Physiology 1 - Renal

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rreavis
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45818
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Physiology 1 - Renal
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2010-11-02 19:52:24
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Physiology Renal
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physiology of renal system
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  1. Kidney
    • produces hormones for regulation of circulatory system, formation of RBC, and bone metabolism
    • Maintenance:
    • regulates composition and volume of body fluids
    • adjust to continuously varying conditions by inc/dec/adjusting urine volume, concentration and composition to actual requirments
    • only need 1/3 to be functional
  2. water - intake and output
    • all intake through intestines
    • (small amount from metabolic water (camels have a lot)
    • somes leaves through lungs as vapor, evaporated off skin, most excreted by kidney
  3. water balance
    • intake = output
    • 2.5 L in = 2.5 L out
  4. kidneys fail
    • transplantaion
    • peritoneal dialysis (inject lots of fluid into abdomen so that high wasteconcentration leaves the blood, fluid can then be drawn out of body)
    • dialysis machine
    • functions of kidneys becoem apperent when then fail
  5. when kidneys fail
    • accumulation of metabolites - urea, creatinine, uric acid, NH4+,
    • disorder of water and electrolyte metabolism - hyperkalaemia (potassium, heart electrial system), hypernatraemia (Na, more in blood volume), hyermagnesaemia, hyerphosphataemia
    • hypertension of arterial blood pressure - renin, angiotensin, aldosterone system(increase Na in blood)
    • hormonal deficiency - anemia, erythropoietin(produced by kidneys
  6. Kidney anatomy
    • retroperitoneal
    • protected by layer of fat
  7. Equine kidney
    triangle in shape
  8. Bovine Kidney
    • no pelvis
    • lobules
  9. Functional unit - Nephron
    • basic unit for formation of urine
    • each kidney contains ~ 1 million nephrons
  10. vasculature
    renal artery - arcuate ateries (form boundary between cortex and medulla - interlobular arteries
  11. Macula Densa
    • measures NaCl concentration to regulate tubular flow
    • causes constriction
    • part of DCT next to afferent arteriole
    • "control center" - for urine flow and concentration
  12. filtration
    • 99% fluid filtered into bowmans capsule is reabsorbed by peritubular capillaries
    • 1% remains and excreted as urine carrying waste
  13. nephron pressure in arterioles
    • 60 mmHg - glomerulus
    • 13 mmHg - peritubular capillaries
    • 15-25% - cardiac output flow through kidneys
    • 1-2% - total renal blood flow through vasa recta
  14. nephron pressure in collecting ducts
    • 18 mmHg - Bowmans capsule
    • 0 mmHg - at end of collecting duct
  15. glomerular filtration
    • humna - 180 L per day
    • excret only 1 L
  16. Glomerular wall
    • visceral epi (podocytes)
    • basement membrane
    • capilary endothelium
    • fenestrated channels - water passage and noncellular components
    • 100 - 500 more permeable than other capillaries
  17. Selective permeability
    • molecular weight of 5200 - filter like water, inulin
    • proteins - almost impermeable
    • pores are negatively charged (proteoglycans) reject negative proteins even if smaller diameter than pore
    • positive > neutral > negative
  18. Nephritis
    • negative charge on membrane is neutralized
    • increased protien found in urine
    • clinically significant - use test strip to test for protein
  19. Glomerular filtrate = no significant amount of protein
  20. Urine
    • fluid is filtered from blood, processed in tubular system
    • Flow speed - highly critical, saturable, directly depends on glomerular filtration rate
    • increase speed, decrease amount of time for reabsorption (lost to urine)
    • decrease speed, waste backup in blood
  21. glomerular filtration - regulated by afferent and efferent arteriole
    rate - fluid volume filtered per min from capillary blood into Bowman's capsule
  22. Normal conditions of GLomerular filtration
    • filtration rate - blood pressure, oncotic pressure, hydrostatic pressure, and oncotic pressure of ultrafiltrate(normally 0)
    • net filtrate = (60-32)-(18-0) = 10 mmHg
    • 60 = mean glomerular blood pressureof afferent and efferent arterioles
  23. Filtration increases = glomerular blood pressure or ultrafiltrate oncotic pressure increases
  24. Filtration decreases = oncotic pressure or the ultrafiltrate hydrostatic pressure icreases
  25. Afferent constriction
    • increases resistance to blood = decreases blood pressure in glomerulus
    • net = 5 mmHg
    • decrease in net filtration pressure
    • decrease consequently the filtration
    • decrease hydrosatic pressure in capsule
  26. Moderate Efferent vasoconstriction
    • increase glomerular blood pressure
    • increase in filtration
    • net = 15 mmHg
  27. Sever Efferent Vasoconstriction
    • increases glomerular blood pressure
    • decrease in blood flow
    • decrease in filtration (less blood passes through per min)
    • increase in blood oncotic pressure
    • net = 5 mmHg
  28. Low GFR
    • decrease in tubular flow
    • extends time for resorption
    • increase reabsorption of wastes
    • more NaCl causes vasodilation by Macula Densa to increase speed of blood flow
  29. High GFR
    • increase speed of tubular fluid
    • decrease time for reabsorption
    • valuable nutrients are lost in urine
    • Macula Densa senses NaCL and causes constriction to decrease speed by secretion of Renin
  30. 5% deviation from normal GFR
    excess loss of solutes and water

    of

    increases retention of waste products
  31. autoregulation of GFR
    • myogenic reflex
    • tubuloglomerular feedback
  32. myogenic reflex
    • increase in arterial pressure streches wall of arteriole b/c of to high of blood flow
    • vessels constrict
    • increased blood flow returns to normal
  33. tubulorglomerular feedback
    • afferent arteriolar vasodilation
    • efferent arteriolar vasoconstriction
    • juxtaglomerular complex
  34. Affernt Arteriolar Vasodilation
    • when - decrease in tubular flow, NaCl - increase in absorption
    • decease in concentration at Macula Densa -

    • decrease in concentration
    • dilation of afferent arteriole
    • increase glomerular filtration pressure
    • increase in fluid filtered
    • increase in tubular fluid flow
  35. Efferent Arteriolar Vasoconstriction
    • NaCl - increase in absorption, decease in concentration at Macula Densa
    • release of Renin from Macula Densa
    • Renin - angiotensin II - constrition of effernt arterioles
    • increase in GFR
  36. Renin - Angiotensin - Aldosterone System
    • short system - angiotensin increases systemic blood pressure (vasoconstrition)
    • long system - aldosterone increases blood volume
  37. Renal vasodilators prostaglandins
    • E2 and I2
    • help maintain renal vascular resistance at normal levels by conteracting angiotensin II
  38. renal vascular tone hormones - Vasoconstrictors
    • endothelin
    • thromboxane A2
    • Angiotensin II
  39. renal vascular tone hormones - Vasodilation
    • Nitric oxide
    • prostaglandin E2 and I2

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