3 - Fuel homeostasis

done till slide 10

Why do we need fuel homeostasis?

Due to the sporadic (occasionally or irregularly) intake of food but constant requirement of tissues for nutrients.

what is CNS very reliant on as a metabolic substrate?

glucose

what does Glucose homeostasis ensure?

that plasma glucose is maintained between 4mM and 7-8mM.

Fuel homeostasis maintains stable energy availability by controlling…:

• Short-term storage – e.g. glucose stored as glycogen.

• Long-term storage – e.g. energy stored as fat.

• Mobilisation of stores – releasing stored energy when needed, e.g. breaking down glycogen or fat.

what is absorptive state?

after eating - when ingested nutrients are entering the blood from the GI tract; ~3hours for an average meal.

what is postabsorptive state?

Between meals - when GI tract is empty and energy is supplied by body stores.

what is food mainly made up of?

Carbohydrates, proteins and fats.

what are carbodyhrates broken down into + absorbed as?

Broken down into glucose, which enters the blood.

what are proteins broken down into + absorbed as?

Broken down into amino acids, which enters the blood.

what are fats broken down into + absorbed as?

• Packaged into chylomicrons, which travel through the lymphatic system to carry fat from the gut to tissues such as fat cells.

what are the main organs involved in fuel homeostasis?

liver, adipose tissue + muscles.

what is liver’s role?

it is a major glycogen store.

what is adipose tissue’s role?

it is a major triacylglycerol store.

what is the muscle’s role?

majority of body mass, major consumer of fuel, some glycogen storage.

what happens to the food in the GI tract?

it is digested in the stomach + intestines.

how are the nutrients absorbed?

into the bloodstream.

what carries the nutrient-rich blood from the gut to the liver for processing?

the Hepatic portal vein.

what does the liver do withthe glucose it takes up from the blood?

stores some as glycogen and converts the excess into fatty acids + other glycerol-related compounds.

what are the fatty acids + glycerol-related compounds used to make?

Triglycerides