University:
Western Sydney University
Course:
MEDI 2003 | Clinical Sciences 2
Academic year:

2024
Views:

86

Pages:

3
Author:

Mariam A. A.

GIT WEEK 4 SAQ STUDY GUIDE QUESTIONS 1. Chlorine is an important anion for diarrhoea a. Draw a mechanism on how chlorine is secreted b. Explain how infections will affect chlorine secretion and what effect that may lead to Answer: a. Chlorine secretion b. An infection such as cholera or VIP activate AC which stimulates the conversion of atp into cAMP -> this will activate PKA -> protein phosphorylation and increase Ca+ 2 -> activate CFTR receptors -> increased Cl- into the lumen -> this will increase the electronegativity so Na+ will flow -> Na+ is osmotically active -> water will follow 2. Describe cathepsin B (1 mark) Answer: Cathepsin B is an endopeptidase that cleaves peptide bonds 3. Describe 4 mutations that may lead to pancreatitis Answer: • • • • SPINK-1 -> if there is a mutation here, this will prevent the inhibition of converting trypsinogen into trypsin Calcium sensing receptor: mutation is here could lead to too many zymogens being released, that is it the mutation results in too much Ca2+ release. If there is low Ca2+ this could mean that there is little vesicle of zymogens secretions, so you end up with a build up of zymogens within the cute little pancreas (at this point I do not care anymore) Chymotrypsin C: a mutation in here leads to decreased trypsinogen degradation Cationic trypsinogen mutation: pre-mature conversion of trypsinogen into trypsin while it is still in the liver 4. There are 6 classes of CFTR mutations. Explain them (6 marks) Answer: Sally Takes Spanish School Class I 1. 2. 3. 4. 5. 6. Class 1: defective protein synthesis Class 2: defective protein trafficking Class 3: defective signalling Class 4: decreased protein synthesis Class 5: defective conductance Class 6: defective ion channel regulation 5. Answer the following questions about saliva a. List FOUR functions of saliva (2 marks) b. Name SIX components of saliva and explain the role of each (5 marks) c. Name ONE pathological condition that results from abnormalities in saliva sections, and comment on the quantity of saliva present (1 mark) Answer: a. Lubrication of food, keeping the mouth moist, mediate taste buds and helps with digestion (mechanical and chemical) b. Components of saliva • HCO3-: neutralises acidity • Water: keeps mouth moist, taste buds and helps you swallow because it makes the food soft • Mucinins: lubrication • Salivary alpha amylase helps with digestion ‘ • Epidermal and nerve growth factors: facilitate pain and other sensation • Lysosomes, lactoferrin and IgA: innate and acquired immunity -> protection c. Xeromastia as this is when the salivary glands are impaired in such a way that causes decreased secretions. This could be due inflammation. For example, when you have got alcohol irritiating the mouth and thus causing inflammation 6. Name two medications for the treatment of cystic fibrosis and briefly describe their mechanism of action (2 marks) Answer: • • Ivacaftor: acts as a CFTR agonist, which opens them up and allows Cl- secretion Lumfactor: corrects CFTR protein folding 7. What is the main difference between the submucosal and myenteric plexuses? (1 mark) Answer: • • • Submucosal: involved in hormonal, HCO3- and ion secretions Myenteric: involved in generating the f #xorce and rate of contraction, helps move bolus from the oral side of the anal side