11.3 The kidney Objectives Define excretion. Draw and label a diagram of the kidney. Annotate a...
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Transcript of 11.3 The kidney Objectives Define excretion. Draw and label a diagram of the kidney. Annotate a...
11.3 The kidneyObjectives
• Define excretion.• Draw and label a diagram of the kidney.• Annotate a diagram of a glomerulus and associated nephron to
show the function of each part.• Explain the process of ultrafiltration, including blood pressure,
fenestrated blood capillaries and basement membrane.• Define osmoregulation.• Explain the reabsorption of glucose, water and salts in the
proximal convoluted tubule, including the roles of microvilli, osmosis and active transport.
Objectives of Topic 11.3
• Explain the roles of the loop of Henle, medulla, collecting duct and ADH (vasopressin) in maintaining the water balance of the blood
• Explain the differences in the concentration of proteins, glucose and urea between blood plasma, glomerular filtrate and urine.
• Explain the presence of glucose in the urine of untreated diabetic patients.
Why do we need excretory system?
• To remove toxic wastes.
• Metabolism produces toxic by-products.
• Nitrogenous wastes are toxic breakdown products of proteins and nucleic acids.
• Animals dispose of nitrogenous wastes in different ways.
© 2012 Pearson Education, Inc.
1- Ammonia (NH3) is
– poisonous,– too toxic to be stored in the body,– soluble in water, and– easily disposed of by aquatic animals.
© 2012 Pearson Education, Inc.
TOXIC WASTES
2- Urea is– produced in the vertebrate liver by combining
ammonia and carbon dioxide,– less toxic,– easier to store, and– highly soluble in water.
© 2012 Pearson Education, Inc.
TOXIC WASTES
3. Uric acid is– excreted by some land animals (insects, land
snails, and many reptiles),– relatively nontoxic,– largely insoluble in water,– excreted as a semisolid paste, conserving
water, but– more energy expensive to produce.
© 2012 Pearson Education, Inc.
TOXIC WASTES
Figure 25.5
Proteins
Ammonia
Nitrogenous bases
NH2
(amino groups)
Nucleic acids
Urea
Uric acid
Mammals, mostamphibians, sharks,some bony fishes
Birds and many otherreptiles, insects, landsnails
Most aquatic animals,including most bonyfishes
Amino acids
• The urinary system– forms and excretes urine and– regulates water and solutes in body fluids.
• In humans, the kidneys are the main processing centers of the urinary system.
© 2012 Pearson Education, Inc.
Figure 25.6_1
Aorta
Kidney
The urinary system
Inferiorvena cava
Renal artery (red)and vein (blue)
Ureter
Urethra
Urinary bladder
Figure 25.6_2
Renal cortex
Renal medulla
Ureter
Renal pelvis
The kidney
Figure 25.6_3
Bowman’s capsule
Tubule
Collectingduct
To renalpelvis
Branch ofrenal artery
Branch ofrenal vein
Renal cortex
Orientation of a nephron within the kidney
Renal medulla
Figure 25.6
Aorta
Kidney
The urinary system
Inferiorvena cava
Renal artery (red)and vein (blue)
Ureter
Urethra
Urinary bladder
Renal cortex
Renal medulla
Renal pelvis
Ureter
The kidney
Proximal tubule
Bowman’s capsule
Tubule
Collectingduct
To renalpelvis
Branch ofrenal artery
Branch ofrenal vein
Renal cortex
Renal medulla
CapillariesGlomerulus
Distaltubule
Fromanothernephron
Bowman’s capsuleArteriole
from renalartery
Arteriolefrom glomerulus
Branch ofrenal vein
Loop of Henlewith capillarynetwork
Detailed structure of a nephron
1
3
2
Orientation of a nephron within the kidney
Collectingduct
• Nephrons
– are the functional units of the kidneys,
– extract a fluid filtrate from the blood, and
– refine the filtrate to produce urine.
• Urine is
– drained from the kidneys by ureters,
– stored in the urinary bladder, and
– expelled through the urethra.
© 2012 Pearson Education, Inc.
Figure 25.6_4
Proximal tubuleGlomerulus
DistaltubuleCollectingDuct
Fromanothernephron
Bowman’s capsule
Arteriolefrom renalartery
Arteriolefrom glomerulus
Branch ofrenal vein
Loop of Henlewith capillarynetwork
Detailed structure of a nephron
Capillaries
1
3
2
Overview: The key processes of the urinary system are filtration, reabsorption, secretion, and excretion
• Filtration– Blood pressure forces water and many small
molecules through a capillary wall into the start of the kidney tubule.
• Reabsorption– refines the filtrate,– reclaims valuable solutes (such as glucose,
salt, and amino acids) from the filtrate, and– returns these to the blood.
© 2012 Pearson Education, Inc.
Figure 25.7
Reabsorption Secretion Excretion
Urine
To renal vein
Filtration
Nephron tubule
Capillary
Interstitial fluid
H2O, other small molecules
Bowman’s capsule
Fromrenalartery
Figure 25.7_1
Filtration
Nephron tubule
Capillary
Interstitial fluid
H2O, other small molecules
Bowman’s capsule
Fromrenalartery
Figure 25.7_2
Reabsorption Secretion Excretion
Urine
To renal veinCapillary
Nephron tubule
• Substances in the blood are transported into the filtrate by the process of secretion.
• By excretion the final product, urine, is excreted via the ureters, urinary bladder, and urethra.
© 2012 Pearson Education, Inc.
Figure 25.7
Reabsorption Secretion Excretion
Urine
To renal vein
Filtration
Nephron tubule
Capillary
Interstitial fluid
H2O, other small molecules
Bowman’s capsule
Fromrenalartery
• Reabsorption in the proximal and distal tubules removes– nutrients,– salt, and– water.
• pH is regulated by– reabsorption of HCO3
– and
– secretion of H+.
© 2012 Pearson Education, Inc.
• High NaCl concentration in the medulla promotes reabsorption of water.
© 2012 Pearson Education, Inc.
Animation: Bowman’s Capsule and Proximal Tubule
Animation: Collecting Duct
Animation: Effect of ADH
Animation: Loop of Henle and Distal Tubule
Figure 25.8 Bowman’scapsule
Blood
Nutrients H2ONaCl
Proximal tubule
Somedrugsand poisonsCortex
Medulla
Interstitialfluid Loop of
Henle
H2O
Filtrate composition
Reabsorption
Filtrate movement
Secretion
Distal tubule1
2 NaCl
NaCl
NaCl
UreaH2O
3K
H
Collectingduct
Urine (torenal pelvis)
H2ONaCl HCO3
H2O
Salts (NaCl and others) HCO3
H
Urea Glucose Amino acids Some drugs
HCO3
H
Figure 25.8_1
Blood
Filtrate composition
Reabsorption
Filtrate movement
Secretion
Bowman’scapsule
Nutrients H2ONaCl HCO3
Proximal tubule
Somedrugsand poisonsCortex
Medulla
H
H2O
Salts (NaCl and others) HCO3
H
Urea Glucose Amino acids Some drugs
Figure 25.8_2
Reabsorption
Filtrate movement
Secretion
NutrientsNaCl HCO3
Somedrugsand poisonsCortex
Medulla
Proximal tubule
Interstitialfluid Loop of
Henle
H2O
NaCl
NaCl
NaCl
UreaH2O
Collectingduct
Urine (torenal pelvis)
Distal tubuleH2O
NaCl HCO3
1
3
2
H2O
H HK
• Antidiuretic hormone (ADH) regulates the amount of water excreted by the kidneys by– signaling nephrons to reabsorb water from the
filtrate, returning it to the blood, and– decreasing the amount of water excreted.
• Diuretics– inhibit the release of ADH and– include alcohol and caffeine.
© 2012 Pearson Education, Inc.
• Kidney failure can result from– hypertension,– diabetes, and– prolonged use of common drugs, including
alcohol.
• A dialysis machine– removes wastes from the blood and– maintains its solute concentration.
CONNECTION: Kidney dialysis can be lifesaving
© 2012 Pearson Education, Inc.
Figure 25.9
Line from artery to apparatus
Pump Tubing made of a selectively permeable membrane
Dialyzingsolution
Fresh dialyzingsolution
Used dialyzing solution(with urea and excess ions)
Line fromapparatusto vein
Figure 25.9_1
Line from artery to apparatus
Pump Tubing made of a selectively permeable membrane
Dialyzingsolution
Fresh dialyzingsolution
Used dialyzing solution(with urea and excess ions)
Line fromapparatusto vein
Figure 25.9_2