1. Slides 1 to 91
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

2. Urinary System Organization
Functions of the Urinary System
Eliminate organic wastes
Regulate plasma ion levels
Regulate blood volume and blood pressure
Adjust water loss
Release cardiovascular hormones
Stabilize blood pH
Conserve nutrients
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

3. Urinary System Organization
Components of the Urinary System
Kidneys
Produce urine, a fluid made of water, ions, soluble compounds
Ureters
Urinary bladder
Urethra
During urination, conducts urine out of the body
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

4. Urinary System Organization
The Components of the Urinary System
Figure 18-1

5. The Kidneys Anatomy of the Kidney Kidneys are retroperitoneal
Left kidney superior to right
Fibrous capsule surrounds the kidney
Renal artery and renal nerve enter at hilum
Renal vein and ureter exit at hilum
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

6. An Overview of Kidney Anatomy
The Kidneys
An Overview of Kidney Anatomy
Figure 18-2a

7. An Overview of Kidney Anatomy
The Kidneys
An Overview of Kidney Anatomy
Figure 18-2(b)

8. The Kidneys Internal Anatomy of the Kidney Nephrons Renal pelvis
Urine produced by nephrons
About a million nephrons per kidney
Renal pelvis
Urine collects here from calyces
Input from two major calyces
Each major calyx is fed by four to five minor calyces
Urine leaves pelvis to ureter
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

9. The Kidneys
The Structure of the Kidney
Figure 18-3(a)

10. The Kidneys
The Structure of the Kidney
Figure 18-3(b)

11. The Structure of the Kidney
The Kidneys
The Structure of the Kidney
Figure 18-3(c)

12. The Kidneys Kidney Blood Supply Renal artery Interlobar arteries
Arcuate arteries
Interlobular arteries
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

13. The Kidneys Kidney Blood Supply Nephron level Afferent arteriole
Branch of interlobular artery
Glomerulus
Efferent arteriole
Peritubular capillaries
Vasa recta
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

14. The Blood Supply to the Kidneys
Figure 18-4(a)

15. The Blood Supply to the Kidneys
Figure 18-4(b)

16. The Blood Supply to the Kidneys
Figure 18-4(c)

17. The Kidneys
The Blood Supply to the Kidneys
Figure 18-4(d)

18. The Kidneys The Nephron Basic functional unit of the kidney
Two parts to the nephron
Renal corpuscle
Renal tubule
Feeds into collecting system
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

19. The Kidneys Pathway of Urine through the Nephron
First, filtered in the renal corpuscle
Urine begins as filtrate
Next, filtrate flows into renal tubule
First, into the proximal convoluted tubule (PCT)
Next, the loop of Henle
Finally, the distal convoluted tubule (DCT)
Last, exits to collecting duct
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

20. A Representative Nephron and the Collecting System
The Kidneys
A Representative Nephron and the Collecting System
Figure 18-5

21. The Kidneys
Key Note
The kidneys remove waste products from the blood; they also assist in the regulation of blood volume and blood pressure, ion levels, and blood pH. Nephrons are the primary functional units of the kidneys.
PLAY
Kidney Function: Urinary System Structure
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

22. The Kidneys Functions of the Nephron Production of filtrate
Glomerulus
Reabsorption of nutrients
PCT
Reabsorption of water and ions
DCT, collecting duct
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

23. The Kidneys Parts of the Renal Corpuscle Glomerulus Bowman’s capsule
Knot of interconnected capillaries with a spherical shape
Bowman’s capsule
Encloses glomerulus with squamous epithelium
Afferent arteriole
Blood supply to glomerulus
Efferent arteriole
Blood drainage from glomerulus
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

24. The Kidneys
The Renal Corpuscle
Figure 18-6(a)

25. The Kidneys
The Renal Corpuscle
Figure 18-6(b)

26. The Kidneys Glomerulus Anatomy
Glomerular capillaries covered by podocytes
Narrow slits separate foot processes of podocytes
Capsular space surrounds glomerulus
Filtrate accumulates here
Bounded by Bowman’s capsule
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

27. The Kidneys Proximal Convoluted Tubule
Reabsorbs critical substances from filtrate
Nutrients (e.g., glucose, amino acids)
Ions
Proteins
Releases them into surrounding interstitial fluid
Enter peritubular capillaries and return to blood stream
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

28. The Kidneys Loop of Henle Descending limb Ascending limb
Permeable to water
Ascending limb
Impermeable to water and solutes
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

29. The Kidneys Distal Convoluted Tubule (DCT) Transport activities
Actively secretes substances into urine
Actively reabsorbs sodium from urine
Juxtaglomerular apparatus
Releases renin, erythropoietin
Located at start of DCT
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

30. The Kidneys Collecting Ducts Receive urine from nephrons
Merge into papillary ducts
Delivers urine to minor calyx
Adjust final osmotic pressure of urine
By reabsorbing water
By transporting ions
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

31. Principles of Urine Production
Primary Purpose of Urine Production
Excretion of dissolved solutes
Metabolic wastes
Urea
Creatinine
Uric acid
Excess ions
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

32. Principles of Urine Production
Processes in Urine Formation
Filtration
Reabsorption
Secretion
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

33. Principles of Urine Production
Filtration at the Glomerulus
Blood pressure forces fluid and dissolved substances across the endothelial wall of glomerular capillaries into the capsular space
Glomerular filtration rate (GFR) depends on blood pressure
Any change in blood pressure affects filtration
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

34. Principles of Urine Production
Renin Release
Decline in filtration pressure (blood pressure) triggers renin release
Released by juxtaglomerular apparatus
Renin leads to increased blood volume and blood pressure
GFR returns toward normal
Restores homeostasis
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

35. Principles of Urine Production
Key Note
Roughly 180 liters of filtrate is produced at the glomeruli each day. That represents 70 times the total plasma volume. Almost all of that fluid volume must be reabsorbed to avoid fatal dehydration.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

36. Principles of Urine Production
Tubular Reabsorption/Secretion
PCT reabsorbs 60–70% of filtrate
Nutrients
Sodium, other ions
Water
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

37. Principles of Urine Production
Tubular Reabsorption/Secretion (cont’d)
Releases them into venous drainage for return to the blood stream
Also, PCT secretes substances into tubular fluid
PLAY
Kidney Function: Urine Formation
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

38. Principles of Urine Production
Tubular Reabsorption/Secretion (cont’d)
Loop of Henle
Reclaims water, ions from filtrate
Ascending limb pumps out sodium and chloride ions
Descending limb absorbs water
Interstitial osmotic pressure pulls water from tubular fluid
Urea concentration rises as fluid is lost
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

39. Principles of Urine Production
Tubular Reabsorption/Secretion (cont’d)
Distal Convoluted Tubule (DCT)
Performs final adjustment
Secretes or reabsorbs ions
Reabsorbs sodium in exchange for secreted potassium and hydrogen ions
Aldosterone increases sodium reabsorption and potassium loss
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

40. Principles of Urine Production
Control by Antidiuretic Hormone (ADH)
Regulates water loss
DCT, collecting tubule, collecting duct made permeable to water by ADH
Water then exits to interstitial fluid and remains in the body
Urine becomes concentrated (low in water, high in solute)
The higher the ADH level, the more concentrated the urine
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

41. Principles of Urine Production
The Effects of ADH on the DCT and Collecting Duct
Figure 18-7(a)

42. Principles of Urine Production
The Effects of ADH on the DCT and Collecting Duct
Figure 18-7(b)

43. Principles of Urine Production
Water Balance in the Kidney
More than 99% of water is reabsorbed from the filtrate by the renal tubules
Water content of normal urine ranges from 93% to 97%
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

44. Principles of Urine Production

45. Principles of Urine Production
A Summary of Kidney Function and Urine Formation
Figure 18-8

46. Principles of Urine Production
Key Note
Reabsorption depends on diffusion, osmosis, and active transport. The mechanism of water reabsorption is “water follows salt.” Many of these processes are regulated by local or hormonal mechanisms. Secretion is a selective, carrier-mediated process.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

47. Principles of Urine Production
Vascular Control of Kidney Function
Automatic regulation of filtration pressure by changes in diameter of afferent and efferent arterioles
Autonomic regulation by sympathetic activation
Powerful vasoconstriction of afferent arterioles
Decreases GFR
Also, redirects blood flow to other organs
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

48. Principles of Urine Production
Hormonal Control of Kidney Function
Angiotensin II
Aldosterone
ADH
Atrial natriuretic peptide (ANP)
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

49. Principles of Urine Production
Roles of the Renin-Angiotensin System in the Regulation of GFR
Figure 18-9

50. Transport, Storage, & Excretion
Transport and Storage of Urine
Urine modification ends when fluid enters the renal pelvis
Ureters, urinary bladder, urethra specialized for transport, storage, and excretion of urine
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

51. Transport, Storage, & Excretion
Ureters
Ureters extend from renal pelvis to urinary bladder
Smooth muscle in walls contract peristaltically
Push urine toward bladder
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

52. Transport, Storage, & Excretion
Urinary Bladder
Distensible muscular sac for urine storage
Internal features include
Trigone
Neck
Internal urethral sphincter
Detrussor muscle
Contraction forces urine into urethra
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

53. Transport, Storage, & Excretion
Organs for the Conduction and Storage of Urine
Figure 18-10(a)

54. Transport, Storage, & Excretion
Organs for the Conduction and Storage of Urine
Figure 18-10(b)

55. Transport, Storage, & Excretion
Organs for the Conduction and Storage of Urine
Figure 18-10(c)

56. Transport, Storage, & Excretion
The Urethra
Longer in males than females
External urethral sphincter formed by a circular band of skeletal muscle of pelvic floor
Under voluntary control
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

57. Transport, Storage, & Excretion
Micturition Reflex and Urination
Urination coordinated by micturition reflex
Initiated by stretch receptors in the bladder wall
Voluntary urination couples reflex with relaxation of external urinary sphincter
Permits internal urinary sphincter to open
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

58. Transport, Storage, & Excretion
The Micturition Reflex
Figure 18-11

59. Fluid, Electrolyte, & Acid-Base
Homeostasis of Fluids
Maintenance of normal volume and composition is crucial to life
Three types of homestasis required
Fluid balance
Electrolyte balance
Acid-base balance
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

60. Fluid, Electrolyte, & Acid-Base
Fluid and Electrolyte Balance
Two fluid “compartments”
Intracellular fluid (ICF)
About 60% of total body water
Extracellular fluid (ECF)
About 40% of total body water
Water moves freely within the ECF
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

61. Fluid, Electrolyte, & Acid-Base
Body Fluid Compartments
Figure 18-12

62. Fluid, Electrolyte, & Acid-Base
Ions in Body Fluids
Figure 18-13

63. Fluid, Electrolyte, & Acid-Base

64. Fluid, Electrolyte, & Acid-Base
Water Balance
Water intake normally equals water loss
Water is gained from
Eating
Drinking
Aerobic metabolism
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

65. Fluid, Electrolyte, & Acid-Base
Fluid Shift—Water movement between the ECF and the ICF
Water moves to establish osmotic equilibrium
Hypertonic ECF pulls water out of cells
Hypotonic ECF push water into cells
Causes cellular swelling
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

66. Fluid, Electrolyte, & Acid-Base
Electrolyte Balance
Total electrolyte concentration affects water balance
Individual concentrations affect a range of cellular functions
Problems commonly result from a mismatch of sodium ion gain/loss
Potassium ion imbalance can be dangerous or deadly
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

67. Fluid, Electrolyte, & Acid-Base
Sodium Ion Balance
Sodium uptake from the gut parallels dietary intake
Sodium loss occurs mainly in urine and sweat
Sodium reabsorption along DCT stimulated by aldosterone
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

68. Fluid, Electrolyte, & Acid-Base
Potassium Ion Balance
Concentration of K+ in ECF normally very low
Urinary excretion increases when sodium levels are low or when potassium levels are high
Aldosterone stimulates potassium ion excretion
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

69. Fluid, Electrolyte, & Acid-Base
Key Note
Fluid balance and electrolyte balance are interrelated. The impact of water gains or losses is reduced by fluid shifts between the ECF and ICF and by hormonal control of intake and excretion. Electrolyte gains or losses are opposed by fluid shifts, adjustments in ion absorption and secretion, and to water gain and loss.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

70. Fluid, Electrolyte, & Acid-Base
Acid-Base Balance
Normal pH of body fluids range from pH 7.35 to pH 7.45
pH > 7.45 is alkalosis (too alkaline)
pH < 7.35 is acidosis (too acidic)
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

71. Fluid, Electrolyte, & Acid-Base
Carbonic Acid and pH
Carbonic acid most important factor on pH
CO2 reacts with H2O to form carbonic acid
Carbonic acid releases H+ when it dissociates
As CO2 levels go up, pH goes down
As CO2 levels go down, pH goes up
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

72. Fluid, Electrolyte, & Acid-Base
The Basic Relationship Between Carbon Dioxide and Plasma pH
Figure 18-14

73. Fluid, Electrolyte, & Acid-Base
Metabolic Acids
Acids produced by metabolism
Lactic acid
Produced by glycolysis
Ketone bodies
Produced in starvation (dieting), diabetes
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

74. Fluid, Electrolyte, & Acid-Base
Buffer Systems
Resist changes in pH
Consist of a weak acid and it anion dissociation product
Three major buffer systems in the body
Protein buffer system (in ECF and ICF)
Carbonic acid-bicarbonate buffer system (in ECF)
Phosphate buffer system (in ICF)
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

75. Fluid, Electrolyte, & Acid-Base
Protein Buffer Systems
Amino acid subunits respond to H+ changes
Important proteins for buffering
Plasma proteins
Hemoglobin within RBCs
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

76. Fluid, Electrolyte, & Acid-Base
Carbonic Acid-Bicarbonate Buffer System
Resists pH changes in ECF caused by metabolic (organic) acids
Phosphate Buffer System
Resists pH changes within cells
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

77. Fluid, Electrolyte, & Acid-Base
Compensations for pH Disturbances
Respiratory compensation—Changes in ventilation lead to changes in pH by raising or lowering CO2 levels
Renal compensation—Kidney varies H+ secretion and bicarbonate reabsorption depending on pH of ECF
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

78. Fluid, Electrolyte, & Acid-Base
Two Classes of Acid-Base Disorders
Respiratory acid-base disorder—Caused by abnormal respiratory function leading to large changes in CO2 levels
Metabolic acid-base disorder—Caused by formation of organic acids or conditions which disturb the level of bicarbonate ion such as diarrhea or vomiting
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

79. Fluid, Electrolyte, & Acid-Base
Key Note
The most common and acute acid-base disorder is respiratory acidosis, which develops when respiratory activity cannot keep pace with the rate of carbon dioxide generation in peripheral tissues.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

80. Aging and the Urinary System
Age-Related Changes in Urinary System
Loss of functional nephrons
Reduced GFR
Reduced response to ADH
Urinary retention in men with prostate enlargement
Drop in body water and mineral content
Disorders of fluid, electrolyte, or acid-base balance
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

81. The Urinary System in Perspective
FIGURE Functional Relationships Between the Urinary System and Other Systems
Figure 18-15
1 of 11
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

82. The Integumentary System
Sweat glands assist in elimination of water and solutes, especially sodium and chloride ions; keratinized epidermis prevents excessive fluid loss through skin surface; epidermis produces vitamin D3, important for the renal production of calcitriol
Figure 18-15
2 of 11
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

83. The Skeletal System
Axial skeleton provides some protection for kidneys and ureters; pelvis protects urinary bladder and proximal portion of urethra
Conserves calcium and phosphate needed for bone growth
Figure 18-15
3 of 11
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

84. The Muscular System
Sphincter controls urination by closing urethral opening; muscle layers of trunk provide some protection for urinary organs
Removes waste products of protein metabolism; assists in regulation of calcium and phosphate concentrations
Figure 18-15
4 of 11
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

85. The Nervous System
Adjusts renal blood pressure; monitors distension of urinary bladder and controls urination
Figure 18-15
5 of 11
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

86. The Endocrine System
Aldosterone and ADH adjust rates of fluid and electrolyte reabsorption in kidneys
Kidney cells release renin when local blood pressure declines and erythropoietin (EPO) when renal oxygen levels decline
Figure 18-15
6 of 11
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

87. The Cardiovascular System
Delivers blood to capillaries, where filtration occurs; accepts fluids and solutes reabsorbed during urine production
Releases renin to elevate blood pressure and erythropoietin to accelerate red blood cell production
Figure 18-15
7 of 11
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

88. The Lymphatic System
Provides specific defenses against urinary tract infections
Eliminates toxins and wastes generated by cellular activities; acid pH of urine provides nonspecific defense against urinary tract infections
Figure 18-15
8 of 11
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

89. The Respiratory System
Assists in the regulation of pH by eliminating carbon dioxide
Assists in the elimination of carbon dioxide; provides bicarbonate buffers that assist in pH regulation
Figure 18-15
9 of 11
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

90. The Digestive System
Absorbs water needed to excrete wastes at kidneys; absorbs ions needed to maintain normal body fluid concentrations; liver removes bilirubin
Excretes toxins absorbed by the digestive epithelium; excretes bilirubin and nitrogenous wastes produced by the liver; calcitrol production by kidneys aids calcium and phosphate absorption along digestive tract
Figure 18-15
10 of 11
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

91. The Reproductive System
Accessory organ secretions may have antibacterial action that helps prevent urethral infections in males
Urethra in males carries semen to the exterior
Figure 18-15
11 of 11
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings