组织胚胎学课件 七年制英文医学班专用 中国医科大学 基础医学院 组胚 — 英文教学组

Chapter 17 Urinary System

1. Components ---kidney : produce urine ---ureters ---bladder -cavity organs, conduct, store and ---urethra remove the urine ---functions: remove waste products of metabolism regulate the homeostasis secrete some bioactive factors- renin, erythropoietin

*cavity organs: mucosa: /epi-transitional epi /lamina propria muscularis: SM adventitia: CT

2. Kidney ---bean-shaped, 10-12cm in length, 5-6cm in width, 3-4cm in thickness ---hilum: BV, LV, N and ureters enter or out *renal pelvis: funnel- shaped expension of upper end of ureter *calyx: branches of renal pelvis

1) General structure: ---capsule: DCT ---cortex: dark stained /medullary ray /cortical labyrinth ---medulla: slight stained /renal pyramid /renal columns /renal papillae: -minor calyx -major calyx -pelvis

*renal lobe: one renal pyramid and its bounding cortical tissue *renal lobule: renal tissue including one medullary ray and cortical tissue surround it

According to function, renal parenchyma is mainly consists of uriniferous tubules ---parenchyma: /uriniferous tubules= renal tubule+ collecting tubules /renal corpuscle =glomerulus + renal capsule(beginning part of renal tubule) /nephron=renal corpuscle + renal tubule ---interstitium: CT, BV, N

2) Nephron: structural and functional unit, 1,000, renal corpuscle: cortical and juxtamedullary nephron /renal glomerulus: /renal capsule ---renal tubule: /proximal tubule: -convoluted portion -straight portion /thin segment /distal tubule: -straight portion -convoluted portion

① renal corpuscle: spherical, 200um in D, two poles: vascular pole and urinary pole ---glomerulus: afferent arterioles→capillary network →efferent arterioles *capillary network: /endothelial cell: pore, nm, no diaphragm /basal lamina: 330nm

*intraglomerular mesangium: /mesangial cell: -small, irregular, with processes -small dark N -EM: RER, Golgi, lysosome, phagocytic vesicles, cytoskeleton-MF, MT,IF and secretory granules -functions: i. produce ground substance ii. phagocytosis iii. contract iv. secrete renin and enzymes /matrix: -type IV collagen -glycoprotein: sulphate chondritin, heparin and dermatan

---renal capsule: two layers capsule – formed by beginning part of renal tubule which is enlarged and invaginated /parietal layer: simple squamous epi. /visceral layer: podocytes /renel capsular cavity: the space between two layers

cells with many processes ( primary and secondary processes-foot processes) Foot processes: interdigitated with each other and embraced the capillaries, slit pore: -narrow intercellular space between foot processes -25 nm, with 4-6 nm diaphragm-slit membrane *podocyte :

---function: produce filtrate by filtration

* filtration barrier or membrane: the structure for filtration is called filtration barrier or membrane, including: fenestrated endothelial cell: negative ions basal lamina: type IV collagen, proteoglycan, laminin-negative ions (sulphate heparin) slit membrane-nephrin(size selective filter: negative ions

② renal tubule: a. proximal tubule: 50-60um in D, 14 mm long ---structure LM: EM: pyramidal cuboidal eosinophilic round N brush-liked border - microvilli(apical canaliculi) longitudinal striation- plasma membrane infolding no clear boundary - lateral extension (rich in Na + K + ATPase)

Proximal tubule

---Function: i. reabsorption : -85% Na + ions and water -All of glucose, aminoacid, polypeptide, proteins and vitamin -50% bicorbonated salt and sulphate salt ii. secrete H +, NH 3, hippuric acid and creatinine

b. thin segment: /10-15 um, simple squamous epi, /facilitate the passage of water and ions /reabsorb Na + and Cl - and 5% water

c. distal tubule: ---structure: LM: EM: cuboidal slight-stained round N no brush-liked border – less microvilli well-developed longitudinal striation – plasma membrane infolding

Distal tubulePlasma membrane infolding

---function: i. reabsorption of 8% water, Na + ions ii. excretion of K +, H +,NH 3 iii. regulated by aldosterone(adrenal gland) and antidiuretic hormone (vasopressin) (pituitary gland)

3) collecting tubule : arched collecting tubules cortical collection tubules medullary collection tubules -simple cuboidal epi. to simple columnar epi. -slight – stained -have clear boundary -reabsorb 4% water

4) juxtaglomerular complex 极周细胞

a. juxtaglomerular cell: ---a groups of modified SM cell of afferent arterioles ---structure: -larger, cuboidal in shaped, with round N -contain secretory granules ---function: i.secrete renin→adrenal gland→aldosterone→blood pressure↑ ↑ angiotensinogen→angiotensin I→angiotensin II→contraction of SM of BV ii. secrete erythropoietin to promote erythropoiesis

b. macula densa ---a group of cells derived from epi. of distal tubule ---cell becomes taller, narrow, with round N apical part arranged ---cells have processes connecting with other cells ---function: chemoreceptors- feel the Na+ ions concentration

c. extraglomerular mesangial cell(polar cushion cell) ---similar to intraglomerular mesangial cell ---transfer the information d. peripolar cell ---structure: EM: -microvilli -junctional complexes -RER, Golgi, and granules ---function: regulate the reabsorption and secretion of renal tubule

5) renal interstitial: CT ---fibers: type I,III,IV collagen ---matrix ---cell: fibroblast macrophage lipid-laden interstitial cell: -stellate cell with processes -osmiophilic lipid droplets: -function: i. involve in formation of F and matrix ii. secret prostaglandin

6) Blood supply to the kidney i. Very large blood flow (1.2L/min) ii. To form cap.two times iii. Glomerular cap. have a high blood pressure iv. Form vasa recta loop near medullary loop v. More larger blood flow in renal cortex

Interlobar arteries → Arcuate arteries →Interlobular arteries →Capsular cap. ↑ ↓ ↓ Renal artery Afferent arterioles Afferent arterioles ↓ ↓ Juxtamedullary nephron Cortical nephron glomerulus glomerulus ↓ ↓ Efferent arterioles Efferent arterioles ↓ ↓ Vasa recta(artery and vein)← Capillary network Capillary network ↓ ↓ ↓ Renal vein←Interlobar vein← Arcuate vein ← Interlobular vein ← Stellate vein