Unit 19-3 Renal Physiology

UN 19-3 apsa RENAL PHYSIOLOGY Date STRUCTURE OF KIDNEY & ITS FUNCTIONAL UNIT:- → The Kidneys aree a pair of been shaped organs located peritonicum & posterior Jour above the wayt brwn the wall of abolomen hence also called rectroperitoneal. Structurce Guternally the Kidneys The outermost layere arce durcrounded by three layere y a thin layere of dense inregulate connective tissue caved renal fascia, the middle layer. the adipose capsule is a mass of fectly tissue surcrrounding recnal capsule, the deep layere, the renal capsule that cornet continuous with the vetere cocet wrectere nephreon fenal Ven Renat Renal pymancus Rensel perver peedulla ureter Loreten Renal faria hau 3 regions - an ovetere coreten, Interinally, the kidney a medulla in middle & the reenas pelvis in the region called nicern of Kidney. → the hiturn is the concave pares wheree blood reuels & nerves entere & met the kidney; it is also the point exet fure vleray Gala → The rencee Medusa conseils of severas come reonal Pyramids called reenal columns. en btwn the pyrtareide shaped arce spares + The Henal coreten & reenal pyramid of renal Nenal medulla or functional poretion y constiterte the parcen cryma the Kidney. within the parenchyma arre functional writ ca of kidney cacccd nephrions + Filtreats freemed by nephrions drrains into large papivary ducts which then drecken into menore & majore calyces. ceep like streercteurce Called 7. From the majore calycer vreire drains into singer lange cavity called reenal pelvis then out thrice the wreetere to the vienancy bladdere. T Bloud & Nerve supply of kidneys Renal blood supply starels with the brearching of aoreta into renal arteries & ends with the exiting of the Henal veins to join inferiors rena lava. the renal centercess spect is to several segmental arteris upon entering kidneys. ento several interedo bare - Each segmental artery further sprits int arteries & enter ine renal culcerens. T + The intersebar arteries sprit at the junction of real conten I needewa to forery arccuate arteries. → Contical radiate arteries. Kadiate out. y ancurate antercies. A enter resal conten here they give of card afferrent anteriores. branches → Each nephrion receives one ints a offerrent acterciolo which divides tangled bell shaped capillary network called jerues. The glomerular capillaries then reunite to forem fjerrent arteriole. → the efferent arterides divide to forem peritubulare capillaries. long, loop Entending from some efferrent artercioles are Shaped capillaries called vasa recta. → the perirubular capillaries eventually recenice to forem Coretical radiate reins which receive $100 of friem vaja Then bloved drains. Three the armate vein to interciobare vein A Bloud leaves the Kidney infercion vena cava. three a singee kenal vein to The NEPHRON:- → Nephrom arce ou functional unit If kidneys. Each nephrion consists of 2 parets :. s: a renal where blood ploumice is fierered a a rende tubule ents which the filterceof feuid paves. → the renal renal corepurele i made up of a networks of capilaris (nown as glomerulas & the доменишан capsule ore Bowmans capsule. → the Hendel rebule conseits of (1) Proxeyal convoluted tubelle (PLT) (2) 1000 y hente & (3) deital convoluted tubule. → The DCT connects & empties its conntenes into collecting duct' apsara Date → The firat Paret y the roop of henee begins is the renal conten I intends downward into renal meduun called the descending loop of hence → It then makes that hairpes euren reeturers to reenal conten where it terminates at the DCt known as asceno limby loup of leish ascending → there are two types of nephrions -which arce Coretical nephrons deep in the renal corten & juntareduciary nephrion which sie in renal coreton close to redusa Affercent anteriols → efferrers anteriore cap Desteel convoluted PET → collecting dent Descenden -Ascending Lineb Capillary Network within the Nephron The capillary network that originates from the renal arteries supplies the nephron with blood that needs to be filtered. The branch that enters the glomerulus is called the afferent arteriole. The branch that exits the glomerulus is called the efferent arteriole. Within the glomerulus, the network of capillaries is called the glomerular capillary bed. Once the efferent arteriole exits the glomerulus, it forms the peritubular capillary network, which surrounds and interacts with parts of the renal tubule. In cortical nephrons, the peritubular capillary network surrounds the PCT and DCT. In juxtamedullary nephrons, the peritubular capillary network forms a network around the loop of Henle and is called the vasa recta. 9. URINE FORMATION Urine is one of the body's waste products It's primarily composed of waters and urea. Urea is a special nitrogenows waste compound that the body. must routinely Kidney in three stages: utinely nemo Urine formation occurs in the Upine Formation Glomerular filtradion ↓ Selective filtration Tubular filtration Glomerular filtration: This takes place through the semi-permeable walls of the capillaries and Bowman's capsule. The afferent arterioles supplying blood to glomerular capsule cappies useful as well as harmful ane glucose, Jions amino substances. The useful substances acids, vitamins, hormones, electrolytes, ions ele and the harmful substances are metabolic wastes such as upea, uric acids, creatinine, ions etc. The diameter of efferent asterioles is nabbower than afferent arteriales. Due to this difference in diameter of arteries, blood leaving the glomerulus creats the pressure known as hydrostatic pressure.) pellaby hydbertadic The glomerulus hydrostatic pressure forces the blood to leaves the glomerulus, resulting in filtration of blood. A capellany hydrostatic pressure of blood of about 45 mmHg (GHP) builds up in the glomerulus. However this pressure 18 opposed by the osmotic pressure of the blood, provided mainly by plasma proteins, about 25mmHg in the glomerulan capsule.) The net filtration pressure is: Therefore; 45-(25+10)=10 mmHg) By the net filtration pressure of 10mmHg, blood is filtered in the glomerular capsule.) Water and other small molecules readily pass through the filtration slits but blood cells, plasma proteins and other lange molecules are too lange to filter through and therefore pemain in the capillaries The filtrate containing lange amount of wate glucose, amino acids, uric acid, urea, electrolytes etc in the glomerular capsule is known as nephrie filtrate of glomerular fittate. Selective reabsorption: As the fitoate passes to the benal tubutes, useful substances including some water, electrolytes and onganic nutrients such as glucose, amino acids, vitamins, hormones elc are selectively reabsorbed from the filtrate back into the blood in the proximal convoluted tubule. tubule. Water is roabsorbed by osmosis, and small proteins are reabsorbed by pinocytosis. Reabsorption of some substance is passive, while some substances are actively transporated. Major portion of water is neabsorbed by Osmosis. - Only 60-70% of filtrate reaches the Henle loop. Much of this, especially waters sodium and chloride, is reabsorbed in the loop, so that only 15-20% of the original filtrate reaches the distal convoluted tubule, More electrolytes are absorbed here, especially sodium, so the filtrate entering the collecting duats is actually quide dilute) ③ Tubular secretion: Tubular secretion -lakes place from the blood in the peritublas capillabies to the filtrate in the renal tubules and can ensure that wastes such as creatinine or excex Ht on exeers k+ ions are actively secreted into the filtrate to be excreted. Excess kt ions is secreted in the tubules and in exchange Nat ion is reabsorbed otherwise it causes clinical condition called Hyperkalemia. a Tubular secretion of hydbogen ions (HT) is very important in maintaining normal blood pH. Substances such as, e.g. drugs including penicillin and aspirin, may not be entirely filtered out of the blood. Because of the shoot time it bemains in the glomerulles. Such subtanees abe deared by secretion from the penitubular capillabies into the filtrate worthin convoluted tub the co tubules. The tubular filtrate is finally known as upine. Human urine is usually hypertonic ting enal REGULATION OF WATER BALANICE The he regulation of water balance by the vital homeostatic proces ensuring that Kidneyı is watere intake matiner output to Maintain plasma osmolality & blood volume. Key Mechanines of Renal water regulation → Renin-Angiotensin - Aldostertone Syetem→ → when blood volume & presscence decreases, the cell secrete enzyme renin suntaglomerule + Renis converels angiotensin I to angiotensis ! Angiotensin in offices reencel physiology in 3 ngoais ways: It decreases the glomerular filtre filtriation rate Enchances reabsorption of wat of watere is PCT It sti meelates adrenal corten to reelocje aldosterone Which increase Na reabsoription & watert follows by Osmoses (2) Antidiuretic Horemore→ ADH stimulates the insection of a woetere leve channel prozein cand equaporin 2" into the apical membrane via -As a result the watere poraceability of principal cuis apical меньнaчe increases ③ Atrial Natriuretic peptide→ T A lange increase in bloot rolence promotes release of ANP from heart. →91 car inhibit reabsorption y wat I watere → Increase urine output & diureesis) Date ④ Counter Clevercent Mechanism → 200p y Hente creates an osmotic gradient with conc. increasing freom corten to redeuna → Vasa recta prevent the washout of Neduscany gradient. The dy crables the body to produce righly concentreat ef Ureene to conserive water. +9+ Maintains the Medusa righ sals conc, vital fore reabsorbing watere from conecting duct. * REGULATION OF AID BASE BALANCE The Kidneys pray a Mayore Hole in maistaising acid-base balance by requeracting tit cons & bicarbonate. Reabsorption of Bicarbonate (Hlo₃) of 80-90% 7 bicarbonate reabsorption occures in Per + Filtered bicarbonate cannot be dèrrectly reccabsorbed Ht es sete se creeted into reebelare cumen This ions combine with bicarbonate to forcer carebonic aid which then converted to cubon dioxide & water catalysed by carbonic anhyolerease.. H+ + HCO3 H2103 102 + H20 Carsonic Coz diffumes across the merebriane back to rubulare epithial cels. Cl2 recombines with intricacumular watere to reejoreng carbonic acid which then dissociates into Ht H returns to blood. T Date Secretion ② excretion of Hydrogen ions To countercant acidosis (low bloed pH) reenal tubulare cutirely transporet H ^ + from blow of into Rubulare Luyen beeping maistais noreyal blood PH. Primarily ccurs in DCT 3 collecting ducts As dihydrogen phosphate H^ + +HPO 4 ^ 2- (H_{2}*P*O_{4})/V which i ix creed by urrine As Ammonia N*H_{B} +H^ + + Ammoniun ③ generation of New Bicarbonate→ - Occurs when H ^ + dot e_{1} excreted as Titratable cecid ephosphate) ore NHyt Each pi ^ + excreted results in I new Hloz in added to b1000%. Detal tubule / collecting deils Regulation: 2-intercarcated cells which gets activated during acidosis secrete f * t ^ t into tubulare semen & reeabsored Hlog into blood. - $-istercarlated cem activats. devring alkalosis decrete Hoog isto lumen & reabsons itt is to blood sara Date * HOMEUSTATIC REGULATION OF TUBUAAR REABSORPTION 주 SECRETION PCT Most Solute reabsorption in PCT Invoires Neat, treansporet occurs ria Symporet & arteporet Mechanism in PCT. → Picterced geucate, arrino acids arce + I watere-soluble vitamins. completely reabsorbed in the ist hay of PCT by deverial types q Nat Symporeteres located in apical membrane- + one such symporeter the Nat Nat-geucose symporciere which 2 vat & a Molecule of glucose attach to segmporitere porcte preotein which carencies them to grlstein from tubulare fluid to tubule cell, the glucose then diffuse into percitubulare cupillaries. → In another proces, the wat - Hit antipornters carry filtered Nat clown its lonc gradient into put cell as It is reemered from cytosol to lumen, ecuring rat to be reabsorbed & Ht to be secreted into tubulare fund. + Solute reabsorption on PCT tebelles promotes osmosis of water. water the more rapidly from usulan tenid bito percitubulare capiuaries 4. & restores osmotic balance. In second noey of PCT, rons et son es present → A water leaves tubular fecid conc. y remaining fieterced Soleuses increases. ce blong tre highest conc.. Diffusion of ce into interstitial fluid potemptes passive + 2+ Heabsorption of cations such as 1st, cast & negat Inloop of Hence t → The hepsion toop reeabsorebs about 15% of filterceof Water 2s - 3i . og fictered Nat & 1st, 35% of filterceaf ce X → the apical Meaubriane of ceus in ascending limb of nephrion loop have w * u ^ - 1 * c ^ - 2 * c u^ - dymporetents Is that Meclaim 1N a^ + 1 st & 2 ce from freeid into tubuwer lumen. → Nat diffuser into vasa recta, c e^ - into raste interestite feuid then into vasa recta, Kt Mover down its Coner greadient back to tubulare fluid. T 27 The Movement of kt ents tubulare fluid leaves intenssita teeid & blood Morce -ve charges hence promotes reabsorption of cations - C a^ + , k ^ + , e * q ^ 2 * t & Ng2t. 15% of filterced water is reabsorbed in afescending loop but no water is recabsorbed in cescending cimo ③ In DCT 7_Collecting duct → 37 → The early paret of DCT Meabsorption of Nat & ce ette occurs by Nat-ce dymponteres in apical Membrane into percitubular capillaries. Preis cipal cens & interecalated ces preesent at the late part of DCT. The principal cells reabsored Nat & The intercalated ces Co Secrete st absored Heo & secrete Ht