ILO WEEK 3 Flashcards
The products of digestion and where they are released for absorption
Carbohydrates -> mono di and poly saccharides -> brush border to monosaccharides -> absorbed in small intestine Co-transport with sodium ions (pr facilitated diffusion for fructose)
Proteins -> digested in stomach and small intestines by multiple protease -> to peptides ->products of digestion are amino acids -> absorbed in small intestine -> active transport
Ribonuclease and deoxyribonuclease -> nucleotides -> active transport
Lipids -> triglycerides -> Fatty acids and monoacylglycerides -> Diffusion into intestinal cells, where they are combined with proteins to create chylomicrons or Simple diffusion for short
Describe the regulation of pancreatic secretion
Regulated by activity of the vagus nerve and hormones. Endocrine control is more important.
The cephalic phase:
Acinar cells and smooth muscle of the pancreas innervated by parasympathetic vagal nerves. Stimulation causes release of zymogen granules from acinar cells and increase in local blood flow. Sympathetic vasocnstriction reduces the blood flow
Under nervous control
(Sight, smell,Taste) Acetylcholine
The gastric phase:
Gastrin; secreted as a response to distension of the stomach and response of amino acids and peptides in the antrum
The intestinal phase:
>70% of total secretion; hormones secreted by the duodenal mucosa; Secretin released in response to low pH and stimulates secretion of bicarbonate rich fluid from ductal cells
CCK secreted when mucosal surface is bathed in monoglycerides, fatty acids, peptides, amino acids -> stimulates production of an enzyme-rich fluid from the acinar cells; also increases secretin effect
Alpha amylase is the only pancreatic enzyme that is released active
Discuss the dietary advice you would give to a patient with pancreatic insufficiency
- low-fat
- high-protein
- high-calorie diet
- with fat-soluble vitamin supplements

PBL WEEK 3 - lean meats, beans and lentils, clear soups, and dairy alternatives (such as flax milk and almond
- milk)
- Spinach, blueberries, cherries, and whole grains
fruit instead of added sugars
•Eat between six and eight small meals throughout the day to help recover from pancreatitis. This is easier on your digestive system than eating two or three large meals.
•Use MCTs as your primary fat since this type of fat does not require pancreatic enzymes to be digested. MCTs can be found in coconut oil and palm kernel oil and is available at most health food stores.
•Avoid eating too much fiber at once, as this can slow digestion and result in less-than-ideal absorption of nutrients from food. Fiber may also make your limited amount of enzymes less effective.
•Take a multivitamin supplement to ensure that you’re getting the nutrition you need. You can find a great selection of multivitamins here.
Discuss possible strategies for improving patient compliance
- Involve patients in making decisions
- Forget; Doesn’t understand why has to take them; Doesn’t like shape taste etc. - Too many medications to take; lack of routine
- Try to explain them the mechanism of drug; try to work through their issues
- Imparting knowledge;
- Modifying patient beliefs;
- Patient communication;
- Leaving the bias; and
- Evaluating adherence.
- Simplifying regimen characteristics;
The role of the Pancreas in the digestion of food in the human gut
Pancreatic juice with pancreatic enzymes:
Lipase -> works with bile salts and acids -> digests fats and fat soluble vitamins
NaHCO3-> secreted to neutralise the acidic stomach juice; enzymes only active in higher pH
Proteases -> trypsin, chymotrypsin, carboxypeptidase, elastase; wide range of peptide bonds; secreted as zymogens and activated in the gut lumen; trypsinogen activated by enterokinase (rest activated by trypsin)
Amylase -> alphaamylase; digests alpha1-4 bonds in starch and glycogen to disaccharides and oligosaccharides which are further digested by enzymes on the brush border of the mucosa
Different specificities of the pancreatic endopeptidases trypsin and chymotrypsin and the
structural basis for these specificities.
Trypsin:
• Trypsin acts on peptides with lysine and arginine on C- terminal side
• but not if there is a proline on the carboxyl side
Chymotrypsin:
• activated by trypsin
• acts on peptide bonds in which carboxyl group is provided by tyrosine and phenylalanine (uncharged forms, aromatic amino acids)
STRUCTURAL BASIS?!?
The actions of amylase on different dietary carbohydrates and the products released
Endoamylase, similar to salivary amylase
• Digests a 1-4 glucose-glucose bonds ONLY!
• Digests starch and glycogen to maltose, maltotriose and dextrins
• Secreted in active form
The kinks in the amylose chain causes a helical structure characteristic of starch. The structure of cellulose is a zig zag or pleated pattern which is an ideal back bone for the plant cell wall.
Our enzymes can digest amylose but not cellulose.
Clinical tests available for pancreatic functions
Test of pancreatic damage:
- Serum amylase
- Urine amylase
- Serum lipase
Test for pancreatic function:
- Direct and indirect (tests based upon the principal that a pancreatic cleaves an absorbable substance from a non-absorbable molecule; not available in UK; DONT REALLY UNDERSTAND THIS!)function test
- Faecal chymotrypsin
- Faecal elastase
Faecal tests:
Measure pancreatic enzymes in faeces (chymotrypsin-> proteolytic enzymes -> low levels indicate insufficiency and elastase->if too high exocrine insufficiency-> uses ELISA kit )
Discuss absorption and transport of Iron from GIT
Non harm iron-> Ferric iron (3+) needs to be transformed into ferrous iron (2+) to be absorbed
transformed using: VITAMIN C FERROREDUCTASE
(DMI1 transporter absorbes it after) cotransport with H+
This happens mostly in duodenal enterocytes
Ham iron easily absorbed -> duodenal enterocytes as well by harm oxygenase
- ferropotin transports it out of the tissues (in 2+ form and the enzymes change it back to 3+ later)
Transferrin -> transports IRON around the body (2X Fe3+)
Most goes into erythropoiesis
Rest goes:
- 10-20% to the liver stored in ferric form
ferropotin back to circulation
unless otherwise regulated by hepcidin
Describe utilisation of Iron in the human body
No mechanism to excrete iron!!! Utilisation: - total body content -> 4 g - Bone marrow and RBCs -> 3g - Reticuloendothelial system -> 200-500mg - Myoglobin -> 200-300mg - Enzymes -> 100mg Most used for erythropoiesis Rest is in the liver; stored or released when needed
Discuss regulation of iron metabolism in human body
Iron homeostasis:
Daily need 1-2mg/day
Western diet 15-20mg/day
Big iron loss in menstruation; need more
Role of Hepcidin (low iron hormone ->inhibits iron transport by binding to the iron export channel ferroportin)
40 g of iron circulates, only small amount of iron from the diet
HEPCIDIN:
- Inhibit function of ferropotin (iron release to circulation)
- Prevents release; decrease plasma iron concentrations
- Spleen macrophages!!!;
(Engulfing old RBC and digestion) BLOCKS it ; iron stays in spleen instead of going into circulation
- Inhibits absorption of iron in the small intestine
Hepsidin production and release:
- inflammatory cytokines (IL-6)
- Increase in plasma iron concentration -> close control
- lipopolisaccharides
MAIN REGULATOR: HFE protein
HFE gene Hemohromatosis
interacts with other proteins to regulate iron absorption
Discuss about the causes and consequences of ‘Hereditary Haemochromatosis’
Mutation in HFE gene -> protein Hereditary Haemochromatosis
Autosomal recessive disorder Reduce Hepcidin production
Iron overload! Iron absorbed from intestine; plasma iron concentration increases; Hepsidin does not work
Body will absorb lots! -> severe consequences
More severe in males; females protected by menstuation and child birth
Raised serum ferritin
More then full saturation; some iron in plasma not bound; v. active metabolically; can cause tissue damage (cirrhosis; diabetes; bronzing of skin; arthritis); Restrictive cardiomyopathy
Treatment -> venesection!
Retrograded starch
some cooking pocesses and some storage processes cause recrystallisation of some starch -> becomes indigestible (mostly by pressure cooker or high pressure food processing or fridge)
Interpretation of the result of pancreatic tests
ADD THE TABLE (still don’t know how :P)
Acute pancreatitis
Gallstones; Alcohol; Infections itd itp
Acute inflammatory condition; From self limiting to fatal
Pancreatic insult-> activation of inactive enzyme precursors -> inflammatory cytokines
Sudden onset abdominal pain; nausea and vomiting; fever, hypotension, shock and multiorgan failure
