Pathophys Flashcards
Sphincter that keeps air from entering the esophagus and stomach when breathing
Upper esophageal sphincter (pharyngoesophageal sphincter)
Remains tonically contracted to prevent reflux, during swallowing it relaxes
Lower esophageal sphincter (gastroesophogeal sphincter)
What helps keep a zone of high pressure around the LES and prevents reflux?
Diaphragm
Contains the opening of the common bile duct and main pancreatic duct
Duodenum
Food is digested and absorbed
Jejunum and Ileum
Blind pouch that projects down at the junction of the ileum and colon - prevents return of feces to small intestine
Cecum
What makes up the innermost (first) layer of the esophagus? The mucosal layer
Lamina propia
Muscularis mucosa
Epithelium lining
What is the function of the first layer of the esophagus
Mucus production Excretion of digestive enzymes Absorption of breakdown products Maintenance of a barrier to prevent the entry of noxious substances and pathogenic organisms Lymphatics
What is the second layer of the esophagus?
Submucosal layer
What is contained within the submucosal layer of the esophagus?
Blood vessels, nerves, and structures that secrete digestive enzymes
What is the third layer of the esophagus?
Muscularis externa
What is the function of muscularis external?
Fascilitates movement
What is the fourth and final layer of the esophagus?
Serosal layer
Contains the blood vessels, nerves, lymphatic vessels that supply the intestine wall. Holds the organs in place and stores fat.
Mesentary
From stomach to cover the transverse colon and folds of the intestine
Greater omentum
Extends between the transverse fissure of the liver and lesser curvature of the stomach
Lesser omentum
Constant level of contraction or tone without regular periods of relaxation
Found in the lower esophagus, upper region of the stomach, ileocecal valve and internal anal sphincter.
Tonic movements
Intermittent contractions responsible for mixing and moving food
Rhythmic movements
The parasympathetic nervous system will ____ activity of the entire enteric nervous system
Increase
Sympathetic innervation _____ activity of the entire enteric nervous system
Inhibits
When are gastric contents emptied into the duodenum?
Between contractions
What is the duodenal pH?
Below 3.5
Slow contraction of the circular muscle layer occlude the lumen and drive contents forward or backward. Function to mix chyme with digestive enzymes and ensure all parts of chyme have adequate exposure to the mucosal surface.
Segmentation waves
Rhythmic propulsive movements to propel chyme to the large intestine
Peristaltic movements
Local digging-like action, makes sure all aspects are exposed to intestinal surface.
Haustrations
Large segment of the colon contracts as a unit moving fecal matter forward
Mass movements
Which nerves supply the internal and external sphincters?
Pedundal
Initiated by distention of the rectal wall with initiation of reflex peristaltic waves that spread through the descending colon, sigmoid colon and rectum
Itrinsic myenteric reflex
Integrated at the level of the sacral cord. When the nerve endings in the rectum are stimulated, signals are transmitted to the sacral cord and then reflexively back to the descending colon, sigmoid colon, rectum, anus and pelvic nerves. Increase peristaltic movements and relax the internal sphincter.
Parasympathetic reflex
Primary function: stimulation of gastric acid secretion. Also has a trophic (growth producing) effect on the mucosa of the GI tract.
Gastrin
Produced by the endocrine cells in the mucosal layer of the fundus of the stomach. It displays potent growth hormone releasing activity and has a stimulatory effect on food intake and digestive function while reducing energy expenditure.
Ghrelin
Where is secretin secreted?
By the S cells in the mucosa of the duodenum and jejunum
What does secretin do?
Inhibits gastrin secretion, stimulates pancrease to produce larger amounts of fluid with high bicarb
What stimulates the release of secretin?
Entry of acid chymeinto the intestine
What type of cells secrete cholecystokinin?
I cells in the intestinal mucosa
What stimulates pancreatic enzyme secretion?
Cholecystokinin
Potentiates the action of secretin, increasing pancreatic bicarb response to low levels of secretin, stimulates biliary secretion of fluid and bicarb, regulates gallbladder contraction and gastric emptying. Has been known to inhibit food intake and mediate appetite.
Cholecystokinin
Increase insulin release after an oral glucose load
Incretin hormones
What type of incretin hormone is released from L cells in the distal small bowel?
GLP-1
What type of incretin hormone is released from K cells in the upper gut and suppresses glucagon release, slows gastric emptying, and decreases appetite and body weight?
GIP
Innervation by the parasympathetic nervous system will ______ salivary secretions
Increase
Secrete HCL and intrinsic factor
Parietal cells
What type of gastric secretion cells secrete pepsinogen, and what does pepsinogen do?
Chief cells
Pepsinogen is an enzyme that initiates the breakdown of proteins
Which type of cells secrete gastrin?
G cells
Which type of cells produce mucus? What is the purpose of these cells?
Epithelial cells
Needed to protect from HCL
What glands produce mucus?
Brunner glands
What acts as a vehicle for absorption, has a pH between 6.5 and 7.5, and is secreted by specialized cells?
Serous fluid
What enzyme separates amino acids?
Peptidases
What surface enzymes split sugars?
Disaccharidases
What is the only secretion produced by the large intestine?
Mucus
Most of our intestinal flora is ?
Anaerobic
Each villi has? 3 things
Artery
Vein
Lymph
Glandular structures that open into the spaces between villi
Crypts of lieberkuhn
Carbs must be broken down into ??
Monosaccharides
What is the first thing to break down starches?
Amylase in the mouth
Where is another place you can find amylase besides in the mouth?
Pancreatic secretions
What breaks disaccharides down into monosaccharides?
Brush border enzymes
What is the first step of fat digestion and absorption?
Emulsification
Increases the number of triglyceride molecules exposed to pancreatic lipase which splits triglycerides into free fatty acids and monoglycerides
Emulsification
Where and with what does protein digestion begin?
In the stomach with pepsin
What converts pepsinogen to pepsin?
The low pH of chyme
Which pancreatic enzymes further break down protein?
Tyrpsin
Chymotrypsin
Carboxypeptidase
Elastase
Are pancreatic enzymes active when they are secreted?
No, they are secreted in their inactive form and then converted
Rhythmic spasmodic movements of the diaphragm, chest wall and abdominal muscles. Precedes or alternates with periods of vomiting.
Retching
Located in the dorsal portion of the reticular formation of the medulla near the sensory nuclei of the vagus
Vomiting center
Located in a small area on the floor of the fourth ventricle where it is exposed to both blood and cerebrospinal fluid
Thought to mediate the emetic effects of blood borne drugs and toxins.
Chemoreceptor
What exerts a direct effect on the vomiting center?
Hypoxia
What types of neurotransmitters suppress vomiting and nausea?
Dopamine and serotonin antagonists