Bile acids, which are amphipathic end products of cholesterol metabolism, are produced by hepatocytes. These acids circulate between the liver and intestine to maintain their mass, while water-insoluble metabolites like cholesterol are transported in bile as mixed micelles.

During periods between meals, bile is stored in the gallbladder where it becomes concentrated. When hormonal and neural signals simultaneously contract the gallbladder and relax the sphincter of Oddi, the bile is released.

The liver plays a crucial role in eliminating certain substances from the bloodstream that would be toxic if allowed to accumulate. These substances include bilirubin and ammonia.

Ammonia has been implicated in the pathogenesis of hepatic encephalopathy, as highlighted by Parekh and Balart in their study published in Clinical Liver Disease in 2015.

Hepatocytes are responsible for the uptake of organic anions, as discussed by Wolkoff in his paper titled "Organic Anion Uptake by Hepatocytes" published in Comprehensive Physiology in 2014.

Gut motility and enteroendocrine secretion were explored by Wu and colleagues in their paper "Gut Motility and Enteroendocrine Secretion" published in Current Opinion in Pharmacology in 2013.

Moving on to the renal system, Chapter 36 of Bruce A. Stanton and Bruce M. Koeppen's book discusses potassium, calcium, and phosphate homeostasis.

Renal function encompasses solute and water transport along the nephron, as detailed in Chapter 34.

Control of body fluid osmolality and volume is a crucial aspect of renal function, covered in Chapter 35.

The kidneys play a pivotal role in regulating acid-base balance, which is discussed in Chapter 37.

Now, let's address the questions that the completion of this chapter should enable students to answer:

1. The filtration barriers to plasma proteins in the glomerulus are the structures that need to be identified.
2. The physiological significance of the juxtaglomerular apparatus should be explained.
3. The blood vessels supplying the kidneys need to be identified.
4. The nerves that innervate the kidneys should be specified.
5. The location and gross anatomical features of the kidneys should be described.
6. The different parts of the nephron and their locations within the cortex and medulla need to be identified.
7. The major components of the glomerulus and the cell types located in each component should be discussed.
8. The concepts of mass balance and their application in measuring the glomerular filtration rate (GFR) need to be explained.
9. The reasons for using inulin clearance and creatinine clearance to measure GFR should be clarified.
10. The clinical use of plasma creatinine concentration in monitoring GFR needs to be highlighted.
11. The elements of the glomerular filtration barrier and their role in determining the amount of protein that enters Bowman's space should be discussed.
12. The Starling forces involved in the formation of the glomerular ultrafiltrate and their impact on GFR when altered should be explained.
13. The concept of autoregulation of renal blood flow and GFR, along with the responsible factors and hormones, needs to be addressed.
14. The hormones that regulate renal blood flow should be identified.
15. The reason why hormones can influence renal blood flow despite autoregulation should be explained.

E. Starling's quote from 1909 emphasizes the kidney's remarkable ability to react to stimuli in a manner that promotes the survival of the organism and suggests a certain level of intelligence within its component parts.
Kanel GC. Liver: anatomy, microscopic structure, and cell types. In: Podolsky DK, et al., eds. Yamada’s Textbook of Gastroenterology. 6th ed. Hoboken, NJ: Wiley Blackwell; 2015.
amphipathic end products of cholesterol metabolism that are produced by hepatocytes. Bile acids circulate between the liver and intestine to conserve their mass, and water-insoluble metabolites (e.g., cholesterol) are carried in bile in the form of mixed micelles.
4.
Bile is stored in the gallbladder between meals, where it is concentrated and released when hormonal and neural signals simultaneously contract the gallbladder and relax the sphincter of Oddi.
5.
The liver is critical for disposing of certain substances that would be toxic if allowed to accumulate in the bloodstream, including bilirubin and ammonia.
Parekh PJ, Balart LA. Ammonia and its role in the pathogenesis of hepatic encephalopathy. Clin Liver Dis. 2015;19:529-537.
Wolkoff AW. Organic anion uptake by hepatocytes. Compr Physiol. 2014;4:1715-1735.
Wu T, et al. Gut motility and enteroendocrine secretion. Curr Opin Pharmacol. 2013;13:928-934.
SECTION 7The Renal System BRUCE A. STANTON AND BRUCE M. KOEPPEN
Chapter 36 Potassium, Calcium, and Phosphate Homeostasis
Elements of Renal Function
Chapter 34 Solute and Water Transport Along the Nephron: Tubular Function
Chapter 35 Control of Body Fluid Osmolality and Volume
Chapter 37 Role of the Kidneys in the Regulation of Acid-Base Balance
Upon completion of this chapter the student should be able to answer the following questions: 1.
Which structures in the glomerulus are filtration barriers to plasma proteins?
2.
What is the physiological significance of the juxtaglomerular apparatus?
3.
What blood vessels supply the kidneys?
4.
What nerves innervate the kidneys?
5.
What is the location of the kidneys, and what are their gross anatomical features?
6.
What are the different parts of the nephron, and what is their locations within the cortex and medulla?
7.
What are the major components of the glomerulus, and what are the cell types located in each component?
8.
How can the concepts of mass balance be used to measure the glomerular filtration rate (GFR)?
9.
Why can inulin clearance and creatinine clearance be used to measure GFR?
10.
Why is plasma creatinine concentration used clinically to monitor GFR?
11.
What are elements of the glomerular filtration barrier, and how do they determine how much protein enters Bowman’s space?
12.
What Starling forces are involved in formation of the glomerular ultrafiltrate, and how do changes in each force affect GFR?
13.
What is autoregulation of renal blood flow and GFR, and which factors and hormones are responsible for autoregulation?
14.
Which hormones regulate renal blood flow?
15.
Why do hormones influence renal blood flow despite autoregulation?
Overview of Renal Function
The kidney presents in the highest degree the phenomenon of sensibility, the power of reacting to various stimuli in a direction, which is appropriate for the survival of the organism; a power of adaptation which almost gives one the idea that its component parts must be endowed with intelligence.
E. STARLING—1909