Endocrine system 4 Flashcards
What is whole body metabolism?
Co-ordinated regulation of etabolic pathways in different organs to maintain adequate energy supply to all cells
1 - Storage of nutrients/break down of stores when required
2 - Maintenance of blood glucose = primary energy source of the brain
What is anabolism?
The use of chemical energy to build up macromolecules from precursors
What is catabolism?
The breakdown of macromolecules to generate chemical energy
What can whole body metabolism be divided into?
- Fed (or absorptive) state → Anabolic
- Fasted (or post-absorptive) state → Catabolic
Summarise the bimolecule processing (how it is used) of carbohydrates:
Carbohydrates –> glucose
Glucose —> glycoen (via glycogenesis)
Glycogen —> glucose (via glycogenolysis)
(In the liver, Skeletal muscle)
Total energy store = 1%
Summarise the bimolecule processing (how it is used) of lipids:
Lipids –> free fatty acids glycerol
Free fatty acids glycerol —> triglycerides (via lipogenesis)
Trigylcerides —> free fatty acids glycerol (via lipolysis)
(Adipose)
Total energy store = 77%
Summarise the bimolecule processing (how it is used) of proteins:
Proteins –> amino acids
Amino acids —> proteins (via protein synthesis)
Proteins —> amino acids (via protein breadown)
(Skeletal muscle)
Total energy store = 22%
Describe the energy balance formula:
Energy input = energy output
Energy input = work performed + heat produced
What can each of the part sof this formula be broken down into:
Energy input = work performed + heat produced
Energy input = food intake & energy from nutrients
Work performed = ~40% - mechanical, chemical, transport
Heat produced = ~60% - maintain body temp
What is positive energy balance?
Energy input > energy output
- Energy in excess of output gets stored
What is negative energy balance?
Energy input < energy output
- Net breakdown of macromolecules to provide energy
What is energy metabolism during fed (absorptive) state like?
- 3-4 hours following meal, nutrients in the bloodstream are plentiful
- Energy input > energy output
- Hormonal control: insulin = anabolic
What is metabolism during fasted (post-absorptive) state like?
- Between meals, energy stores must be mobilised = catabolic
- Energy input < energy output
- Hormonal control: glucagon & other counter-regulatory hormones to insulin
- Maintain energy source for brain and other neuronal tissue
Regulation of insulin release:
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What can happen to glucose in the liver?
- Glycogen synthesis (inc glucose levels)
- Glycogen breakdown (dec glucose levels)
- Gluconeogenesis (dec glucose levels)
What can happen to glucose in the muscle?
- Glucose uptake - via GLUT-4 (inc glucose)
- Protein synthesis (inc glucose)
- Protein breakdown (dec glucose)
What can happen to glucose in adipose tissue?
- Glucose uptake - via GLUT-4 (inc glucose)
- Lipogenesis (inc glucose)
- Lipolysis (dec glucose)
What is the main action of insulin?
Red blood glucose
Mediated by insulin receptors (tyrosine kinase receptor family)
Effect of insulin on glucose uptake (SkM, adipose)
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What is the release of glucagon stimulated by?
- Stimulated by low blood glucose (<3.5mmol/L or mM) para- and sympathetic NSs
- Inhibited by high blood glucose
What are the actions of glucagon?
Raise blood glucose
- Stimulate hepatic glycogenolysis
- Stimulate hepatic gluconeogenesis
- Simulate lipolysis
Describe the actions of how blood glucose is lowered when too high:
- alpha-cell produces less glucagon
- beta-cell produces more insulin
Dec blood glucose = back to normal
Describe the actions of how blood glucose in increased when too low:
- alpha cell produces more glucagon
- beta-cell produces less insulin
Inc blood glucose = back to normal
What is the normal range of blood glucose?
4-8mmol/L
