CHAPTER OUTLINE
■ GROSS ANATOMY OF THE KIDNEYS AND URINARY BLADDER
■ THE NEPHRON
Nephron Components
■ FORMATION OF URINE
Distribution of Blood at the Glomerulus
■ GLOMERULAR FILTRATION
Dynamics of Filtration
Filtration Factors
Autoregulation
■ TUBULAR REABSORPTION AND SECRETION
Reabsorption of Na+, Cl-, Glucose,,and Amino Acids
Reabsorption of Water and Urea
Secretion of H+, K+, NH3, and Organic Molecules
Transport Maximum
■ COUNTERCURRENT MECHANISM
Countercurrent Multiplier System
Countercurrent Exchanger System
Role of Urea
■ CONCENTRATION OF URINE
Antidiuretic Hormone and Osmoregulation
Concentration Failure
■ EXTRACELLULAR FLUID VOLUME REGULATION
■ ALDOSTERONE
■ OTHER HORMONES WITH KIDNEY ASSOCIATION
Parathyroid Hormone
Erythropoietin
Prostaglandins
■ MICTURITION
Transfer of Urine to the Urinary Bladder
Micturition Reflexes
Descriptive Terms
■ CHARACTERISTICS OF MAMMALIAN URINE
■ RENAL CLEARANCE
Creatinine Clearance Application
■ MAINTENANCE OF ACID-BASE BALANCE
Acids and Bases
Relationship of pH to H+ Concentration
Chemical Buffer Systems
Mechanism of H+ Secretion by the Kidneys Role of Respiratory System
■ AVIAN URINARY SYSTEM
Anatomic Features
Renal Portal System
Uric Acid Formation and Excretion
Concentration of Avian Urine Modification of Ureteral Urine Urine Characteristics and Flow
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The kidneys are usually thought to have the excretion of metabolic waste products as their only function. Another function, which is at least equally important, is the regulation of the volume and composition of the body’s internal environment, the extracellular fluid (ECF).
It has been said that the composition of the body fluids is determined not by what the mouth takes in but by what the kidneys keep. Both functions - excretion of metabolic waste products and regulation of volume and composition of ECF - are performed by the kidneys because of their perfusion with blood, resulting in the formation of urine, a fluid of varying composition.
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