fundus of the stomach?
Food storage
What is the body of the stomach?
Food mixing
What are the 3 regions of the pyloric part?
Pyloric antrum
Pyloric canal
Pyloric sphincter
What is the pyloric antrum?
Connects to body
What is the pyloric canal?
leads to pylorus
What is the pyloric sphincter?
Rugae (mucosal folds)
leads to duodenum
What are the layers of the stomach wall?
Mucosa
Submucosa
Muscularis
Serosa
What are the 3 layers of muscularis in the stomach?
- Oblique
- Circular
- Longitudinal
What are the types of exocrine gland cells in the stomach?
- Surface and mucous neck cells
- Parietal cells
- Chief cells
- Enteroendocrine cells
What do mucous, parietal and chief cells secrete?
Gastric juice
What do enteroendocrine cells secrete in the stomach?
Gastrin hormone
What do surface mucous cells secrete specific?
Alkaline fluid with mucin
what do mucous neck cells secrete specific?
acidic fluid with mucin
what do parietal cells secrete specific?
Intrinsic factor
Hydrochloric acid
what do chief cells secrete specific?
Pepsinogen and gastric lipase
What is the function of intrinsic factor?
Protein made to facilitate absorption of B12
what is the function of HCL?
chemically digest food
activate pepsin
kill bacteria
What is the function of pepsin?
digest proteins
deactivated form= pepsinogen
What is the function of gastric lipase?
digest triglycerides
What is intestinal juice?
In small intestine
Clear, yellow fluid
vehicle for absorption of substances in the chyme
What are the 3 parts of the small intestine?
- Duodenum
- jejunum
- illeum
What is the jejunum?
Primary site for chemical digestion and nutrient absorption
What are the layers of the small int wall?
- Mucosa
- submucosa
- muscularis
- serosa
What cells are in the intestinal villus?
- Microvilli
- Goblet cells
- Unicellular gland cells
- Enteroendocrine cells
What do unicellular gland cells do?
Synthesises enteropeptidase
What does enteroendocrine cells do in the small int?
Secretes hormones:
-Secretin
-cholecystokinin
-Gastric inhibitory peptide
What doe the submucosa of the small int. contain?
Duodenal Glands
aka Brunner’s glands
Secrete alkaline mucous
What are the structures of the Large intestine?
- cecum
- Ascending colon
- transverse colon
- Descending colon
- Sigmoid colon
- Rectum
- Anal canal
What are the four layers of the Large intestine wall?
- Mucosa
- Submuscoa
- Muscularis
- Serosa
What else does the large intestine contain in its wall?
Intestinal glands
Teniae coli
Haustra
What cells are in the large intestine?
- Absorptive cell -Absorbs water
- Goblet cells -Mucous
What is the structure of the liver?
4 incompletely separated lobes and two ligaments
Ligamentum teres
What are hepatocytes?
Functional unit of the liver that produce 800-1000mL of bile a day
What are ducts in the liver?
Bile ductules and ducts
Right/Left hepatic ducts
Common hepatic ducts
Cystic duct
Common bile duct
What are the hepatic structures?
- Hepatic sinusoid
- Hepatic lobules
3.Bile canaliculi - Hepatocytes
- Reticuloendothelial cells (macrophages)
What is the portal triad?
Bile ductule
Hepatic portal vein
Hepatic artery
What is the gallbladder?
Attached to inferior surface of liver
stores and concentrates bile
What are the three regions of the gallbladder?
- Neck
- Body
- Fundus
What is the cystic duct?
Connects gall bladder to common bile duct
What are the exocrine functions of the pancreas?
Secrete pancreatic juice into duodenum via main pancreatic duct (juice= enzymes + mucin)
What cells secrete pancreatic juice?
Acinar cells
What is the structure of the pancreas?
head, body and tail