Learning objectives
Upon completion of this chapter, you should be able to:
1.
Review the anatomy of the kidney, including the structure of the nephron.
2.
Explain the basic processes of the kidney and where these processes occur.
3.
Explain the control of calcium, sodium, potassium and chloride in the nephron.
4.
Discuss the countercurrent mechanism and the control of urine concentration and dilution, applying these
effects to various clinical scenarios.
5.
Describe the renin–angiotensin–aldosterone system, including controls and clinical situations where this
system is active.
6.
Discuss the roles of the kidney in acid–base balance, calcium regulation and red blood cell production,
integrating this information to explain the clinical manifestations of renal failure.
Test your current knowledge of the kidneys and urinary tract with a PrepU Practice Quiz!
Glossary of key terms
aldosterone:
hormone produced by the adrenal gland that causes the distal tubule to retain sodium, and therefore water, while losing
potassium into the urine
antidiuretic hormone (ADH):
hormone produced by the hypothalamus and stored in the posterior pituitary gland; important in
maintaining fluid balance; causes the distal tubules and collecting ducts of the kidney to become permeable to water, leading to an
antidiuretic effect and fluid retention
carbonic anhydrase:
a catalyst that speeds up the chemical reaction combining water and carbon dioxide, which react to form
carbonic acid and immediately dissociate to form sodium bicarbonate
countercurrent mechanism:
process used by medullary nephrons to concentrate or dilute the urine in response to body stimuli to
maintain fluid and electrolyte balance
filtration:
passage of fluid and small components of the blood through the glomerulus into the nephron tubule
glomerulus:
the tuft of blood vessel between the afferent and efferent arterioles in the nephron; the fenestrated membrane of the
glomerulus allows filtration of fluid from the blood into the nephron tubule
nephron:
functional unit of the kidney, composed of Bowman’s capsule, the proximal and distal convoluted tubules and the collecting
duct prostate gland: gland located around the male urethra; responsible for producing an acidic fluid that maintains sperm and
lubricates the urinary tract
reabsorption:
the movement of substances from the renal tubule back into the vascular system
renin–angiotensin–aldosterone system:
compensatory process that leads to increased blood pressure and blood volume to ensure
perfusion of the kidneys; important in the continual regulation of blood pressure
secretion:
the active movement of substances from the blood into the renal tubule
Introduction to the kidneys
and the urinary tract
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