Phis 206 1nd EditionExam # 3 Study Guide Lectures: 20-28Renal SystemRenal System1.) Kidney-we have 2 of them2.) Urine bladder Kidneys- Major function- to regulate:1.) Total fluid volume2.) H+ concentration in extracellular fluid3.) Regulate salt balance4.) Elimination of wastes- Have 2 kidneys with outer capsule- Beneath capsule is cortexo Reddish in coloro Vigorous blood supply- Beneath that is medullao Gray in coloro Sparse blood supply- Kidneys get about 25% of blood flow, goes to the nephrons- Blood came in through renal artery- Blood leaves through renal vein- Some fluid leave blood, in kidneys- This fluid then leaves through ureter- Afferent arteriole breaks into capillary bed, in cup, then glomerulus capillaries- They empty into efferent arteriole, it breaks up into another bed of capillaries, Peritublar Capillaries- blood supply for most of nephron, drain into a venule, which carries blood off.Portal System- You have arteriole drain into capillaries bed to another arteriole to another capillary bed to venule.- Collecting duct gathers from many nephrons.- Collecting ducts eventually flows to ureters.2 Kinds of Nephrons1.) 80% are Cortical Nephrons- it is entirely located in the renal cortex.2.) 20% are Juxtamedullary Nephrons- Bowan’s & convoluted tubule in cortex, but the Loop of Henle is in the medulla; Loop of Henle is very longa. “next to the medulla” -- Only about 15% of blood flow gets into the Renal Medulla. -- The medulla is bigger; so blood flows 20x faster in cortex.Three Major happenings in Kidneys1.) Glomerular Filtration- just as in other capillaries, does not let out proteinsoccurs in the glomerulus Hydrostatic pressure is higher, so more fluid goes out.  The pressure in glomerulus is higher than most capillaries, due to a resistance vessel.-- 20% of plasma volume filtered out- known as glomerular filtrate. plasma without the protein Average everyday, filters out 180 Liters or 50 gallon a day Urinate about a liter a day- reabsorb 179 Liters out of every 180 liters produced. Kidneys will reabsorb about 99% of solute, as well.During the movement through the Nephron:1.)will reabsorb some stuff-out of lumen into ECF-99.5%-different solutes will be reabsorbed at different rates.2.) Reabsorption, secretion, and Glomerular Filtration are 3 processes that account for most of the functions of kidneys.Because of 2nd Arteriole:- Pressure in capillary is higher than in most systemic capillaries, so little fluid gets reabsorbed.- 20% of plasma volume gets pushed into Bowman’s Capsule- Then after moves through second arteriole, into another capillary bed, has lower pressure, due to lower volume, so when it gets into peritubular capillaries, it has lower volume, so it makes it closer to systemic capillaries.- 99% leaves instead of 100%; this is a 2-step processGlomerular Filtration Rate (GFR)Rate = 125mL/min.- this can vary due to the hydrostatic pressure- driving force- Higher pressure = higher rate- Anatomically this is set up to be easy, if you constrict efferent, you increase pressure upstream, which increases GFR. Constrict afferent, reduce GFR.- Most of physiological control comes from sympathetic stimulation, and the sympathetic nerves supply is much denser to afferent than to efferent, so afferent constricts, so reduces GFR.GF protein is free plasma in out urine - add to secreted.2. Reabsorptiono tends to be active/useful reabsorbedo sluggish/toxious2 classes for:1.) Active Transportation- moves uphill against gradient- needs energy (ATP)2.) Passive Transportation- facilitated diffusion (carrier molecules;mostly protein) High Concentration  Low Concentration- Simple Diffusion across cell membrane- Huge amount of sodium & reabsorbed Responsible for osmotic pressure.- Drives passive reabsorption of negative ion- Most other active transport systems only work with sodium reabsorption.Sodium ReabsorptionoControl of body sodium level is controlled by kidney by varying the amount we loseAll of the control is done in the distal tubeThe amount that gets reabsorbed in the distal tube determines the amountof sodium in the bodyoSodium goes from the lumen of the nephron to the bloodstreamGets pumped out of the nephron cells into the ECF (active transport)-Allows for sodium in the lumen of the nephron to then move into the cellThen diffuses into the capillaries from ECFoAmount of Sodium Reabsorbed80% reabsorbed in Proximal12% in the Loop of Henle7.5% in the distal tubeoTubular LoadAmount of compound entering tubuleFor glucose = 1 mg/mL x 125 mL/min = 125 mg/min-Amount of glucose that enters your nephron per minute (average)oTm of glucose400 mg/minNephrons can absorb up to that amount (if it is present)Means that glucose does not wind up in the urineoWater follows concentration of glucose osmoticallyCauses an overall increase in blood plasmaDiabetics cannot control glucose levels-Have high urine levels-Have sweet peeoChloride is reabsorbed passively due to being attracted by the positive charge of sodiumoReabsorbing 99.5% of water (in nephron)Means that everything left behind is in higher concentration than beforeAnything left behind that can diffuse across nephron membrane WILL diffuse- Na+ enters Bowman’s capsule 100%~Not subject to control  proximal tubule 100% enters 80% reabsorbed Loop of Henle 20% enters (10-12) ~All control excerted here  Distal tubule 8% enters collecting duct; urine 1% or less.- Glucose & Amino Acids Active TransportTransport Maximum- maximum amount of glucose being reabsorbed in nephrons (400mg/min.)Diabetes Mellitus- urine volume goes up with high volumes of glucose.-- When actively reabsorb sodium, passively reabsorb chloride.-- Also reabsorb water due to reabsorption of chloride.3. Secretiona. Our of capillaries and into tubular fluidSome secretions are added to tubule:Hydrogen Ion (H+)- actively secreted most important for fine tuning of the pHPotassium Ion (H+) & Organics (Drugs)- actively secretedPlasma Clearance: volume of plasma containing amount or “x” that appears in the urine in1 minuteo This is use because the larger the amount of volume that is cleared; the more efficient the removal is.- Typically produce 1-2L a day (1mL a min.)- That amount is the difference of the plasma that is filtered and the plasma that is reabsorbed.- One useful way to look at amount it is from what volume of plasma would you