metabolic response to sepsis and injury vs starvation

Question 1

what happens 5-12 hours into a fast?

Answer 1

5-12 hrs

• > blood glucose is reduced and the pancreas senses this so releases glucagon
• > this stimulated glycogenolysis and glycogen in the liver is broken down to glucose and released into the blood for energy

Question 2

what happens 24hrs into a fast?

Answer 2

the liver uses amino acids for gluconeogenisis to make glucose
the glucose is released into the blood to provide energy

Question 3

what happens 1-3 days into a fast?

Answer 3

fatty acids are broken down into acetylcoA for energy- but this cannot cross the BB to give energy to the brain

acetyl-coA is also unable to join oxcasloacetate in krebs cycle as glucose is no longer being broken down

the leads to an accumulation of acetylcoA- the liver converts this to ketone bodies that the brain is able to use

Question 4

what are the 3 ketone bodies?

Answer 4

1. acetoacetate
2. b-hydroxybutyrate
3. acetone-> this is not metabolically useful and is exhaled from the lungs

Question 5

which cells cannot use ketone bodies?

Answer 5

RBC- bc they don’t have mitochondria

Question 6

what does high urea in the urine of someone who is starving indicate?

Answer 6

That they are breaking down protein from their muscles.

Question 7

Why does anorexia cause death?

Answer 7

Survival time depends on the fat stores after the fat stores have been depleted the only source of energy is protein
protein is degraded it can cause damage to the heart liver or kidney and death can result from the loss of function of vital organs

Question 8

How would you differentiate between diabetic and alcoholic ketoacidosis?

Answer 8

In diabetics the glucose would be high this is because no insulin is being produced so that glucose cannot be utilised. But the ketones would be high because they are the alternative energy source.

in alcoholics the ketones would be high because they are malnourished and ethanol is metabolised to acetic acid (ketone) and they will not have high glucose

Question 9

how do ketones stabilise their own production?

Answer 9

• stimulate release of insulin- even if their is low glucose
• increase the sensitivity of adipose tissues to insulin
• directly inhibit lipolysis

Question 10

what is the difference in metabolic usage in starvation vs stress?

Answer 10

• in stress the body uses fat and amino acids but in simple starvation it only uses fat
• in stress there is ptoteolysis, but in simple starvation there is not
• in stress there is more energy expenditure
• in stress there is also an increase in counter-regulatory hormones

Question 11

why is there an increase in lactate in sepsis?

Answer 11

There is tissue hypoperfusion and impaired tissue oxygenation leads to anaerobic metabolism lactic acid is a product of anaerobic metabolism.

Question 12

What happens in the hypermetabolic response to injury trauma and surgical or critical illness?

Answer 12

• increased blood pressure and heart rate
• peripheral insulin resistance.
• increased resting energy expenditure
• increased body temperature
• increase protein and if it’s catabolism.

Question 13

Why is glucose hi during critical illness?

Answer 13

• stress mediators oppose the anabolic actions of insulin
• enhanced lipolysis and proteolysis
• increase in gluconeogenic substrates like glycerol, alanine and lactate to increase glucose production
• high levels of cortisol and other catacolamines
• increase in glycogen breakdown

Question 14

how does muscle wasting relate to insulin resistance?

Answer 14

• muscles take up 75% of insulin stimulated glucose uptake

- decrease in muscle results in insulin resistance

Question 15

what causes lean muscle to breakdown in injury and illness?

Answer 15

proinflamatory cytokines such as TNF

Question 16

what are endocrine complications of starvation?

Answer 16

pituitary abnormalities;
low GNRH, LH,FSH,Estradiol 
- leads to...
- amenorrhoea and infertility  
- hypogonadotrophic gonadism
- leptin (the signal to stop eating) is lowered 
- bone loss is severe

Question 17

what endocrine changes occur in the adrenals from severe starvation?

Answer 17

• high cortisol results in muscle and collagen breakdown

Question 18

what thyroid complications can occur due to starvation?

Answer 18

Euthyroid sick syndrome is a condition in which serum levels of thyroid hormones are low in clinically euthyroid patients with nonthyroidal systemic illness.

there is also a reduction in metabolic rate