Chapter 24
Lecture Notes
• Urinary System
• Cardiovascular system (CVS) delivers nutrients (from digestive tract) and O2 (from lungs) to cells
in peripheral tissues
• CVS carries CO2 and waste products from peripheral tissues to sites of excretion
– CO2 removed at lungs
– Most physiological waste products removed by urinary system
– Urinary System (Figure 24.1a)
• Urinary System (Figure 24.1b)
• Introduction to the Urinary System
• Functions of the kidneys
– removes waste products and converts filtrate into urine
– Formation of calcitriol
• synthesizes final enzyme in calcitriol hormone formation
– Production and release of erythropoietin
• indirectly measures oxygen level of blood
• secretes erythropoietin (EPO) in response to low blood oxygen
– stimulates red bone marrow to increase rate of erythrocyte formation
– erythrocytes transporting additional oxygen from lungs
– Introduction to the Urinary System
• Functions of the kidneys(continued)
– Regulation of ion levels and acid-base balance
• helps control blood’s inorganic ion balance
• e.g., Na+, K+, Ca2+
• aids in maintaining acid-base balance
, – alters levels of H+ and HCO3-
– Regulation of blood pressure
• alters amount of fluid lost in urine
– helps regulate blood volume
• releases renin enzyme
– required for production of angiotensin II
» hormone increasing blood pressure
• Introduction to the Urinary System
• Functions of the kidneys(continued)
– Potential to engage in gluconeogenesis
• during prolonged fasting or starvation
• produces glucose from noncarbohydrate sources
• helps maintain normal blood glucose levels
• Introduction to the Urinary System
• Blood Flow and Filtered Fluid Flow:
Filtrate, Tubular Fluid, and Urine Flow
• Definitions
– Filtrate
• Blood flowing through glomerulus
• Both water and solutes filtered from blood plasma
• Moves across wall of glomerular capillaries and into capsular space
• Forms filtrate
– Tubular fluid
• Filtrate renamed as enters proximal convoluted tubule
• Flows through PCT, nephron loop, DCT
• Enters collecting tubules to collecting ducts
, • Blood Flow and Filtered Fluid Flow:
Filtrate, Tubular Fluid, and Urine Flow
• Definitions (continued)
– Urine
• Tubular fluid renamed as leaves collecting ducts
• Enters papillary duct located within renal papilla
• Flows within renal sinus of kidney
• Flows from minor calyx, to major calyx, to renal pelvis
• Renal pelvis connecting to ureter
• Ureter connecting to urinary bladder
– stored and excreted from body through urethra
• Structures That Transport Fluids Through the Urinary System (Figure 24.9)
• Production of Filtrate Within the Renal Corpuscle: Overview of Urine Formation
• Urine formed from three processes (filtration, tubular reabsorption, tubular secretion)
– Filtration
• in glomerular capillaries
• separates some water and dissolved solutes from blood plasma
• water and solutes entering capsular space of renal corpuscle
– due to pressure differences across the filtration membrane
• separated fluid termed filtrate
• Production of Filtrate Within the Renal Corpuscle: Overview of Urine Formation
• Urine formed from three processes (continued)
– Tubular reabsorption
• movement of components within tubular fluid
• move by diffusion, osmosis, or active transport
• move from lumen of tubules and collecting ducts across walls
Lecture Notes
• Urinary System
• Cardiovascular system (CVS) delivers nutrients (from digestive tract) and O2 (from lungs) to cells
in peripheral tissues
• CVS carries CO2 and waste products from peripheral tissues to sites of excretion
– CO2 removed at lungs
– Most physiological waste products removed by urinary system
– Urinary System (Figure 24.1a)
• Urinary System (Figure 24.1b)
• Introduction to the Urinary System
• Functions of the kidneys
– removes waste products and converts filtrate into urine
– Formation of calcitriol
• synthesizes final enzyme in calcitriol hormone formation
– Production and release of erythropoietin
• indirectly measures oxygen level of blood
• secretes erythropoietin (EPO) in response to low blood oxygen
– stimulates red bone marrow to increase rate of erythrocyte formation
– erythrocytes transporting additional oxygen from lungs
– Introduction to the Urinary System
• Functions of the kidneys(continued)
– Regulation of ion levels and acid-base balance
• helps control blood’s inorganic ion balance
• e.g., Na+, K+, Ca2+
• aids in maintaining acid-base balance
, – alters levels of H+ and HCO3-
– Regulation of blood pressure
• alters amount of fluid lost in urine
– helps regulate blood volume
• releases renin enzyme
– required for production of angiotensin II
» hormone increasing blood pressure
• Introduction to the Urinary System
• Functions of the kidneys(continued)
– Potential to engage in gluconeogenesis
• during prolonged fasting or starvation
• produces glucose from noncarbohydrate sources
• helps maintain normal blood glucose levels
• Introduction to the Urinary System
• Blood Flow and Filtered Fluid Flow:
Filtrate, Tubular Fluid, and Urine Flow
• Definitions
– Filtrate
• Blood flowing through glomerulus
• Both water and solutes filtered from blood plasma
• Moves across wall of glomerular capillaries and into capsular space
• Forms filtrate
– Tubular fluid
• Filtrate renamed as enters proximal convoluted tubule
• Flows through PCT, nephron loop, DCT
• Enters collecting tubules to collecting ducts
, • Blood Flow and Filtered Fluid Flow:
Filtrate, Tubular Fluid, and Urine Flow
• Definitions (continued)
– Urine
• Tubular fluid renamed as leaves collecting ducts
• Enters papillary duct located within renal papilla
• Flows within renal sinus of kidney
• Flows from minor calyx, to major calyx, to renal pelvis
• Renal pelvis connecting to ureter
• Ureter connecting to urinary bladder
– stored and excreted from body through urethra
• Structures That Transport Fluids Through the Urinary System (Figure 24.9)
• Production of Filtrate Within the Renal Corpuscle: Overview of Urine Formation
• Urine formed from three processes (filtration, tubular reabsorption, tubular secretion)
– Filtration
• in glomerular capillaries
• separates some water and dissolved solutes from blood plasma
• water and solutes entering capsular space of renal corpuscle
– due to pressure differences across the filtration membrane
• separated fluid termed filtrate
• Production of Filtrate Within the Renal Corpuscle: Overview of Urine Formation
• Urine formed from three processes (continued)
– Tubular reabsorption
• movement of components within tubular fluid
• move by diffusion, osmosis, or active transport
• move from lumen of tubules and collecting ducts across walls
