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DAT Excretory System

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  1. Front
    Nitrogenous waste is usually converted to what?
    Back
    Ammonia (later converted into urea in humans) (Note: excretion handling differs between organisms)
  2. Front
    Where are the places in the human body where excretion takes place?
    Back
    lungs, liver, skin, kidneys
  3. Front
    What is the overview of excretion in the lungs?
    Back
    CO2 and H20 (gases) diffuse from blood and are continually exhaled.
  4. Front
    What is the overview of excretion in the liver?
    Back
    processes: - nitrogenous waste - blood pigment wastes - other chemicals produces: - urea
  5. Front
    What is the overview of excretion in the skin?
    Back
    sweat glands in skin secrete H20 and dissolved salts, regulating body temperature. (Note: skin is largest organ. sweat gland function decreases as we age)
  6. Front
    What is the overview of excretion in the kidneys?
    Back
    takes in blood, filters and excretes substances based off homeostatic needs.
  7. Front
    What are the three regions of the kidney?
    Back
    1. outer cortex 2. inner medulla 3. renal pelvis (drains to ureter)
  8. Front
    What is the path of waste when it reaches the kidney?
    Back
    kidney -> ureter -> bladder -> urethra
  9. Front
    When blood pressure is too high or too low, what organ directly functions to adjust accordingly?
    Back
    kidney
  10. Front
    What is the functional unit of the kidney?
    Back
    nephron
  11. Front
    What are the components of the renal corpuscle?
    Back
    1. Glomerulus 2. Bowman's capsule
  12. Front
    What household item does the glomerulus act like?
    Back
    sieve - strains out unwanted materials
  13. Front
    What are the two important arterioles associated with Bowman's capsule?
    Back
    1. afferent arteriole (in) 2. efferent arteriole (out)
  14. Front
    How does plasma transfer to the Bowman's capsule?
    Back
    hydrostatic pressure forces plasma through fenestrations. screens out large plasma proteins (this pressure can be adjusted based on the body's needs- such as blood pressure regulation)
  15. Front
    what is the substance that gets into the Bowman's capsule called?
    Back
    filtrate/primary urine
  16. Front
    What are cells in Bowman's capsule that filter blood and hold back large molecules and allow smaller molecules to get through?
    Back
    podocytes
  17. Front
    When the efferent arteriole passes back out of the glomerulus, where does it go?
    Back
    webs around the entire nephron structure forming peritubular capillaries and vasa recta. Eventually, it joins the renal branch of the renal vein.
  18. Front
    What is the function of the peritubular capillaries?
    Back
    surround proximal convoluted tubule and distal convoluted tubule and reabsorb materials
  19. Front
    What is the function of the vasa recta?
    Back
    surrounds the Loop of Henle/maintains concentration gradient
  20. Front
    When substances are reabsorbed from the tubules (or secreted into them), where does it takes place?
    Back
    interstitium (Note: network of capillaries that lets us reabsorb into/secrete from the blood)
  21. Front
    What are the componenets of the renal tubule?
    Back
    1. proximal convoluted tubule 2. loop of Henle 3. distal convoluted tubule 4. collecting duct (Note: the renal tubule as a whole is the 2nd part of the nephron)
  22. Front
    Active reabsorption of what substances take place in the proximal convoluted tubule (PCT)?
    Back
    almost all glucose, amino acids, and some NaCl
  23. Front
    Passive reabsorption of what substances begins in the PCT?
    Back
    K+ and HCO3-
  24. Front
    Why is the renal cortex not salty?
    Back
    water follows ions out of the PCT
  25. Front
    What get secreted into the filtrate in the PCT?
    Back
    drugs, toxins, NH3, and H+ ions (by anti-port with Na+)
  26. Front
    What is the net result of the PCT
    Back
    - reduce amount of filtrate - keep concentration the same
  27. Front
    Due to a large amount of active reabsorption in the PCT cells, they will have a lot of which organelle inside their cells?
    Back
    mitochondria
  28. Front
    What structure makes up the majority of the nephron?
    Back
    Loop of Henle
  29. Front
    To what substance is the descending loop only permeable to?
    Back
    water (via lots of aquaporins)
  30. Front
    How does the medulla stay salty if the descending loop is permeable to water?
    Back
    the water is picked up by the vasa recta, keeping the medulla salty
  31. Front
    What happens to the solute concentration in the descending loop of Henle?
    Back
    it increases
  32. Front
    What substance is the ascending loop permeable to?
    Back
    solutes (NaCl)
  33. Front
    What substance is the ascending loop impermeable to?
    Back
    water
  34. Front
    How does the medulla grow salty at the ascending loop?
    Back
    first passively, then actively by pumping out NaCl
  35. Front
    What happens to solute concentration in the ascending loop?
    Back
    it decreases
  36. Front
    What ions of the filtrate get actively pulled out of the DCT and reabsorbed in the body?
    Back
    NaCl and HCO3-
  37. Front
    What ions are actively secreted into the DCT?
    Back
    K+ and H+
  38. Front
    What happens to water in the DCT?
    Back
    passively pulled out
  39. Front
    What happens to the filtrate concentration in the DCT?
    Back
    overall, it is lowered (even though some water passively moves out)
  40. Front
    What hormones can act on the end of the DCT to increase its permeability to water, which is normally not permeable?
    Back
    Aldosterone, and to a lesser extend ADH
  41. Front
    What is the function of the collecting duct?
    Back
    - collects the remaining filtrate - functions are highly dependent on what hormones are acting on it
  42. Front
    What can happen to NaCl in the upper medulla portion of the collecting duct?
    Back
    filtered out of the collecting duct and resorption into circulation
  43. Front
    How permeable is the collecting duct to water?
    Back
    not permeable, unless ADH acts on it
  44. Front
    Why is urea resorbed at the collecting duct?
    Back
    maintain the medulla's osmolarity (can re-enter the loop of henle - called urea recycling)
  45. Front
    What are the two hormones that can change the concentration of urine in the collecting duct?
    Back
    ADH and aldosterone
  46. Front
    how does ADH (vasopressin) act in the kidneys?
    Back
    increased aquaporins (because of concentrated medulla, water wants to leave the tubule)
  47. Front
    how does aldosterone act?
    Back
    - increases Na+/K+ anti-port - water follows Na+ ions out
  48. Front
    Why does alcohol increase urine output?
    Back
    alcohol blocks the creation of ADH (vasopressin), so less resorption of H20
  49. Front
    What are the 4 steps of urine formation?
    Back
    1. Filtration 2. Reabsorption 3. Secretion 4. Excretion
  50. Front
    Of what does the filtration step of urine formation consist?
    Back
    fluid passes through glomerulus (passive process driven by hydrostatic pressure of blood)
  51. Front
    Of what does the reabsorption step of urine formation consist?
    Back
    glucose, salts, and amino acids are reabsorbed from the filtrate and return to the blood
  52. Front
    Where does the majority of reabsorption take place?
    Back
    PCT via active transport
  53. Front
    What is the only passive transport in the reabsorption process?
    Back
    movement of water and the leaving of bicarbonate
  54. Front
    Of what does the secretion step of urine formation consist?
    Back
    substances go from the peritubular capillaries into the nephron (both passive and active transport)
  55. Front
    What is the overall path of the excretory system?
    Back
    - renal corpuscle - proximal convoluted tubule - descending loop of Henle - ascending loop of Henle - distal convoluted tubule - collecting duct - renal calyx - ureter - urinary bladder - urethra
  56. Front
    What is the macula densa?
    Back
    area of closely packed specialized cells lining the DCT
  57. Front
    What does the juxtaglomerular apparatus do if the blood pressure is too low?
    Back
    granular cells —> secrete renin —> angiotensin cascade —> tells adrenal cortex to synthesize aldosterone —> more water is reabsorbed from the DCT —> blood pressure rises
  58. Front
    What is the end goal of the juxtaglomerular apparatus?
    Back
    regulate blood pressure (by monitoring filtrate pressure of the DCT)
  59. Front
    What is created by the entering and exiting of solutes, and increases from the cortex to the medulla?
    Back
    osmolarity gradient
  60. Front
    What term describes the fact that the descending loop is permeable to water and the ascending loop is permeable to salts and ions, the medulla is very salty and facilitates water reabsorption.
    Back
    counter current multiplier
  61. Front
    The innervations of the sympathetic nervous system primarily affect what?
    Back
    afferent arterioles (constrict it —> reduces urine output)
  62. Front
    For humans, how much fluid is filtered and reclaimed, and how much is excreted per day?
    Back
    ~180 liters is filtered and reclaimed and 1-2 L are excreted per day

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