Fed, Fasted and Starvation Flashcards
What is the absorptive state known as?
Fed State, just after eating a meal and therefore are actively absorbing nutrients.
What is the post absorptive state?
Fasted state, after nutrients and energy has already been absorbed and therefore you must acquire energy from the stores within the body.
Where do the absorbed nutrients enter into first and which organ is required?
Portal blood first
First port of call is the liver
In the liver what is glucose converted to?
Glycogen
In muscle what is glucose converted to?
Glycogen
In other tissues what can glucose be converted to?
Kerbs cycle energy
In adipose tissue what can Glucose be converted to?
TG
What are amino acids converted to in the liver?
Keto acids and energy
What are amino acids converted to in the muscles?
Proteins
What is the hormone controlling the switch between post absorptive and absorptive states?
Insulin.
Due to increased glucose and insulin in the blood
Where is insulin secreted?
Beta cells of the islets of Langerhans in the pancreas.
What is the trigger for insulin release?
High blood glucose and amino acid levels
Which transported is responsible for glucose uptake into the beta cells?
GLUT2 which is insulin insensitive.
What happens when glucose is transported into the beta cells.
Triggers generation of ATP from glucose metabolism and Ca influx
Raised intracellular Ca causes insulin exocytosis.
After insulin is released what leads to glucose uptake in cells?
After insulin secretion
GLUT4 is recruited to cells and enables glucose to be up taken.
This leads to decreased blood glucose concentration and therefore removal of insulin
What does insulin do when it is present in the liver after receptor is stimulated?
Makes no difference to GLUT2 on liver surface
Stimulates
Increased Glycogen synthesis
Increased Glycolysis
Decreased Glycogenolysis
What is the role of insulin in muscle cells?
Drives GLUT4 to the cell membrane allowing for increased glucose uptake.
Increase glycogen synthesis
Increase glycolysis
Increase lipogenesis
What is the role of insulin in adipocytes?
Drives GLUT4 is recruited to the membrane
Increased glucose up take
Increased Glycolysis and TG synthesis
Stimulate Lipogenesis and inhibit lipolysis
What is being utilised when in the post absorptive state?
Utilisation of energy stores since glucose is not being absorbed from the GIT
What reactions to ultilise energy from stores occur when in the post absorptive state?
Glucose supplying reactions (reactions generating glucose)
Glucose sparing reactions (reactions which generate other energy substrates such as FAs)
What is the biggest contributor for energy in the post absorptive state?
Glucose sparing reactions
What is a common example of a glucose supplying reaction and where do they occur?
Glycogenolysis
Gluconeogenesis
Occurs in the liver
What examples are there for glucose sparing reactions?
Beta oxidation of fats from adipose tissue into Free FAs which enter the blood to be oxidised at other targets.
What is diabetes mellitus characterised by?
High blood sugar
What is Type 1 diabetes?
Young onset
Destruction of beta cells and therefore loss of insulin
Severe metabolic derangement due to inability to utilise glucose
(effectively stuck in the fasted state)
What are some characteristics of type 1 diabetes?
Use other fuels for energy (fasted state)
leads to marked weight loss and metabolic disturbance
What is Type 2 diabetes?
Prevalence increases with age
Insulin levels usually normal or high but has reduced action
Treated with lifestyle (diet) or insulin
What kind of damage does type 2 diabetes lead to?
Cause long term damage due to high glucose levels and lipid abnormalities.
less Severe metabolic derangements
What happens in type 1 diabetes in the liver?
Decreased glycogen synthesis
Increased glycogenolysis
What happens in type 1 diabetes in adipocytes?
Decreased glucose uptake since GLUT4 is not being recruited
Increased lipolysis
Breakdown of fats releasing fatty acids into circulation (used as alternative energy source to glucose)
What happens in type 1 diabetes in muscles?
Increased extracellular glucose as it cannot be absorbed since GLUT4 is not being recruited
Breakdown of protein to amino acids as substrates for gluconeogenesis
What does type 1 diabetes in muscles lead to?
Muscle wasting
What are the problems with metabolic derangement caused by diabetes?
Level of glucose in blood is high because uptake is not stimulated.
Insulin is not produced and therefore mediated inhibition of glycogenolysis and lipolysis cannot occur
What is the major issue with diabetes affecting the liver?
- Increased circulation of FAs directed to the liver where they are used in beta-oxidation.
- Increase in Acetyl CoA generated in hepatocytes which inhibits Krebs pushing Acetyl CoA towards ketogenesis.
- Ketones then used in extra hepatic tissues where it is reconverted into Acetyl CoA where it can then enter krebs outside of the liver.
What are some clinical features of uncontrolled diabetes?
Polyuria (glucose reabsorption exceeded leading to glucosuria and thus more urination) Polydipsia(thirst)
Dehydration
Infections (thrush) Weight loss (muscle and fat wasting)
Metabolic acidosis (due to ketones) leading to confusion or coma
What treatments are there for uncontrolled diabetes?
Rehydration with IV saline
Insulin
Monitor correct serum electrolytes
What is the impact of chronic diabetes?
High glucose may have other adverse metabolic effects as high glucose is toxic.
Advanced Glycation (altering protein function)
Sorbitol Toxicity (leads to glycation of other tissues)
What are the long term metabolic consequences microvascular?
Retinopathy - leads to blindness / vision impairment
Nephropathy - kidney damage leading to kidney failure
Neuropathy - Decreased sensation as well as impaired immune and wound healing system
What are some macrovascular complications?
Atherosclerosis
strokes
heart attacks
