Urinary System

1
Chapter 21

• Urinary System

2
Overview

• Function
• Structures
• Nephron unit
• Urine formation
• Urine composition
• Plumbing

3

• Excretion
• Body systems work interdependently to maintain
• homeostasis by excretion
• Urinary
• Digestive
• Respiratory
• Integumentary

4
Checkpoint 21-1 The main function of the urinary
system is to eliminate waste. What are some other
systems that eliminate waste?
5
Kidneys
6
Male urinary system, showing blood
vessels.   Zooming In u What vessel supplies
blood to the kidney? What vessel drains the
kidney?
7
Checkpoint 21-2 What are the organs of the
urinary system?
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• The Kidneys
• Membranous renal capsule of fibrous connective
  tissue
• Adipose capsule of fat
• Fascia anchors kidney to peritoneum and abdominal
  wall
• Retroperitoneal space

9

• Blood Supply to the Kidney
• Renal artery supplies blood
• Nephrons are functional units
• Renal vein drains blood

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Checkpoint 21-3 The kidneys are located in the
retroperitoneal space. Where is this
space? Checkpoint 21-4 What vessel supplies
blood to the kidney and what vessel drains blood
from the kidney?
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• Structure of the Kidney
• Hilum
• Renal cortex (outer portion)
• Renal medulla (inner portion)
• Renal pyramids
• Renal pelvis
• Calyces

12
Longitudinal section through the kidney. Its
internal structure is shown (left), along with an
enlarged diagram of nephrons (right). Each kidney
contains more than 1 million nephrons.   Zooming
In u What is the outer region of the kidney
called? What is the inner region of the kidney
called?
13
Checkpoint 21-5 What are the outer and inner
regions of the kidney called?
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• The Nephron
• Functional kidney unit
• Glomerular (Bowman) capsule
• Glomerulus
• Afferent arteriole
• Peritubular capillaries
• Proximal convoluted tubule (PCT)
• Loop of Henle
• Descending limb
• Ascending limb
• Distal convoluted tube (DCT)
• Collecting duct

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A nephron and its blood supply. The nephron
regulates the proportions of water, waste, and
other materials according to the bodys
constantly changing needs. Materials that enter
the nephron can be returned to the blood through
the surrounding capillaries.   Zooming In u Which
of the two convoluted tubules is closer to the
glomerular capsule? Which convoluted tubule is
farther away?
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Checkpoint 21-6 What is the functional unit of
the kidney called? Checkpoint 21-7 What name
is given to the coil of capillaries in the
glomerular (Bowman) capsule?
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• The Juxtaglomerular (JG) Apparatus
• Specialized cells that regulate kidney function
• Triggered by low blood pressure
• Secretes renin enzyme

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Structure of the juxtaglomerular (JG) apparatus.
Note how the distal convoluted tubule contacts
the afferent arteriole (right). Cells in these
two structures make up the JG apparatus.   Zooming
In u The JG apparatus is made up of cells from
which two structures?
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• Functions of the Kidney
• Excretion
• Urea
• Water balance maintenance
• Body fluid acidbase regulation
• Blood pressure regulation
• Angiotensin
• Aldosterone
• Red blood cell production regulation

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Checkpoint 21-8 What substance is produced by
the JG apparatus and under what conditions is it
produced?
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• Formation of Urine
• Glomerular filtration
• Glomerular filtrate
• Tubular reabsorption
• Diffusion
• Osmosis
• Active transport
• Tubular secretion
• Countercurrent mechanism
• Concentration of urine
• Antidiuretic hormone (ADH)

22
Checkpoint 21-9 The first step in urine
formation is glomerular filtration. What is
glomerular filtration?
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Summary of urine formation in a nephron.
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Checkpoint 21-10 What are the four processes
involved in the formation of urine?
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• The Ureters
• Long, slender, muscular tubes
• Epithelial cell lining
• Involuntary muscle layer
• Fibrous connective tissue coat
• Entirely extraperitoneal
• Extend from kidney to urinary bladder
• Move urine by gravity and peristalsis

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• The Urinary Bladder
• Temporary reservoir for urine
• Multiple layers
• Mucous membrane
• Transitional epithelium
• Rugae
• Connective tissue
• Three-layered coat of involuntary muscle tissue
• Incomplete coat of peritoneum
• Trigone

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• The Urethra
• Tube that extends from the bladder to the outside
• Male
• Part of both reproductive and urinary systems
• Female
• Entirely separate from reproductive system

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• Urination
• Process of expelling urine from bladder
  (micturition)
• Involuntary control
• Internal urethral sphincter
• Voluntary control
• External urethral sphincter

29
Checkpoint 21-11 What is the name of the tube
that carries urine from the kidney to the
bladder? Checkpoint 21-12 What is the name of
the tube that carries urine from the bladder to
the outside?
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• The Urine
• 95 water, 5 dissolved solids and gases
• pH averages 6.0
• Specific gravity measures amount of dissolved
  substances
• Normal range 1.002 to 1.040

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• Normal Constituents
• Dissolved solids normally found in urine
• Nitrogenous waste products
• Urea
• Uric acid
• Creatinine
• Electrolytes
• Sodium chloride
• Sulfates
• Phosphates
• Pigment

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• Abnormal Constituents
• Urinalysis is evaluation of urine
• Glucose
• Glycosuria
• Albumin
• Albuminuria
• Blood
• Hematuria
• Ketones
• Diabetes mellitus and starvation
• White blood cells
• Pyuria
• Casts
• Nephron disease

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Disorders of the Urinary System Portion of
urinary system most prone to disorders is kidney
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• Kidney Disorders
• Kidney disorders may be acute or chronic
• Acute glomerulonephritis
• Most common kidney disease
• Pyelonephritis
• Hydronephrosis
• Polycystic kidney
• Tumors
• Kidney stones (calculi)
• Renal failure

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Checkpoint 21-13 What is the difference between
acute and chronic kidney disorders?
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• Renal Dialysis and Kidney Transplantation
• Dialysis
• Hemodialysis
• Peritoneal dialysis
• Kidney transplantation
• Final option for treatment of kidney failure

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• Disorders of the Ureters
• Subdivision at renal pelvis
• Constricted or abnormally narrow parts
  (strictures)
• Renal ptosis
• Ureterocele
• Ureteral stones

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Checkpoint 21-14 What is the scientific name for
stones, as may occur in the urinary tract?
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• Disorders of the Bladder
• Rupture
• Tumors
• 90 arise from epithelial lining
• Cystitis
• Interstitial cystitis
• Urinary incontinence
• Stress incontinence
• Urge incontinence
• Overflow incontinence
• Enuresis

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Checkpoint 21-15 What is the term for
inflammation of the bladder?
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• Disorders of the Urethra
• Congenital anomalies
• Narrowing of opening or urethra itself
• Presence of valve-like structure at junction of
  urethra and bladder
• Hypospadias
• Urethritis
• Straddle injuries

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• The Effects of Aging
• Loss of ability to concentrate urine
• Decrease in number and size of nephrons
• Increase in blood urea nitrogen (BUN)
• Urinary infections
• Prostate enlargement
• Decreased bladder capacity
• Incontinence