Urinary System

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  • Retroperitoneal - between the body wall and peritoneum
  • Urinary System

    1. 1. Urinary System COCEPTS Identify and describe the components of the urinary system and their function Describe the (histological) organization of the nephron Identify the blood vessels that supply blood to the nephrons Describe the blood flow through and around the nephron
    2. 2. Functions of Urinary System (Kidneys): <ul><ul><li>Regulate fluid balance (fluid volume) of the body </li></ul></ul><ul><ul><li>Excrete organic waste products and conserve nutrients, etc </li></ul></ul><ul><ul><li>Stabilize pH </li></ul></ul><ul><ul><li>Regulate ion concentrations in the blood </li></ul></ul>
    3. 3. Kidney Location Lateral to vertebral column high on body wall, under floating ribs in retro-peritoneal position
    4. 4. Surface Anatomy <ul><ul><li>Size of bar of soap </li></ul></ul><ul><ul><li>Bean shaped </li></ul></ul><ul><ul><li>Hilus – indentation </li></ul></ul><ul><li>Three layers </li></ul><ul><li>Renal fascia – fibrous tunic </li></ul><ul><li>Adipose capsule – protects kidney </li></ul><ul><li>Renal capsule – anchors kidney to body wall, continuous with peritoneum </li></ul>
    5. 5. Sectional Anatomy <ul><li>Cortex: outer layer, light reddish brow, granular appearance (due to many capillaries) </li></ul><ul><li>Medulla: darker striped appearance (due to tubules) Subdivided into distinct renal pyramids, terminating with a papilla. Separated by renal columns from the cortex . </li></ul>
    6. 6. Urine collection: <ul><li>Ducts within each renal </li></ul><ul><li>papilla release urine </li></ul><ul><li>into minor calyx </li></ul>major calyx renal pelvis ureter
    7. 7. Renal Circulation <ul><li>Segmental arteries </li></ul><ul><li>Interlobar arteries </li></ul><ul><li>Arcuate arteries </li></ul><ul><li>Interlobular arteries </li></ul><ul><li>Afferent arterioles </li></ul><ul><li>Glomerulus </li></ul><ul><li>Efferent arterioles </li></ul><ul><li>Peritubular capillaries </li></ul><ul><li>Segmental veins </li></ul><ul><li>Interlobar veins </li></ul><ul><li>Arcuate veins </li></ul><ul><li>Interlobular veins </li></ul><ul><li>Venules </li></ul>Renal Artery Renal Vein
    8. 8. Functional unit: Nephron <ul><li>Renal corpuscle: </li></ul><ul><ul><li>Glomerulus </li></ul></ul><ul><ul><li>Bowman’s capsule </li></ul></ul><ul><li>Tubular passageways with associated blood vessels: </li></ul><ul><ul><li>PCT </li></ul></ul><ul><ul><li>LOH </li></ul></ul><ul><ul><li>DCT </li></ul></ul><ul><ul><li>CD </li></ul></ul>(>mio/kidney)
    9. 9. Filtration: Passage across Three Barriers <ul><li>Capillary endothelium </li></ul><ul><ul><li>Fenestrated </li></ul></ul><ul><ul><li>What gets through? </li></ul></ul><ul><li>Basement membrane </li></ul><ul><li>Glomerular epithelium (= visceral layer of Bowman’s capsule) </li></ul><ul><ul><li>slit pores between pedicels of podocyte </li></ul></ul>
    10. 10. Two Types of Nephrons <ul><li>Cortical nephrons (85%) shorter, mostly in cortex of kidney, produce &quot;standard&quot; urine </li></ul><ul><li>Juxtamedullary nephrons (15%), &quot;juxta-next-to&quot; the medulla - responsive to ADH, can concentrate urine </li></ul>
    11. 11. Juxtaglomerular Apparatus <ul><li>Macula densa </li></ul><ul><li>+ </li></ul><ul><li>Juxtaglomerular cells (smooth muscle fibers from afferent arteriole) </li></ul><ul><li>= Juxtaglomerular Apparatus </li></ul><ul><li>= Endocrine system structure (renin and EPO) </li></ul>
    12. 12. Urine Transport, Storage, and Elimination <ul><li>Trace drop of urine from kidneys to outside world </li></ul><ul><li>Lining of these parts? </li></ul><ul><li>Nephroptosis (= floating kidneys) </li></ul><ul><li>Nephrolithiasis </li></ul>
    13. 13. Transitional Epithelium empty bladder full bladder from renal pelvis to neck of urethra.
    14. 14. Nephrolithiasis Occurs when urine becomes too concentrated and substances crystalize. Symptoms arise when stones begin to move down ureter causing intense pain. Kidney stones may form in the pelvis or calyces of the kidney or in the ureter.
    15. 15. Anatomy of Urinary Bladder <ul><li>Retroperitoneal, behind pubis </li></ul><ul><li>Internal folds - rugae - permit expansion (max. holding capacity ~ 1L) </li></ul><ul><li>Trigone - area at base delineated by openings of ureters and urethra - without muscle </li></ul><ul><li>Internal urethral sphincter - involuntary sphincter </li></ul><ul><li>Histology </li></ul><ul><li>1. transitional epithelium </li></ul><ul><li>2. detrusor muscle – smooth muscle </li></ul>
    16. 16. Urethra <ul><li>External urethral sphincters – voluntary at pelvic floor </li></ul><ul><li>Female - short – from base of bladder to vestibule </li></ul><ul><li>Male </li></ul><ul><li>1. prostatic urethra – from base of bladder through prostate gland </li></ul><ul><li>2. membranous urethra – between prostate gland & base of penis </li></ul><ul><li>3. penile (spongy) urethra – traverses penis to orifice </li></ul>
    17. 17. Male versus Female UTIs (esp. E.coli )
    18. 18. <ul><li>Kidneys may sustain 90% loss of nephrons and still not show apparent symptoms!!! </li></ul><ul><li>2-4 % of population only have 1 kidney! </li></ul>POINTS TO NOTED

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