Digestive Physiology Flashcards
What are the two main sections of the digestive system?
alimentary canal
accessory organs
What makes up the alimentary canal?
mouth pharynx esophagus stomach intestines
What makes up the accessory structures?
liver pancreas gallbladder teeth salivary glands
What are the four main tissue layers that make up the wall of the digestive tract?
mucosa
submucosa
muscularis
serosa/adventitia
What occurs in the digestive system?
Peristalsis Segmentation Secretion Digestion Absorption Elimination
What does saliva do?
Allows food to be swallowed more easily
Contains amylase that digests carbohydrates
Contains Lysozyme that inhibits bacteria and contains IgA
Dissolves food
What does movement of the mouth and tongue and chemicals in the mouth stimulate?
Parasympathetic nervous system to increase saliva
What are the parotid glands stimulated by?
Glossopharyngeal nerve (CN IX)
What are the submandibular and sublingual glands stimulated by?
Facial nerve (CN VII)
What does the uvula and soft palate do during swallowing?
they move up to keep food and liquid out of the nasal cavity
What does the epiglottis do during swallowing?
Moves down and covers the larynx to keep food and liquid out of the air passages
What are the two sphincters of the esophagus?
Upper and Lower (cardiac)
What kinds of digestion occur in the stomach?
Mechanical, chemical (HCL), and enzymatic
What do Goblet cells in the mucosa of the stomach do?
Secrete alkaline mucous which protects the stomach from HCL
What are the Mucosal cell types?
Mucus Chief Parietal G Mark Can Pass Gas
What do the mucosal cells produce?
Mucus - Mucus Chief - Pepsinogen Parietal - HCL/Pepsin G - Gastrin Mark Passes Hot Gas
What does Gastrin do?
Increases stomach mobility & gastric gland secretion
What triggers the Cephalic phase?
Smell, taste, sight, and thought of food send signals to the medulla oblongata
What is the Cephalic phase?
The vagus nerve CN X sends signals to the gastric glands to release acetylcholine which causes gastric gland secretion to increase
What triggers the Gastric phase?
Stretching of the stomach, high pH, and peptides send signals to the medulla oblongata
What is the Gastric phase?
The vagus nerve CN X sends signals to the gastric glands and releases acetylcholine which causes gastric gland secretion to increase
What is the intestinal phase of Gastric Secretion?
Stimulated by food entering the duodenum, intestinal gastrin is released and as the duodenum is further stretched– secretin and CCK is also released
What is the Duodenum?
First section of the small intestine, secretes hormones, secretions, and bile to complete digestion
What do the Jejunum and Ileum do?
Absorb water and nutrients, the ileocecal valve regulates the movement of food into the large intestine
How is the movement of food in the small intestine regulated?
Movement increase via vagus nerve
Movement decrease via sympathetic nerves
What does the Liver do for digestion?
Makes bile from cholesterol and bilirubin
What are other functions of the Liver?
Stores glycogen, vitamins, and minerals, converts nutrients, detoxifies, removes ammonia, and synthesizes blood protein
What does the Gall bladder do?
Stores and concentrates bile
What does bile do?
Emulsifies fat, like making a vinaigrette
Helps small intestines absorb fats and cholesterol
Is sent back to the Liver and recycled
What is cholecystokinin (CCK)?
Released by the duodenum; causes the gall bladder to contract, relaxes hepatopancreatic sphincter to allow bile to enter duodenum, and stimulates secretion of pancreatic juice into duodenum
What does the pancreas secrete for digestion?
Digestive juices and bicarbonate
What regulates the main pancreatic duct’s secretions into the duodenum with the bile duct?
Hepatopancreatic sphincter (Oddi)
What is the different between the main pancreatic duct and the accessory duct?
The accessory duct directly empties into the duodenum
What is pancreatic juice?
Secreted by Acinar cells, it contains bicarbonate to neutralize acidic food coming from the stomach and protects the intestinal lining while providing proper pH for pancreatic enzymes to work
What do the bacteria in the large intestine do?
Digest material and synthesize vitamins K and B complex
What are the Splanchnic nerves?
Greater
Lesser
Least
