Session 13: The Absorptive State Flashcards
Define the absorptive state
The period from the start of absorption until absorption is completed. Normal duration would be up to 3hors after eating a meal, but can last up to 10 hours
Explain what Acetyl CoA is
Pyruvate is oxidised to form acetyl coenzyme A through glycolysis. Acetyl CoA, which makes the acetyl group more reactive, is a cofactor of the vitamin pantothenate
Define an enzyme
A protein, in small amounts, that speeds up the rate of biological reactions w/o itself being used up, i.e. a catalyst
Define an endocrine hormone
Compounds secreted by endocrine cells in endocrine glands, reaching their target cells by following the transport through blood
State the main function of insulin
Promotes absorption of glucose from blood into skeletal muscle and adipose tissue
State the main function of glucagon
Raises blood sugar levels by converting glycogen into glucose in the liver
Explain the fed or absorptive state by indicating the interrelationship between tissues
Refer to diagram
Describe the structure of a lipoprotein
Contain proteins and phospholipids on the surface, w/ the the hydrophilic region interacting w/ water. Hydrophobic regions and cholesterol esters are on the interior of lipoproteins. The hydroxyl group of cholesterol is near the surface.
Compare the origin and fate of chylomicrons to that of VLDL
CHYLOMICRONS
Origin:
Intestinal absorption of dietary fat causes assembly of chylomicrons on the epithelial surface of small intestines
Fate:
Triacyclglycerols are released into the lymphatic system and reach the circulation through the thoracic duct
VLDL
Origin:
Triacyclglycerols are produced mainly from glucose, in the liver
Fate:
- When these lipoproteins pass through peripheral tissues,
the TGs are hydrolysed to form free FAs and glycerol
- In adipose tissue, the free FAs combine with the glycerol
3 phosphate from from glucose via DHAP resulting in
TGs which are stored
- In muscle cells, free FAs are used as fuel in beta-
oxidation
- Chylomicrons remnants are cleared by the liver and
VLDL remnants may be cleared by the liver or from LDL,
carrying cholesterol to lipoproteins
which are stored
List the fate of amino acids after a meal
Leaves the intestines and enters the free amino acid pool and are taken up by various tissues, where they are either synthesised to proteins or NPN compounds, or yield energy after being oxidised
Explain the problem of “impaired glucose tolerance”
Inability of uptake of glucose in muscle and adipose tissue ( i -insulin dependent). Indicated by an abnormal response when large amounts of carbohydrates are consumed
It usually takes about 3-5 hours to reach the baseline level, and not the normal 2 hours; present w/ hyperglycemia but not yet >= 11.1 mmol/L
Explain what insulin resistance is
Insulin opposition at receptor sites on target cells- especially muscle and fat tissue. Other causes may be an abnormal insulin molecule, or an excessive amount of circulating antagonist against insulin
Name the disease related to insulin resistance
Type 2 diabetes
Mr Applebod’s high levels of cholesterol are related to type 2 DM. How ?
In type 2 DM muscle and adipose tissue are relatively resistant to the action of insulin in promoting glucose uptake into cells and conversion to glycogen or storage as TGs
Explain the “oxidation of glucose”
Glycolysis
Explain “oxidation of fatty acids”
Lipolysis
List the criteria for Metabolic Syndrome and indicate the reference values
Raised BP: systolic BP >= 130 and diastolic BP >= 85 mm Hg or treatment of previously diagnosed hypertension
Raised triglycerides: or treatment of this lipid abnormality
Raised fasting plasma glucose: >= 5.6 mmol/L or treatment of previously diagnosed w/ type 2 DM
Reduced HDL cholesterol: or specific treatment of this lipid abnormality
State the blood glucose levels that are diagnostic for DM as determined by the WHO (compare the fasting glucose levsls, random, and 2 hours after a meal)
- fasting level: >= 7.0 mmol/L
- random: >= 11.1 mmol/L
- 2 hours after meal: >= 11 mmol/L
