Chapter 11: Energy Metabolism Flashcards
Energy extraction or catabolism occurs in what 4 stages in the body?
Stage 1: metabolic fuels are hydrolyzed in GI tract to monomeric building blocks (glucose, amino acids, and fatty acids) and absorbed
Stage 2: building blocks are degraded to a common metabolic intermediate, acetyl- CoA
Stage 3: the citric acid (Krebs, or tricarboxylic acid) cycle oxidizes acetyl-CoA to CO2. The energy released in this process is primarily conserved by reducing NAD to NADH or FAD to FADH2
Stage 4: The final stage is oxidative phosphorylation in which the energy of NADH and FADH2 is released via the ETC and used by an ATP synthase to produce ATP. This process requires O2
The action of insulin is opposed by what hormones?
glucagon, epinephrine, cortisol, and growth hormone
Anabolic and catabolic pathways are controlled at 3 important levels. What are they?
Allosteric inhibitors and activators of rate-limiting enzymes
Control of gene expression by insulin and glucagon
Phosphorylation (glucagon) and dephosphorylation (insulin) of rate limiting enzymes
What are the 3 major target tissues for insulin?
liver,
muscle
adipose tissue
After a meal, most of the energy needs of the liver are met by what metabolic process?
by the oxidation of excess amino acids
Which 2 tissues are insensitive to insulin (insulin independent)?
The brain and RBCs
Be able to draw out basic energy metabolism of those in a well-fed (absorptive) state.
Place diagram here
Be able to draw out basic energy metabolism of postabsorptive state.
Place diagram here
What is the RDA for carbs?
4 kcal/gm
What is the RDA for protein?
4 kcal/gm
What is the RDA for fat?
9 kcal/gm
What is the RDA for alcohol?
7 kcal/gm
What is the recommended daily calorie budget?
2100 kcal diet
Complete combustion of ketones uses about how many kcal/g?
4 kcal/g
What is the preferred fuel of the liver in the well-fed state?
glucose and amino acids are
What is the preferred fuel of the sk. muscle in the well-fed state?
glucose
What is the preferred fuel of cardiac muscle in the well fed state?
fatty acids
What is the preferred fuel of adipose tissue in the well fed state?
glucose
What is the preferred fuel of the brain in the well-fed state?
glucose
What is the preferred fuel of the RBCs in the well-fed state?
glucose
What is the preferred fuel of the liver in the fasting state?
fatty acids
What is the preferred fuel of the sk. muscle in the fasting state?
fatty acids, ketones
What is the preferred fuel of cardiac muscle in the fasting state?
fatty acids, ketones
What is the preferred fuel of adipose tissue in the fasting state?
fatty acids
What is the preferred fuel of the brain in the fasting state?
glucose (ketones in prolong fast)
What is the preferred fuel of the RBCs in the fasting state?
glucose
What are the 2 major roles of the liver in fuel metabolism?
maintain a constant level of blood glucose under a wide range of conditions
synthesize ketones when excess fatty acids are being oxidized
What 3 things in the liver provide C skeletons for glucose synthesis?
lactate, glycerol, and amino acids
LPL, an enzyme found in the capillary bed of adipose tissue is induced by what hormone?
insulin
During the fasting state, the decrease in insulin and increase in epinephrine activate what hormone in fat cells?
hormone sensitive lipase
Another name for triglyceride?
triglycerol
During the fasting state, the adipose tissue has what major metabolic functions to maintain homeostasis in the body?
During the fasting state, the decrease in insulin and the increase in epinephrine activate hormone-sensitive lipase in fat cells, allowing fatty acids to be released in to the circulation
Where does lactate go once secreted in the blood?
goes to be converted back to glucose in the liver
What type of glycolysis do fast twitch muscles participate in?
In anaerobic glycolysis
Describe fast twitch muscles.
involved in primarily short-term activities and high intensity exercise; quick to fatigue
Describe slow twitch muscles. (Where they are found, what type of exercise, fatigue level, vascularization)
found in the arms and leg
are heavily vascularized and primarily oxidative
used during prolonged low to moderate intensity exercise and resist fatigue
During the fetal life the cardiac muscle primarily uses what as an energy source?
glucose
Post-natally what energy source does cardiac muscle use?
B-oxidation of fatty acids
In the failing heart what are the major sources of energy for the heart?
glucose oxidation increases and B oxidation of fatty acids decreases
In hypoglycemic conditions how does the brain regulate glucose levels in the blood?
centers in the hypothalamus sense a fall in blood glucose level (<70 mg/dL) , and the release of glucagon and epinephrine is triggered
