Digestive System Flashcards
What are the accessory digestive organs?
Liver, Pancreas, Gallbladder, Salivary glands
What is peristalsis?
An organized contraction and relaxation of smooth muscle that propels through the alimentary canal in one direction
What is segmentation?
Contractions of smooth muscle that moves chyme back and forth within the canal to allow mixing and further breakdown
What are the layers of the alimentary canal? What are their basic functions
Lumen, mucosa (lines lumen), submucosa (support layer), muscularis externa (muscle layer), serosa (outer layer)
In which of the 4 main layers of the alimentary canal would you expect to find an epithelium?
Mucosa and serosa
What are the 3 sublayers of the mucosa?
- epithelium 2. lamina propria 3. Muscularis externa
Characteristic of the Submucosa
Highly vascularized and nutrient absorbent
What is the submucosal nerve plexus?
controls secretions of glands & muscularis mucosa contractions
What is the submucosal nerve plexus?
Controls secretions of glands and muscularis mucosa contractions
What is the muscularis externa made up of?
2 layers of smooth muscle: circular and longitudinal
What is the myenteric nerve plexus and where is it found?
Controls peristalsis and segmentation; found within the muscularis externa
What is the enteric nervous system?
Controls the smooth muscle and glands of alimentary canal; “brain in the gut”; made of 2 nerve plexuses
What is the serosa made of?
Simple squamous epithelium + a thin loose areolar CT
What type of epithelium would you expect to find lining the oral cavity?
Stratified squamous
What is rough surface found on the tongue called?
Filiform papillae
What is the lingual frenulum?
Fold of mucosa layer that connects the tongue to the floor of the mouth
What are the primary salivary glands?
Parotid gland, submandibular gland, sublingual gland
What are the types of permanent teeth?
Incisors, Canines, Premolars, molars
What are the regions of a tooth? Where are they found?
Crown: part above gum line
Neck: contained within gum tissue
Root: contained within bone
What part of the tooth provides nutrients and sensation?
Pulp
Enamel is the…
… hardest substance in the body
What is the periodontal ligament?
Dense CT that attached cement of tooth to bony socket
What is the function of the pharynx?
Connects oral cavity to esophagus and nasal cavity
What are the parts of the pharynx?
Oropharynx, laryngopharynx, Nasopharynx
What is the epithelium of the oropharynx and the laryngopharynx?
Stratified squamous
Characteristics & Function of Esophagus
connects pharynx to stomach; stratified squamous; mucous glands secrete mucus to lubricate bolus of food
What is the muscularis externa layer of the esophagus made up of?
Upper 1/3: skeletal muscle
Middle 1/3: skeletal & smooth muscle
Lower 1/3: smooth muscle
What is the outer layer of the esophagus?
Adventitia
What absorption takes place in the stomach?
Limited to water and alcohol
What is the lining mucosa epithelium of the stomach? What else is found here?
Simple columnar; Cells that produce bicarbonate-buffered mucus & the lining is dotted with gastric pits
What are the rugae of the stomach?
“wrinkles”, folds of mucosa that increase SA and allow stomach to expand.
What are the sphincters of the stomach and what are their functions?
Cardiac sphincter: prevents food from moving back into esophagus
Pyloric Sphincter: controls the release of chyme into duodeum
What are the layers of the muscularis externa in the stomach?
- oblique 2. circular 3. longitudinal
What are the specialized cells found in the gastric pits of the stomach? What are their functions?
Parietal cells: produce and secrete HCl and GIF which necessary for vitamin b12 absorption in the SI
Chief Cells: produce and secrete pepsinogen and gastric lipase
Enteroendocrince cells: release hormones
Undiff. Stem Cells: replaced every 3-7 days
What is pepsin? How is it created?
Pepsin breaks down proteins in food. It is created when pepsinogen mixes with HCl
Characteristics & Functions of the Small Intestine
Simple columnar; site of most absorption and chemical digestion
What are the segments of the SI?
Duodenum, Jejunum, Ileum
What do the circular folds of the SI do?
Increase SA and force chyme to spiral through the small intestine which slows it down allowing for increased absorption of nutrients
Characteristics of Villi
Made of absorptive cells (enterocytes); Have capillaries (absorb proteins & carbs) and Lacteals (absorb fat)
What are absorptive enterocytes made of?
Lots of mitochondria because absorption of nutrients requires energy
What are the specialized cells found in the mucosa of the SI? What are their functions?
Absorptive enterocytes; Goblet cells (secrete mucus); enteroendorcine cells (secrete hormones to control the release of other substances); Intestinal crypts (between villi, produce intestinal juice); Paneth cells (secrete enzymes to destroy unwanted bactera)
What are the inputs to the duodenum?
Stomach contributes chyme, gallbladder adds bile; Pancreas adds digestive enzymes, pancreatic juice
Chyme enter duodenum from stomach and activates enteroendocrine cells… the presence of fats stimulates the release of ____.
CCK: signals release of store bile to break down fats for better absorption.
Chyme enter duodenum from stomach and activates enteroendocrine cells… the presence of acids stimulates the release of ____.
Secretin: signals release of pancreatic juice to neutralize acids
Label the Gross Anatomy of the Large Intestine
add: epipolic appendages, teniae colie; haustra; ascending colon, transverse colon, descending colon, sigmoid colon
What type of epithelium would you expect to find lining the large intestine?
Simple columnar
What are the specialized cells of the LI? What are the functions?
Colonocytes: absorb water & electrolytes
Goblet Cells: secrete mucus
Intestian crypts: stem cells are replaced every 7 days
What are the sphincters in the anal canal? What are the characteristics of each?
External Anal Sphincter: skeletal muscle, voluntary control
Internal Anal Sphincter: smooth muscle, involuntary control
Where is bile produced?
Liver;
What does the hepatic portal vein of the liver do?
Gathers blood from digestive organs and transports it to the liver
What does the hepatic artery proper of the liver do?
Provides oxygen-rich blood to the liver
What does the inferior vena cava of the liver do?
removes blood from liver after it has been processed
What does each portal triad contain? What does each part do?
Bile duct (transports bile out of lobule); Portal venule (transports nutrient-rich blood into lobule); Portal arteriole (transports oxygen-rich blood into the lobule)
What is the primary cell of the liver?
Hepatocytes
What is the role of liver sinusoids? Where are they found?
Between plates of hepatocytes; Site where arterial and venous blood mix (gives hepatocytes access to oxygen & nutrients) and carried to the central vein
What does the central vein do?
Drains blood from sinusoids out of liver
What are stellate macrophages?
Move through sinusoids to destroy unwanted microorganisms
What is the path of the bile in the liver?
Bile moves from hepatocytes to bile canaliculus to bile ducts
What does the gallbladder do?
Stores and concentrates bile
What is the exocrine function of the Pancreas?
Acinar cells produce and secrete pancreatic juices
What is the endocrine function of the pancreas?
Beta cells produce insulin & alpha cells produce glucagon
What is the mesentery?
Double-sided serous membrane that suspends organs within abdominal cavity
What is the mesentery?
Double-sided serous membrane that suspends organs within abdominal cavity
What are Ulcers?
Crater-like erosions of the mucosa
