Download Urinary System Contribution to Homeostasis Urinary System

Chapter 15
The Urinary
System
Suggested Lecture
Presentation
Robert J. Sullivan
Marist College
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Urinary System Contribution to Homeostasis
 Regulates body water levels
 Excess water taken in is excreted
 Output varies from 2-1/2 liter/day to 1 liter/hour
 Regulates nitrogenous and other solute waste
 Nitrogen from amino acids are made into urea in
liver and transported to kidney as waste
 Other solutes
 Sodium, chloride, potassium, calcium, hydrogen
ions, creatinine
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Urinary System
Cortex
Kidney
Renal artery
Renal vein
Nephrons
Aorta
Inferior
vena cava
Cortex
Renal
pelvis
Medulla
Ureter
Bladder
Medulla
Collecting
duct
Ureter
Urethra
a) The components of the urinary system.
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b) Internal structure of the kidney.
c) The cortex and medulla of the kidney
are composed of numerous nephrons.
Figure 15.2
1
Functions of Renal Organs
Table 15.2
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Organs of the Urinary System
 Kidneys
 Principle organ
 Cortex
 Medulla
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Urinary System
Cortex
Kidney
Renal artery
Renal vein
Nephrons
Aorta
Inferior
vena cava
Cortex
Renal
pelvis
Medulla
Ureter
Bladder
Medulla
Collecting
duct
Ureter
Urethra
a) The components of the urinary system.
Copyright © 2009 Pearson Education, Inc.
b) Internal structure of the kidney.
c) The cortex and medulla of the kidney
are composed of numerous nephrons.
Figure 15.2
2
Organs of the Urinary System
 Ureters
 Transport urine to bladder
 Urinary bladder
 Stores urine (600
(600–1000
1000 ml)
 Urethra
 Carries urine from body
 Two sphincters
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Organs of the Urinary System
Urinary
bladder
Rectum
Prostate
gland
Internal
urethral
sphincter
Uterus
Vagina
Penis
External
urethral
sphincter
Rectum
Urethra
Testis
a) The male
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b) The female
Figure 15.3
Tubular and Vascular Nephron Components
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Figure 15.5
3
Nephrons: Produce Urine
 Tubules
 Function
 Filter fluid and reabsorb needed
substances
 Structures
 Proximal tubule
 Loop of Henle
 Distal tubule
 Collecting duct
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Nephrons: Produce Urine
 Blood vessels associated with tubules
 Arterioles
 Afferent
 Efferent
 Capillaries
 Glomerular
 Peritubular
 Vasa recta
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Formation of Urine
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Figure 15.6
4
Formation of Urine: Glomerular Filtration
 Glomerular filtration
 Filters fluid from capillaries into glomerular
capsule
 Rate of filtration
 Resting rate under local chemical control
 Stress causes sympathetic nervous
system to reduce blood flow to kidneys
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Formation of Urine: Tubular Reabsorption
 Tubular reabsorption returns water and needed
solutes to blood capillaries
 Sodium moved by active transport from tubule
cells to interstitial fluid and diffuses to capillaries
 Chloride passively accompanies sodium
(balanced charge)
 Water reabsorbed with salts
 Movement of sodium creates energy to transport
glucose and amino acids into renal tubule then
diffuses to the interstitial fluid
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Tubular Secretion
 Tubular secretion removes other
substances from blood
 Purpose
g
of chemical levels in body
y
 Regulation
 Excretion of harmful chemicals
 Substances secreted
 Penicillin, cocaine, marijuana, pesticides,
preservatives, hydrogen ions, ammonium,
potassium
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Concentration or Dilution of Urine: ADH
 Dilute urine
 Excreting excess water
 Mechanism
 Cycling of NaCl and urea create a
concentration gradient in the medulla that
allows water to diffuse from the renal
tubules into the interstitial fluid and then
into the blood capillaries
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Formation of Dilute Urine
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Figure 15.10
Concentration or Dilution of Urine: ADH
 Concentrated urine
 Conserving water
 Mechanism
 Countercurrent exchange
 Increased ADH causes increased
permeability to the collecting tubules and
increased conservation of water
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Formation of Concentrated Urine
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Figure 15.11
Urination
 Micturition reflex
 Internal urethral sphincter
 Smooth muscle
 External urethral sphincter
 Skeletal muscle
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Kidney’s Role in Homeostasis
 Maintains water balance
 Adjusts blood volume and blood pressure
 Aldosterone, renin, ANH help maintain salt
balance in order to control blood volume
 Maintains acid–base balance and blood
pH
 Regulates red blood cell production via
erythropoietin
 Activates an inactive form of vitamin D
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Kidney’s Role in Homeostasis
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Figure 15.13
Kidney’s Role in Homeostasis
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Figure 15.15
Disorders of the Urinary System
 Kidney stones
 Crystallized minerals
 Block urine flow
 Urinary tract infections (UTI)
 Bacteria
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Disorders of the Urinary System
 Acute and chronic renal failure
 Therapies
 Dialysis
 Kidney transplant
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