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1、CMUUrinary System2024/7/312General outline component urinary organs: kidneysmicturition organs: ureter, bladder and urethra function discharge metabolite regulate the balance of water and electrolyte endocrine function: renin, erythropoietin, prostaglandin2024/7/313KidneyGeneral structureEach kidney
2、 has a 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.2024/7/314Renal anatomic structure Fibrosa Pare
3、nchyma Cortex Cortical labyrinthMedullary rayMedullaRenal pyramidsRenal columns2024/7/315Cortex: 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, whos
4、e bases radially send out the medullary rays that separate the cortex into cortical labyrinth.2024/7/316Renal cortexRenal medulla2024/7/317Renal histological structure nephronRenal corpuscles collecting duct juxtaglomerular apparatusRenal tubulesGlomerulus Bowmans capsule2024/7/318Nephron: About 14
5、million per kidney.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
6、important role in the formation of hypertonicity circumstances in kidney.2024/7/319Renal 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 proxi
7、mal convoluted tubule leaves the corpuscle.2024/7/3111Structure of Renal corpuscle:Glomerulus afferent arteriolecapillary networkmesangial cellsefferent arterioleBowmans capsuleparietal layer: simple squamous Epi.capsular cavity: filtratevisceral layer: podocytes(primary and secondary processes, sli
8、t membrane)2024/7/3112Renal corpuscle2024/7/3113renal 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 mesangium. 2024/7/3114glomerulus capsule (Bowmans capsule):
9、 * 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 microtubules. 2024/7/3115Mesangial cells: exist in
10、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.2024/7/3116The Cap. of renal glomerulus are embraced by interdigitating pedicels. The 25nm
11、-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 amount of nutrients, and is abo
12、ut 150200 liters per day.2024/7/3117* 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 substances whose molecule w
13、eight are less than 70 kDa. 2024/7/3118Podocyte 2024/7/3119Renal corpuscleGlomerulus 2024/7/3120Functions of Renal corpuscle: Produce filtrate (primary urine) Filtration membranefenestrated endotheliumbasement membraneslit membrane of podocyte(filtration barrier) relevant factors of filtratemolecula
14、r weightcharges2024/7/3121Renal tubules:proximal convoluted tubulestraight tubulethin segmentdistal straight tubuleconvoluted tubuleHenles loops2024/7/3122Kidney contains numerous uriniferous tubules, which are composed of nephrons and collecting tubules.2024/7/31232024/7/3124Convoluted segments of
15、proximal and distal tubules2024/7/3125Henles 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 T-H protei
16、n. Impermeable to water.2024/7/3126Thin segment and straight segment of distal tubule2024/7/3128Renal 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.
17、Cellular interlocks 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. 2024/7/3129Distal convo
18、luted tubule: lined by simple 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 valu
19、e in body are adjusted to stable status.2024/7/3130Compared 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
20、 and less nuclei can be seen in one PCT section.2024/7/3131Collecting 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
21、in cortex and by simple columnar epithelium in medulla. 2024/7/3132Cells of collecting duct have distinct boundary and clear cytoplasm, and the function of water re-absorption is regulated by ADH.2024/7/3133Straight segment of distal tubule and collecting tubule2024/7/3134Juxtaglomerular apparatus:
22、Locate at vascular poles.1. Juxtaglomerular cells: Derive 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 reni
23、n, a hormone and also a kind of enzyme, which can regulate aldosterone release and can activate the angiotensin system to elevate the blood pressure.2024/7/3135Juxtaglomerular cell2024/7/31362. Macula densa: A group of cells that derive from the distal convoluted tubule cells. Cells of macula densa
24、are columnar and have nuclei in their apex of cytoplasm, and their 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.2024/7/3137Macular densa 2024/7/31383. Extraglomerular cel
25、ls: Locate between macula densa and Bowmans capsule. Have gap junctions with mesangial cells and juxtaglomerular cells. May secrete erythropoietin.2024/7/3139Juxtaglom-erular apparatus2024/7/3140Characteristics of blood supply in kidney:1. High blood pressure: The kidney arteries directly derive fro
26、m aorta, and the efferent arteriole is thinner than afferent arteriole.2. Kidneys consume about 1/4 1/5 of the whole blood volume.3. Portal circulation and parallel Cap.2024/7/3141Blood vessels of kidney2024/7/3142Micturition organs(ureter, bladder,) mucosaEpi: transitional EpiLamina propria: L.C.T.
27、 muscle layer: smooth muscle adventitia: fibrosa serosa2024/7/3143Urinary bladder: Lined by transitional epithelium. The middle layer of bladder is much thicker, and adventitia is CT but serous membrane covers its upper part.2024/7/3144Bladder 2024/7/3145Ureter 2024/7/3146Overview nWhat is the struc
28、ture of a nephron?nDescribe the relationship between the structure of renal corpuscle 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?2024/7/3147See you
