Chapter 22: The Digestive System Flashcards
What are the organs of the Digestive system? (5)
- teeth
- tongue
- salivary glands
- liver
- gallbladder
- pancreas
What are the processes of the digestive system? (7)
- ingestion
- secretion
- propulsion
- peristalsis
- digestion
- absorption
- defecation
What are the forms of Motility?
- swallowing
- churning
- peristalsis
- defection
What nerve regulated motility?
Enteric nervous system (ENS)
What are the 4 layers of the digestive system?
- mucosa
- submucosa
- muscularis externa
- serosa
Three components of the Mucosa?
- Lamina propria
- muscularis mucosae
- regenerative epithelial cells
Submucosa
- composed of dense irregular CT, lymphatic vessels, submucosal glands
- regulates secretion and blow flow to the area
Muscularis externa
- thick smooth muscle (found in most of the DS)
- 2 layers composed in circular and longitudinal layers
- regulated by ENS called the myenteric plexus
serosa
-simple squamous epithelium and loose CT
What is the Peritoneal Membrane consist of?
- outer parietal peritoneum
- inner visceral peritoneum
- between is the peritoneal cavity
What is it called when the visceral peritoneum folds over itself?
Mesenteries (supports and binds organs together)
What is the 2 mesenteries?
- greater omentum
- lesser omentum
What is the splanchnic circulation?
blood vessels that supply and drain the abdominal digestive organs
What are the 3 main clusters of nerves that serve the digestive organs?
- celiac plexus
- superior mesenteric plexus
- inferior mesenteric plexus
What are the components of saliva?
- water
- enzymes
- mucus
- other solutes
Functions of Saliva
- moistens
- lubricates
- cleanses the oral mucosa
What is salivation?
process of secretion from the 3 salivary glands
-controlled by the PNS
What cells is the Pharynx lined with?
stratified squamous epithelium
What cells is the esophagus lined with?
stratified squamous nonkeratinized epithelium
What does the gastroespogeal sphincter do?
regulates the passage of bolus into the stomach
describe the voluntary phase of swallowing
tongue pushes bolus posteriorly towards the oropharynx
describe pharyngeal phase of swallowing
- bolus enters the oropharynx
- soft palate and epiglottis seal off the nasopharynx and larynx
describe esophageal phase of swallowing
peristaltic waves move the bolus down the esophagus to the stomach
What are the 5 regions of the stomach?
- cardia
- fundus
- body
- pyloric antrum
- pylorus
What does the muscularis externa do in the stomach?
- additional inner layer of smooth muscle and the fibers are oriented obliquely
- allows for churning
What are the 4 main types of cells in gastric glands?
- enteroendocrine cells (gastrin)
- chief cells (pepsin)
- parietal cells (HCL)
- mucous neck cells (acidic mucus)
What are the 3 phases of secretion during eating?
- cephalic phase
- gastric phase
- intestinal phase
What are the three motility of the stomach
- receive food from esophagus
- churn the incoming bolus into chyme
- control the rate at which chyme empties into the small intestine
What are the four main processes of the small intestine?
- secretion
- digestion
- absorption
- propulsion
3 parts of the small intestine
- duodenum
- jejunum
- ileum
What does the duodenum do?
- houses major duodenal papilla
- where secretion from the gallbladder and pancreas enter the small intestine
- duodenal gland protects against acidic chyme
What does the jejunum do?
chemical digestion and absorption
What does the ileum do?
-prevents materials in the large intestine from coming back into the small intestine
Circular fold?
involve both mucosa and submucosa
slows down chyme to give time for nutrients to absorbed
Villi?
houses glands for both enteroendocrine cells and mucus secreting goblet cells
microvilli?
brush border
helps breaks down peptides
what is the composition of pancreatic juice?
water
multiple digestive enzymes
other proteins
ducts cells (secrete bicarbonate ion)
CCK?
- produced by duodenal enteroendocrine cells in response to lipids and partially digested proteins in the duodenum
- acts on acinar cells to trigger secretion of digestive enzymes
Secretin?
- released by duodenal cells in the response to acid and lipids in the duodenum
- triggers ducts cells tos secrete bicarbonate ions
Hepatocytes?
primary cell in the liver, arranged in the shape of a hexagon, stacked on top of each other with a small central vein
Portal triad?
found at the corner of the lobule composed of -hepatic arteriole -portal venule -small bile duct
Hepatic arterioles and Portal vein?
- drain into hepatic sinusoids
- then into central vein
- then into inferior vena cava
How does bile flow in the Liver?
bile flows through the liver in opposite direction, from hepatocytes to bile canaliculi to bile duct
Hepatopancreatic Ampulla and Hepatopancreatic sphincter?
- where the common bile duct joins the pancreatic duct
- controls the emptying of bile and pancreatic fluids into the duodenum
What does salivary amylase do?
breaks long polysaccharides into shorter oligosaccharides (finished digesting in the small intestine by the enzymes from enterocytes)
What happens to carbohydrates when digested?
once broken down the monosaccharides they are ready to be reabsorbed, once in the blood they are taken to the liver via haptic portal vein
Na+/glucose cotransporter?
glucose and galactose are transported across the enterocyte apical membrane by secondary active transport mechanism
Where are proteins digested?
stomach and small intestine
How are proteins broken down in the stomach?
- Pepsinogen becomes pepsin (has to have a pH of 2)
- pepsin catalyzes reactions that digest protein into smaller polypeptides, oligopeptides, and some free amino acids
Trypsin?
- found in the small intestine
- converts other enzymes to active forms
- breaks down protein to oligopeptide and some free amino acids
Brush border?
- found in the small intestine on the enterocytes of the villi
- catalyze digestion of oligopeptides into free amino acids
What happens once protein is digested into oligopeptides and free amino acids?
- oligopeptides are broken down to free amino acids
- free amino acids then exit by facilitated diffusion
- then enter capillaries in the villi
- taken to the liver
