Chapter 15 - The Urinary System
Kidneys dispose of waste products in urine
Nitrogenous wastes
Toxins
Drugs
Excess ions
Kidneys’ regulatory functions include:
Production of renin to maintain blood pressure
Production of erythropoietin to stimulate red blood cell production
Conversion of vitamin D to its active form
Organs of the Urinary System
Kidneys
Location and structure · The kidneys are situated against the dorsal body wall in a retroperitone
Ureters
Slender tubes 25–30 cm (10–12 inches) attaching the kidney to the urinary bladder · Continuo
Urinary Bladder
Smooth, collapsible, muscular sac situated posterior to the pubic symphysis · Stores urine tem
1
, Urethra
Thin-walled tube that carries urine from the urinary bladder to the outside of the body by perist
Fluid, Electrolyte, and Acid-Base Balance
Blood composition depends on three factors
Diet
Cellular metabolism
Urine output
Kidneys have four roles in maintaining blood composition
2
, Excreting nitrogen-containing wastes (Urea, uric acid, ammonia,...)
Maintaining water balance of the blood
Maintaining electrolyte balance of the blood
Ensuring proper blood pH
Maintaining Water Balance of the Blood
Normal amount of water in the human body
Young adult females = 50%
Young adult males = 60%
Babies = 75%
The elderly = 45%
Water is necessary for many body functions, and levels must be maintained
Water occupies three main fluid compartments
Intracellular fluid (ICF)
Fluid inside cells
Accounts for two-thirds of body fluid
Extracellular fluid (ECF)
Fluids outside cells; includes blood plasma, interstitial fluid (IF), lymph, and transcellular
fluid
Plasma (blood) is ECF, but accounts for 3L of total body water
Links external and internal environments
3
Kidneys dispose of waste products in urine
Nitrogenous wastes
Toxins
Drugs
Excess ions
Kidneys’ regulatory functions include:
Production of renin to maintain blood pressure
Production of erythropoietin to stimulate red blood cell production
Conversion of vitamin D to its active form
Organs of the Urinary System
Kidneys
Location and structure · The kidneys are situated against the dorsal body wall in a retroperitone
Ureters
Slender tubes 25–30 cm (10–12 inches) attaching the kidney to the urinary bladder · Continuo
Urinary Bladder
Smooth, collapsible, muscular sac situated posterior to the pubic symphysis · Stores urine tem
1
, Urethra
Thin-walled tube that carries urine from the urinary bladder to the outside of the body by perist
Fluid, Electrolyte, and Acid-Base Balance
Blood composition depends on three factors
Diet
Cellular metabolism
Urine output
Kidneys have four roles in maintaining blood composition
2
, Excreting nitrogen-containing wastes (Urea, uric acid, ammonia,...)
Maintaining water balance of the blood
Maintaining electrolyte balance of the blood
Ensuring proper blood pH
Maintaining Water Balance of the Blood
Normal amount of water in the human body
Young adult females = 50%
Young adult males = 60%
Babies = 75%
The elderly = 45%
Water is necessary for many body functions, and levels must be maintained
Water occupies three main fluid compartments
Intracellular fluid (ICF)
Fluid inside cells
Accounts for two-thirds of body fluid
Extracellular fluid (ECF)
Fluids outside cells; includes blood plasma, interstitial fluid (IF), lymph, and transcellular
fluid
Plasma (blood) is ECF, but accounts for 3L of total body water
Links external and internal environments
3
