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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Functions of the Urinary System  Elimination of N wastes, toxins, drugs  Regulate.

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Presentation on theme: "Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Functions of the Urinary System  Elimination of N wastes, toxins, drugs  Regulate."— Presentation transcript:

1 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Functions of the Urinary System  Elimination of N wastes, toxins, drugs  Regulate aspects of homeostasis  Water, electrolytes, pH  Blood pressure  Red blood cell production  Activation of vitamin D

2 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Organs of the Urinary system  Kidneys  Ureters  Urinary bladder  Urethra Figure 15.1a

3 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Nephron  Basic unit that forms urine  Filters fluid and reabsorbs needed substances  Bowman’s capsule  Tubule: proximal, loop of Henle, distal, collecting

4 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Tubular and Vascular Nephron Components Figure 15.5  Blood vessels associated with tubules:  Arterioles: afferent, efferent  Capillaries: glomerular, peritubular, vasa recta

5 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Formation of Urine Figure 15.6 1. Filtration - passive, nonselective 2. Reabsorption - water, glucose, amino acids 3. Secretion - active; H +, NH 4 +, K +, drugs

6 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings  Overall: returns water and solutes to blood capillaries  1. Na + moved by active transport from tubule cells to interstitial fluid and diffuses to capillaries  2. Cl - passively follows Na + (balanced charge)  3. Water reabsorbed with salts  4. glucose and amino acids are cotransported with Na + into tubule cells; then they diffuse into the interstitial fluid  ONLY energy input is to move Na + out of tubule cell (step 1) Tubular Reabsorption

7 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Tubular Secretion  Tubular secretion: removes other substances from blood  Purposes: regulate chemical levels in body, excrete harmful chemicals  Substances secreted: penicillin, cocaine, marijuana, pesticides, preservatives, H +, NH 4 +, potassium

8 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Formation of Dilute Urine Figure 15.10

9 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Regulation of Water and Electrolyte Reabsorption  Regulation is primarily by hormones  Antidiuretic hormone (ADH) prevents excessive water loss in urine  Aldosterone regulates Na + content of extracellular fluid  Triggered by the renin-angiotensin mechanism  Cells in the kidneys (juxtaglomerular apparatus) and hypothalamus are active monitors

10 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Regulation of Blood Solutes, Volume

11 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Maintaining Water Balance  Water intake must equal water output  Sources for water intake  Ingested foods and fluids  Water produced from metabolic processes  Sources for water output  Vaporization out of the lungs  Lost in perspiration  Leaves the body in the feces  Urine production

12 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Blood Buffers - Review  Blood pH must remain between 7.35 and 7.45 to maintain homeostasis  Buffer molecules react to prevent changes in H + concentration  Bind to H + when pH drops  Release H + when pH rises  Three major chemical buffer systems  bicarbonate, phosphate, protein  Respiratory buffer system

13 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Renal Mechanisms of Acid-Base Balance  Slower than chemical regulation, but effective at maintaining blood pH 1. Reabsorption of bicarbonate ions 2. Excretion of H + (as NH 4 +)  Urine pH varies from 4.5 to 8.0

14 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Urinary Bladder  Smooth, collapsible, muscular sac  Temporarily stores urine Figure 15.6

15 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Urethra  Thin-walled tube that carries urine from the bladder to the outside of the body by peristalsis  Release of urine is controlled by two sphincters  Internal urethral sphincter (involuntary)  External urethral sphincter (voluntary)

16 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Characteristics of Urine Used for Medical Diagnosis  Colored yellow due to the pigment urochrome and solutes  Sterile  Slightly aromatic  Normal pH of around 6  Specific gravity of 1.001 to 1.035

17 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Disorders of the Urinary System  Kidney stones  Acute and chronic renal failure  Therapies:  Dialysis  Kidney transplant


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