The Lipostat Theory Predicts the Feedback Regulation of Adipose Tissue

Gulation Prise Alimentaire

The lipostat theory postulates a mechanism that inhibits eating behavior and increases energy consumption whenever body weight exceeds a certain value the set point the inhibition is relieved when body weight drops below the set point Fig. 23-30 . This theory predicts that a feedback signal originating in adipose tissue influences the brain centers that control eating behavior and activity metabolic and motor . The first such factor, leptin, was discovered in 1994, and several others are now...

Why Pythagoras Wouldnt Eat Falafel Glucose 6Phosphate Dehydrogenase Deficiency

Fava beans, an ingredient of falafel, have been an important food source in the Mediterranean and Middle East since antiquity. The Greek philosopher and mathematician Pythagoras prohibited his followers from dining on fava beans, perhaps because they make many people sick with a condition called favism, which can be fatal. In favism, erythrocytes begin to lyse 24 to 48 hours after ingestion of the beans, releasing free hemoglobin into the blood. Jaundice and sometimes kidney failure can result....

Why Doe Aicar Accumulate In The Presence Of Sulfanilamide

a What is the role of p-aminobenzoate in these bacteria Hint See Fig. 18-16 . b Why does AICAR accumulate in the presence of sul-fanilamide c Why are the inhibition and accumulation reversed by addition of excess p-aminobenzoate 12. Pathway of Carbon in Pyrimidine Biosynthesis Predict the locations of 14C in orotate isolated from cells grown on a small amount of uniformly labeled 14C succinate. Justify your prediction. 13. Nucleotides As Poor Sources of Energy Under starvation conditions,...

Glucagon Counters Low Blood Glucose

Liver State

Several hours after the intake of dietary carbohydrate, blood glucose levels fall slightly because of the ongoing oxidation of glucose by the brain and other tissues. Lowered blood glucose triggers secretion of glucagon and decreases insulin release (Fig. 23-27). Glucagon causes an increase in blood glucose concentration in several ways (Table 23-4). Like epinephrine, it stimulates the net breakdown of liver glycogen FIGURE 23-26 The well-fed state the lipogenic liver. Immediately after a...

What Is The Importance Of Relatively Inactivation Circulating Hormones

ATP and Phosphocreatine as Sources of Energy for Muscle During muscle contraction, the concentration of phosphocreatine in skeletal muscle drops while the concentration of ATP remains fairly constant. However, in a classic experiment, Robert Davies found that if he first treated muscle with 1-fluoro-2,4-dinitrobenzene p. 97 , the concentration of ATP declined rapidly while the concentration of phosphocreatine remained unchanged during a series of contractions. Suggest an explanation. 2....

Changes in the Hereditary Instructions Allow Evolution

Despite the near-perfect fidelity of genetic replication, infrequent, unrepaired mistakes in the DNA replication process lead to changes in the nucleotide sequence of DNA, producing a genetic mutation Fig. 1-32 and changing the instructions for some cellular component. Incorrectly repaired damage to one of the DNA strands has the same effect. Mutations in the DNA handed down FIGURE 1-32 Role of mutation in evolution. The gradual accumulation of mutations over long periods of time results in new...

The Fitness of the Aqueous Environment for Living Organisms

Organisms have effectively adapted to their aqueous environment and have evolved means of exploiting the unusual properties of water. The high specific heat of water the heat energy required to raise the temperature of 1 g of water by 1 C is useful to cells and or- ganisms because it allows water to act as a heat buffer, keeping the temperature of an organism relatively constant as the temperature of the surroundings fluctuates and as heat is generated as a byproduct of metabolism. Furthermore,...

Hormonal Regulation of Fuel Metabolism

The minute-by-minute adjustments that keep the blood glucose level near 4.5 mM involve the combined actions of insulin, glucagon, epinephrine, and cortisol on metabolic processes in many body tissues, but especially in liver, muscle, and adipose tissue. Insulin signals these tissues that blood glucose is higher than necessary as a result, cells take up excess glucose from the blood and convert it to the storage compounds glycogen and tria-cylglycerol. Glucagon signals that blood glucose is too...

Complementary Interactions between Proteins and Ligands The Immune System and Immunoglobulins

Our discussion of oxygen-binding proteins showed how the conformations of these proteins affect and are affected by the binding of small ligands O2 or CO to the heme group. However, most protein-ligand interactions do not involve a prosthetic group. Instead, the binding site for a ligand is more often like the hemoglobin binding site for BPG a cleft in the protein lined with amino acid residues, arranged to render the binding interaction highly specific. Effective discrimination between ligands...