GIT Pathophysiology

Question 1

Dietary sources of fats?

Answer 1

1. Fats such as butter
2. Plant derived fats
3. Animal derived fats

Question 2

Metabolic sources of fats?

Answer 2

Denovo synthesis of fats

1. Lipogenesis – hepatic fatty acid synthesis using acetyl-CoA from glucose via glycolysis or fats via β-oxidation of FFAs
2. cholesterol synthesis in the liver from acetyl-CoA via the mevalonate pathway
3. Triacylglycerol (TAG) synthesis in adipose tissue (from fatty acids and glucose)

Question 3

Fat digestion and absorption?

Answer 3

LOOK AT NOTES FOR THIS

J1. Lipases (lingual, gastric and pancreatic) digest fat
in the gastrointestinal tract.
2.Bulk of fat digestion occurs in the small intestines.
Bile salts emulsify fats in the small intestines forming
mixed micelles.
3. Lipases hydrolyse triglycerides to free fatty acids
and monoglycerides
4. Fatty acids, monoglycerides, fat soluble vitamins
taken up by intestinal absorptive enterocyte

Question 4

Explain TAGS process in enterocyte?

Question 5

Physiological functions?

Answer 5

1. Energy storage – fat is an essential dietary constituent – critical in oral diet, enteral nutrition & or parenteral admixtures
2. Energy provision in times of starvation/fasting and in diabetic patients
   Facilitation of absorption of fat soluble vitamins
3. Cushions organs and provide insulation for temperature regulation
4. Substrate for synthesis of phospholipids
5. Substrate for synthesis of signalling molecules – inositol triphosphate (IP3) and diacylglycerol (DAG)

Question 6

What are fat soluble vitamins?

Answer 6

ADEK

Vitamin A
Vitamin D
Vitamin E
Vitamin K

Question 7

Fat soluble vitamin deficiencies?

Answer 7

ADEK

Vitamin A - Night blindness and Teratogenic(1st trimester)
Vitamin D-Rickets & Osteomalacia
Vitamin E-Haemolytic anaemia when free radicals rupture fragile premature RBCs
Vitamin K- Bleeding disorders, premature neonates, patients with fat malabsorption & wardarin a vitamin K anatagonist

Question 8

Types/classes of fats?

Answer 8

1. Saturated fatty acids
2. Monounsaturated fatty acids
3. Polyunsaturated fatty acids

Question 9

Saturated fatty acids?

Answer 9

Saturated fats lack double bonds between the individual carbon atoms

Question 9

Monounsaturated fatty acids ?

Answer 9

There is one double bond in the fatty acid chain.

Question 10

Desaturases enzyme?

Answer 10

an enzyme that removes two hydrogen atoms from a fatty acid, creating a carbon/carbon double bond.

Question 11

Polyunsaturated fatty acids?

Answer 11

There is two or more double bond in the fatty acid chain.

Question 12

Example of the below classes?

1. Saturated fatty acids
2. Monounsaturated fatty acids
3. Polyunsaturated fatty acids

Answer 12

1. Saturated fatty acids- Stearic acid: 18 carbon saturated fatty acid
2. Monounsaturated fatty acids- Oleic acid: 18 carbon monounsaturated fatty acids
3. Polyunsaturated fatty acids-Linoleic acid: 18 carbon polyunsaturated fatty acids

Question 13

Which fatty acids are preferred in energy metabolism?

Answer 13

Saturated fatty acids

Question 14

Which fatty acids are preferred for hormone synthesis?

Answer 14

unsaturated fatty acids are important STRUCTURALLY and for HORMONE synthesis

Question 15

Which CVS disease is associated with which type of fatty acid?( for decreased levels)

Answer 15

UNSATURATED fatty acids are associated with DECREASED blood cholesterol

Question 16

Which CVS disease is associated with which type of fatty acid?( for increased levels)

Answer 16

SATURATED fatty acids are associated with INCREASED blood cholesterol

Question 17

Which percentage of unsaturated fatty acids are in which form?

Answer 17

95% of unsaturated fatty acids are in the cis- conformation

Question 18

Which fatty acids causes CVS disease?

Answer 18

Trans- fatty acids increase the risk of heart disease

Question 19

What are the functions of triglycerides?

Answer 19

1. Most common lipid in diets
2. Storage FORM OF FATTY ACIDS & are in adipocytes

Question 20

What are the functions of phospholipids?

Answer 20

1.Biological membranes
2. Signaling molecules – IP3 & DAG
3. Pulmonary surfactant

Question 21

Aetiology of neonatal respiratory distress syndrome?

Answer 21

Neonatal respiratory distress syndrome is caused by deficiency of phospholipids [Dipalmitidyl Phosphatidyl Choline (PC) in the lungs. PC is a
surfactant that decreases surface tension in the lungs & allows O2 to dissolve. Deficiency causes LUNGS TO COLLAPSE & compromise gas exchange

Question 22

Phosphatidyl Choline?

Answer 22

PC is a surfactant that decreases surface tension in the lungs & allows O2 to dissolve

Question 23

Functions of cholesterol ?

Answer 23

Cholesterol is used as a raw material to synthesise

Has a STRUCTURAL ROLE in in biological/cell membranes. Its presents in cell membranes affect membrane fluidity

Question 24

Hormones made by cholesterol ?

Answer 24

1. Bile salts
2. Vitamin D
3. Testosterone

Question 25

What do eicosanoids include what?

Answer 25

The EICOSANOIDS include PROSTAGLANDINS, PROSTACYCLINS, LEUKOTRIENES and THROMBOXANES. Eicosanoids are synthesised from precursors made from EFAs

Question 26

Synthesis of eicosanoids?

Answer 26

Page on 9 on notes

Question 27

Which drugs are used inhibit process for eicosanoids for PLA2?

Answer 27

1. Corticosteroids (cortisol, dexamethasone)

Question 28

Which drugs are used inhibit process for eicosanoids for Cyclooxygenases?

Answer 28

NSAIDs(aspirin, paracetamol, diclofenac & ibuprofen)

Question 29

Which drugs are used inhibit process for eicosanoids for lipoxygenase?

Answer 29

Benoxaprofen

Question 30

What are the gastrointestinal pathophysiology and nutritional disorders?

Answer 30

1. Essential fatty acid deficiency
2. Exocrine pancreatic insufficiency and associated gastrointestinal disorders
3. Cholestatic liver disease and associated gastrointestinal tract disorders
4. Cystic fibrosis and associated gastrointestinal tract disorders