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68 Cards in this Set
- Front
- Back
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What is the classification of the kidney? |
Compound tubular gland |
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What are the major functions of the kidney? |
Filtration, secretion and absorption |
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What is the thin capsule of the kidney made of? |
Fibroblasts and myofibroblasts |
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What is the renal corpuscle made of? |
Aka Malpighian corpusle capillary glomerulus + Bowman's capsule |
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What are medullary rays? |
Bundles of tubules in the cortex which extend into medulla |
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Which structure can be subdivided into zones to reflect the distribution of its tubules? |
Medulla |
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What does the renal sinus contain? |
Renal pelvis with minor/major calyces branches of renal arteries, veins, and nerves and fatty CT |
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Define a lobe of the kidney |
Medullary pyramid and associated cortical substance |
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Define a lobuls of the kidney |
Medullary ray and cortical tissue associated with it |
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What is the uriniferous tubule? |
Nephron + collecting tubule (duct) |
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What is the functional unit of the kidney? |
Nephron |
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What are the parts of the nephron? |
Bowman's capsule Proximal thick segment (convoluted/straight) Thin limb (descending/ascending) - Loop of Henle Distal thick segment (straight/convoluted)
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Where are the renal corpuscles and loops of hendle located in the cortical/subcapsular nephrons? |
Renal corpuscles- Outer cortex Loop of Henle- restricted to outer medulla and cortex |
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Where are the renal corpuscles and loops of Henle located in juxtamedullary nephrons? |
Renal corpuscles- near corticomedullary junction Loops of Henle - deep into pyramids |
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T/F: The short loops of Henle participate in concentration of urine. |
False, long loops of the juxtamedullary nephrons |
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What is the route of blood supply in the kidney? |
Renal artery -> interlobar -> arcuate -> interlobular -> afferent arteriole -> glomerulus -> efferent arteriole -> arcuate vein |
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What is the difference of venous draining between glomeruli in the subcapsular region vs. the juxtamedullary region? |
Subcapsular = peritubular capillary network Juxtamedullary = vasae rectae, hairpin turn in medulla
Both drain into arcuate vein |
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T/F: Visceral layer of Bowman's membrane is continuous with beginning of proximal convoluted tubule? |
False: continuous with parietal layer at urinary pole |
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What is the renal corpuscle made of? |
Bowman's membrane (parietal/visceral) and glormuli |
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What is the function of the renal corpuscle? |
Filtration of plasma from glomerular capillary |
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Classify the lining of the glomerular capillary? |
Fenestrated endothelium with open fenestrae. |
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Describe the parietal layer of Bowman's capsule. |
Simple squamous epithelium |
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What is the visceral layer of the Bowman's membrane made of? |
Podocytes, interdigitating pedicels, separated by slit pores and spanned by slit membranes |
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What size of molecules do the open fenestrae of the glomerular endothelium restrict? |
Restricts larger than 70kD into glomerular basement membrane |
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What is the glomerular basment membrane made of? |
Appears trilaminar and contains type IV collagen, heparan sulfate, laminin and fibronectin. |
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What is the function of heparan sulfate? |
Negative charge limits movement of neg. charged proteins (less than 70kD) past the basement membrane (but can reach to the point of BM). |
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What is the slit membrane formed by? |
Adhesion protein - nephrin & its anchoring complex |
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What supplementary method does the kidney use to limit passage of negatively charged molcueles into filtrate? |
Polyanionic glycocalyx of podocytes |
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Describe Glomeerular nephritis? |
Auto-antibodies to GBM produce most severe form (Goodpasture syndrome). Antigen-antibody complexes accumulate in GBM to produce acute glomerulonephritis |
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Describe congenital syndrome |
Defect in gene producing nephrin Leads to low albumin in blood, high in urine |
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What is the filtration barrier made of? |
Glomerular endothelium, glomerular basement membrane, slit membrane |
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Where are mesangial cells located? |
- Stalk of capillary tuft (intraglomerular mesangium) - Vascular pole (extraglomerular mesangium) |
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What are the functions of mesangial cells? |
- Maintenance of basement membrane through phagocytosis - Structural support - Regulate blood flow through glomerulus - Secrete IL-1 and PDGF (platelet derived GF) |
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T/F: Mesangial cells are derived from monocytes |
False: derived from smooth muscle cells |
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What are the functions of the proximal tubule? |
- 2/3 of glomeluar filtrate recovery (water, ions, glucose, amino acids, small proteins) - Active transport of Na+ and passive diffusion of Cl- (hence water) - Secretion of creatinine, some dyes and drugs |
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How does water follow ions out of the proximal tubule? |
-Paracellular and transcellular routes -Aided by aquaporin-1 channels PM of proximal tubule cells |
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Classify the epithelium of the proximal tubule |
-simple cuboidal epithelium -brush border (apical microvilli) - Basal striations/lateral interdigitating folds of PM - Endocytic apparatus with pinocytic vesicles, vacuoles, and lysosomes for intracellular degradation |
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T/F: Proximal tubules are in close proximity to vasae rectae. |
False: close proximity to peritubular capillaries |
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What is the epithelium of the thin limb? |
simple squamous epithelium |
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T/F: Thin limb is in close proximity to vasa rectae |
True |
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Describe the permeability of the ascending portion of the thin limb. |
-Impermeable to water - Has Na+/K+ ATPase pump to increase osmotic gradient in interstitium |
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T/F: The distal tubule contains an endocytic system. |
False, little endocytic activity
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Classify the epithelium of the distal tubule |
Simple cuboidal epithelium with few short apical microvilli (no brush border) - Lateral interdigitations and basal striations (mitochondria) for active Na+ and bicarbonate absorption & K+/H+ secretion |
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What is the absorption of Na+ in the distal tubule controlled by? |
Aldosterone |
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What capillaries are the straight and convoluted portions of the distal tubule in close proximity to? |
Straight = vasa rectae Convoluted = peritubular capillaries |
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What are the secretions of the macula densa? |
- ATP - adenosine - nitric oxide - prostaglandins |
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Where is the macula densa located and where do they release their secretions? |
- wall of distal tubule at site of contact with afferent arterioles - Release secretion at basal surface |
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What do the macula densa cells respond to? |
- Low Na+ and low BP - Form part of juxtaglomerular apparatus |
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What are the two functions of angiotensin II? |
Vasoconstrictor and stimulates adrenal cortext o produce aldosterone |
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What is the pathway of increasing BP and Na+ in the blood? |
macula densa -> JG cells -> renin (protease) -> angiotensinogen -> angiotensin I -> angiotensin II -> aldosterone -> absorption of Na+ (water follows) |
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What are the three parts that make up the JG apparatus? |
- Macula densa cells - JG cells - Extraglomerular mesangium (function unknown) |
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What is the structure of collecting ducts (ducts)? |
Arched collecting tubules -> straight collecting ducts -> papillary ducts -> papilla -> minor calyx |
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What are the cells lining the collecting ducts? What are their functions? |
Light (principal cells) - reabsorb Na+, secrete K+ (respond to ADH- water channel insertion = aquaporin 2) Dark (intercalated) cells - reabsorb K+, secrete H+/HCO3- (regulate acid-base balance) |
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What is the epithelium of the collecting ducts? |
Smaller = simple cuboidal Larger = simple columnar |
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Hoe does aldosterone cause Na+ intake? |
Binds to distal convoluted tubule cells Increase uptake which is transferred to blood via peritubular cpaillary network |
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What is the cause of diabetes insipidus? |
- Defect in ADH effectiveness - polydipsia (increased water consumption), polyuria (increased urination) |
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In diabetes mellitus what does high glucose act as? |
Osmotic diuretic |
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What are the endocrine functions of the interstitial cells? |
- Erythropoietin (RBC production in bone marrow) - thrombopoietin (platelet production in bone marrow) - Hydroxylation of vitamin D precursor -> hormonally active form |
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Where are interstitial cells found? |
Medulla & cortex |
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What are excretory passages lined by? |
In minor calyces, major calyces, renal pelvis, ureter and bladder = transitional epithelium
Walls thicken near bladder |
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Describe the layers of the renal pelvis/ureter. |
Mucosa- transitional epithelium + dense lamina propria Muscularis- inner long., outer circ., outer long. (only in lower portion of ureter) Adventitia - Ureter surrounded by adipose tissue |
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What are prominent features of the bladder mucosa? |
- Thick trans. epithalium (3-10 layers) - Interdigitated cell borders (faciliate distension) - Surface cells with plaques of thick asymmetrical plasma membranes & fusiform vesicles in apical cytoplasm |
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What are fusiform vesicles? |
Reserve packets of membrane material (can fold inward and reinsert for distension) |
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Where does the internal sphincter of the ureter come from? |
Circular layer of the muscularis of the bladder which is thickened near opening of urethra |
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Describe the mucosa of the female urethra. |
- Transitional epithelium bear bladder = stratified squamous + patches of stratified/pseudostratified columnar
- Many elastic fibers in lamina propria
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What glands are present in the mucosa of the female urethra? |
Mucous glands of Littre |
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What is different about the muscularis in the female urethra? |
No outer longitudinal muscular layer |
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Where does the external sphincter of urethra come from? |
Skeletal muscle from urogenital diaphragm. |
