Ch. 23 BSC 216 Notes
Ch. 23 BSC 216 Notes 10617
Popular in Human Anatomy & Physiology II
verified elite notetaker
Popular in Department
This 25 page Class Notes was uploaded by Gretchen Pierce on Friday March 27, 2015. The Class Notes belongs to 10617 at University of Alabama - Tuscaloosa taught by Jason Pienaar in Spring2015. Since its upload, it has received 131 views.
Reviews for Ch. 23 BSC 216 Notes
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 03/27/15
Urinary System Chapter 23 Overview 0 Organs of the urinary system and their functions Kidney Anatomy 0 Renal Circulation Urinary System Organs Six organs 0 2 kidneys multiple functions 0 2 Ureters transports urine 0 1 bladder store urine 0 1 Urethra transportsexcretes urine Kidney Functions 0 Urinary system rids the body of metabolic waste products 0 Kidneys are the primary functional organ Filters metabolic waste 0 Filter blood plasma separate waste from useful chemicals 0 Returns useful chemicals to blood 0 Eliminates waste nitrogenous waste Excretion getting rid of a waste product Excretion 0 Separation of wastes from body fluids amp elimination 0 Metabolic Waste waste substance produced by the body food residue in feces is NOT metabolic waste 0 Metabolic waste includes both nitrogenous wastes and C02 0 4 body systems carry out excretion 0 Respiratory system COZ trace amounts of other gases 0 Integumentary system inorganic salts lactic acid urea in sweat o Digestive system salts COZ lipids bile pigments cholesterol other metabolic wastes and food residue 0 Urinary system nitrogenous metabolic wastes toxins drugs hormones salts Kidney Excretes 4 kinds of Nitrogenous wastes o Ammonia 0 Most toxic o NH2 removed from amino acids forms NH3 Liver converts to Urea 0 Converting ammonia to Urea is NOT a function of the kidneys liver does 0 Urea Urinary System Chapter 23 0 Less toxic than ammonia o By adding 2 urea becomes less toxic Uric acid 0 Product of nucleic acid metabolism Creatinine 0 Product of Creatinine phosphate metabolism 139 E N c H H H u nl Ammonia Urea O NH n a n m C c u C 20 m N quotmt c c N c 05 o H o Uric acid Creatinine 0 Blood Urea NitrogenBUN Level of toxic nitrogenous wastes in blood stream 0 Normal 10 20 mgdL Elevated BUN Azotemia Can progress to Uremia o Diarrhea and vomiting because you are trying to get rid of these wastes o Dehydration dyspnea cardiac arrhythmia convulsions coma and death Kidney Functions Kidneys also have a multitude of other functions 0 Regulate blood volume amp pressure by eliminating or conserving water 0 Regulate body fluid osmolarity by controlling water solute elimination ratio 0 Secrete renin an enzyme that activates hormonal control of blood pressure 0 Secrete erythropoietin that stimulates red blood cell synthesis 0 Collaborate with lungs to regulate pH of body fluids Add Hydroxyl group to calcitrol 9 calcium homeostasis o Initiate gluconeogenesis from amino acids during extreme starvation O Urinary System Chapter 23 Kidney Location Located retroperitoneally Protected by lower rib cage fat and a fibrous capsule Fat capsule attached kidney to body wall cushions Fibrous capsule hard protects against infection Fascia Dense CT anchors kidney in place I 21 e Aona Inferior 39 quot 39 vena cava r Perllo neum I III Renal win I l Renal nle or artery 39 renal lascl 39II I squot v if Posterior 39 renal fascia 12th rlb all Fibrous capsule Renal cortex Renal medulla Renal papilla Renal sinus Adipose tissue in Renal sinus Renal pelvis major calyx minor calyx Renal column Renal pyramid Ureter Renal blood vessels Renal Circulation Kidneys make up 04 of body weight but receive 25 of cardiac output Urinary System Chapter 23 Blood flow and filtrate filtered out of the blood make into urine to exit body Starts with aorta and branch out into renal arteries which go into kidneys by Hilum and into renal sinus Renal arteries go into segmental arteries interlobar arteries of kidney Veins are just there to flow back into systemic circuit Cortical radiate arteries flow into spaghetti like messquot where filtration takes place Arcuate arteries lnterlobar vein Interlobar artery Segmental artery Renal artery pernubular capillaries Renal Vein afferent arteriole k efferent arteriole n cortical radiate vein conical radiate artery The Nephron Each kidney has 12 million nephrons Pyramid shapes Each is an identical functional unit they all do the same thing Comprised of 2 parts 0 Renal corpuscle filters blood plasma 0 Renal tubule coiled tube that converts filtrate into urine reabsorption Cortical amp Juxtmedullary Nephrons Cortical Nephrons o 85 of all nephrons 0 Short nephron loops Urinary System Chapter 23 o Efferent arterioles branch into peritubular branch into peritubular capillaries surrounding distal and proximal convoluted tubules Juxtmedullary Nephrons o 15 of all nephrons 0 Long nephron loops maintain salinity gradients o Efferent arterioles branch into vase recta around each nephron loop Renal Corpuscle Vascular pole vasuclaration blood will enter 0 Urinary pole urine will exit Afferent arteriole going into Golumerular capsule Efferent Arteriole exit the Golumerular capsule Podocytes filter blood that enter efferent arteriole Simple squamous tissue forms into simple cuboidal tissue Golumerular capsule gt blood ow gt filtrate ow Afferent anerlole parietal layer simple squamous capsule space filtrate collecting visceral layer podocytes renal tubule simple cuboidal Efferent arteriole l Vascular pole Urlnary pole Renal Tubules 4 regions Proximal convoluted tubule PCT all twisted and it extends but can fit into small space merges into nephron loop is combined of both simple squamous and simple cuboidal The Distal Convoluted Tubule DCT sends it to collecting duct and does not have reabsorption factor now A lot of things empty into the collecting duct Urinary System Chapter 23 e v 4 regions Renal Distal convoluted tubule DCT quot OOprBCb Proxlmal convoluted tubule PCT Nephron loop Loop of Henle Collecting duct gtfinrato ow Renal Tubule Proximal Convoluted tubule 0 Long tubule 0 Simple cuboidal epithelium with prominent microvilli brush border 0 Lots of absorption of water mainly Renal Tubule Distal Convoluted o Shorter less coiled than PCT o Cuboidal epithelium devoid of microvilli 0 End of the nephron Collecting duct 0 Receives fluid from the DCT s of several nephrons 0 Numerous collecting ducts converge near the ti of the medullary pyramids to form papillary ducts o Papillary ducts end in pores where urine passes into minor calyx Fluid Flow Summary Glomerular filtrate what comes out of capillaries and what is left goes to efferent arteriole Then goes to PCT and to nephron loop which is simple squamous where water is the goes to DCT and it is waste that we need to get rid off Urinary System Chapter 23 straight on to collecting duct which is where a ton of things are filtering in Then to minor calyx to major calyx which is on renal pelvis then finally goes to ureter urinary bladder and urethra to finally exit a 39 4regions W quot Distal convoluted tubule DCT l Proxlmal convoluted tubule PCT Nephron loop Loop of Henle Collecting duct w uato ow Overview Urine Formation o Glomerular filtration o Tubular filtration and reabsorption 0 Water conservation Basic Stages of Urine Formation 0 Conversion of glomerular filtrate to urine involves the removal and addition of chemicals by tubular reabsorption and secretion 0 Occurs through PCT and DCT o Tubular fluid is modified Normal blood urea level is 20 mg Steps involved include o 1 Glomerular filtration forcing the liquid component out of the fenestrated capillaries o 2 Tubular reabsorption o 3 Tubular secretion removed from blood added to filtrate Urinary System Chapter 23 o 4 Water conservation removes water from urine and returns it to blood gt Bloodllow Glomerular filtration Creates a plasma like ltrate of the blood Renal oorpuscle Flow of ltrate Tubular reabsorption Removes useful solutes from the ltrate returns them to the blood Petitubulx capilalies Tubular secretion Removes additional wastes from the blood adds them to the ltrate Renal tubule Water conservation Removes water from the urine and returns it to blood concentrates wastes i Fin Glomerular Filtration Important to understand that as we trace fluid through the nephron it has different names that reflect changing composition Glomerular filtrate the fluid in the capsular space 0 Similar to blood plasma except that it has almost no protein Tubular fluid fluid from the proximal convoluted tubule through the distal convoluted tubule o Substances have been removed or added by tubular cells Urinary System Chapter 23 Urine fluid that enters the collecting duct 0 Undergoes little alteration beyond this point except for changes in water content The Filtration Membrane Glomerular Filtration special case of the capillary fluid exchange process in which water and some solutes in the blood plasma pass from capillaries of the glomerulus into the capsular of the nephron Filtration Membrane 3 barriers through which fluid passes o 1 Fenestrated Endothelium of glomerular capillaries 7090 nm filtration pores exclude blood cells highly permeable o 2 Basement Membrane Proteoglycan gel negative charge excludes molecules greater than 8nm Albumin repelled by negative charge Wont make it into the filtrate Blood plasma is 7 protein the filtrate is only 03 protein 0 3 Filtration Slits Podocyte cell extensions pedicels wrap around the capillaries to form a barrier layer with 30 nm filtration slits Negatively charged which is an additional obstacle for large anions Filtration Membrane allows passage of water and solutes small into glomerular capsule o 1 Fenestrated endothelium of glomerular capillaries o 2 Basement membrane gluing endothelium of capsule together 0 3 Filtration slits Podocytes of visceral membrane of glomerular capsule Urinary System Chapter 23 Micron arteriole Cytoplasmbc oxtmtons Glomewlar capsular space Filtration slim Podocyte 00quot body PMNII Iayo 0 glomomlar capsule Ptoximal convoml Glomewlar 901151 cazlllaryr mmquot oova p0 0c capillary containing Viacom lays Numb ondothdlum of glometular capsule m Wm podocyle col no 39 quot9 basement m membrane W removed Owbu 0 Urinary System Chapter 23 Turned back Blood cells Plasma proteins Large anions Proteinbound minerals and hormones Most molecules gt 8 nm in diameter tions Bloodstream Afferent arteriole is much larger than efferent Basement membrane so thick you couldn t force anything through itsome make it through some do not What doesn t make it through 0 Blood cells 0 Plasma proteins 0 Large anions some make it but have hard time making it through basement membrane 0 Protein bound minerals and hormones 0 Most molecules less than 8nm in diameter because of basement membrane What does make it through 0 Water high pressure will help Electrolytes dissolve in water Glucose Amino Acids charged ones have hard time Fatty Acids not triglycerides Vitamins ones that are dissolved into blood stream Urea nitrogenous waste Uric Acid nitrogenous waste OOOOOOO Urinary System Chapter 23 o Creatinine nitrogenous waste The Filtration Membrane Almost any molecule smaller than 3 nm can pass freely through the filtration membrane 0 Some substances of low molecular weight are bound to plasma proteins and cannot get through membrane 0 Calcium iron thyroid hormone 0 Unbound fraction passes freely into filtrate Filtration Pressure 0 Blood Hydrostatic Pressure BHP 0 Much higher in glomerular capillaries 60 mmHg compared to 1015 in most other capillaries 0 Because afferent arteriole is larger than efferent arteriole larger inlet and smaller outlet 0 Primary means of pushing solutes and water out of blood across filtration membrane 0 You can change the pressure and diameters here 0 Kidney damage is the first thing to go when you have high BP 0 Hydrostatic Pressure in Capsular Space 0 18mmHg due to high filtration rate and continual accumulation of fluid in the capsule 0 Pressure within capsule tends to push water back into glomerulus high filtration rate 0 Forces fluid into Capsular Space 0 Colloid Osmotic Pressure COP of Blood due to proteins in blood 0 About the same here as elsewhere 32 mmHg 0 Glomerular filtrate is almost proteinfree and has no significant COP 0 Proteins in glomerular blood tend to pull water back into glomerulus 0 Higher outward pressure of 60 mmHg opposed 2 inward pressures at 18 mmHg and 32 mmHg 0 601832 if out of glomerulus 0 151832 if 0 Higher outward pressure of 60 mmHg opposed by 2 inward pressures of 18 mmHg and 32 mmHg 0 Net filtration pressure 60 out 18 in 32 in 10 mmHg out o Glomerulus a more efficient filter than other capillaries because Urinary System Chapter 23 Filtration membrane with large surface area High blood pressure within glomerulus 60 mmHg vs 15 mmHg Result High net filtration pressure Blood hydrostatic pressure BHP so mm Hg Ooloid osmotic pressure COP 32 mm Hg Capsllar pressure C 18 mm Hg Het titration pressure HF 10 mm Hg Glomerular Filtration Rate Glomeruler filtration rate GFR the amount of filtrate formed per minute by the 2 kidneys combined 0 GFR 125 mLmin male 0 GFR 105 mLmin female Total amount of filtrate produced equals 50 to 60 times the amount of blood in the body 0 99 of filtrate is reabsorbed since only 12L urine excreted per day Regulation of Glomerular Filtration GFR must be controlled 0 GFR too high 0 Fluid flows through the renal tubules too rapidly for them to reabsorb the usual amount of water and solutes o Urine output rises Urinary System Chapter 23 o Chance of dehydration electrolyte rises GFR too low 0 Too many wastes reabsorbed o Azotemia may occur accumulation of harmful waste 0 GFR controlled by adjusting glomerular blood pressure from moment to moment GFR control is achieved by 3 homeostatic mechanisms 0 Renal Autoregulation o Sympathetic control 0 Hormonal control 1 Renal Autoregulation Renal Autoregulation the ability of the nephrons to adjust their own blood flow and GFR without external nervous or hormonal control Enables them to maintain a relatively stable GFR in spite of changes in systemic arterial blood pressure 0 2 methods of Autoregulation myogenic mechanism and tubuloglomerular feedback Myogenic mechanism based on the tendency of smooth muscle contract when stretched 0 Increased arterial blood pressure stretches the afferent arteriole 9 arteriole constricts and prevents blood flow into the glomerulus from changing 0 When blood pressure falls 9 efferent arteriole relaxes and allows blood flow more easily into glomerulus Result filtration remains stable 0 Tubuloglomerular feedback mechanism by which glomerulus receives feedback on the status of the downstream tubular fluid and adjusts filtration to regulate the composition of the fluid stabilize its own performance and compensate for fluctuation in systemic blood pressure 0 Juxtaglomerular apparatus complex structure found at the very end of the nephron loop where it has just reentered the renal cortex 0 3 special kinds of cells occur in the juxtaglomerular apparatus 0 Macula Densa senses variations in flow or fluid composition and secretes a paracrine that stimulates JG cells 0 Juxtaglomerular JG cells when stimulated by the macula they dilate or constrict the arterioles o Mesangial cells connected to macula densa and JG cells by gap junctions and communicate by means of paracrines Constrict or relax capillaries to regulate flow Urinary System Chapter 23 The Juxtaglomerular Apparatus my em Reduced cm 39 I l WHOM w Com Inc Feminism M firm cram Constriction of afferent arteriole I Rapid flow of filtrate in renal tubules I Sensed by Paracan I a I macula dons quot500 i I Sympathetic 39 Q I nerve ber Podocytes 39 3 19 Mesangial cells p y Juxtaglomerular Efferent arteriole quot l 39 39 cells f p Negative feedback Afferent arteriole control of GFR Smooth muscle cells Macula densa Nephron 3900 Figure 23134 2 Sympathetic Control Sympathetic nerve fibers richly innervate the renal blood vessels Sympathetic nervous system and adrenal epinephrine constrict the afferent arterioles in strenuous exercise or acute conditions like circulatory shock o Reduces GFR and urine output 0 Redirects blood from kidneys to heart brain and skeletal muscles 0 GFR may be as slow as a few mL per min 3 Hormonal Control Renin Angiotensin Aldosterone Mechanism Renin secreted by JG cells if blood pressure drops Renin converts angiotensinogen a blood protein into angiotensin I 0 In the lungs and kidneys angiotensinconverting enzyme ACE converts angiotensin I to angiotensin II the active hormone 0 Works in several wats to restore fluid volume and BP 0 Result these 3 mechanisms raise BP Urinary System Chapter 23 Basic Stages of Urine Formation 0 Conversion of glomerular filtrate to urine involves the removal and addition of chemicals by tubular reabsorption and secretion Urinary System Chapter 23 o Occurs through PCT to DCT o Tubular fluid is modified Steps involved 0 1 Glomerular Filtration o 2 Tubular Reabsorption o 3 Tubular Secretion o 4 Water Conservation Glomerular ltration Rural oorpuoclo Creates a plasma like ltrate of the blood Flow 0 lltrato Tubular reabsorption Removes useful solutes from the ltrate returns Pentium them to the blood 9quot Tubular secretion Removes additional wastes from the blood adds them to the ltrate m mom Water conservation Removes water from the urine and returns it to blood concentrates wastes A The Proximal Convoluted Tubule PCT PCT reabsorbs about 65 of glomerular filtrate removes some substances from the blood and secretes them into the tubular fluid for disposal in urine 0 Prominent microvilli and great length 0 Abundant mitochondria provide ATP for active transport 0 PCT s alone account for 6 of ones resting ATP and calorie consumption Tubular reabsorption process of reclaiming water and solutes from the tubular fluid and returning them to the blood Urinary System Chapter 23 2 routes of reabsorption o Transcellular Route Substances pass through the cytoplasm of the PCT epithelial cells and out their base 0 Paracellular Route Substances pass between PCT cells Junctions between epithelial cells are leaky and allow water to pass through Solvent drag water carries with it dissolved solutes Taken up by peritubular capillaries Two Routes of Reabsorption Peritubular Tlssue capinary ulid Tubule epithelial cells Tubular uid W mm Transcellular route Through cytoplasm mum Of PCT epithelial cells 4 Paracellular route 31 3ftm Between PCT epithelium cells Tubular Reabsorption Sodium reabsorption is the key to everything else 0 Creates an osmotic and electrical gradient that drives the reabsorption of water and other solutes 0 Most abundant o Creates steep concentration gradient that favors its diffusion into the epithelial cells 2 types of transport proteins in the apical cell surface are responsible for sodium uptake 0 1 Symports that simultaneously bind NA and another solute such as glucose amino acids or lactate Urinary System Chapter 23 as glucose amino acids or lactate Apical ce smface Pgitliillaaular Tissue P uid Tubule epithelial cells Tubular uid Sodiumglucose transport protein SGLT symport mm I f M 2 NAH antiport that pulls NA into the cell while pumping out H into tubular fluid Peritubular Tissue 9mm uid Tubule epithelial cells Tubular uid can Sodium is prevented from accumulating in the epithelial cells by NAK pumps in the basal surface of the epithelium 0 Pumps Na out into the extracellular fluid 0 Picked up by peritubular capillaries 0 ATP consuming active transport pumps Urinary System Chapter 23 Peritubular Tissue 9mm uid Tubule epithelial cells Tubular uid w r A NaH antiport 39 MI I 4 K K D a 4 x mm l Negative Chloride ions follow the positive Sodium ions by electrical attraction 0 Various antibodies in the apical cell membrane that absorb CI in exchange for other anions they eject into tubular fluid 0 KCl symport drives chloride and potassium OUT of epithelial cells Peritubular Tissue 93quot uid Tubule epithelial cells Tubular uid an K 4 Potassium magnesium and phosphate ions diffuse through the Paracellular route with water Some calcium is reabsorbed through the Paracellular route in the PCT but most Ca2 reabsorption occurs later in the nephron Urinary System Chapter 23 4060 of urea is reabsorbed through Paracellular route with water Nearly all uric acid is reabsorbed but secreted back later All of these Paracellular movements are driven by solvent cl ra g Pgltlil39raular Tissue P 39V uid Tubule epithelial cells Tubular uid CA L 7 7 H20 urea uric acid Na K Cquot M923 Ca 2 Pi Reabsorption of all the salt and organic solutes makes the tubule cells and tissue fluid hypertonic 0 Water follows solutes by osmosis through both Paracellular and Transcellular routes through water channels called aquaporin39s o In PCT water is reabsorbed at constant rate called obligatory water reabsorption Pgitlillfaular ssue P 39V uid Tubule epithelial cells Tubular uid r V 7 Aquaporin K KD was 4 r 7 H20 urea uric acid Na K Cl M922 Ca 2 Pi Urinary System Chapter 23 The Transport Maximum There is a limit to the amount of solute that the renal tubules can reabsorb Limited by the number of transport proteins in the plasma membrane If all transporters are occupied as solute molecules pass 0 Excess solutes appear in urine Transport max is reached when transporters are saturated Each solute has its own max transport 0 Any blood glucose level above 220 mgdL results in glycosuria Wm WM m VOIIII39 gm Tubular Secretion Tubular Secretion process in which renal tubule extracts chemicals from capillary blood and secretes them into tubular fluid 2 purposes in PCT and nephron loop 0 Waste Removal Urinary System Chapter 23 urea uric acid bile acids ammonia catecholamine s prostaglandins and a little creatine are secreted into tubule Secretion of uric acid compensates for its reabsorption earlier in PCT Clears blood of pollutants morphine penicillin aspirin and other drugs a Explains need to take prescriptions 34 times a day to keep pace with the rate of clearance o AcidBase Balance Secretion of hydrogen and bicarbonate ions help regulate pH of body fluids Nephron Loop 0 Primary function of nephron loop is to generate salinity gradient that enables collecting ducts to concentrate the urine and conserve water 0 Electrolyte reabsorption from filtrate 0 Thick segment reabsorbs 25 of Na K and Cl Ions leave cells by active transport and diffusion n NaCl remains in the tissue fluid of renal medulla a Water cannot follow since thick segment is impermeable Tubular fluid very dilute as it enters distal convoluted tubule DCT Urinary System Chapter 23 DCT Thick segment Thin segment Distal Convoluted Tubule DCT and Collecting Duct Fluid arriving in the DCT still contains about 20 of the water and 7 of the salts from the glomerular filtrate o If this were all passed as urine it would amount to 36Lday DCT and collecting duct reabsorb variable amounts of water salt and are regulated by several hormones o Aldosterone atrial natriuretic peptide ADH and parathyroid hormone Aldosterone the saltretaining hormonequot o Steroid secreted by the adrenal cortex Functions of aldosterone o Acts on thick segment of nephron loop DCT and cortical portion of collecting duct Stimulated the reabsorption of more Na and secretion of K Water and Cl follow the Na Net effect is that the body retains NaCl and water a Helps maintain blood volume and pressure Urinary System Chapter 23 Urine volume is reduced Urine has an elevated K concentration Atrial natriuretic peptide ANP secreted by atrial myocardium of the heart in response to high blood pressure 0 4 actions result in the excretion of more salt and water in the urine which reduces blood volume and pressure 0 Dilates afferent arteriole constricts efferent arteriole o Inhibits renin and aldosterone secretion 0 Inhibits secretion of ADH o Inhibits NaCl reabsorption by collecting duct Antidiuretic hormone ADH secreted by posterior lobe of pituitary in response to dehydration and rising blood osmolarity Action make collecting duct more permeable to water 0 Water in the tubule fluid reenters the tissue fluid and bloodstream rather than being lost in urine Parathyroid hormone PTH secreted from parathyroid glands in response to calcium deficiency hypocalcemia o Increases phosphate content and lowers calcium content in urine 0 Because phosphate is not retained the calcium ions stay in circulation rather than precipitating into the bone tissue as calcium phosphate
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'