c518230a-d48c-4d0b-b3d6-f151b39c0e3c_Urinary_system

Urinary system 1 Urinary system Definition major excretory sytem. a system→ cleanse body of waste products Composed of: structure Kidneys Gross anatomy of kidney retroperitoneal→ at superior lumbar region Bean shaped sized → tightly clenched fist Urinary system 2 Right kidney is lower than left; run from → T12 → L1to l3 right=lower due to right lobe of liver 12.5 cm long, 6cm wide, 2.5 cm thick weight =150g each kidney External anatomy Renal capsule → wraps kidney, Renal Fascia or Gerota's fascia→ wraps fat/adipose tissue in kidney Pepinephrine fat Renal Hilum found→ medial side of each kidney renal artery and nerves enter→ kidney Renal vein, ureter, lymphatic vessels exit→ kidney Internal anatomy and histology Kidneys = divided into two major regions Renal cortex-outer layer Contains nephrons (nephrons= structural, functional unit of kidneys, WHERE URINE IS FORMED) urine collected→ empy into calyx → renal pelvis → ureter calyx funnel shape → surround tip→ each pyramid renal calyces converge= Renal pyramids NEPHRONS functional unit → kidney each kidney = aprox→ 1.3m nephrons 5 to 10 % lost when aging Each nephron consist of: renal corpuscle filtration portion of nephron Urinary system 3 Bowman capsule Enlarged end→ nephron→ serves a double walled chamber Inner layer Podocytes(foot process)= Specialized cells → wrap → glomerular capillaries (glomerulus) Filtration slits= filtered blood(filtrate)→ exit outer layer Simp Sq Epithelial cells Glomerulus (glomerular capillaries) tuft→ capillaries lies within bowman capsule surrouned by foot process (podocytes=has ability to diameter of glomerulus) afferent arteriole Supplies blood → glomerulus→ for filtration efferent arteriole move filtered blood→ away from glomerulus Filtration membrane juxtaglomerular apparatus juxtaglomerular cells cuff specialized smooth mscl cells→ afferent arteriole enters renal corpuscle pressure in afferent arteriole= changes in production of Juxtaglomerular cells Urinary system 4 surround wall → afferent arteriole&distal convoluted tubule release hormone renin= help control BP,filtrate formation macula dense lies btwn afferent, efferent artrioles, next to→ renal corpuscle sensitive→ sodium, help production→ renin area where filtration happens 1. endothelium of glomerular capillaries 2. podocytes 3. basement membrane process of filtration 1. Blood Enters the Glomerulus Blood flows into the glomerulus (a network of tiny capillaries) through→ afferent arteriole→ pressure = high→ helps push fluid out of the blood. 2. Filtration Membrane The filtration membrane three parts: Capillary walls A basement membrane Podocytes 3. Filtrate Formation The pressure pushes fluid. These small substances form a fluid Urinary system 5 called filtrate, which collects in the Bowman's capsule. 4. Filtered Blood Leaves Blood cells, proteins stay in blood → leave through → efferent arteriole. 5. Filtrate Moves On The filtrate (now the start of urine) flows into the kidney tubules for further processing. renal tubules Proximal convuluted tubule Loop of henle Thin&thick descending limb Thin&thick ascending limb distal convuluted tubule collecting ducts COllerton urine, coming from distal convuluted tubule (pink=simp cubiodal epithelium→actively transport molecules, ions) (green= Simp Sq epithelium→ water&solutes pass through walls by diffusion) 2 types of nephrons (based on extensions→ loop of henle) Cortical nephron 85% of nephrons→ kidney loops of henle= not extend→ medulla Juxtamedullary nephron Urinary system 6 15% of nephrons → kidney loops of henle= extend → medulla Renal medulla-inner layer 5-12 renal pyramids Cntains tubules cone shaped based located→ boundary bw cortex & medulla apex projected → towards center → kidney Blood flow to the kidneys (R.I)(A.I)(A.G.E.)(P.V.I.)(A.I) 1. Renal artery 2. Interlobar artery 3. arcuate artery 4. interlobular artery 5. afferent arteriole 6. glomerulus 7. efferent arteriole 8. peritbular capillaries 9. vasa recta (specialized portion deep into medulla, surrounds Loop of henle&conducting ducts 10. interlobular vein 11. arcuate vein 12. interlobar vein Ureters definition Trans epithelium Small tubes, carry urine→ renal pelvis to postrior inferior portion (urinary bladder) Urinary system 7 Urinary bladder definition Hollow muscular container, lies in pelvic cavity(stores urine) holds max of 1000ml of urine 30ml per hrs excreted, in 4 hrs 30x4=120ML First urge 150mL, 2nd urge 350 mL transitional epithelium (stretched= SQUAMOUS CELLS) Trigone (IMPORTANT STRUCTURE) Non contractile (steady and funnel) traingle shaped portion located bw→ opening of ureters & urethra Urethra Definition Tube, carries urine→ urinay bladder to outside (urine,semen=one duct) Males: 20cm, extends → end of penis (diff ducts) Females: 4cm, opens → into vestibule(anterior to vaginal opening) Internal urethral sphincter Definition at the junction→ urinary bladder & urethra prevents urine leakage from urinary bladder males: keep semen from entering the urinary bladder(during sex) Parasym,involuntary External urethral sphincter definition skeletal muscle→ surrounds the urethra allows person→ voluntarily start or stop → flow of urine Cerebral cortex Urinary system 8 Functions of the urinary system Excretion Kidneys remove waste products from blood products = cell metabolism substances in intestine Regulation→ Blood volume, pressure kidneys=Controlling → ECF volume through urine production regulation → concentration solutes in blood major molecules ad ions, → glucose, Na+, CL-. K+ Ca2+, HCO3, HPO4 2Regulation→extracellular fluid pH kidneys= excrete variable amounts →H+ to regulate blood pH Regulation→ RBC synthesis kidneys=secrete eythropoietin→ RBC synthesis regulation→ VIT D synthesis kidneys=In turn, VIT D→ control blood levels→ Ca2+ URINE FORMATION (PHYSIOLOGY) sorting→ substances from blood→ removal or return to blood takes place in NEPHRONS 3 major processes Filtration mvmnt→ materials→ across filtration membrane into bowman capsule → form filtrate Definition passive process- remove excess fluid,waste products→ out of blood→ into collecting tubules→ kidney nonselective process; mats separated by size or charge driving force: BP(glomerular capillary pressure) Urinary system 9 21% cardiac output sent→ kidneys= filtration 180L filtrate a day→ 1% becomes urine filtration pressure incr filtratrion pressure INCR filtrate volume, urine volume pressure gradient → filtrate formation forces fluid→ from glomerular capillary→ bowman capsule pressures glomerular capillary pressure(greater than capsular pressure&colloid osmotic pressure) blood pressure within glomerulus move fluid from blood into bowman capsule support filtration Capsular pressure pressure inside bowman capsule moves fluid from capsule into blood opposes filtration colloid osmotic pressure produced→ concentration → blood proteins (common:Albumin) moves fluid from bowman capsule into blood by osmosis regulation of filtration ANS also has part in regulating filtration BP→ within glomerular capillaries→ fairly constant sympathetic stimulation: constriction→ renal arteries→ DEC bloodflow& filtrate formation→ DEC urine formation ex: circulatory shock or intense exercise Urinary system 10 tubular reabsorption Definition selective, active process→ reAb→renal tubules 99%→ orginal filtrate volume→ ReAb, enter peritubular capillaries solutes reabsorbed→ areas of tubules→ process of osmosis Areas of tubulues Proximal convuluted tubule primary site→ solute,water ReAb reabsorbed Proteins,amino acids, glucose, fructose molecules, NA+, K+ Ca2+, HCO3-, Clwater 65% filtrater volume→ reAb (by osmosis) Descending limb(hoop of henle) further concentration of filtrate osmosis some solutes by diffusion 15%ofwater filtrate is reAb Ascending limb (hoop of henle) tries to dilute → filtrate (removing remaining solutes) thin segment→ (-) water, (+) solutes , simple diffusion thick segment→ (-water), actively transport Na+ Distal convoluted tubule& collecting duct:water and addtional solutes and additiona solutes (na+, Cl-) from filtrate Reabsorption → controlled→ ADH& ALDOSTERONE Tubular secretion solutes secreted→ wall of nephrons into filtrate remove toxic substances form blood Urinary system 11 excess ions, unwatned substances (metabolic waste) ← FOR ELIMINATION Ex: ammonia(toxic) diffuses into lumen of nephron= H+, K+, creatinine, histamine, penicillin removal by active transport REGULATION OF URINE CONCENTRATION AND VOLUME kidneys (change contentration → body fluids INC body fluid concentration→ inc water Reab→ Small Vol (concentrated urine)→ solutes lost, water conserved→ DEC body fluid concentration DEC body fluid concentration→ DEC water reAb→ large vol (dilute urine)→ water lost, solutes conserved→ INC body fluid concentration Influenced by 3 major hormonal mechanisms RENIN-ANGIOTENSIN-ALDOSTERONE MECHANISM sensitive→ changes→ Bp initiated→ low bp conditions angiotensin II (acts on adrenal gland) can also vasoconstriction Dec BP→ cells of JGA→ renin, Liver→ Angiotensinogen→ renin converts angiotensinogen→ angiotensin I→ ACE(from lungs) → converts AGN I → angiotensin II→ stimulates adrenal cortex → secrete aldosterone→ inc ReAb→ Na+ Cl-, in DCT& collecting ducts→ water follows→ inc BV,BP ANTIDIURETIC HORMONE(ADH) mechanism sensitive → changes→ blood concentration stimulated by high blood solute concentration How it is stimulated? Urinary system 12 increase in solute concentration of blood→ AP (hypothalamus)→ stimulates secretion→ ADH in Posterior pituitary gland ADH activity increase permability of DCT& collecting ducts to water EFFECT: more warter is ReAb from filtrate kidneys produce small vol → concentrated urine ATrial natriuretic hormone sensitive→ changes in BP triggered→ increased BP secreted→ from cardiac muscles cells (IN RIGHT ATRIUM) when pressure in R.A is abnormal acts on kidney→ DEC→ Na+ ReAb→ water moves(osmosis) → into nephron toward Na+→ INC urine vol→ DEC BV&BP FLOW OF URINE Papillary ducts empty urine → calyces→ ureter PATHE OF URINE DRAINAGE (C.P)(M.M) (R.U.U) 1. Collecting duct 2. Papillary duct 3. minor calyx 4. major calyx 5. renal pelvis 6. ureter 7. urinary bladder Urinary system 13 MICTURITION REFLEX (URINARY REFLEX) Activated→ stretch→urinary bladder wall physiology urinary bladder fills with urine→ pressure INCR→ stimulate stretch receptors in bladder wall→ AP from urinary bladder→ pelvic nerves→ S.C(sacral portion)→ integration of reflex→ AP → conducted along parasypathetic nerve fibers→ urinary bladder→ urinary bladder contract role of higher center in brain? inihibition of micturition sending APs through S.C→ DECR→ intensity of autonomic reflex→ stimulates urinary bladder contractions→ and stimulate nerve fibers→ keep external urethral sphincter contracte→ prevent micturition FACTS ABOUT MICTURITION REFLEX Age 2-3 years→ age when u can control or stop micturition voluntary initiation→ micturition→possible→ when cebrum send AP→ voluntarily relax→ external urethral sphincter voluntary contraction→ abdominal muscles→ INCR abdominal pressure→ embraces micturition reflex CHARACTERISTICS OF URINE in 24 hrs, 1.0-1.8 L (urine)= produced yellow color= pigment urochrome(from destruction→ HGB&solutes) strile slightly aromatic normal pH→ around 6 (presence of hydrogen) Solutes normally found in urine 1. sodium, pottasium ions 2. urea,uric acid, creatinine 3. ammonia 4. bicorbonate ions Solutes not normally found in urine 1. glucose (large molecules) 2. blood proteins Urinary system 14 5. hydrogen 3. RBC (trauma to any part of urinary tract) 4. Hemoglobin 5. WBC(pus) (possible infection) 6. Bile specific gravity (measures concentration of urine) 1.001→ 1.035 High gravity= very concentrated (decrease water content) vice versa if low gravity