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Endocrine 03 - Body Fuel Homeostasis and Metabolism


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How many kcal/g are found in glucose/lactate?
4 kcal.
How many kcal/g are found in fatty acids/ketone bodies?
9 kcal.
How many kcal/g are found in amino acids?
4 kcal.
How do you calcluate total kcals in a granola bar that contains 10g of fat, 20g of carbohydrates, and 3g of protein?
10g * 9 kcal/g = 90 kcal
20g * 4 kcal/g = 80 kcal
3g * 4 kcal/g = 12 kcal
TOTAL = 182 kcal
What are 3 examples of direct calorimetry?
1) Basal metabolic rate - energy required to keep the body functioning at rest.
2) Thermogenesis (non-shivering) - maintainenance of body heat.
3) Exercise.
What are 2 examples of indirect calorimetry?
1) Diet-induced thermogenesis, which activates sympathetic nerve system to stimulate lipolysis while eating.
2) Fidgeting (involuntary).
What is respiratory quotient?
The molecular ratio of CO2/O2 required to metabolize fuel. Respiration is directly involved in fuel metabolism.
What are the substrates for gluconeogenesis?
1) Glycerol (from TAG)
2) Amino acids (from protein)
3) Lactate (from muscle)
4) Pyruvate (from glycolysis)
What is the normal range of physiological plasma glucose?
60-110 mg/dl.
Name three metabolic processes that utilize circulating amino acids.
1) Gluconeogenesis
2) Ketogenesis
3) Ureagenesis
Where are fatty acids synthesized?
Liver and adipose tissue.
What is the fate of plasma FFA's in the circulation?
30-40% are oxidized by various muscle for energy.
50-70% are re-esterified into TAG's.
What supplies glucose to the brain during fasting?
1) Glycogenolysis
2) Gluconeogenesis
During fasting, what substrate other than glucose supplies all tissues outside the CNS?
Free fatty acids.
What product results from an excess oxidation of FFA?
Ketones (ketoacids).
What will the brain utilize as an energy substrate during a very prolonged fast when glucose is no longer available?
Ketones (ketoacids).
What substrates are required for anaerobic exercise (short-term, intense activity)?
1) Creatine phosphate
2) ATP
3) Muscle glycogen
What 5 substrates are required for aerobic exercise (long-term, sustained activity)?
1) Plasma glucose
2) Muscle glycogen
3) Liver glycogen
4) Plasma FFA's
5) TAG's from adipose tissue.
At rest, describe the uptake of glucose by the muscle.
It is insulin-dependent.
During exercise, describe the uptake of glucose by the muscle.
It is insulin-independent (AMP-kinase pathway).
Why is it beneficial for a diabetic patient to exercise?
Because exercise causes muscle to take up glucose from the circulation without the help of insulin (which is deficient or absent in diabetics). This is an AMP-kinase pathway.
*What is the role of leptin in energy storage feedback regulation?
Leptin is released from adipose tissue as the number of adipose cells increase. Leptin will bind to receptors in the brain, stimulating sympathetic nervous response, and decrease the size of adipose tissue by decreasing food intake/appetite, increasing metabolic rate, increasing activity level, increasing temperature, modulating hormones.
What hormones result in the storage of carbohydrates?
1) Insulin
2) Growth Hormone
What hormones result in the release of glucose into the circulation?
1) Glucagon (liver)
2) Epinephrine (catecholamines)
What hormone results in the storage of lipids as adipose tissue?
What hormones are responsible for the release of free fatty acids into the circulation from adipose tissue stores?
1) Epinephrine (catecholamines)
2) Glucagon
3) Growth Hormone
4) Cortisol (glucocorticoids)
What hormones result in the storage of amino acids in protein?
1) Insulin
2) Growth Hormone
What hormones result in the release of amino acids into the circulation from protein?
1) Glucagon
2) Epinephrine (catecholamines)
How do high amounts of free fatty acids in the circulation affect glucose homeostasis?
High FFA's in the circulation inhibit uptake of glucose by the muscle by blocking insulin.
Why are humans so vulnerable to diabetes?
Because insulin stands alone as the regulator of blood glucose. Damage to insulin production will cause a great deal of problems with glucose regulation.

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