Fate of Nutrients: hormonal control Flashcards
how long does the absorptive state last for during and after each meal?
4 to 6 hours
what is the absorptive (postprandial) state?
time during and after eating a meal
what happens in the postprandial state?
end product of nutrient digestion undergo anabolic processes leading to nutrient storage in format of glycogen and TAG and contribute to energy production and undergo oxidative disposal
in the postpranial state what are most dietary amino acids used for?
protein synthesis
what is the postabsorptive state?
period when the GIT is empty and energy comes from the breakdown of our body reserves
- rate of glucose release from the liver is increases
- lipolysis of TG in adipose tissue is increases
what is the role of increased lipolysis in sparing glucose?
FFA are oxidised to cover energy demands of muscle and other tissues
FFA are used for synthesis of ketone bodies and glycerol us substance for gluconeogeness
what is metabolism in the post absorptive state like?
directed to maintain blood glucose levels
in the postabsorptive state what is the first available store of glucose?
how long can these stores maintain blood sugar levels?
livers store of glycogen
3 hours
what is the process of guconeogenesis?
activated in liver and glucose is synthesised from lactate, pyruvate, glycerol and amino acids
what are the metabolic and hormonal responses in the absorptive state?
- increased glucose
- increased TG
- decreased blood NEFA
- decreased B-hydroxybutyrate
*increased insulin
*decreased glucagon
what are the metabolic and hormonal responses in the postabsorptive state?
- decreases glucose
- decreased TG
- increased blood NEFA
- increased B-hydroxybutyrate
*decreased insulin
*increased glucagon
what is the role of insulin in regulation and metabolism during absorptive state?
essentially all of the events that occur in the absorptive state are directed by insulin
what is the effect of insulin on CHO metabolism?
-stimulates glucose uptake by cells
- stimulates glycolyses
- stimulates glycogen synthesis
- inhibits glycogen catabolism
what is fat mobilisation catalysed by?
enzyme = hormone sensitive lipase (HSL)
how and when is hormone sensitive lipase inactive?
when insulin levels are high
by dephospho rylation in response to high concentration of insulin
what impact does insulin have on the process of re-esterification?
insulin stimulates process of re-esterification (synthesis of TAG) by provision of glycerol-3 phosphate
how does insulin have an effect on the clearance of chylomicrons and VLDL?
- increases the activity of lipoprotein lipase (LPL) activity in adipose tissue
- LPL resides son the capillary endothelium of adipose and muscle tissue
- increases in LPL activity provides clearance of TAG from both chylomicrons and VLDL
how does a lack of insulin have an effect on protein synthesis?
loss of protein from the body due to “melting of flesh into urine”
what effect does insulin have on protein synthesis?
- increases uptake of amino acids
- increases activity of protein synthesis enzymes
- reduces activity of protein catabolic enzymes
what is insulin released stimulated by?
- increased blood glucose
- increases amino acids in plasma
- neural stimulation of pancreas
- gut hormones
when is insulin release decreased by?
- reduction of blood glucose
- sympathetic neural stimulation
what is the role of glucagon in regulation of metabolism during post-absorptive state?
- released by A cells of islets of langerhans
- increases glycogen breakdown in liver
- increases lipolysis
- increases gluconeogenesis in liver
- increases ketone body synthesis
what can a severe negative energy balance lead to?
- a decline in metabolism
- decreases in bone mass
- reductions in thyroid hormones
- reductions in testosterone levels
- an inability to concentrate
- reduces physical performance
what are the consequences of a positive energy balance?
- plaque can build up in arteries
- blood pressure increases
- total and LDL-cholestrol and TAG increases
- insulin’s resistance develops which leads to type 2 diabetes
- risk for cancer increases
what happens to the control of nutrient metabolism during stress?
during stress the hypothalamus;amic-pituitary adrenal HPA axis is activated to regulate many body processes, including energy storage and expenditure
what does cortisol do in control of nutrient metabolism during stress?
helps to regain glucose homeostasis:
- increases blood glucose through gluconeogenesis
- important role in glycogenolysis (breakdown of glycogen glucose) in liver and muscle tissue by facilitation of the activation of glycogen phosphorylase
how does cortisol redistribute glucose in the control of nutrient metabolism during stress?
redistributes it to areas of the body that need it the most (heart brain) and away from digestive and reproductive organs
what is the role of epinephrine and norepinephrine in control of nutrient metabolism during stress?
to provide increase in fatty acids required for energy ATP production by
- inhibiting insulin secretion by pancreas
- triggering glucagon secretion in the pancreas
- stimulating glycogenolysis in the liver and muscle
- stimulating glycolysis in muscle
what is the role of growth hormone in the control of nutrient metabolism during stress?
- promotes lipolysis and fatty acid oxidation
- reduces liver uptake of glucose and helps to maintain plasma glucose concentration
- promotes gluconeogenesis in the liver
what are hormonal responses to surgery?
- anterior pituitary ACTH increases
- growth hormone increases
- adrenal cortex cortisol increases
- aldosterone increases
- insulin often decreases
- glucagon usually small increases
- thyroid, thyroxine, tri-iodothyronine decrease
what is the overall metabolic effect of the hormonal changes during surgery?
increases catabolism which mobilises substrates to provide energy sources and metabolism to retain salt and water and maintain fluid volume and cardiovascular homeostasis
what do neuroendocrine, metabolic and inflammatory responses result in ?
substrate mobilisation
muscle protein loss
sodium and water retention
suppression of Anabolic hormone secretion
does local anaesthesia or general anaesthesia associate with more patient stress?
general anaesthesia
