exam_3_20150304203003 Flashcards
What are the two types of nephrons?
Cortical (85%) and Juxtamedullary (15%)-juxtamedullary have longer distal tubules that extend into the medulla (lower oxygen level here)
What is the glomerulus and Bowman’s Capsule?
glomerulus is a tuft of capillaries and the Bowman’s capsule is over the glomerulus-the parietal epithelium is the outermost layer of the Bowman’s capsule
What is the visceral epithelium and podocytes of kidneys?
visceral epithelium is also called podocytes. These are cells with radiating rootlike processes, form a network of intercellular clefts called filtration slits and the foot like process are connected by proteins
Glomerular basement membrane
-negatively charged-selectively permeable network of glycoproteins and mucopolysaccharides *allow water and small solutes through *small pores and filtration slits make the glomerular basement membrane less permeable to larger molecules like proteins *the membrane repels proteins because protein molecules are negatively charged
What happens when there is a loss of the negative charge on the basement membrane of the glomerulus?
loss of negative charge or injury to podocytes causing larger pores and slits will allow protein through the glomerular basement membrane
What is the function of the mesangium?
-contains mesangium cells that have macrophages, intrinsic glomerular cells-form mesangial matrix-have contractile and proliferative function
Juxtoglomerular apparatus
contains juxtoglomerular cells-smooth muscle cells in the afferent arteriole next to the distal tubule; sense stretch; manufacture, store and release renin
What does the Macula densa cells do?
distal tubular cells nearest the glomerulussense Na content
Renal blood flow
-25% of CO-from cortex to medulla
Why is PaO2 less in the medulla?
it is less in the medulla because it goes to the cortex first. however more O2 is needed in the medulla to generate ATP for transporting substances—>makes it more susceptible to injury
What does the juxtaglomerular cells do?
assesses perfusion pressure
Autoregulation is provided by tubuloglomerular feed back by which two cells?
- macula densa=decreased Na triggers renin->afferent arteirole vasodilation and efferent arteriole vasoconstiction-increased Na= afferent arteriole vasoconstriction and efferent arteriole vasodilation2. juxtaglomerular cells=assess perfusions press ion-increased MAP (stretch) causes constriction of afferent artierole-decreased MAP stimulates renin release and afferent arteriole vasodilatation
Neural Regulation and Humoral Regulation of kidneys
SNS: vasoconstrict, renin production NO PNS innervationvasoconstriction from angiotensin II, vasopress (ADH), endothelia’svasodilation from NO, adenosine, prostaglandins, dopamine
What is the best indicator of renal function?
creatinine clearance-amount of creatinine excreted in the urine per minute -slightly overestimates GFR-Normal GFR= 120 ml/min, pregnancy 120-160 ml/min-Failure<20ml/min
Serum Creatinine and BUN for renal function
-serum creatinine is common method of estimating trending GFR (normal: 0.8-1.0)*if double then GFR is about 50% of normal and if it is 3x high then GFR is about 25% of normal-BUN: levels increase as glomerular filtration drops-about 50-60% of renal function must be lost before a significant rise in BUN occurs
Excretion of Na in kidney
normal: over 99% of filtered Na is reabsorbed and 1%
What are casts and how are the important in UA?
casts are tube shaped particles of leukoproteins of tubular epithelial cells and whatever blood cells that are in there.RBC do not pass through filtration process-So when you have Red cell casts it indicates bleeding in the tubules-white cell casts are associated with inflammatory process-epithelial cell casts indicate degeneration of the butler lumen on necrosis of the renal tubules
Terms: GF, filtrate, compensatory hyperfiltration
GF: movement of fluids from capillaries across basement membrane and to the tubules (then called filtrate)filtrate is usually free of cellular elements and essentially protein freeloss of nephrons results in compensatory hyper filtration => increased GFR per nephron
Where does the concentration of tubular fluid occur?
occurs in loop of Henle
Where does the concentration of urine occurs?
collecting duct under influence of ADH and aldosterone
What is vitamin D made from?
-made from cholesterol in our skin by the action of ultraviolet light; source of inactive vitamin D includes dietary source-inactive vitamin D is transported to the liver and converted to an inactive compound -intermediate compound is taken to kidneys and under two step process activated under influence of PTH -active vitmain D stimulates the absorption of Ca and Ph by small intestine and stimulates osteoclasts to reabsorb bone to increase Ca
Water/Na reabsorption occurs in…
proximal tubule, descending thin limb of the loop of Henle, distal tubule and collecting ducts (Cl passively follows in the ascending limb, proximal tubule and distal and collecting ducts)
Aldosterone controls water and Na absorption in the Vasopressin (ADH) secreted by hypothalamus increases reabsorption of water in the
distal tubule and collecting duct collecting duct
Final place for reabsorption…
distal tubule and collecting ducts