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123 Cards in this Set
- Front
- Back
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3 functions of the kidneys:
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1. Excretory
2. Homeostatic 3. Endocrine |
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How much urine do the kidneys produce daily?
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1500 ml
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What does the kidney excrete?
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-Excess water/ions
-Drugs/toxins/toxin byproducts -Urea/Creatinine |
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What are the 2 main homeostatic functions of the kidney?
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1. Regulate/maintain the ECF
2. Maintain Acid/base balance |
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3 Endocrine functions of the kidney:
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1. Erythropoeitin
2. Renin 3. Vit D activation |
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What is the general macroscopic structure of the kidney like?
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-Solid organ
-Mostly parenchyma -Little stroma -2 subdivisions (medulla/cortex) |
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What is the appearance and consistency of the cortex?
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-Granular
-Homogenous |
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Medullary Rays:
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Extensions of the medulla into cortex.
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What is the appearance of the medulla?
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Striated
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What makes up the medulla?
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6-18 Renal pyramids
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What is the apex of each pyramid called?
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Renal papilla
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What is a Kidney Lobe?
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A macroscopic subdivision of the kidney - consists of:
-Renal pyramid -Its surrounding cortex |
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What is a Kidney Lobule?
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A microscopic subdivision - consists of:
-Medullary ray -Cortical tissue on either side |
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How are cortical nephrons connected to the medulla?
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Via collecting ducts
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What surrounds the kidney?
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A capsule consisting of mainly fibrous connective tissue
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How much of CO does the kidney recieve?
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20-25%
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How much of the total body weight are the kidneys together?
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0.5%
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How much blood volume passes thru the kidneys every 4/5 minutes?
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All of it
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How much of the blood flowing through the kidney is extracted each minute? (filtered)
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125 mL
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How much of that 125 ml is reabsorbed and excreted?
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Reabsorbed: 124 ml
Excreted: 1 ml |
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6 Levels in the Arterial Supply hierarchy of the kidney:
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1. Renal artery
2. Lobar artery 3. Interlobar artery 4. Arcuate artery 5. Interlobular artery 6. Afferent arteriole / Subcapsular artery |
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Pneumonic for the vascular supply:
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RL IAIA S
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What are the 2 capillary plexes associated with each nephron?
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-Glomerulus
-Tubular Capillary Plexus |
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What supplies the glomerular capillary plexus?
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The afferent arteriole
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What drains the glomerulus?
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The efferent arteriole
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What supplies the tubular capillary plexus?
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The efferent arteriole
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What are the Vasa Recta part of? What are they?
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Part of the tubular plexus - long capillary loops.
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What type of nephrons are the vasa recta part of?
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Juxtamedullary nephrons
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Where are juxtamedullary nephrons located?
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Near the cortex-medulla border
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What percentage of all nephrons are juxtamedullary?
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15%
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What is the veinous drainage of the kidney like?
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Follows the arterial pattern.
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What is a nephron from a developmental perspective?
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-Renal corpuscle
-Proximal/intermed/distal tubules |
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What is a nephron from a functional perspective?
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-Renal corpuscle
-All tubules -Collecting duct |
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Collecting ducts are aka:
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Uriniferous tubules
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What is the Renal Corpuscle?
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A spherical double-layered sac that surrounds a network of capillaries.
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What is the double-layered sac called?
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Renal capsule
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What are the 2 poles of the renal corpuscle?
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-Vascular pole (where arterioles enter and exit)
-Urinary pole (continuous with the proximal tubule) |
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Where can renal corpuscles be found?
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Only in the cortex!
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2 Components of the renal corpuscle:
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-Glomerulus
-Renal Capsule (Bowman's) |
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What is the role of the Afferent and Efferent arterioles in supplying/draining the glomerulus?
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The maintain the filtration pressure.
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What exactly is Bowman's capsule?
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A double layered epithelial sac surrounding the glomerulus.
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What type of epithelium is the outer (Parietal) layer of bowman's capsule?
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Simple squamous
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What is the visceral layer of Bowman's capsule?
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Simple epithelium, but cells are specialized Podocytes
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What are podocytes?
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Specialized cells with primary processes + 2ndry foot processes
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What are the 2ndry foot processes in podocytes called?
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Pedicles
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What are the pedicles of podocytes aligned along?
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The glomerular capillary basement membrane.
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What is the space between the visceral and parietal layers of the renal capsule called? What is it continuous with?
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The urinary space - continuous with the proximal tubule.
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Why is the urinary space important?
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Because that's where filtrate from bowman's tuft flows into.
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What is the Glomerular Filtration Barrier, and what are its 3 components?
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The kidney's filtration membrane:
1. Capillary endothelium 2. Basement membrane 3. Visceral layer of bowman's capsule |
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What type of endothelium is the glomerular capillary endothelium (GCE)?
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Discontinuous
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How big are the pores in the Gcap endothelium?
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70-90 nm
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What is the GCE permeable to?
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-Freely permeable to water
-Freely permeable to solutes <6-8 kD -Semipermeable to solutes 8-16kD |
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What is Podocalyxin?
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A coating on the luminal surface of the GCE that gives it a net negative charge.
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What is unique about the thickness of the Glomerular Basement Membrane (GBM)?
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it is 2-3X thicker than the normal basement membrane.
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What is the function of the GBM's thickness?
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Prevents protein from entering the filtrate.
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What are 2 ways in which the glomerular basement membrane is a barrier to proteins?
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-Physical barrier to proteins >70 kD
-Charge barrier to proteins <70kD |
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3 layers of the basement membrane seen on EM:
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-Internal Lucent layer
-Dense layer -External lucent layer |
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Why are the internal and external layers of GBM lucent?
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Because they are rich in polyanions
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Why is the middle layer dense?
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Because it has Type IV collagen.
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5 components that make up GBM:
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1. Type IV collagen
2. Sialoglycoprotiens 3. Non-collagenous glycoproteins 4. Proteoglycans 5. Glycosaminoglycans |
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What is the Visceral layer of bowman's capsule made up of?
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Podocytes - epithelial cells
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How is the visceral layer of podocytes related to the GBM?
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Pedicles interdigitate along it.
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What are pedicles again?
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2ndary foot processes on podocytes.
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And podocytes are?
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Specialized epithelial cells with Primary and 2ndry foot processes.
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What are the spaces between pedicles called?
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Filtration slits
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How wide are filtration slits? Are they just open?
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25 nm wide - bridged by an electron dense diaphragm.
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What covers the urinary surface of podocytes and filtration slits?
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Another layer of Podocalyxin
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What is the Mesangium?
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A layer of cells and ECM that abut the inner side of the GBM (glom basmnt memb).
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What are the cells in the mesangium?
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Modified pericyte/smooth muscle cells w/ receptors for ANP and ANG ii
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What does the mesangium ECM contain?
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Fibronectin
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3 Functions of the Mesangium:
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-Physical support of glomerulus
-Regulation of glomerular bflow -Maintain endothelial side of GBMemb via phagocytic activity |
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What results when one or more components of the glomerular filtration barrier, or the mesangium, becomes damaged?
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Glomerulonephritis
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What clinical problems are seen with glomerulonephritis?
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-Increased permeability of filtration membrane
-Proteinuria -Sometimes hypertension |
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What is the beginning of the Proximal Tubule? Where is it?
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The convoluted portion beginning at the urinary pole - in the cortex.
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What type of epithelial cells line the convoluted prox tubule?
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Cuboidal to columnar.
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What is at the apex (lumenal side) of each epithelial cell lining the tubule?
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A brush border coated w/ glycocalyx.
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What are Apical Canaliculi?
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Infoldings of the apical cell membrane that provide additional surface for endocytosis.
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What section of the proximal tubule comes after the convoluted segment?
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Straight portion
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What makes the straight portion different from convoluted?
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Less absorption, and extends from cortex into medulla.
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What is the intermediate tubule?
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The loop of henle
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4 parts of the Loop of Henle:
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1. Straight portion of proximal tubule
2. Thin descending loop 3. Thin ascending loop 4. Straight portion of distal tubule |
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Where are the components of Henle's loop found primarily?
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In the medulla
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What kind of henle's loop do Cortical nephrons have?
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Only a descending thin limb
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What kind of Henle's loop do Juxtamedullary nephrons have?
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Ascending AND desc. thin limbs
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What type of epithelial cells line the loops of Henle at their
-Thin segments -Thick segments |
Thin = simple squamous
Thick = cuboidal |
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Are the ascending limbs permeable to water? Why/why not?
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No - because lateral borders of cells are highly interdigitated and thus water impermeable.
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What is the nature of the fluid in the:
-Descending limb? -Ascending limb? |
Descending = hypotonic
Ascending = isotonic |
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2 components of the distal tubule:
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-Straight portion
-Convoluted portion |
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What is the Straight portion of the distal tubule really?
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The thick portion of the ascending limb of Henle's loop.
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What marks the border between the end of the straight portion and start of convoluted?
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When the ascending tubule touches its contributing renal corpuscle at the Macula Densa
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What is the macula densa?
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Specialized distal tubule epithelial cells at the arterial pole of the corpuscle
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What type of epithelium lines the straight and convoluted ascending tubules?
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Simple cuboidal w/ fewer microvilli and lots of basal mitochondria.
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What exactly are collecting tubules?
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Transition segments between the nephron and collecting duct.
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What is the distinct feature of the epithelial cells lining the collecting ducts?
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They have ADH sensitive AQP-2 water channels.
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What happens in collecting ducts when ADH is present?
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Urea and water diffuse out of the collecting duct into renal interstitium. Urine tonicity increases.
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What happens when ADH is absent?
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Water is excreted, leading to Polyuria and Hypotonic urine
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What type of diabetes is associated with polyuria and hypotonic urine?
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Diabetes insipidus
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What 2 pathological deposits can be left in the collecting duct?
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-Gout urate crystals
-Calcium deposits |
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What is the main problem that results from tubular disease?
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Acidosis due to inability to excrete acid.
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Where is the Renal Interstitium?
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Meulla
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What does the Renal Interstitium do?
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Its fibroblasts secrete the interstitial connective tissue
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What type of cells are in the interstitium? What do they secrete?
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Stellate cells - secrete Medullipin I.
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What happens to medullipin I?
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It is converted in the liver to Medullipin II
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What does Medullipin II do?
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suppresses symp activity - counteracts RAS functions.
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What is the Countercurrent Multiplier Effect?
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Interaction between collecting ducts, portions of henle's loops, and vasa recta for modifying/concentrating urine.
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What does the Countercurrent Multiplier Effect yield?
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Hypotonic fluid in the distal tubule
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2 reasons why distal tubule fluid is hypotonic:
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1. Asc limb of henle's loop is impermeable to water
2. Desc limb of henle's loop is somewhat water permeable. |
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What is the function of the Countercurrent Exchanger?
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To maintain the ionic gradient established by the countercurrent multiplier effect.
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4 Endocrine secretions of the kidney:
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1. Medullipin
2. Renin 3. EPO 4. Activated Vit D |
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3 components of the juxtaglomerular apparatus:
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1. Renin producing JG cells
2. Extraglomerular Mesangial cells 3. Macula densa |
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What do the Macula densa cells do?
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Detect Cl and Na concentration in filtrate and alter the filtration rate and blood vol autoregulation in response.
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What does the Acute Renal Failure clinical picture include? Chronic?
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Azotemia and high toxins in blood - oliguria/ischemia.
Chronic is irreversible; uremia and hematuria are features. |
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What are the Excretory passageways of the urinary system?
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1. Calyces/Pelvis/Ureters
2. Urinary bladder 3. Urethra |
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What type of epithelium lines the mucosa of the excretory passageways?
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Transitional epithelium
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What does the middle layer of the walls of the ureters contain?
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Smooth muscle - the Muscularis
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What is the Adventitia made of?
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Fibrous connective tissue.
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What covers the urinary bladder?
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More transitional epithelium
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How many layers are in the bladder muscularis?
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3
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How long is the urethra in:
-Males -Females |
Males = 15-20 cm
Females = 3-5 cm |
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3 subdivisions of the male urethra:
What type of epithelium lines each part? |
-Prostatic - Transitional
-Membranous -Penile (Last 2 lined w/ Stratified to Pseudostratified columnar epith) |
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What type of epithelium lines the navicular fossa at the distal tip of the penile urethra?
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Stratified squamous
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What lines the female urethra?
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-Initially transitional epithel
-Then stratified squamous |
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3 common clinical problems that obstruct excretory passages:
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1. Nodular hyperplasia (benign prostatic hypertrophy)
2. Renal calculi (kidney stones) 3. Bladder cancer |
