1、CMUUrinary System2022-7-252General outline component urinary organs:kidneysmicturition organs:ureter,bladder and urethra function discharge metabolite regulate the balance of water and electrolyte endocrine function:renin,erythropoietin,prostaglandin2022-7-253KidneyGeneral structureEach kidney has a
2、 concave border,the hilum,where blood vessels and ureter exit and communicate the kidney.The renal pelvis,the expanded upper end of the ureter,branches and rebranches into major calyces and minor calyces.Capsule:CT containing rich fat cells.2022-7-254Renal anatomic structure Fibrosa Parenchyma Corte
3、x Cortical labyrinthMedullary rayMedullaRenal pyramidsRenal columns2022-7-255Cortex:Mainly locates at periphery with the renal column,the pillar-shaped cortex that exists between pyramid-like medulla.Medulla:Centrally located 10 18 pyramid-like structures known as renal pyramids,whose bases radially
4、 send out the medullary rays that separate the cortex into cortical labyrinth.2022-7-256Renal cortexRenal medulla2022-7-257Renal histological structure nephronRenal corpuscles collecting duct juxtaglomerular apparatusRenal tubulesGlomerulus Bowmans capsule2022-7-258Nephron:About 14 million per kidne
5、y.Juxtamedullary nephrons and cortical nephrons:1.About one seventh of the nephrons,which locate near the medulla,especially in the renal column,are called juxtamedullary nephrons.2.The juxtamedullary nephrons have very long Henles loops that extend into deep medulla.Play an important role in the fo
6、rmation of hypertonicity circumstances in kidney.2022-7-259Renal corpuscle:The place where the blood is filtered to form pre-urine.Has vascular pole,where the afferent arteriole enters and thinner efferent arteriole leaves renal corpuscle,and urinary pole,where the proximal convoluted tubule leaves
7、the corpuscle.2022-7-2510Nephron:The structural and functional unit of kidney.a.renal corpuscle:renal glomerulus(C)+glomerulus capsule(C).b.renal tubule:proximal convoluted tubules(C)+thinand thick limbs of Henles loop(from C to M to C via MR)+distal convoluted tubules(C).Functions of kidney:Clearan
8、ce of metabolism wastes in blood stream;Regulation of mineral level and pH value in body;hormone release.2022-7-2511Structure of Renal corpuscle:Glomerulus afferent arteriolecapillary networkmesangial cellsefferent arterioleBowmans capsuleparietal layer:simple squamous Epi.capsular cavity:filtratevi
9、sceral layer:podocytes(primary and secondary processes,slit membrane)2022-7-2512Renal corpuscle2022-7-2513renal glomerulus:anastomizing fenestrated Caps without diaphragm.The cell coat lining their inner surface contains negative ions.This primary Cap network of portal circulation are linked by mesa
10、ngium.2022-7-2514glomerulus capsule(Bowmans capsule):*parietal layer:lined by simple squamous epithelium.*visceral layer:composed of podocytes that have prominent G in cell body and primary processes,from which derive the secondary processes(pedicels),which contain numerous microfilaments and microt
11、ubules.2022-7-2515Mesangial cells:exist in the mesangial matrix where the basal lamina forms a sheath that is shared by 2 or more capillaries.Contain many kinds of enzymes and renin.Responsible for cleaning the basal lamina in the filtration membrane.2022-7-2516The Cap.of renal glomerulus are embrac
12、ed by interdigitating pedicels.The 25nm-wide spaces between the pedicels,the filtration slits,are covered by 6nm thick slit membranes that span the adjacent pedicels.*Bowmans spaces:the spaces between the 2 layers.Accommodate the pre-urine that comes from the filtration of the blood,contains a great
13、 amount of nutrients,and is about 150200 liters per day.2022-7-2517*filtration membrane(blood-urine filtration barrier):composed of endothelia,slit membrane and basement membrane,which is about 0.1 m thick and derives from the fusion of the basal laminae of capillaries and podocytes.Permeable for su
14、bstances whose molecule weight are less than 70 kDa.2022-7-2518Podocyte 2022-7-2519Renal corpuscleGlomerulus 2022-7-2520Functions of Renal corpuscle:Produce filtrate(primary urine)Filtration membranefenestrated endotheliumbasement membraneslit membrane of podocyte(filtration barrier)relevant factors
15、 of filtratemolecular weightcharges2022-7-2521Renal tubules:proximal convoluted tubulestraight tubulethin segmentdistal straight tubuleconvoluted tubuleHenles loops2022-7-2522Kidney contains numerous uriniferous tubules,which are composed of nephrons and collecting tubules.2022-7-25232022-7-2524Conv
16、oluted segments of proximal and distal tubules2022-7-2525Henles loop:consists of 4 segments.*thick descending limb:similar in structure to the proximal convoluted tubule.*thin descending limb:lined by simple squamous epithelium.*thin ascending limb:lined by simple squamous epithelium covered by acid
17、 T-H protein.Impermeable to water.2022-7-2526Thin segment and straight segment of distal tubule2022-7-2527*thick ascending limb:has similar structure to that of distal convoluted tubule.Thick ascending limb is impermeable to water.Sodium chloride is actively transported out of the tubule to establis
18、h the gradient of hypertonicity,which is crucial for urine condensation.2022-7-2528Renal tubules:proximal convoluted tubule:the crucial place for pre-urine re-absorption.Lined by acidophilic simple cuboidal epithelium and surrounded by the secondary Cap network of portal circulation.Cellular interlo
19、cks with each other result in obscure boundaries.Microvilli(brush border)are greatly developed.Well developed basal membrane invaginations and canaliculi,which locate between the bases of microvilli,play an important role in large molecule re-absorption.2022-7-2529Distal convoluted tubule:lined by s
20、imple cuboidal epithelium.Basal membrane invaginations,where exist numerous MT,are greatly developed.Responsible for ion exchanges(Na+,K+,H+,NH4+,etc.)that are regulated by aldosterone and antidiuretic hormone.The important place where osmotic pressure and pH value in body are adjusted to stable sta
21、tus.2022-7-2530Compared with DCT,the PCT have following characteristics:*Cells of PCT are more acidophilic.*Cells of PCT are larger and taller.*Cells of PCT have clear brush border.*Lumens of PCT are smaller.*More PCT can be seen in cross section.*Less cells and less nuclei can be seen in one PCT se
22、ction.2022-7-2531Collecting tubule and duct:Responsible for water re-sorption and urine drainage.1.Collecting tubule:Collects urine in distal convoluted tubule and join each to form collecting duct.2.Collecting duct:Lined by simple cuboidal epithelium in cortex and by simple columnar epithelium in m
23、edulla.2022-7-2532Cells of collecting duct have distinct boundary and clear cytoplasm,and the function of water re-absorption is regulated by ADH.2022-7-2533Straight segment of distal tubule and collecting tubule2022-7-2534Juxtaglomerular apparatus:Locate at vascular poles.1.Juxtaglomerular cells:De
24、rive from the smooth muscle fibers in the wall of afferent arteriole,where the inner elastic membrane disappears.Cells are cuboidal and slight basophilic,and contain rich RS and G.The secretory granules in cytoplasm are PAS(+)and contain renin,a hormone and also a kind of enzyme,which can regulate a
25、ldosterone release and can activate the angiotensin system to elevate the blood pressure.2022-7-2535Juxtaglomerular cell2022-7-25362.Macula densa:A group of cells that derive from the distal convoluted tubule cells.Cells of macula densa are columnar and have nuclei in their apex of cytoplasm,and the
26、ir basal laminae are incomplete.Sensitive to mineral level.Send signals to the adjacent juxtaglomerular cells to facilitate the renin release when Na+level in urine decreases.2022-7-2537Macular densa 2022-7-25383.Extraglomerular cells:Locate between macula densa and Bowmans capsule.Have gap junction
27、s with mesangial cells and juxtaglomerular cells.May secrete erythropoietin.2022-7-2539Juxtaglom-erular apparatus2022-7-2540Characteristics of blood supply in kidney:1.High blood pressure:The kidney arteries directly derive from aorta,and the efferent arteriole is thinner than afferent arteriole.2.K
28、idneys consume about 1/4 1/5 of the whole blood volume.3.Portal circulation and parallel Cap.2022-7-2541Blood vessels of kidney2022-7-2542Micturition organs(ureter,bladder,)mucosaEpi:transitional EpiLamina propria:L.C.T.muscle layer:smooth muscle adventitia:fibrosa serosa2022-7-2543Urinary bladder:L
29、ined by transitional epithelium.The middle layer of bladder is much thicker,and adventitia is CT but serous membrane covers its upper part.2022-7-2544Bladder 2022-7-2545Ureter 2022-7-2546Overview nWhat is the structure of a nephron?nDescribe the relationship between the structure of renal corpuscle
30、and the formation of filtrate(original urine).nCompare the morphous and structural characteristic of each part of renal tubules with that of collecting tubules,and discuss about their main functions.nHow many structures does the juxtaglomerular apparatus consist of?What are the morphous and structural characteristics of each structure?nWhat are the common structural characteristics of the passages for excretion of urine?2022-7-2547See you
