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Functions of the urinary system

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Functions of the urinary system. Excretion The removal of organic waste products from body fluids Elimination The discharge of waste products into the environment Homeostatic regulation of blood plasma Regulating blood volume and pressure Regulating plasma ion concentrations - PowerPoint PPT Presentation

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Page 1: Functions of the urinary system
Page 2: Functions of the urinary system

• Excretion– The removal of organic waste products from body fluids

• Elimination– The discharge of waste products into the environment

• Homeostatic regulation of blood plasma– Regulating blood volume and pressure– Regulating plasma ion concentrations– Stabilizing blood pH– Conserving nutrients

Functions of the urinary system

Page 3: Functions of the urinary system

Figure 26.1

Figure 26.1 An introduction to the Urinary System

Page 4: Functions of the urinary system

Figure 26.2 The Position of the Kidneys

Figure 26.2a, b

Page 5: Functions of the urinary system

Figure 26.3

Figure 26.3 The Urinary System in Gross Dissection

Page 6: Functions of the urinary system

• Superficial outer cortex and inner medulla– The medulla consists of 6-18 renal pyramids– The cortex is composed of roughly 1.25 million

nephrons

• Major and minor calyces along with the pelvis drain urine to the ureters

Sectional anatomy of the kidneys

Page 7: Functions of the urinary system

Figure 26.4a, b

Figure 26.4 The Structure of the Kidney

Page 8: Functions of the urinary system

Figure 26.5 The Blood Supply to the Kidneys

Figure 26.5c, d

Page 9: Functions of the urinary system

Figure 26.5 The Blood Supply to the Kidneys

Figure 26.5a, b

Page 10: Functions of the urinary system

Figure 26.6 A Representative Nephron

Figure 26.6

Page 11: Functions of the urinary system

• Production of filtrate

• Reabsorption of organic nutrients

• Reabsorption of water and ions

• Secretion of waste products into tubular fluid

Nephron functions include:

Page 12: Functions of the urinary system

• Cortical nephrons– ~85% of all nephrons– Located in the cortex

• Juxtamedullary nephrons– Closer to renal medulla– Loops of Henle extend deep into renal pyramids

Two types of nephron

Page 13: Functions of the urinary system

Figure 26.7a

Figure 26.7 Cortical and Juxtamedullary Nephrons

Page 14: Functions of the urinary system

Figure 26.7b, c

Figure 26.7 Cortical and Juxtamedullary Nephrons

Page 15: Functions of the urinary system

Figure 26.8 The Renal Corpuscle

Figure 26.8a, b

Page 16: Functions of the urinary system

Figure 26.8 The Renal Corpuscle

Figure 26.8c, d

Page 17: Functions of the urinary system

• Proximal convoluted tubule (PCT)– Actively reabsorbs nutrients, plasma proteins

and ions from filtrate– Released into peritubular fluid

• Loop of Henle– Descending limb– Ascending limb– Each limb has a thick and thin section

Functional anatomy of the nephron

Animation: Urinary System AnatomyPLAY

Page 18: Functions of the urinary system

• Distal convoluted tubule (DCT)– Actively secretes ions, toxins, drugs– Reabsorbs sodium ions from tubular fluid

Functional anatomy of the nephron

Animation: Urinary System Dissection and FlythroughPLAY

Page 19: Functions of the urinary system

SECTION 26-3 Principles of Renal Physiology

Page 20: Functions of the urinary system

• Regulating blood volume and composition

• Excreting waste products– Urea– Creatinine– Uric acid

Urine production maintains homeostasis

Page 21: Functions of the urinary system

• Filtration– Blood pressure – Water and solutes across glomerular capillaries

• Reabsorption– The removal of water and solutes from the

filtrate

• Secretion– Transport of solutes from the peritubular fluid

into the tubular fluid

Basic processes of urine formation

Page 22: Functions of the urinary system

• Filtration in the kidneys modified by carrier mediated transport– Facilitated diffusion– Active transport– Cotransport– Countertransport

• Carrier proteins have a transport maximum (Tm)

– Determines renal threshold

Carrier Mediated Transport

Page 23: Functions of the urinary system

• Accomplished via diffusion, osmosis, and carrier-mediated transport

• Tm determines renal threshold for reabsorption of substances in tubular fluid

Reabsorption and secretion

Page 24: Functions of the urinary system

Figure 26.9 An Overview of Urine Formation

Figure 26.9

Page 25: Functions of the urinary system

Figure 26.10 Glomerular Filtration

Figure 26.10

Page 26: Functions of the urinary system

Figure 26.10 Glomerular Filtration

Figure 26.10a, b

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• Amount of filtrate produced in the kidneys each minute

• Factors that alter filtration pressure change GFR

Glomerular filtration rate (GFR)

Page 28: Functions of the urinary system

• A drop in filtration pressure stimulates Juxtaglomerular apparatus (JGA)– Releases renin and erythropoietin

Factors controlling the GFR

Page 29: Functions of the urinary system

Figure 26.11a

Figure 26.11 The Response to a Reduction in the GFR

Page 30: Functions of the urinary system

Figure 26.11b

Figure 26.11 The Response to a Reduction in the GFR

Page 31: Functions of the urinary system

• Produces powerful vasoconstriction of afferent arterioles– Decreases GFR and slows production of filtrate

• Changes the regional pattern of blood flow– Alters GFR

• Stimulates release of renin by JGA

Sympathetic activation

Page 32: Functions of the urinary system

• Glomerular filtration produces fluid similar to plasma without proteins

• The PCT reabsorbs 60-70% of the filtrate produced – Reabsorption of most organic nutrients– Active and passive reabsorption of sodium and

other ions– Reabsorption of water

• Secretion also occurs in the PCT

Reabsorption and secretion at the PCT

Animation: Early Filtrate ProcessingPLAY

Animation: Glomerular filtrationPLAY

Page 33: Functions of the urinary system

Figure 26.12 Transport Activities at the PCT

Animation: Proximal Convoluted TubulePLAY

Figure 26.12

Page 34: Functions of the urinary system

The loop of Henle and countercurrent multiplication

• Countercurrent multiplication – Between ascending and descending limbs of

loop– Creates osmotic gradient in medulla– Facilitates reabsorption of water and solutes

before the DCT – Permits passive reabsorption of water from

tubular fluid

Page 35: Functions of the urinary system

Figure 26.13a

Figure 26.13 Countercurrent Multiplication and Concentration

of Urine

Page 36: Functions of the urinary system

Figure 26.13b

Figure 26.13 Countercurrent Multiplication and Concentration

of Urine

Page 37: Functions of the urinary system

Figure 26.13c

Figure 26.13 Countercurrent Multiplication and Concentration

of Urine

Page 38: Functions of the urinary system

• DCT performs final adjustment of urine– Active secretion or absorption

• Absorption – Tubular cells actively resorb Na+ and Cl-

– In exchange for potassium or hydrogen ions (secreted)

Reabsorption and secretion at the DCT

Page 39: Functions of the urinary system

Figure 26.14

Figure 26.14 Tubular Secretion and Solute Reabsorption at the

DCT

Animation: Distal Convoluted TubulePLAY

Page 40: Functions of the urinary system

Figure 26.14c

Figure 26.14 Tubular Secretion and Solute Reabsorption at the

DCT

Page 41: Functions of the urinary system

Reabsorption and secretion along the collecting system

• Water and solute loss is regulated by aldosterone and ADH

• Reabsorption– Sodium ion, bicarbonate, and urea are resorbed

• Secretion – pH is controlled by secretion of hydrogen or

bicarbonate ions

Page 42: Functions of the urinary system

Control of urine volume and osmotic concentration

• Urine volume and osmotic concentration are regulated by controlling water reabsorption– Precise control allowed via facultative water

reabsorption

Page 43: Functions of the urinary system

Figure 26.15

Figure 26.15 The Effects of ADH on the DCT and Collecting Ducts

Page 44: Functions of the urinary system

Figure 26.15a, b

Figure 26.15 The Effects of ADH on the DCT and Collecting Ducts

Page 45: Functions of the urinary system

• Removes solutes and water – Balances solute reabsorption and osmosis in the

medulla

Function of the vasa recta

Page 46: Functions of the urinary system

Figure 26.16 A Summary of Renal Function

Figure 26.16a