Endocrine Pancreas 1 Flashcards
Body energy =
energy intake - energy ouput
Energy (food) intake is determined by balance of activity of which 2 hypothalamic centres?
Feeding centre
Satiety centre
What is the function of the feeding centre?
Promotes feelings of hunger and drive to eat
What is the function of the satiety centre?
Promotes feelings of fullness by suppressing the feeding centre
What is the glucostatic theory?
Food intake is determined by blood glucose: as [BG] increases, the drive to eat decreases (-feeding centre; +satiety centre)
What is the lipostatic theory?
Food intake is determined by fat stores: as fat stores increase, the drive to eat decreases (-feeding centre; +satiety centre)
What part does leptin play in the lipostatic theory?
Leptin is a peptide hormone released by fat stores which depresses feeding activity (not the only signal in the system, as obesity proves…)
What can result from disruption of these pathways?
Obesity
What are the 3 categories of energy output?
Cellular work
Mechanical work
Heat loss
Describe cellular work
transporting molecules across membranes; growth + repair; storage of energy (e.g. fat, glycogen, ATP synthesis)
Describe mechanical work
movement, either on large scale using muscle or intracellularly
Describe heat loss
associated with cellular and mechanical work - accounts for half of our energy output
What is the only part of energy output we can regulate voluntarily?
Mechanical work
What is metabolism?
Integration of all biochemical reactions in the body
What are the 3 elements of metabolism?
- extracting energy from nutrients in food
- storing that energy
- utilising that energy for work
Describe anabolic pathways
‘BUILD UP’
net effect is synthesis of large molecules from smaller ones, usually for storage purposes
Describe catabolic pathways
‘BREAK DOWN’
net effect is degradation of large molecules into smaller ones, releasing energy for work
What state do we enter after eating?
Absorptive state
Describe the absorptive state
state where ingested nutrients supply the energy needs of the body and excess is stored = anabolic
What state do we enter between meals and overnight?
Post-absorptive state
Describe the post-absorptive state
The pool of nutrients in the plasma decreases and we enter this state where we rely on body stores to provide energy = catabolic
What is the brain described as?
‘Obligatory Glucose Utiliser’ !!
What substances can the brain use for energy?
ONLY glucose
Not fats, carbs or protein like other cells
Due to the brain being an OGI, in the post-absorptive state, even tho no new carb is gained, we must…
maintain blood glucose concentration sufficient to meet the brain’s requirements
What does failure to maintain blood glucose concentration in the post-absorptive state result in?
Hypoglycaemia which can lead to coma and death
How is blood glucose maintained?
By synthesising glucose from glycogen (glycogenolysis) or amino acids (gluconeogenesis)
In hyperglycaemia (like in diabetics), what does the body do with the excess glucose?
Tries to eject it via urine
How is glucose stored in the body?
As glycogen, which is stored in the liver and turns it to fat
What is the NORMAL range of blood glucose?
4.2 - 6.3mM
remember 5 mmoles !!
What BG level is considered hypo- and hyper- glycaemia?
Under 4 is too low, under 3 is emergency
Around 10/11 is hyper - symptoms develop slowly