Post absorptive mechanisms and energy balance Flashcards
What are some diseases associated with metabolic problems?
- Type 1 diabetes
- obesity
- lipid disorders
- people being unable to process enzymes
What are carbohydrates broken down into?
glucose
What are proteins broken down into?
Amino acids
What are fats broken down into?
Triglycerides
Where is glucose absorbed?
From the intestine
Where is glucose transported to, to be processed?
The liver
Where does the liver transport glucose?
Muscle, Brain, RBCs, Adipocytes (fat cells for storage)
How is glucose stored and processed in the liver?
- Stored as glycogen, ready to be released at a later time
- Made into Acetyl CoA which is formed into triglycerides or can go into Krebs cycle to make ATP
- the triglycerides made join with a protein to make a lipoprotein e.g. VLDL (which carries triglycerides)
What hormone regulates the uptake of glucose?
Insulin. It also facilitates the glycogen storage and well as glucose uptake
What happens to glucose in the muscles?
- Glucose in the blood stream is made into glycogen so it can be stored
What happens to glucose in the brain?
Made into Acetyl CoA which enters Krebs cycle to form ATP
What happens to glucose in the RBCs?
Glucose is not stored in RBCs nor is there a Krebs cycle taking place here
- So it is made into pyruvate and lactate which can be used as sources of energy
What happens to glucose in adipocytes?
With the help of insulin, glucose is made into ATP and Triglycerides (for storage)
What does amino acids absorbed from the intestine turn into?
- Proteins
- Various compounds e.g. hormones
- Krebs cycle to make ATP
What does triglycerides absorbed from the intestine turn into?
They combine with proteins to make them soluble so they can be transported around the blood stream.
- Made into chylomicrons which go into the lymphatic system
What do we need to do when fasting?
Blood glucose needs to be maintained so the body’s stores are broken down
How does the body obtain glucose when a short fast has taken place?
- Body uses the glycogen stores in the liver which is broken down into glucose and transported to the brain and RBCs
- This process of glycogen to glucose is called glycogenolysis
What hormone promotes the breakdown of glycogen to glucose?
Glucagon
How does the body obtain glucose when a longer fast has taken place?
- No glycogen stores
- Amino acids (from muscles), lactate (from RBCs), Glycerol (from adipocytes) are fed back into the liver to make glucose within the body from other substances
- This is called gluco-neogenesis
How are fats used during a short fast?
- Triglycerides are broken into glycerol and fatty acids which are transported to the liver
- Here they are converted into glucose and ketones
- The ketones are an alternate energy to glucose
- Fatty acids are also used by the kidneys and muscles for energy
- This process is called lipolysis (break down of fats)
- Glucagon promotes this breakdown
How do we maintain blood glucose levels on an extreme pro-longed fast when we can’t make new glucose?
- Switch to ketones for energy
- Fatty acids enter the liver, which makes ketones which are used in the brain
- Due to using ketones, there is a decreased use of glucose so any made can be available for RBCs as they can’t use ketones
What substances can be measured in the blood?
- Glucose
- Ketones
- Insulin
- Lactate
- Triglycerides
What hormones regulate fuel metabolism that come from the pancreas?
- Insulin (Anabolic)
- Glucagon
What hormones regulate fuel metabolism that come from the adrenal gland?
- Cortisol
- Adrenaline
- Noradrenaline
What hormones regulate fuel metabolism that come from the thyroid gland?
Thyroxine
What hormones regulate fuel metabolism that come from the pituitary gland?
- Growth hormone
- Somatostatin
Is insulin anabolic or catabolic?
Anabolic (build larger molecules out of small)
- glycogen storage
- fat storage
- protein synthesis
Is glucagon anabolic or catabolic?
Catabolic (breaking down large molecules into small)
- glycogenolysis
- gluconeogenesis
- ketogenesis
What are the effects of cortisol on fuel metabolism?
Preparation for stress response
- Lipolysis
- Protein breakdown
- Gluconeogenesis
- Glycogen storage
- Protein breakdown
Long term increase in cortisol is bad
What are the effects of adrenaline on fuel metabolism?
- Glycogenolysis
- Gluconeogenesis
- Lipolysis
Fight or flight response
What are the effects of thyroxine on fuel metabolism?
- Glycolysis
- Cholesterol synthesis
- Glucose uptake
- Protein synthesis
- Sensitises tissues to adrenaline
What are the effects of growth hormone on fuel metabolism?
- Gluconeogenesis
- Glycogen synthesis
- Lipolysis
- Protein synthesis
- Decreased glucose use
What are three factors that contribute towards obesity?
- Genetics
- Environment
- Energy dysregulation
What does leptin do?
- Found in fat cells, goes to brain and in normal weight it suppresses appetite
- In obesity, high leptin levels so there is leptin resistance so appetite not suppressed
What does ghrelin do?
- From the stomach to brain
- Increases before meals
- To stimulate appetite
