Function of Prohormones What are the possible advantages of synthesizing hormones as prohormones?

Thermogenesis Caused by Thyroid Hormones is intimately involved in regulating the basal metabolic rate. Liver tissue of animals given excess thyroxine shows an increased rate of $\mathrm{O}_2$ consumption and increased heat output (thermogenesis), but the ATP concentration in the tissue is normal. Different explanations have been offered for the thermogenic effect of thyroxine. One is that excess thyroxine causes uncoupling of oxidative phosphorylation in mitochondria. How could such an effect account for the observations? Another explanation suggests that thermogenesis is due to an increased rate of ATP utilization by the thyroxine-stimulated tissue. Is this a reasonable explanation? Why or why not?

Excessive Amounts of Insulin Secretion: Hyperinsulinism Certain malignant tumors of the pancreas cause excessive production of insulin by $\beta$ cells. Affected individuals exhibit shaking and trembling, weakness and fatigue, sweating, and hunger.
(a) What is the effect of hyperinsulinism on the metabolism of carbohydrates, amino acids, and lipids by the liver?
(b) What are the causes of the observed symptoms? Suggest why this condition, if prolonged, leads to brain damage.

Metabolic Differences between Muscle and Liver in a "Fight-or-Flight" Situation When an animal confronts a "fight-or-flight" situation, the release of epinephrine promotes glycogen breakdown in the liver, heart, and skeletal muscle. The end product of glycogen breakdown in the liver is glucose; the end product in skeletal muscle is pyruvate.
(a) What is the reason for the different products of glycogen breakdown in the two tissues?
(b) What is the advantage to an animal that must fight or flee these specific glycogen breakdown routes?

Water-Soluble versus Lipid-Soluble Hormones On the basis of their physical properties, hormones fall into one of two categories: those that are very soluble in water but relatively insoluble in lipids (e.g., epinephrine) and those that are relatively insoluble in water but highly soluble in lipids (e.g., steroid hormones). In their role as regulators of cellular activity, most water-soluble hormones do not enter their target cells. The lipid-soluble hormones, by contrast, do enter their target cells and ultimately act in the nucleus. What are the correlation between solubility, the location of receptors, and the mode of action of these two classes of hormones?

Peptide Hormone Activity Explain how two peptide hormones as structurally similar as oxytocin and vasopressin can have such different effects.

Calculations of $\Delta G$ at Physiological Concentrations Calculate the actual, physiological $\Delta G$ for the reaction

$$\text { Phosphocreatine }+\text { ADP } \rightarrow \text { creatine }+\text { ATP }$$

at $37^{\circ} \mathrm{C}$, as it occurs in the cytosol of neurons, with phosphocreatine at $4.7 \mathrm{mM}$, creatine at $1.0 \mathrm{mM}, \mathrm{ADP}$ at $0.73 \mathrm{mM}$, and ATP at $2.6 \mathrm{mM}$.

Why is a measure of serum lactate obtained in the initial assessment of a trauma patient?

Define physiology. Describe the relationship between physiology and anatomy.

It is wise to study anatomy alongside physiology because

A) it makes for more efficient use of students' and teachers' time

B) to understand anatomy requires a complete understanding of physiology

C) physiology is only explainable in terms of the underlying anatomy

D) anatomy and physiology are practically the same thing.

Indicate whether each statement is true or false. Valine is probably more water-soluble than arginine.

Define tissue. List the four major types of tissue. Which of these types is most widely distributed in the body?

A 100 W lightbulb is brighter than a 60 W lightbulb when both operate at the same voltage of 120 V. If, instead they were both operated at the same current of 0.5 A, which would be brighter? Explain.

How does Einstein's explanation account for each of these characteristics of the photoelectric effect? a. The photoelectric current is zero for frequencies below some threshold. b. The photoelectric current increases with increasing light intensity. c. The photoelectric current is independent of $\Delta V$ for $\Delta V \geq 1 \mathrm{V}$. d. The photoelectric current decreases slowly as $\Delta V$ becomes more negative. e. The stopping potential is independent of the light intensity. Which of these cannot be explained by classical physics? Explain.