S2 L1 - Glycogen and Fat Flashcards
- *Glucose:**
- Which is the preferred fuel for tissues?
- Which tissues have an absolute requirement for glucose
- Hypoglycaemia - 2.8mmol/L, 1.7mmol/L, 1.1mmol/L, 0.6mmol/L
- How can blood glucose be kept at the required level
- Which is the preferred fuel for tissues?
Glucose
- Which tissues have an absolute requirement for glucose
Red blood cells, neutrophils, inner cells of kidney medulla, lens of the eye
- Hypoglycaemia - 2.8mmol/L, 1.7mmol/L, 1.1mmol/L, 0.6mmol/L
Between 2.8-1.1, symptoms: muscle weakness, nausea, confusion, muscle cramps
0.6mmol/L symptoms: brain damage, death
- How can blood glucose be kept at the required level
Glycogen
- *Glycogen:**
- How and where is it stored?
- Glycogen structure
- *- How and where is it stored?**
- – Muscle glycogen (Distinction between intra- and inter- myofibrillar glycogen
- – Liver glycogen (glycogen storage granules in hepatocytes)
- *- Glycogen structure (pic)**
- *Glycogenesis**
- Full pathway with all of the enzymes
- *Glycogenolysis**
- Full pathway and enzymes
Glycogen stores serve different functions in liver and muscle.
What happens to the glycogen in each organ (with pathways)
How is glycogen metabolism (i.e. glycogenesis and glycogenolysis) regulated?
- *Glycogen storage diseases:**
- What’s usually the problem?
- Example of these diseases
- Glucagon, Adrenaline
- Insulin
(see pic)
Glycogen storage disease:
- What’s usually the problem?
with enzyme
- Example of these diseases
von Gierke’s disease (glucose-6-phosphatase deficiency)
McArdle disease (muscle glycogen phosphorylase deficiency)
- *Gluconeogenesis**
- When does this occur (time-frame after eating)
- Where does this occur?
- Three main precursors that feed into the pathway of gluconeogenesis
- When does this occur (time-frame after eating):
Beyond ~ 8 hours of fasting, liver glycogen stores start to deplete and an alternative source of glucose is required: Gluconeogenesis
- Where does this occur?
Occurs in Liver and to lesser extent in Kidney cortex
- Three major precursors:
Lactate - From anaerobic glycolysis in exercising muscle and red blood cells (Cori cycle) What is the Cori cycle - pic
Glycerol - Released from adipose tissue breakdown of triglycerides. Amino acids - Mainly alanine.
- *Gluconeogenesis
- **Full pathway
- 3 key enzymes
- PEPCK
- Fructose-1,6-Bisphosphatase
- Glucose-6-phosphatase
- *Gluconeogenesis**
- Regulation of gluconeogenesis
- Time Course of Glucose Utilisation
- Glucagon
- Insulin
(pic)
Time Course of Glucose Utilisation:
Glucose from food (2 hours)
Glycogenesis (Up to 8-10 hours)
Gluconeogenesis (8-10 hours onwards)
- *Lipid storage
- **Name of lipid storage equation and lipid breakdown equation
- *Triacylglycerol**
- Characteristics
- Is it an efficient energy store?
- When is the store used?
- How is the store mobilised?
- *Adipocytes**
- What are these?
- What does it look like? (white fat)
- Name of lipid storage equation and lipid breakdown equation:
Glycerol + 3 Fatty acids -> Triacylglycerol + 3 water
Esterification
Triacylglycerol + 3 water -> Glycerol + 3 Fatty acids
Lipolysis
- *- Triacylglycerol - Characteristics**
- Hydrophobic, anhydrous form (adipose tissue)
- Highly efficient energy store
- Utilised in prolonged exercise, stress, starvation, during pregnancy.
- The storage & mobilisation of TAGs is under hormonal control
- *Adipocytes**
- Adipocytes are large lipid droplet (mainly TAG and cholesterol ester)
- Adpiocytes cytoplasm and organelles are pushed to the edge
Overview of dietary triacylglycerol metabolism
- *Lipogenesis**
- where does this take place mainly?
- Pathway
- 2 key regulatory enzymes (one of these is the main regulartory enzyme)
- How is the ‘main regulartory’ enzyme regulated?
- Liver
- Acetyl coA carboxylase and fatty acid synthase complex
- Regulated:
Glucagon/adrenaline
Insulin
Comparison of fatty acid synthesis and beta-oxidation
Fat mobilisation (lipolysis)
