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Copyright 2010, John Wiley & Sons, Inc. Chapter 9 The Urinary System.

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Presentation on theme: "Copyright 2010, John Wiley & Sons, Inc. Chapter 9 The Urinary System."— Presentation transcript:

1 Copyright 2010, John Wiley & Sons, Inc. Chapter 9 The Urinary System

2 Copyright 2010, John Wiley & Sons, Inc. Urinary System Two kidneys and two ureters Urinary bladder & urethra Effector organ for 1.Regulation of Plasma ion composition 2.Regulation of Body water Volume (BP) 3.Regulation of blood pH (with lung) 4.Production of Hormones 5.Excretion of waste

3 Copyright 2010, John Wiley & Sons, Inc. Urinary System

4 Copyright 2010, John Wiley & Sons, Inc. Kidney Divided into cortex –outer portion Medulla- inner portion  Contain renal pyramids & renal columns Urine goes into renal pelvis  Edges are made of major & minor calyces Then out ureter

5 Copyright 2010, John Wiley & Sons, Inc. Kidney

6 Copyright 2010, John Wiley & Sons, Inc. Renal Blood Supply 20-25% resting CO goes through kidneys  L. & R. renal arteries then  Segmental  interlobar  arcuate  interlobular  afferent arterioles  glomerulus (capillary network)  efferent arterioles  peritubular capillaries  veins    renal vein Capillaris Units –nephrons grouped at pyramids

7 Copyright 2010, John Wiley & Sons, Inc. Renal Blood Supply

8 Copyright 2010, John Wiley & Sons, Inc. Renal Blood Supply

9 Copyright 2010, John Wiley & Sons, Inc. Nephron Unit of renal function: corpuscle & tubule Corpuscle: forms filtrate Glomerulus & Glomerular capsule (cortex) Proximal convoluted tubule (cortex)  Descending Loop of Henle (into medulla)  ascending Loop of Henle (into medulla)  Distal convoluted tubule (cortex)  Collecting duct  minor calyx

10 Copyright 2010, John Wiley & Sons, Inc. Nephron

11 Copyright 2010, John Wiley & Sons, Inc. Basic Operation Glomerular filtration-filter plasma Tubular reabsorption  Reabsorb needed compounds & water from filtrate Tubular Secretion  Secrete some materials into filtrate

12 Copyright 2010, John Wiley & Sons, Inc. Glomerular Filtration Two layers of capsule surround glomerulus Between is capsular space Podocytes support capillary epithelium Form filtration membrane Permeable to water & solute but not most proteins & blood cells

13 Copyright 2010, John Wiley & Sons, Inc. Filtration Pressure Blood pressure for filtration Opposed by colloid osmotic pressure and capsular pressure Efferent and afferent arteriole diameters adjust to maintain a net filtration pressure  Even with small changes in blood pressure

14 Copyright 2010, John Wiley & Sons, Inc. Glomerular Filtration Rate = GFR 105-125 ml/min Determines net reabsorption because it determines filtrate flow ANP(Atrial natriuretic peptide) increases GFR  Responds to increased blood volume Sympathetic stimulation  vasoconstriction  decreased GFR  Urine production

15 Copyright 2010, John Wiley & Sons, Inc. Glomerular Filtration

16 Copyright 2010, John Wiley & Sons, Inc. Tubular Reabsorption Proximal tubule  ~65% Na + & H 2 O  Normally 100% nutrients  ~100% HCO 3 - (depends on blood pH) Active transport of solutes Osmosis moves water Cells distal to proximal tubule fine tune reabsorption under control

17 Copyright 2010, John Wiley & Sons, Inc. Tubular Secretion Takes place all along tubule Major substances : H +, K +, ammonia, urea, creatine, drugs like penicillin Helps regulate plasma pH 7.35-7.45 Diet is acid  urine is typically acidic

18 Copyright 2010, John Wiley & Sons, Inc. Urine Route Collecting ducts to calyces Calyces to ureter Ureter to bladder Bladder to urethra

19 Copyright 2010, John Wiley & Sons, Inc. Filtration, Reabsorption, Secretion

20 Copyright 2010, John Wiley & Sons, Inc. Hormonal Regulation Angiotensin II & aldosterone  Angiotensin II- stimulates NaCl in proximal tube  Aldosterone- increases Na + reabsorption & K + secretion in DCT & CD  More ions reabsorbed  more water ANP-increases GFR & inhibits aldosterone action  less Na + reabsorbed ADH- responds to increased concentration of solute in blood + fall in BP 

21 Copyright 2010, John Wiley & Sons, Inc. Hormonal Regulation ADH: important to body water balance Increased concentration of solute in blood + fall in BP   ADH With no ADH: DCT & CD walls are impermeable to water  dilute urine With ADH: water reabsorption occurs  concentrated urine

22 Copyright 2010, John Wiley & Sons, Inc. Components of Urine Urine = 1-2 l /day 95% water + urea, creatine, K +, ammonia, uric acid, Na +, Cl -, Mg 2+, sulfate, phosphate & Ca 2+ Depends on diet and state of health  See table 21.3

23 Copyright 2010, John Wiley & Sons, Inc. Regulation of Water Reabsorption

24 Copyright 2010, John Wiley & Sons, Inc. Urine Route Collecting ducts  calyces  Ureter  Lined with mucus & transitional epithelium  Pass under bladder  Full bladder prevents backflow  Bladder- directly in front of rectum  Can stretch (700-800 ml)  Smaller in females because of uterus  Three layers of detrussor muscle  Urethra- internal urethral sphincter External urethral sphincter (voluntary)

25 Copyright 2010, John Wiley & Sons, Inc. Urine Route

26 Copyright 2010, John Wiley & Sons, Inc. Micturition = Urination Autonomic reflex- internal sphincter  Responds to stretch like rectum Parasympathetic  detrusor muscle contraction Conscious control-external sphincter

27 Copyright 2010, John Wiley & Sons, Inc. Aging Kidneys shrink- decrease in capacity Thirst decreases  dehydration  urinary tract infections Males: prostate enlargement  frequent urination & slow flow Females: more prone to leakage of external sphincter (incontinence) Both: nocturia

28 Copyright 2010, John Wiley & Sons, Inc. Fluid, Electrolyte and Acid-Base Balance

29 Copyright 2010, John Wiley & Sons, Inc. Fluid Compartments Total body water = 55-60% of lean body mass  Remainder: solid parts of bone, muscles, tendons Major compartments (3): ICF, IF, plasma  Intracellular fluid (ICF): inside cells= 2/3  Extracellular Fluid (ECF): outside cells = 1/3 Interstitial fluid (IF): 80% of ECF  Includes: lymph; cerebrospinal, synovial, pericardial, pleural and peritoneal fluids; fluid in eyes and ears Blood plasma: 20% ECF

30 Copyright 2010, John Wiley & Sons, Inc. Fluid Compartments

31 Copyright 2010, John Wiley & Sons, Inc. Barriers Between Compartments Plasma membrane: between ECF and ICF Blood vessel walls: between plasma and interstitial fluid Fluid balance correct distribution of water & solutes Water redistributes rapidly by osmosis Thus fluid balance depends on solute (electrolyte) balance

32 Copyright 2010, John Wiley & Sons, Inc. Fluid Balance Fluid balance requires  Appropriate total volume of body fluid  Appropriate distribution of water and solutes Fluid balance depends on solute (electrolyte and nonelectrolyte) balance  Fluids and electrolytes are closely linked Water redistributes rapidly by osmosis

33 Copyright 2010, John Wiley & Sons, Inc. Fluid Balance Interactions Animations Water and Fluid Flow You must be connected to the internet to run this animation.

34 Copyright 2010, John Wiley & Sons, Inc. Water Gain and Loss Gain: ingestion + metabolic reactions  Ingestion (food and drink): 2300 mL/day  Metabolism: 200 mL/day Gain should = loss  Daily intake = daily output. Both 2500 mL/day Loss: skin, lungs, kidneys, GI tract  Kidneys: ~1500 mL/day  Skin: sweat evaporates ~600 mL/day  Lungs: 300 mL/day; more if fever  GI tract: ~100 mL/day; more if diarrhea

35 Copyright 2010, John Wiley & Sons, Inc. Water Balance

36 Copyright 2010, John Wiley & Sons, Inc. Regulation of Gain Thirst center in hypothalamus ~2% dehydration will cause  BP  Increase in body osmolality  dry mouth  thirst  Hormonal responses High osmolality  hypothalamus releases ADH  water retention by kidneys  BP  renin released from kidney  angiotensin II  aldosterone  water retention by kidneys Sensation of thirst may be decreased, especially in elderly

37 Copyright 2010, John Wiley & Sons, Inc. Regulation of Gain

38 Copyright 2010, John Wiley & Sons, Inc. Regulation of Salt and Water Loss Urinary NaCl loss mainly determines body fluid volume  Na + = main solute in ECF determining osmosis Fluid intake varies so loss must vary also ANP, angiotensin II and aldosterone regulate ADH regulates water loss

39 Copyright 2010, John Wiley & Sons, Inc. Regulation of Salt and Water Loss

40 Copyright 2010, John Wiley & Sons, Inc. Movement of Fluid ICF and ECF are normally at the same osmolality Water moves freely  interstitial fluid osmolality  cell swelling and vice versa Most often due to Na + change ADH responds rapidly: prevents significant cell change

41 Copyright 2010, John Wiley & Sons, Inc. Electrolytes in Body Fluids Functions of electrolytes 1.Confined to compartments; control osmosis 2.Help maintain acid-base balance 3.Carry electrical currents 4.Serve as cofactors for enzymes

42 Copyright 2010, John Wiley & Sons, Inc. Electrolyte Distribution Electrolyte content of ICF and ECF differ significantly  ICF: K + major cation; protein, HPO 4 2- : anions  ECF: Na + major cation; Cl - major anion Na + /K + pump maintains the cation difference The two ECF fluids are similar  Electrolytes in plasma similar to those in IF  One difference: plasma contains more protein than interstitial fluid (IF) Colloid osmotic pressure (due largely to plasma proteins) “holds onto” fluid in capillaries

43 Copyright 2010, John Wiley & Sons, Inc. Electrolyte Distribution

44 Copyright 2010, John Wiley & Sons, Inc. Other Electrolytes K + high in ICF, low in ECF  Regulated by aldosterone Mg 2+ and SO 4 2- high in ICF, low in ECF Ca 2+ high in ECF, low in ICF  Regulated in plasma (PTH, calcitriol, and calcitonin)  Bones serve as Ca 2+ reservoir

45 Copyright 2010, John Wiley & Sons, Inc. Acid- Base Balance Input: diet, products of metabolism  Such as lactic acid, ketones Output  Lungs: exhale CO 2  Kidney: can eliminate H + or HCO 3 - Regulatory mechanisms 1.Buffers: fastest but incomplete 2.Respiratory responses: fast but incomplete 3.Renal responses: slowest but complete elimination

46 Copyright 2010, John Wiley & Sons, Inc. 1: Buffer Systems Protein in cells or plasma  Carboxyl and amino groups of amino acids  Hemoglobin (protein) in red blood cells Carbonic acid-bicarbonate  Especially important in plasma  CO 2 + H 2 O  H 2 CO 3 ↔ HCO 3 - + H + Phosphate  H 2 PO 4 -  H + + HPO 4 2-

47 Copyright 2010, John Wiley & Sons, Inc. 2: Exhalation of Carbon Dioxide H + + HCO 3 - ↔ H 2 CO 3 ↔ CO 2 + H 2 O Decrease of CO 2 ↔ decrease of H + Increase of CO 2 ↔ increase of H + Change of rate and depth of ventilation rapidly alters plasma pH Negative feedback loop regulates

48 Copyright 2010, John Wiley & Sons, Inc. 2: Exhalation of Carbon Dioxide

49 Copyright 2010, John Wiley & Sons, Inc. 3. Renal Responses Kidney Excretion of H +  Slow but only way to actually eliminate acid or base  Secrete H + and replace with HCO 3 -

50 Copyright 2010, John Wiley & Sons, Inc. Imbalances Acidosis: arterial blood pH < 7.35   Depresses CNS  Below pH 7.0 can be fatal Alkalosis: arterial blood pH > 7.45   Overexcitation of CNS  Muscle spasms, convulsions Compensation  Respiratory or renal mechanisms  Respiratory very rapid; renal slower

51 Copyright 2010, John Wiley & Sons, Inc. Aging Decrease in control of water and electrolyte balance can lead to pH problems Decreases in respiratory and renal functioning Decreased capacity to sweat


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