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28 Cards in this Set
- Front
- Back
What is the primary function of the kidneys? Other functions?
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Primary function: Maintain Whole-body Homeostasis
Other functions: Acid-base balance [Electrolyte] regulation BV control BP control |
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What is the basic structural and functional unit of the kidney?
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The nephron
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What is the epithelial lining of the nephron?
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Simple squamous
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Nephrons occupy wedges in the kidney. Which way do the apices of these wedges face?
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Wedges face the hilum (toward the center)
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Is Bowman's capsule found in the cortex or medulla of the kidney? What structure does Bowman's capsule embrace?
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Cortex
Bowman's capsule embraces glomerular capillaries |
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What cells line the outer, parietal side of Bowman's capsule? The inner, visceral side?
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Out, parietal = Simple Squamous
Inner, visceral = podocytes with foot processes |
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What is the function of the Proximal Convoluted Tubule?
What is its epithelial lining? |
PCT: Reabsorbs most minerals and nutrients from tubular fluid and passes them into peritubular capillaries
Epithelial lining: Simple cuboidal with BRUSH BORDER of microvilli |
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Where in the kidney is the Loop of Henle located? What is its function?
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In Medulla
Fn: Aids in concentration of urine by creating a HYPERTONIC saline environment in medulla |
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Describe the changes in epithelial composition and girth in the Loop of Henle.
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Descending limb: Initial short, thick segment that is structurally similar to PCT
Followed by long thin segment lined with SIMPLE SQUAMOUS epithelium Ascending limb: Thin portion with simple squamous Followed by thick segment with cuboidal epithelium |
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Would you expect to see glomerular capillaries when looking at a slide of the Loop of Henle?
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No, because Loop is in Medulla. Glomeruli are in Cortex.
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What is the function of the Distal Convoluted Tubule? How would you distinguish it from the PCT histologically?
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Function: Continues return of useful materials from filtrate to blood in peritubular capillaries
Lined with simple cuboidal epithelium (as is PCT), but the DCT LACKS a brush border |
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What is the function of the Collecting Duct? In what area of the kidney are they located?
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Collecting Duct "collects" urine from DCT
Located in Medulla |
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How would you identify a Collecting Duct histologically?
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Lined by simple cuboidal epithelium and have distinct cell borders.
If on a slide, would only be able to compare with Loop of Henle (CT and Loop of Henle go really deep into medulla) Loop of Henle is simple squamous at that point (thin). CD is simple cuboidal and a lot wider. |
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Describe the flow of urine from Collecting Ducts to Ureters.
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CD-->Papillary Ducts-->Renal Pelvis-->Ureters
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Describe the portal system employed by the kidney.
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First capillary bed: Glomerulus
Second capillary bed: VASA RECTA or PERI-TUBULAR CAPILLARY PLEXUS (PCTP) via efferent artery Vasa Recta (straight arteries) are important in maintaining osmotic gradient in the medulla. |
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What glomerular features allow for ultrafiltration?
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-Glomerulus is extensively convoluted and contains fenestrated capillaries WITHOUT diaphragms
-Visceral layer of Bowman's Capsule has podocytes with foot processes that encircle basement membrane |
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What comprises the basement membrane of the Glomerular Capillary - Bowman's Capsule interface?
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-Basement membrane = basal laminae of podocytes plus basal lamina of glomerulular epithelium
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What about podocytes contributes to filtration?
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Each podocyte has pedicels (foot processes) which rest on filtration membrane. Between adjacent pedicles are gaps called FILTRATION SLITS which permit free passage of fluid filtrate into Bowman's space.
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Where does reabsorption of nutrients occur?
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PCT
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Where does most reabsorption of water occur?
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PCT
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Where does Na+/K+ regulation occur?
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DCT
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What cells does ADH mediate its effect on? What is the effect of ADH?
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ADH = Anti-Diuretic Hormone; increases permeability of DCT duct cells to water, which makes urine more concentrated.
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What are Juxtaglomerular cells?
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JG-Cells are specialized SMOOTH MUSCLE cells that are located within walls of afferent arterioles near point where they enter glomeruli.
They secrete RENIN. |
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What comprises the Juxtaglomerular apparatus?
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JG Cells and MACULA DENSA
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What is the macula densa? Function?
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Area of closely packed cells lining DCT at point of return of nephron to vascular pole of parent glomerulus.
Fn: Detect ionic content and H2O volume of fluid in DCT, can promote renin secretion by JG cells. |
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Describe how the Renin-angiotensin-aldosterone system regulates blood pressure?
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Angiotensin is made by the liver
Angiotensin-->Ag I via RENIN (JG cells) Ag I --> Ag II via ACE enzyme from lung Ag II promotes ALDOSTERONE secretion by adrenal cortex Aldosterone promotes Na+ reabsorption by DCT, leading to water retention and maintaining BP |
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What is the epithelial lining of the ureters? What ducts give rise to the ureters?
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Transitional
Papillary Ducts join to give rise to ureter |
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What shape are transitional cells in when they're relaxed?
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Dome-shaped!
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