Download Chapter 19

THIRD EDITION
HUMAN PHYSIOLOGY
AN INTEGRATED APPROACH
Dee Unglaub Silverthorn, Ph.D.
Chapter 19
The Kidneys
PowerPoint® Lecture Slide Presentation by
Dr. Howard D. Booth, Professor of Biology, Eastern Michigan University
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Excretory System: Anatomy Review
• Kidney
• Cortex
• Medulla
• Pelvis
• Nephrons
• Ureter
• Bladder
• Urethra
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 19-1: Anatomy Summary: The Urinary System
3 processes of the nephron are: filtration,
reabsorption and secretion.
Figure 19-2: Filtration, reabsorption, secretion, and excretion
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Kidney Functions: Overview
Figure 19-3: The excretion of a substance depends on the amount that was filtered, reabsorbed, and secreted
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
FILTRATION
Glomerulus + Bowman's Capsule = Renal corpuscle
Fenestrated capillaries
Filtration slits
3 barriers to filtration:
1. Glomerular capillary endothelium
2. Basal lamina (acellular; collagen and
glycoproteins)
3. Epithelium of Bowman’s capsule
(podocytes)
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 19-4: Structure of the renal corpuscle
Have actin and can contract to alter
filtration.
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Glomerular Flow Rate (GFR):
average GFR is 125 mls/min!
• Glomerular Capillary
• Hydrostatic pressure out
(55 mmHg)
• Colloid osmotic pressure
in ( 30 mmHg)
• Bowman’s Capsule pressure
• “Back” hydrostatic
pressure in (15 mmHg)
• Net Filtration 10 mmHg
• GFR  180L/day (about 1% is
excreted)
• Do you urinate
180L/day???
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 19-6: Filtration pressure in the renal corpuscle
Glomerular Flow Rate (GFR)
urine
Figure 19-5: The filtration fraction
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Regulation of GFR: Tubuloglomerular FB
•Macula densa + juxtaglomerular cells = Juxtaglomerular apparatus
Figure 19-9: The juxtaglomerular apparatus
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Reabsorption: Can be ACTIVE or PASSIVE
• Passive diffusion in: molecules travel down their
concentration/electrochemical gradients.
• Active Transport : molecules pushed against
their gradients. Must use primary or secondary
active transport.
• Reabsorption of:
• Sodium
• Urea
• Glucose
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Sodium Reabsorption: Primary Active Transport
Proximal tubule
Figure 19-11: Sodium reabsorption in the proximal tubule
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Reabsorption:
Secondary Active Transport of glucose
• Na+ linked 20 transport
• A lot of “stuff” follows
sodium out of the tubule
lumen.
• Symports make this happen
• Glucose
• Ions
• Amino acids
• Proximal tubule, key site
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 19-12: Sodium-linked glucose reabsorption in the
proximal tubule
Reabsorption:
Passive Transport of Urea
• IN the proximal tubule
• 1. sodium and other solutes
are reabsorbed.
• 2. Water follows.
• When water leaves, no urea
has left yet.
• You have smaller volume
with same amount of urea.
• Urea concentration is
higher.
• 3. NOW urea will be
reabsorbed passively down
its concentration gradient.
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Reabsorption: The concept of saturation
• Saturation – refers to the maximum rate of transport (of
glucose, or something) that occurs when all available carriers are
occupied with substrate.
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Saturation; a closer look
Glucose on a carrier
Blood
nephron
Glucose
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Glucose carrier
Reabsorption: Receptors can Limit
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 19-15: Glucose handling by the nephron