Urinary System Notes PDF

The Urinary System functions of urinary system anatomy of kidney urine formation – glomerular filtration – tubular reabsorption and secretion – water conservation urine and renal function tests urine storage and elimination 23-1  Waste Pro...

The Urinary System functions of urinary system anatomy of kidney urine formation – glomerular filtration – tubular reabsorption and secretion – water conservation urine and renal function tests urine storage and elimination 23-1  Waste Products & Kidney Function metabolism creates toxic waste products urinary system – main way to remove wastes kidney functions: – regulate blood volume and pressure, erythrocyte count, blood gases, blood pH, and electrolyte and acid base balance urologists – treat both urinary and reproductive disorders (esp. in men) 23-2  Urinary System Diaphragm Adrenal gland Kidney Ureter Urinary bladder Urethra (a) Anterior view (b) Posterior view urinary system consists of 6 organs: 2 kidneys, 2 ureters, urinary bladder, and 23-3  Functions of the Kidney filters blood plasma, separates waste from useful chemicals, returns useful substances to blood regulates blood volume & pressure by eliminating or conserving water regulates the osmolarity of the body fluids (with lungs) regulates the PCO2 and acid-base balance of body fluids gluconeogenesis from aa’s (extreme starvation) 23-4  Functions of the Kidney secretes hormone, renin, to control blood pressure and electrolyte balance secretes the hormone, erythropoietin, to make RBC’s final step in synthesizing hormone, calcitriol, which contributes to calcium homeostasis (Vit D) 23-5  waste – any substance that is useless to the body (or present in excess amounts) Nitrogenou urea – proteins amino acids NH2 s Wastes removed ammonia liver Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or converts to urea display. H O uric acid N C H H H2N NH2 – from nucleic acid catabolism Ammonia Urea creatinine – from creatine phosphate O H NH C catabolism C N HN C C O HN N CH3 C C N C CH2 N O blood urea nitrogen (BUN) – H H O level of nitrogenous waste in the Uric acid Creatinine blood 23-6  Anatomy of Kidney against posterior abdominal wall, level of T12-L3 about size of bar of soap lateral surface is convex; medial surface concave with a slit (hilum) receives renal nerves, blood vessels, lymphatics, and ureter protective connective tissue coverings – perirenal fat capsule - cushions & holds in place – fibrous capsule encloses and protects from trauma and infection 23-7 Gross Anatomy of Kidney Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Renal cortex Renal medulla Renal papilla Renal pelvis Major calyx Minor calyx Renal column Renal pyramid Ureter (a) 23-8 Ralph Hutchings/Visuals Unlimited  Anatomy of Kidney renal parenchyma: glandular tissue that forms urine two zones of renal parenchyma: – outer renal cortex – inner renal medulla renal columns – extensions of the cortex that project inward renal pyramids – 6 to 10 with broad base facing cortex and renal papilla (pointy part) facing inward 23-9  Anatomy of Kidney – minor calyx – cup/tube that nestles the papilla of each pyramid collects its urine – major calyces - formed by convergence of 2-3 minor calyces – renal pelvis – formed by convergence of 2-3 major calyces – ureter - a tubular continuation of the pelvis; drains the urine down to the urinary bladder 23-10  Anatomy of Kidney Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Renal cortex Renal medulla Renal papilla Renal pelvis Major calyx Minor calyx Renal column Renal pyramid Ureter Renal blood vessels (b) 23-11  Renal Circulation kidneys account for only 0.4% of body weight, they receive about 21% of the cardiac output (renal fraction) Filtration of waste (from blood) is constantly occurring 23-12  The Nephron each kidney has about 1.2 million nephrons each has two parts: – renal corpuscle – filters the blood plasma – renal tubule – long coiled tube that converts filtrate into urine renal corpuscle is made of the glomerulus & a capsule enclosing it (glomerular or Bowman’s capsule) – outer layer of capsule: simple squamous epithelium – inner layer of capsule has cells called podocytes that wrap around the capillaries of the glomerulus 23-13  Renal Corpuscle Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Glomerular capsule: Key Parietal layer Flow of blood Capsular space Flow of filtrate Podocytes of Afferent visceral layer arteriole Glomerulus Blood flow Proximal convoluted tubule Efferent arteriole Glomerular capillaries (podocytes and capillary wall Blood flow removed) (a) Note: afferent arteriole is larger than the efferent arteriole. 23-14  Renal Tubule renal tubule – a duct that leads away from the glomerular capsule and ends at the tip of the medullary pyramid divided into four regions: – proximal convoluted tubule, nephron loop, distal convoluted tubule – parts of one nephron – collecting duct receives fluid from many nephrons 23-15  Renal Tubule proximal convoluted tubule (PCT) – starts at glomerular capsule – longest and most coiled region nephron loop (loop of Henle) – U-shaped portion – descending limb and ascending limb – thick segments initial part of descending limb and part or all of the ascending limb active transport of salts; many mitochondria – thin segment forms lower part of descending limb cells very permeable to water 23-16  Renal Tubule distal convoluted tubule (DCT) – begins shortly after the ascending limb reenters the cortex – shorter and less coiled than PCT – end of a single nephron collecting duct – receives fluid from the DCTs of several nephrons – numerous collecting ducts converge toward the tip of the medullary pyramid 23-17  Renal Tubule flow of fluid from the glomerulus to the point where urine leaves the body: glomerular capsule → proximal convoluted tubule → nephron loop → distal convoluted tubule → collecting duct → papillary duct → minor calyx → major calyx → renal pelvis → ureter → urinary bladder → urethra 23-18  Renal capsule The Nephron Renal Nephron cortex Collecting duct Renal medulla Minor calyx Renal Renal corpuscle: Glomerular capsule papilla Glomerulus Efferent Convoluted tubules arteriole (PCT and DCT) Afferent arteriole Proximal Cortex convoluted Distal tubule (PCT) convoluted Nephron loop: tubule (DCT) Medulla Descending limb Ascending limb Collecting duct (CD) Thick segment Thin segment Nephron loops Collecting Papillary duct duct 23-19 Two types of nephrons: 1. Cortical (~80%) -short nephron loops 2. Juxtamedullary (~15%) - Long nephron loops, the ascending loop has a thin portion and a thick portion 23-20 ? 23-21  Overview of Urine Formation blood plasma to urine in Blood flow three stages: 1 Glomerular filtration: Renal Corpuscle Creates a plasmalike filtrate of the blood 1. glomerular filtrate – fluid in capsular space Flow of filtrate – blood plasma without 2 Tubular reabsorption: protein Removes useful solutes Peritubular from the filtrate, returns Capillaries them to the blood 2. tubular fluid Tubular secretion: – fluid in renal tubule Removes additional wastes from the blood, – tubular cells remove and adds them to the filtrate Renal tubule add substances 3 Water conservation: 3. urine H2O Removes water from the – In collecting duct urine and returns it to H2O blood H2O – only remaining change is water content 23-22 Urine  Podocyte cell body Afferent arteriole Glomerulus Foot processes (separated by narrow filtration slits) Efferent arteriole (a) 100 µm (b) 5 µm Capsular space Podocyte Foot processes Structure of Glomerulus Filtration slits Basement membrane Filtration pore Endothelial cell Blood plasma Erythrocyte (c) 0.5 µm 23-23  Filtration Membrane glomerular filtration –water and some solutes in the blood plasma pass from the capillaries of the glomerulus into the capsular space of the nephron filtration membrane has 3 barriers through which fluid passes: 1. fenestrated endothelium of glomerular capillaries 2. basement membrane (has negative charge) 3. filtration slits podocyte cell extensions (pedicels) wrap around the capillaries to form a barrier layer also negatively charged 23-24  Filtration Pores and Slits Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Turned back: Endothelial cell of Blood cells glomerular capillary Plasma proteins Basement membrane Large anions Protein-bound Filtration slit minerals and Filtration pore hormones Most molecules Foot process of > 8 nm in podocyte diameter Passed through filter: Water Electrolytes Glucose Amino acids Fatty acids Vitamins Urea Uric acid Creatinine Bloodstream Capsular space 23-25  Filtration Membrane molecules smaller than 3 nm pass freely through the filtration membrane – water, electrolytes, glucose, fatty acids, amino acids, nitrogenous wastes, and vitamins – Large molecules shouldn’t go through kidney infections or trauma can damage the membrane and allow albumin or blood cells through – proteinuria (albuminuria) – presence of protein in the urine – hematuria – presence of blood in the urine – distance runners and swimmers often experience temporary proteinuria or hematuria – prolonged, strenuous exercise reduces perfusion of kidney, glomerulus deteriorates (temporary) 23-26  Filtration Pressure blood hydrostatic pressure (BHP) – much higher in glomerular capillaries (60 mm Hg compared to 10 to 15 in most other capillaries) – b/c afferent arteriole is larger than efferent arteriole hydrostatic pressure in capsular space – 18 mm Hg due to high filtration rate and continual accumulation of fluid in the capsule colloid osmotic pressure (COP) of blood – about the same here as elsewhere: 32 mm Hg net filtration pressure: 60out – 18in – 32in = 10 mm Hgout  Filtration high BP in glomerulus makes kidneys Pressure vulnerable to hypertension BHP 60 out can lead to rupture of COP 32 in NFP 10 out glomerular capillaries, CP 18 in produce scarring of the kidneys, and atherosclerosis of renal blood vessels, ultimately leading to Blood hydrostatic pressure (BHP) 60 mm Hgout renal failure Colloid osmotic pressure (COP) -32 mm Hgin Capsular pressure (CP) -18 mm Hgin Net filtration pressure (NFP) 10 mm Hgout 23-28  Glomerular Filtration Rate glomerular filtration rate (GFR) – the amount of filtrate formed per minute by the 2 kidneys combined total amount of filtrate produced per day equals 50 – 60X the amount of blood in the body – 99% of filtrate is reabsorbed since only 1 to 2 liters urine excreted / day 23-29  Regulation of Glomerular Filtration GFR too high: – fluid flows through the renal tubules too rapidly for them to reabsorb the usual amount of water and solutes – urine output rises – chance of dehydration & electrolyte depletion GFR too low: – wastes reabsorbed 23-30  Regulation of Glomerular Filtration GFR controlled by adjusting glomerular blood pressure from moment to moment GFR control is achieved by three homeostatic mechanisms: – renal autoregulation – sympathetic control – hormonal control 23-31  Renal Autoregulation of GFR renal autoregulation – the ability of kidneys to adjust their blood flow and GFR without external (nervous or hormonal) control allows control of GFR in spite of changes in systemic arterial blood pressure monitored by a structure called the juxtaglomerular apparatus 23-32 Renal Autoregulation of GFR 23-33 Sympathetic Control of GFR sympathetic nerve fibers richly innervate the renal blood vessels sympathetic nervous system & adrenal epinephrine constrict the afferent arterioles in strenuous exercise or acute conditions like circulatory shock – reduces GFR and urine output – redirects blood from the kidneys to the heart, brain, and skeletal muscles 23-34  Renin-Angiotensin-Aldosterone Mechanism Drop in blood Liver pressure renin secreted by Angiotensinogen juxtaglomerular cells if BP Renin drops dramatically Kidney Angiotensin I renin converts Angiotensin- converting angiotensinogen, a blood enzyme (ACE) Angiotensin II Lungs protein, into angiotensin I Hypothalamus in the lungs and kidneys, Cardiovascular Adrenal system cortex angiotensin-converting Aldosterone enzyme (ACE) converts Vasoconstriction Kidney angiotensin I -> angiotensin II, the active hormone Thirst and Sodium and – works to restore fluid volume and water retention drinking BP Elevated bp  Falling BP & Angiotensin II potent vasoconstrictor, raising BP throughout body constricts efferent arteriole, raises GFR directly lowers BP in peritubular capillaries, enhancing reabsorption of NaCl & H2O stimulates adrenal cortex to secrete aldosterone, promoting Na+ & H2O reabsorption in DCT & coll. duct stimulates posterior pituitary to secrete ADH which promotes water reabsorption by collecting duct stimulates thirst & H2O intake 23-36 ? 23-37  Urine Formation: Tubular Reabsorption and Secretion Blood flow 1 Glomerular filtration Rental Corpuscle Creates a plasmalike filtrate of the blood Converting glomerular filtrate  Flow of filtrate urine involves tubular 2 Tubular reabsorption: Removes useful solutes Peritubular reabsorption (back from the filtrate, returns them to the blood Capillaries into blood) & Tubular secretion: secretion (from Removes additional wastes from theblood, blood) adds them to the filtrate Rental tubule 3 Water conservation: H2O Removes water from the urine and returns it to H2O blood H2O Urine 23-38 Proximal Convoluted Tubule PCT reabsorbs about 65% of glomerular filtrate, plus secretes additional waste into the tubular fluid for disposal in urine – microvilli and long length for absorption – abundant mitochondria provide ATP for active transport – PCTs alone account for ~ 6% of one’s resting ATP and calorie need 23-39  Sodium sodium reabsorption is the key to everything else – creates an osmotic and electrical gradient that drives the reabsorption of water and other solutes – most abundant cation in filtrate – high con. favors its diffusion into the PCT cells two types of transport proteins in the apical cell surface are responsible for sodium uptake: – symports that simultaneously bind Na+ and another solute such as glucose, amino acids or lactate (no ATP) – a Na+ - H+ antiport that pulls Na+ into the cell while pumping out H+ into tubular fluid (no ATP) 23-40  Sodium sodium doesn’t build up in the PCT epithelial cells b/c of Na+ - K+ pumps in the basal surface – Na+ that is pumped out is picked up by peritubular capillaries and returned to the blood negative chloride ions follow the positive sodium ions by electrical attraction – antiports in the apical cell membrane can swap Cl- for HCO3- if needed (Cl comes in, bicarbonate leaves) 23-41  Reabsorption in the PCT: Other Electrolytes K, Mg, and PO4 ions diffuse with water some calcium is reabsorbed through the paracellular route in the PCT, but most Ca+2 continues on glucose is cotransported with Na+ by sodium-glucose transport (SGLT) proteins. urea diffuses through the tubule epithelium with water – we reabsorb 40 to 60% from tubular fluid – kidneys remove about half of the urea from the blood – creatinine is not reabsorbed at all 23-42 Reabsorption in the PCT Peritubular Tissue capillary fluid Tubule epithelial cells Tubular fluid Sodium–glucose Glucose transport protein Na+ (SGLT) (Symport) ATP Na+ Glucose Na+–K+ pump K+ Na+ Na+–H+ ADP + H + antiport K+ Pi Cl– Cl––anion antiport Cl – Anions K+–Cl– Aquaporin symport H 2O Tight junction Solvent drag Transcellular route Brush H2O, urea, uric acid, Paracellular route border Na+, K+, Cl–, Mg2+, Ca 2+ , Pi 23-43  Water Reabsorption kidneys reduce 180 L of glomerular filtrate to 1-2 L of urine each day 2/3 of water in filtrate is reabsorbed by the PCT reabsorption of all the salt and organic solutes makes the tubule cells and tissue fluid hypertonic – water follows solutes by osmosis (through water channels called aquaporins) – in PCT, water is reabsorbed at constant rate called obligatory water reabsorption 23-44  Transport Maximum Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Normoglycemia Hyperglycemia There’s a limit to the amount of solute that the Glomerular renal tubules can reabsorb filtration Glucose limited by the number of transport protein transport proteins in the plasma membrane Glucose reabsorption if all transporters are occupied (transport maximum), excess solutes appear in urine (a) Normal (b) Increased urine volume, urine volume, glucose-free with glycosuria 23-45  Tubular Secretion Adding additional waste/substance into filtrate two purposes in PCT and nephron loop: 1. waste removal urea, uric acid, uneeded paracrines & some creatinine are secreted into tubule clears blood of toxins and drugs – need to take prescriptions 3 to 4 times/day b/c of this clearance 2. acid-base balance secretion of H+ and bicarbonate ions help regulate the pH of the body fluids 23-46 Function of Nephron Loop primary function of nephron loop is to generate salinity gradient that enables collecting duct to concentrate the urine and conserve water thick segment reabsorbs 25% of Na+, K+, and Cl- NaCl remains in the tissue of renal medulla H2O can’t follow - thick segment is impermeable tubular fluid very dilute as it enters DCT 23-47  DCT and Collecting Duct fluid arriving in the DCT still has about 20% of the water and 7% of the salts from glomerular filtrate – if all passed as urine, it would be 36 L/day DCT and collecting duct reabsorb variable amounts of water and salt and are regulated by several hormones: – Aldosterone – ADH – ANP 23-48  DCT and Collecting Duct aldosterone - the “salt-retaining” hormone – steroid secreted by the adrenal cortex when blood Na+ concentration falls or when K+ conc. rises or drop in bp renin release angiotensin II formation adrenal cortex secretes aldosterone functions of aldosterone: causes reabsorption of more Na+ & secretion of K+ water and Cl- follow the Na+ net effect is that the body retains NaCl and water – helps maintain blood volume and pressure 23-49  DCT and Collecting Duct antidiuretic hormone (ADH) secreted by posterior lobe of pituitary response to dehydration & rising blood osmolarity – stimulates hypothalamus – hypothalamus stimulates posterior pituitary action - make collecting duct more permeable to water (add aquaporins) – more water in the tubular fluid is reabsorbed 23-50  DCT and Collecting Duct atrial natriuretic peptide (ANP) - secreted by atrial myocardium of the heart in response to high blood pressure Increases excretion of salt & water in the urine, thus reducing blood volume & bp 1. dilates afferent arteriole, constricts efferent arteriole -  GFR (so it doesn’t get too low) 2. inhibits renin, aldosterone and ADH secretion 23-51 ? 23-52 Summary of Tubular Reabsorption and Secretion PCT reabsorbs 65% of Glucose Amino acids Na+ K+ glomerular filtrate & returns it to Protein Vitamins Ca2+ Mg2+ Na+ peritubular capillaries Lactate Cl– Cl– Urea HCO3– HCO3– Uric acid H2O H2O PCT DCT nephron loop reabsorbs another 25% of filtrate Urea H+ DCT reabsorbs Na+, Cl- and Uric acid NH4 water (hormonal control) + Creatinine Some drugs Na+ Nephron loop: K+ Cl– Descending limb Collecting tubules also extract drugs, Ascending limb duct wastes, & some solutes from the H2O H2O blood & secrete them into Urea Urea tubular fluid Key Tubular reabsorption collecting duct conserves H2O Tubular secretion 23-53  Urine Formation: Water Conservation the kidney eliminates metabolic wastes from the body, but also prevents excessive water loss as the kidney returns water to the tissue fluid and bloodstream, the fluid remaining in the renal tubules becomes more concentrated 23-54  Collecting Duct Concentrates Urine Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or as CD passes through the display. medulla, it concentrates Tubular fluid (300 mOsm/L) urine up to four times medullary portion of CD Cortex is more permeable to 300 water than to NaCl Osmolarity of tissue fluid (mOsm/L) Medulla as urine passes through 600 H2O the increasingly salty medulla, water leaves by H 2O Collecting osmosis, concentrating 900 duct urine H 2O H 2O Nephron loop 1,200 H 2O Urine 23-55 (up to 1,200 mOsm/L) Countercurrent Multiplier the ability of kidney to concentrate urine depends on salinity gradient in renal medulla – 4X as salty in the renal medulla as in the cortex nephron loop acts as countercurrent multiplier – multiplier - continually recaptures salt and returns it to medulla which multiplies the salinity – countercurrent - because of fluid flowing in opposite directions in adjacent tubules of loop 23-56 Countercurrent Multiplier fluid flowing downward in descending limb (thin) – very permeable to water but not to NaCl – water passes out of tubule, leaving salt behind – water is removed by vasa recta/ peritubular caps. – tubular fluid very concentrated at bottom of loop fluid flowing upward in ascending limb (mostly thick) – impermeable to water – reabsorbs Na+, K+, and Cl- into ECF – maintains high osmolarity of renal medulla recycling of urea: lower CD permeable to urea – urea remains concentrated in the collecting duct and some of it always diffuses out into the medulla, adding to osmolarity 23-57 Countercurrent Multiplier of Nephron Loop 1 More salt is continually added by the PCT. 300 100 5 The more salt that is pumped out of the ascending limb, the saltier the ECF is in the renal medulla. 200 2 The higher the osmolarity 400 Na+ of the ECF, the more water Na + K+ leaves the descending limb K+ Cl– by osmosis. Cl– H2O H2O Na+ Na+ 600 400 K+ K+ Cl– Cl– H2O H2O Na+ Na+ K+ K+ Cl– Cl– 700 3 The more water that leaves 900 H2O 4 The saltier the fluid in the the descending limb, the ascending limb, the more saltier the fluid is that salt the tubule pumps into remains in the tubule. the ECF. 1,200 23-58  Maintenance of Osmolarity in Renal Medulla Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Osmolarity of ECF (mOsm/L) 300 300 100 300 300 300 100 300 Vasa recta 200 Cortex 400 Medulla Na+ 400 400 K+ Cl– Na+ 200 K+ Urea Cl– 400 Na+ 500 K+ H2O H2O 600 Urea 600 Cl– 400 Na+ 600 K+ Cl– Urea NaCl NaCl H2O Na+ 600 K+ 700 H2O 400 H2O Cl– Urea H2O 900 900 Key Urea 900 900 700 NaCl NaCl Active transport Urea Urea 1,200 Diffusion through H2O 1,200 a membrane channel 1,200 1,200 23-59 Nephron loop Collecting duct  Control of Water Loss how concentrated the urine becomes depends on body’s state of hydration water diuresis – drinking large volumes of water will produce a large volume of hypotonic urine producing hypertonic urine: – dehydration causes less, more concentrated urine – high blood osmolarity (even if not dehydrated) stimulates posterior pituitary to release ADH – more water is reabsorbed by collecting duct 23-60  Urine Volume normal volume for avg. adult – 1-2 L/day polyuria - output in excess of 2 L/day oliguria – output of less than 500 mL/day anuria - 0 to 100 mL/day – low output from kidney disease, dehydration, circulatory shock, prostate enlargement – If urine output is less than 400 mL/day, the body cannot maintain a safe, low concentration of waste in the plasma 23-61 Composition & Properties of Urine urinalysis – the examination of the physical and chemical properties of urine appearance - clear, almost colorless to deep amber - yellow color due to urochrome pigment from breakdown of hemoglobin (RBCs) – other colors from foods, drugs or diseases – cloudiness or blood could suggest urinary tract infection, trauma or stones specific gravity - compared to distilled water pH - range: 4.5 to 8.2, usually 6.0 (mildly acidic) chemical composition: 95% water, 5% solutes – abnormal to find: glucose, free hemoglobin, albumin, ketones, bile pigments 23-62  Diabetes diabetes – any metabolic disorder resulting in chronic polyuria at least four forms of diabetes: – diabetes mellitus type 1, type 2, and gestational diabetes high concentration of glucose in renal tubule opposes the osmotic reabsorption of water more water passes in urine (osmotic diuresis) glycosuria – glucose in the urine – diabetes insipidus ADH hyposecretion, causing not enough water to be reabsorbed in the collecting duct more water passes in urine 23-63  Diuretics diuretics – any chemical that increases urine volume – some increase GFR: caffeine dilates the afferent arteriole – reduce tubular reabsorption of water: alcohol inhibits ADH secretion – act on nephron loop (loop diuretic): inhibit Na+-K+-Cl- symport impairs countercurrent multiplier collecting duct unable to reabsorb as much water as usual commonly used to treat hypertension & congestive heart failure – reduces the body’s fluid volume & bp 23-64 ? 23-65 Urine Storage & Elimination urine is produced continually urination is episodic – occurring when we allow it made possible by storage apparatus and neural controls 23-66  The Ureters ureters – retroperitoneal, muscular tubes that extend from the kidney to the urinary bladder – about 25 cm long – pass posterior to bladder & enter it from below – flap of mucosa acts as a valve into bladder – lumen very narrow, easily obstructed by kidney stones 23-67  Urinary Bladder urinary bladder - muscular sac on floor of pelvic cavity 3 layers: – parietal peritoneum superiorly, fibrous adventitia in other areas – muscularis - detrusor muscle - 3 layers of smooth muscle – mucosa - transitional epithelium rugae – distinct wrinkles in relaxed bladder trigone – smooth-surfaced triangular area marked with openings of ureters and urethra 23-68  Urinary Bladder Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Ureter Detrusor muscle Ureteral openings Trigone Internal urethral sphincter Urethra External urethral External urethral orifice sphincter 23-69 (a) Female  Kidney Stones renal calculus (kidney stone) - hard granule of calcium phosphate, calcium oxalate, uric acid, or a Mg salt called struvite usually small enough to pass unnoticed in the urine – large stones might block renal pelvis or ureter passage of large jagged stones is excruciatingly painful; may damage ureter, causing hematuria Causes: hypercalcemia, dehydration, pH imbalances, frequent UTI’s, or enlarged prostate gland 23-70  Kidney Stones treatment includes stone dissolving drugs, surgery, or lithotripsy –nonsurgical technique that pulverizes stones with ultrasound 23-71  Female 3-4 cm long, bound to Urethra anterior wall of vagina external urethral orifice between vaginal orifice & Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or clitoris display. Ureter Detrusor muscle internal urethral sphincter Ureteral openings – smooth muscle under involuntary control Trigone Internal urethral Urethra sphincter external urethral sphincter External urethral External urethral – where urethra passes orifice sphincter through the pelvic floor (a) Female – skeletal muscle under voluntary control 23-72  Male Urethra Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 18 cm long Ureter 3 regions of male urethra: Rugae Detrusor – prostatic urethra muscle Ureteral openings through prostate Trigone – membranous urethra Prostate gland Internal urethral sphincter passes through Prostatic urethra muscular floor of pelvic Urogenital Membranous urethra diaphragm cavity External urethral– spongy (penile) urethra sphincter passes through penis in Spongy (penile) urethra corpus spongiosum Penis internal urethral sphincter external urethral sphincter External urethral orifice 23-73 (b) Male Urinary Tract Infection (UTI) cystitis – infection of the urinary bladder – especially common in females due to short urethra – frequently triggered by sexual intercourse – may cause fever and burning upon urination, but sometimes asymptomatic – can spread up the ureter causing pyelitis pyelitis – infection of the renal pelvis 23-74 Urinary Tract Infection (UTI) pyelonephritis – infection that reaches the cortex and the nephrons – can result from blood-borne bacteria – fever, backache, burning or bloody urine glomerulonephritis – infection of the glomeruli; more common in children – after strep infection – fatigue, swelling of hands/feet, high bp 23-75  Voiding Urine micturition – the act of urinating micturition reflex - spinal reflex that partly controls urination – although it is involuntary, we learn to control it as children between acts of urination, the bladder is filling – detrusor muscle relaxes, urethral sphincters are tightly closed – stretch of bladder causes contraction of detrusor muscle – enough stretch will cause micturition, if not for control of external sphincter 23-76  Renal Insufficiency & Hemodialysis renal insufficiency – when the kidneys cannot maintain homeostasis due to extensive destruction of nephrons causes of nephron destruction: – hypertension, chronic kidney infections, trauma, prolonged ischemia and hypoxia, poisoning by heavy metals or solvents, blockage of renal tubules in transfusion reaction, atherosclerosis, or glomerulonephritis nephrons can regenerate and restore kidney function after short-term injuries – other nephrons hypertrophy to compensate 23-77  Renal Insufficiency & Hemodialysis can survive with one-third of one kidney when 75% of nephrons are lost and urine output drops to 30 mL/hr (normal 50-60 mL/hr), homeostasis cannot be maintained – causes acidosis, uremia, also anemia hemodialysis – procedure for artificially clearing wastes from the blood – wastes leave bloodstream and enter the dialysis fluid as blood flows through a semipermeable cellophane tube; also removes excess body water 23-78  Hemodialysis Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Thermometer Dialysis Dialysis tubing fluid Artery Vein Shunt To Blood drain pump Flow Bubble meter Cutaway view trap of dialysis chamber 23-79 Hank Morgan/Photo Researchers, Inc.