Metabolic Changes and Disease Flashcards
What is the most tightly controlled nutrient
Glucose
Metabolism is either in one of two states, name these states and explain a bit about them
- Fed (absorbative) state - Shortly after a meal when new nutrients are available
- Fasted (postabsorbative) - Body needs to draw upon its feul stores
What occurs in the fed state metabolism?
This is anabolic. Nutrients are used to provide energy stores or for growth and maintenance of cells and tissues.
What occurs in fasted state metabolism
Catabolic.
Body calls on energy stores so they become depleted
What are the key hormones involved in regulating metabolism?
Insulin, Glucagon, adrenaline and noradrenaline
The actions of the key metabolic regulatory enzymes are mediated by what?
Activation of intrecellular protein kinases and phosphorylation of proteins on tyrosine, serine or threonin reisudes
What do Beta-cells do?
Secrete insulin
What stimulates beta-cells
elevated blood glucose levels and the parasympathetic nervous system
What are the endocrine cells of the pancrease?
Islets of langerhans
What does insulin stimulate?
- Glycogen synthesis in liver and muscle
- Uptake of glucose into muscle and adipose tissue
- Glycolysis and hense fatty acid synthesis in liver
- Formation of triglycerides in fat tissue
- Protein synthesis in muscle
What do alpha-cells of the pancreas release?
Glucagon
When do alpha cells release glucagon?
When blood glucose levels fall during fasting state
What is the main target of glucagon and what does it stimulate?
Target - liver
Stimulates;
Release of glucose from glycogen.
Gluconeogenesis bu inhibits glucose incorporation into glycogen
How is glucagon involved in the breakdown of triglycerides?
When glucagon is present there is a lack of insulin meaning triglycerides can be broken down
In the fed state, what molecule dominates and what does this lead too?
Insulin dominates leading too increased; Glucose oxidation, glycogen synthesis, fat synthesis and protein synthesis
In the fasted state, what molecule dominates and what does this lead too?
Glucagon dominates leading to increased; Glycogenolysis, gluconeogenesis and ketogenesis
Where are adrenaline and noradrenaline secreted?
Secreted by adrenal medulla and neurons of the sympathetic NS when blood glucose falls
What is the function of adrenaline and noradrenaline? and where do they act on?
They drive the breakdown of glycogen and triglycerides, lower glucose uptake so fatty acids are released by adipose tissue and used as fuel and they increase glucagon secretion and inhibit insulin secretion. They mainly act on the liver to produce glucose-6-P
What type of molecules are adrenaline and noradrenaline?
Catecholamine neurotransmitters
What are the normal ranges for blood glucose?
Between 80mg/ml before a meal to 120mg.100ml after a meal. (4-8mmol/liter)
What are the levels of blood glucose to be classed as hypoglycaemia?
<3mmol/liters
What are the levels of blood glucose to be classed as hyperglycaemia?
> 11mmol/liter
Fuel stores are sufficent for how many months of starvation?
1-3months depending on physical activity
What occurs in the first day of starvation?
- Carbohydrate stores only last a day or less so blood glucose levels will fall.
- Metabolism adjusts to maintain glucose at adequate level for the brain as it is completely dependant on glucose.
- Triglycerides limited ability to be converted into glucose
- Muscle starts to use fatty acids from adipose tissue as fuel so to spare glucose for brain
- Liver uses fats, pyruvate, lactate and alanine from muscle and fat to create as much glucose for brain.
