Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
52 Cards in this Set
- Front
- Back
|
Other than peristalsis, what are the 2 types of movement which occur in the small intestine? Which comes first? Which plexus regulates it? |
- segmentations and Migrating Motility Complex - segmentations - myenteric plexus |
|
|
Briefly describe what segmentations are? |
- allow mixing of chyme - smooth muscle contraction produces segments in the small intestine - smooth muscle then contracts again, splitting each segment into 2 - the smooth muscle then relaxes - forming 1 again - the cycle repeats moving the chyme back and forth within the segments |
|
|
Where do segmentations mainly occur? How often do they occur? |
- strongest in the duodenum - around 12 times a minute in the duodenum; reduced to around 8 times a minute in the ileum |
|
|
Briefly describe the MMC and its overall function |
- a cyclic, recurring motility pattern occuring in the stomach and small bowel - occurs during fasting and it is interrupted by feeding - moves chyme, debris and undigestable materials through the small bowel |
|
|
Describe the 4 phases of the MMC |
1. state of quiescence with only minimal activity; lasts around 45-60 minutes 2. gradual increase in perstalitic contraction over 30 minutes 3. most active phase: rapid contractions lasting 5-15 minutes; accompanied by opening of the pyloric sphincter 4. transition between the high activity of phase 3 and low activity of phase 1 (gradual decline in contraction) |
|
|
Whata is the total length of time for one cycle of an MMC? What hormone regulagtes the MMC? |
- 3-5 hours - motilin |
|
|
Starting from inside the small intestine, list all tissue layers |
- simple columnar epithelium (mucosa) - lamina propria (mucosa) - muscularis mucosae (mucosa) - submucosa - circular smooth muscle (muscularis) - longitudinal smooth muscle (musclaris - serosa |
|
|
Which cell type lines the epithelium in the small intestine? |
- simple columnar epithelium |
|
|
List the cell types found it the mucosa of the small intestine and briefly describe their function (6) |
- absorptive cells: digest and absorb nutrients - goblet cells: secrete mucous - Paneth cells: secrete lysosyme - S cells: secrete secretin - CCK cells: secrete cholecystokinin - K cells: secrete Glucose-Dependent Insulinotropic Peptide (GIP) |
|
|
In what glands would you find Paneth cells? What type of immune tissues are found in the small intestine and where would you find them (2)? |
- intestinal glands/crypts of Lieberkuhn - MALT tissue is found in the lamina propria and Peyer's patches are found in the mucosa of the ileum |
|
|
What glands would you find in the submucosa of the small intestine and what is their function (1)? |
- Brunner's glands: produce alkaline secretions |
|
|
What structural modifications exist in the small intestine (3)? What is their overall combined function? |
- circular folds (plicae circulares), villi and microvilli - increase surface area for absorption |
|
|
|
|
|
Where do circular folds begin and end? |
- begin at the start of the duodenum and end midway throuhgh the ileum |
|
|
Describe the main structural features of villi i.e. what is their composition |
- covered with epithelium - lamina propria core - each has a arteriole, venule, capillary network and a lacteal |
|
|
What is a lacteal? Broadly describe what happens to nutrients absorbed through villi |
- lymphatic capillary - they are either absorbed into the blood stream through the capillary netwrok, or into the lymphatic system throug lacteals |
|
|
What do microvilli collectively form? What filament are they predominantly composed of? What is the pH of intestinal juice? |
- brush border - actin - 7.6 |
|
|
List the 8 enzymes released in pancreatic juice, their substrate and their products? |
- pancreatic amylase acts on starches (polysaccharides) to maltose, sucrose and lactose - trypsin acts on proteins to produce peptides - chymotrypsin acts on proteins to produce peptides - elastase acts on proteins to produce peptides - carboxypeptidase acts on the carboxyl end of peptides to produce and peptide and amino acids - pancreatic lipase acts on triglycerides emulsified by bile salts to produce fatty acids and monoglycerides - ribonuclease acts on ribonucleic acid to produce nucleotides - deoxyribonuclease acts on deoxyribonucleic acid to produce nucleotides |
|
|
List the brush border enzymes found in the small intestine for carbohydrates (4), proteins (2) and nucleotides (2) |
- carbohydrates; alpha-dextrinase, maltase, sucrase and lactase - proteins: aminopeptidase and dipeptidase - nucleotides: nucleosidases and phosphatases |
|
|
Which cells produce pancreatic enzymes? |
- Acinar cells |
|
|
Describe the digestion of carbohydrates through the GI tract, including their products at each stage |
- salivary amylase: maltose, sucrose and lactose - pancreatic amylase: maltose, sucrose and lactose - brush border enzymes (alpha-dextrinase, maltase, sucrase and lactase) break disaccharides into monosacharides (glucose, fructose and galactose) |
|
|
Describe the digestion of proteins through the GI tract, including their products at each stage |
pepsin in the stomach: produces peptides trypsin, chymotrypsin, carboxypeptidase and elastase in pancreatic juice: produces peptides and amino acids - amino peptidase and dipeptidase in bush border enzymes: produces amino acids |
|
|
Describe the digestion of lipids through the GI tract, including their products at each stage |
- lingual lipase: triglycerides broken down into fatty acids and monoglycerides - gastric lipase: triglycerides broken down into fatty acids and monoglycerides - pancreatic lipase: triglycerides broken down into fatty acids and monoglycerides - requires emulsification by bile salts for easier digestion and the formation of micelles |
|
|
Describe the digestion of nucleic acids through the GI tract, including their products at each stage |
- ribonucleases and deoxyribonucleases in pancreatic juice: digests RNA and DNA to nucleotides - nucleosidases and phophatases in brush border: produces pentoses |
|
|
State the 4 mechanisms by whichh aborption is enabled i.e. types of transport |
- diffusion - facilitated diffusion - osmosis - active transport |
|
|
Describe how monosacharides are absorbed following digestion |
- facilitated and active transport - glucose and galactose pass through GLUT-1 in the apical membrane - required co-transport with Na+ - Fructose passes through the apical membrane through GLUT-5 - fructose, glucose and galactose all pass through the basolateral membrane through GLUT-2 and then diffuse into the capillaries or lacteal |
|
|
Describe how amino acids are absorbed following digestion |
- active transport through the apical membranea and diffuision through the basolateral membrane - simialr to monosacharide absorption in that active transport required co-transport with Na+ - PepT transporters |
|
|
Describe how dipeptides and tripeptides are absorbed following digestion |
- active transport followed by diffusion - symporters using H+ (apical) |
|
|
Describe the location of the pancreas (2) |
- retroperitoneal and posterior to the greater curvature of the stomach |
|
|
List the 5 regions of the pancreas |
- uncinate process - head - neck - body - tail |
|
|
What is the name of the 2 main ducts in the pancreas? |
- acccessory duct (duct of Santorini) - pancreatic duct (duct of Wirsung |
|
|
The hepatopancreatic ampulla marks the union of which 2 ducts? |
- pancreatic duct and the common bile duct |
|
|
What prevents the activation of proteolytic enzymes in the pancreas? Which cells secrete it? |
- trypsin inhibitor - acinar cells |
|
|
Other than digestive enzymes, what other two important compeonents are produced in the pancreas? |
- water and bicarbonate ions |
|
|
Describe the process of bicarbonate production in the pancreas |
1.Carbon dioxide diffuses to the interior of the cell from the bloodand, under the influence of carbonic anhydrase, combines with waterto form carbonic acid (H2CO3). The carbonic acid in turn dissociatesinto bicarbonate ions and hydrogen ions (HCO3− and H+). Then thebicarbonate ions are actively transported in association with sodiumions (Na+) through the luminal border of the cell into the lumen ofthe duct. 2.The hydrogen ions formed by dissociation of carbonic acid inside thecell are exchanged for sodium ions through the blood border of thecell by a secondary active transport process. This supplies thesodium ions (Na+) that are transported through the luminal borderinto the pancreatic duct lumen to provide electrical neutrality forthe secreted bicarbonate ions. 3.The overall movement of sodium and bicarbonate ions from the bloodinto the duct lumen creates an osmotic pressure gradient that causesosmosis of water also into the pancreatic duct, thus forming analmost completely isosmotic bicarbonate solution. |
|
|
List the 4 stimuli which cause pancreatic secretion and briefly describe what happens (6) |
- acetylcholine: released from parasympathetic vagus nerves and stimulate secretion from acinar cells - cholecystokinin: secreted from the mucosa in the duodenum and jejunum when food enters the small intestine; stimulate secretion from acinar cells - secretin: secreted from the mucosa in the duodenum and jejunum when food enters the small intestine; stimulates the secretion of large quantities of water and sodium bicarbonate from the ductal cells in the pancreatic epithelium - gastrin: secreted in large amounts by the stomach in response to gastric distention and irritation. In addition to stimulating acid secretion by the parietal cell, gastrin stimulates pancreatic acinar cells to secrete digestive enzymes. |
|
|
What are the 3 phases of pancreatic secretion (3) |
- cephalic, gastric and intestinal |
|
|
Describe what happens in the cephalic phase |
- acetylcholine is released from parasympathetic vagus nerves causing secretion from acinar cells (little secretion flows into the duodenum as it requires water) - only about 20% of secretions are produced in this phase |
|
|
Describe what happens in the gastric phase |
- same as for the cephalic phase: acetylcholine is released from parasympathetic vagus nerves causing secretion from acinar cells (little secretion flows into the duodenum as it requires water) - a further 5-10% of secretions is released |
|
|
Describe what happens in the intestinal phase |
- secretin: once the acidic chyme enters the duodenum - with an acididty of <5 - the HCl causes secretin to bereleased from S cells in the mucosa of the duodenum and jujunum. This causes acinar cells in the pancreas to secrete large quantities fluid containing sodium bicarbonate - neutralising the acid and raising the pH for the activation of pancreatic enzymes - cholecystokinin is release from I cells in the duodenum and jujunum when food enters the small intestine. CCK acts on acinar cells causing them to massively increase the production of pancreatic secretions - accounting for 70-80%of pancreatic secretions |
|
|
What are the three types of pancreatits. Give an example of 2 causes for each. |
- chronic calcifying pancreatis: alcohol and smoking - chronic obstructive pancreatitis: blunt trauma and tumours (e.g. adenocarcinoma) - steroid-responsive (one cause: autoimmune pancreatitis (types 1 and 2) |
|
|
Briefly describe the Balthazar system of classifying pancreatitis |
- graded A-E -A: Normal -B: Focal or diffuse gland enlargement; small intra-pancreatic fluidcollection -C: Any of the above plus peri-pancreatic inflammatory changes and<30% gland necrosis - D: Any of the above plus single extra-pancreatic fluid collection and30% to 50% gland necrosis -E: Any of the above plus extensive extra-pancreatic fluid collection,pancreatic abscess, and >50% gland necrosis. |
|
|
Describe the difference between oedematouos and haemorrhagic pancreatitis |
- oedematous pancreatits: associated with increased interstitial fluid (oedema) in the parenchyma and surrounding retroperitoneal structures - haemorrhagic pancreatitis: associated with bleeding into the parenchyma and surrounding retroperitoneal structures, and pancreatic necrosis |
|
|
Describe the general pathophysiology of pancreatitis (essay answer) |
- develops from acute - associated with the activation of zymogens due to a build up pancreatic secretions which overwhelms trypsin inhibitor - leading to the activation of proteolytic enzymes - various causes i.e. chronic calcifying pancreatits (calcification), chronic obstructive pancreatitis (tumours) and autoimmune pancreatitis (inflammation) - results in distortion and narrowing of the pancreatic ducts and atrophy of the pancreas |
|
|
Give 6 signs and symptoms of pancreatitis |
- vomiting - anoerexia - abdominal pain (mid-epigastric) - tachycardia - fever - diabetes |
|
|
Give 8 risk factors for pancreatits |
- alcohol (biggest risk factor) - smoking (oxidative stress) - genetics (PRSS1 and SPINK1 genes) - gallstones - tumours - trauma - infections - drugs (e.g. azathioprine) |
|
|
List 6 tests which can be supportive of a diagnosis of pancreatitis |
- elevated serum lipase - elevated serum and urinary amylase - ALT/AST >3 times normal (indicative of obstruction) - haematocrit >44% (indicative of pancreatic necrosis) - chest X-ray (may show pleural effusion) - ultrasound (may show pancreatic inflammation, peri-pancreatic stranding, calcifications or fluid collection) |
|
|
Give 8 dietary recommendations for someone with pancreatitis |
- take Pancreatic Enzyme Replacement Therapy (PERT) - take vitamins to account for lost lipid-soluble ones (A, D, E, K) - eat smaller meals (5-6 per day) - don't smoke or drink (exacerbates damage and LOF) - medium chain triglycerides (direclty absorbed by mucosa making them useful for poeple struggling to gain weight) - suitable fat content in diet (amount is debatable) - drink plenty of fluids (espectially with diarrheaoa) - avoid processed foods (contain hydrogenated oils which can be hard to digest) |
|
|
List 8 barriers to compliance |
- poor communication - poor understanding - lack of trust - denial of illness - financial problems - logistical problems e.g. transport - language/cultural barriers - side-effects |
|
|
List 6 strategies for compliance |
- SIMPLE - S: simplify treatments e.g. one pill a day) - I: impart knowledge (with simple and limited information) - M: modify patient beliefs (work with patient) - P: patient communication - L: leaving the bias (treat all patients the same) - E: evaluate adherence |
|
|
|
|
|
Where is vasoactive intestinal peptide found? What is its function (3)? |
- submucosa - smooth muscle relaxation (lower esophageal sphincter, stomach, gallbladder) - secretion of water and electrolytes into pancreatic juice and bile - inhibition of gastric acid secretion and absorption from the intestinal lumen |
