Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
APHY 201 Exam 4d1
Ch. 18 Drills - The Digestive System
| Question | Answer |
|---|---|
| how does the digestive tract function as an immune barrier? | Simple columnar epithelium with tight junctions prevents swallowed pathogens from entering body, and Immune cells in connective tissue of the tract promote immune responses |
| what are the 3 parts to deglutition? | oral, pharyngeal, esophageal phases |
| What triggers the involuntary pharyngeal phase of deglutition? | Receptors in the posterior oral cavity and oropharynx initiate it. |
| peristalsis is controlled by | the swallowing center of the brain stem |
| How does muscle control transition along the esophagus? | The upper esophagus contains skeletal muscle with voluntary somatic control, while the lower esophagus has smooth muscle with involuntary autonomic control. |
| (recognize for multiple choice) What are the 5 main functions of the stomach? | The stomach stores food, churns it with gastric secretions, begins protein digestion, kills bacteria with acid, and moves chyme into the small intestine. |
| (bolded) Which cells secrete histamine and serotonin as paracrine signals? | Enterochromaffin-like (ECL) cells. |
| (bolded) What do D cells secrete? | somatostatin hormone. |
| How is H+ transported during the formation of HCl? | H+ is moved into the lumen via primary active transport by H+/K+ ATPase pumps. |
| What are the 3 main functions of HCl in the stomach? | HCl drops the pH to 2, denatures ingested proteins, and converts inactive pepsinogen into active pepsin. |
| What is the role of pepsin in digestion? | Pepsin is a protease that catalyzes the hydrolysis of peptide bonds in ingested proteins. |
| With what 3 ways does the stomach defend its lining against acid and pepsin? | It utilizes an adherent layer of alkaline mucus, tight junctions between epithelial cells, and rapid cell mitosis that replaces the epithelium every three days. |
| How are peptic ulcers typically treated? | They are treated with a combination of K+/H+ pump inhibitors (like omeprazole) and antibiotics. |
| How do NSAIDs contribute to acute gastritis? (hint: what is needed to stimulate alkaline mucus production?) | NSAIDs inhibit prostaglandin activity, which is needed to stimulate protective alkaline mucus production. |
| How is the duodenum naturally protected from acidic chyme? | It is protected by a mucosal layer and bicarbonate secreted by Brunner’s glands and the pancreas. |
| How does a Roux-en-Y gastric bypass work? | It creates a small pouch in the gastric fundus to which the mid-jejunum is directly attached. |
| What happens during a vertical sleeve gastrectomy? | About 85% of the stomach (specifically the fundus and body) is removed, but the intestinal pathway remains unaltered. |
| What are the main risk factors for developing GERD? | Risk factors include obesity, pregnancy, and a hiatal hernia. |
| Which 5 nutrients are absorbed in the duodenum and jejunum? | Sugars, lipids, amino acids, CALCIUM, and IRON are absorbed in the duodenum and jejunum. |
| Which 4 substances are absorbed in the ileum? Bile salts, vitamin B12, water, and electrolytes are absorbed in the ileum. | |
| What type of tissue and what type of cells make up the villi? (hint: the cells secrete mucus) | The villi are made of columnar epithelium with mucus-secreting goblet cells. |
| (starred) which brush border enzyme produces free amino acids, dipeptides, and tripeptides? | aminopeptidase |
| (starred) which brush border enzyme activates trypsin, which indirectly activates other pancreatic juice enzymes? | enterokinase |
| How does peristalsis in the small intestine compare to the stomach? what about segmentation in the small intestine? is it stronger or weaker than in the stomach? | Peristalsis in the small intestine is weaker, resulting in much slower movement of food than in the stomach. Segmentation is stronger in the small intestine than in the stomach and serves to mix the chyme in place. |
| How does acetylcholine (ACh) from the parasympathetic nervous system affect intestinal motility? | It interacts with muscarinic ACh receptors to increase the amplitude and duration of slow waves. |
| What is the sequence of 9 regions that food passes through in the large intestine? | It travels from the ileocecal valve into the cecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum, anal canal, and finally out the anus. |
| What structures are found in the mucosa of the large intestine? (what type of tissue and what else?) importantly, what does it not have? | It contains columnar epithelial cells with goblet cells, crypts, and lymphatic nodules, but it does not have villi. |
| what is produced by microbes that benefit the digestive system, provide energy for large intestine epithelial cells and help absorb electrolytes like sodium and chloride? | short-chain fatty acids |
| What 3 mechanisms help protect the intestinal tract from bacteria? | Protection is provided by mucus from goblet cells, the secretion of defensin by Paneth cells, and the secretion of IgA antibodies by plasma cells. |
| How does the normal intestinal microbiota help maintain the epithelial barrier? (2 benefits) | good bacteria limit inflammation and promote the repair of damaged epithelium. |
| How do commensal bacteria help reduce food allergies? what WBC do they promote the production of, and what do those do? | They promote the production of regulatory T lymphocytes, which help increase tolerance to antigens from food. |
| Which cells act as antigen-presenting cells to activate T-reg cells against commensal bacteria? | Intestinal dendritic cells. |
| What role does the appendix play in the digestive system? | It does not function in digestion, but it contains lymphoid nodules and a population of commensal bacteria to help replenish normal intestinal microbiota when needed. |
| How do bacteria like Salmonella, Campylobacter, and Shigella produce inflammatory diarrhea? | They produce it by invading the mucosa and causing damage and inflammation. |
| What do the longitudinal rectal muscles do during defecation? | They contract to increase pressure as the anal sphincters relax. |
| Which 2 conditions are classified under inflammatory bowel disease (IBD)? | Crohn’s disease and ulcerative colitis. |
| What physiological changes in the intestines increase permeability and lead to ulcerations in IBD? | Decreased mucus secretion by goblet cells and changes in the tight junctions between epithelial cells. |
| what is the difference between the enterohepatic circulation and the portal system? what does each accomplish? | HPS is 1-way vein network w/nutrient- & toxin-rich blood from digestive organs to the liver. EC loops & recycles specific substances (like bile acids) between the liver and the intestines. (Circular loop: Liver → Bile Duct → Intestine → Blood → Liver) |
| Which 7 organs drain venous blood into the hepatic portal vein? | The pancreas, gallbladder, stomach, omentum, spleen, small and large intestines |
| What is the pathway of blood in the hepatic portal system? | from capillaries to veins to capillaries and back to veins: blood flows from the capillaries of the GI tract and spleen into the hepatic portal vein, breaks down into the capillaries (sinusoids) of the liver, and exits via the hepatic veins into the IVC |
| What 3 structures make up a portal triad? | A bile duct, a hepatic artery, and a hepatic portal vein. |
| (starred) Which 3 endogenous compounds have a high percentage reabsorbed through enterohepatic circulation? | Bile salts, urobilinogen, and cholesterol. |
| (starred) What is the relative reabsorption rate and circulation status of the endogenous phospholipid lecithin? | A small percentage is reabsorbed and it undergoes enterohepatic circulation. |
| (starred) Does endogenous conjugated bilirubin undergo enterohepatic circulation? | No, it has no enterohepatic circulation. |
| (starred) What is the relative reabsorption rate and circulation status of exogenous drugs like ampicillin, streptomycin, and tetracycline? | A high percentage is reabsorbed and they undergo enterohepatic circulation. |
| (starred) What is the relative reabsorption rate and circulation status of exogenous drugs like sulfonamides and penicillin? | A small percentage is reabsorbed and they undergo enterohepatic circulation. |
| With what 4 ways does the liver detoxify the blood? | Through phagocytosis by Kupffer cells, chemical alteration of molecules, production of less toxic compounds like urea, and excretion of molecules in bile. |
| What 3 roles does the liver play in lipid metabolism? | It synthesizes triglycerides and cholesterol, excretes cholesterol in bile, and produces ketone bodies from fatty acids. |
| What is the composition of bile? (5 items) | It is composed of bile pigment (bilirubin), bile salts, phospholipids (lecithin), cholesterol, and inorganic ions. |
| Where is bilirubin produced (3 regions) and what is it derived from? | It is produced in the spleen, liver, and bone marrow, and is derived from the heme group of hemoglobin (minus the iron). |
| What is the group of heme-containing enzymes in hepatocytes that degrade drugs... steroids and exogenous environmental toxins? | cytochrome P450 enzymes |
| How can grapefruit interact with cholesterol medications like Lipitor? | Compounds called furanocoumarins (like bergamottin) slow down a P450 enzyme, causing the drug to be metabolized more slowly. |
| What are the most common causes of cirrhosis? (4 of them) | Hepatitis B virus, hep C virus, alcoholism, and nonalcoholic steatohepatitis (NASH). |
| What enzyme metabolizes alcohol into acetaldehyde in the liver? | Alcohol dehydrogenase. |
| How are gallstones made? | Gallstones are produced when the liver secretes enough cholesterol to create a supersaturated solution, and cholesterol crystals, together with mucus secreted by the gallbladder, can form a sludge that may be visible in an ultrasound. |
| What are the endocrine and exocrine functions of the pancreas? | The endocrine Islets of Langerhans make insulin (beta cells) and glucagon (alpha cells), while the exocrine acinar cells make pancreatic juice. |
| How is bicarbonate secreted into the pancreatic juice? (mechanism) | It is countertransported with chloride (Cl-) across the membrane. |
| What are the typical causes of acute and chronic pancreatitis? | Acute pancreatitis is usually caused by gallstones or drug reactions, while chronic pancreatitis is usually due to chronic alcohol abuse. |
| What are short reflexes in the digestive system? | They are neural reflexes that do not involve the brain. |
| (starred) What is the function of secretin secreted by the small intestine? | It stimulates water and bicarbonate secretion in pancreatic juice and potentiates the actions of CCK on the pancreas. |
| (starred) What are the 4 functions of cholecystokinin (CCK) secreted by the small intestine? | It stimulates gallbladder contraction, stimulates pancreatic juice enzyme secretion, inhibits gastric motility and secretion, and maintains the structure of the exocrine pancreas. |
| (starred) What is the function of Gastric inhibitory peptide (GIP) secreted by the small intestine? | It inhibits gastric motility and secretion and stimulates the secretion of insulin from pancreatic islets. |
| (starred) What is the function of guanylin secreted by the ileum and colon? | It stimulates intestinal secretion of Cl−, causing the elimination of NaCl and water in the feces. |
| What triggers the secretion of HCl and pepsinogen in the stomach? | The entry of proteins into the stomach. |
| Which cells initiate and regulate the secretion of HCl and pepsinogen? | G cells (gastrin), D cells (somatostatin), and ECL cells (histamine). |
| How does positive feedback work during the gastric phase? | As more proteins are broken down, more secretions are released to continue breaking them down. |
| How does negative feedback work during the gastric phase? | As the pH drops below 2.5 due to more HCl, somatostatin is released, which inhibits gastrin secretion. |
| How do proteins and polypeptides affect the pH of the stomach? | Large amounts of proteins and polypeptides buffer the pH, allowing secretion to match protein concentration. |
| What triggers the intestinal phase of gastric regulation? | The arrival of chyme into the duodenum, causing distension and an increase in osmotic pressure. |
| How does stretch in the duodenum affect gastric stimulation? | It activates a neural reflex that inhibits gastric activity via the vagus nerve. |
| What does the presence of fats in the duodenum stimulate? | It stimulates the secretion of enterogastrone hormones that inhibit gastric motility and secretion. |
| What are four enterogastrone hormones that inhibit gastric motility and secretion? | GIP, somatostatin, CCK, and GLP-1. |
| Which structures does the ENS innervate to intrinsically regulate peristalsis? | It innervates the interstitial cells of Cajal and smooth muscle. |
| How does the enteric nervous system coordinate peristalsis? | It causes the muscle to contract behind the bolus and relax in front of the bolus. |
| What do enterochromaffin-like cells in the intestinal mucosa secrete in response to pressure and food chemicals? | They secrete serotonin and motilin to stimulate muscle contractions. |
| What is the gastroileal reflex? | It is when increased gastric activity leads to increased ileum activity and the movement of food through the ileocecal valve. |
| What is the ileogastric reflex? | It is when distension of the ileum causes a decrease in gastric motility. |
| What is the intestino-intestinal reflex? | It is when over-distension of one portion of the intestine causes the relaxation of other portions. |
| What triggers the production of cholecystokinin (CCK) in the duodenum? | The presence of partially digested proteins and fats in the chyme. |
| What stimulates the production of the pancreatic enzymes trypsin, lipase, and amylase? | Acetylcholine (ACh) from the vagus nerve, CCK, and secretin. |
| Which second messengers are used by ACh, CCK, and secretin in the pancreas? | ACh and CCK use Ca2+ as a second messenger, while secretin uses cAMP. |
| Which enzyme continues the digestion of carbohydrates in the intestines? | Pancreatic amylase continues the breakdown of short chains into disaccharides and maltriose. |
| What finishes the breakdown of disaccharides into simple sugars like glucose? | Brush border enzymes in the small intestine finish this process. |
| How are monosaccharides initially absorbed across the intestinal epithelium? | They are absorbed via secondary active transport with sodium, followed by chloride. |
| How do monosaccharides move into the interstitial fluid and capillary blood? | They move by facilitated diffusion through GLUT carriers. |
| How is water absorbed along with glucose and NaCl? | Water follows the NaCl through a paracellular route via osmosis. |
| (starred) Which 4 pancreatic enzymes finish protein digestion in the duodenum and jejunum? | Pancreatic trypsin, chymotrypsin, elastase, and carboxypeptidase. |
| (starred) Which brush border enzyme assists in the final digestion of proteins? | Aminopeptidase. |
| How are free amino acids absorbed into the epithelial cells? | They are cotransported with sodium (Na+). |
| How do dipeptides and tripeptides cross into the epithelial cells? | They cross via secondary active transport using a hydrogen (H+) gradient. |
| How do free amino acids move into the blood capillaries of the villi? | They move by facilitated diffusion into the interstitial fluid and then to the blood capillaries. |
| What enzyme digests phospholipids like lecithin into fatty acids and lysolecithin? | Phospholipase A from the pancreas. |
| (starred) How are fatty acids, monoglycerides, and lysolecithin transported to the brush border? | They move into bile micelles and are transported to the brush border. |
| (starred) What happens to fat molecules after they reach the brush border? | They leave the micelles and diffuse into the epithelial cells of the villi. |
| (starred) What are fat molecules regenerated into inside the epithelial cells? | They are regenerated into triglycerides, cholesterol, and phospholipids, and combined with proteins to form chylomicrons. |
| (starred) How do chylomicrons enter the lymphatic system? | They are secreted by exocytosis into the central lacteal of the villus. |
| (starred) Which enzyme digests chylomicrons to release free fatty acids for muscle use or fat storage? | Lipoprotein lipase. |
| What do Very-Low-Density Lipoproteins (VLDLs) do? | They are formed in the liver and deliver endogenously produced triglycerides to body cells. |
| What do Low-Density Lipoproteins (LDLs) do? | After triglycerides are removed from VLDLs, they become LDLs, which transport endogenous cholesterol to various organs and are known as "bad cholesterol." |
| What do High-Density Lipoproteins (HDLs) do? | They remove and degrade cholesterol from blood vessels and return it to the liver, and are known as "good cholesterol." |
| What are the products of pancreatic amylase working on starch in the duodenum? | It produces maltose, maltriose, and oligosaccharides. |
| What is the optimal pH and product of pancreatic lipase working on triglycerides in the small intestine? | The optimal pH is 8.0 and it produces fatty acids and monoglycerides. |
| (starred) what brush border enzyme category is needed for absorption of dietary calcium--an enzyme that is regulated by vitamin D? | Phosphatases--includes Ca2+,Mg2+-ATPase and alkaline phosphatase (the latter of which removes phosphate groups from organic molecules) |
Created by:
elianayu
Popular Physiology sets