Biology 172 Exam 2 Osmoregulation and excretion

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  1. a. eliminates one nitrogen atom per molecule
    b. very toxic and requires lots of water to eliminate
    c. characteristic excretory product of aquatic organisms (e.g., fish and amphibians)
    ammonia (NH3)
  2. a. eliminates two nitrogen atoms per molecule
    b. far less toxic and requires less water for elimination
    c. energetically costly
    d. characteristic excretory product of mammals and sharks
    urea (CO(NH2)2)
  3. a. eliminates four nitrogen atoms per molecules
    b. eliminated as a semi-solid paste, requiring very little water
    c. energetically most costly
    d. characteristic excretory product of birds, reptiles, & insects
    uric acid (C5H4O3N4)
  4. Functions of Excretory Systems in Animals
    • 1. elimination of metabolic wastes
    • 2. regulation of water and solute balance
    • 3. regulation of blood pressure
    • 4. regulation of plasma electrolytes
    • 5. maintenance of plasma pH
  5. osmoregulator:
    regulates osmotic balance of internal fluids
  6. osmoconformer:
    cannot regulate osmotic balance; solute concentrations of internal fluids reflect those outside the animal
  7. euryhaline:
    tolerates a broad range of salinities
  8. stenohaline:
    can only survive within a narrow range of salinities
  9. three major regions of the adult human kidney
    • 1. cortex
    • 2. medulla
    • 3. pelvis
  10. 1) contains glomeruli and convoluted tubules
    2) glomeruli = sites of ultrafiltration
    3) convoluted tubules involved in selective resorption and secretion
    cortex of adult human kidney
  11. 1) composed of renal pyramids
    2) renal pyramids with loops of Henle and collecting ducts
    3) loops of Henle involved with generating a salt concentration gradient within renal pyramid
    4) collecting ducts collect urine from nephrons and regulate water content of urine
    medulla of human kidney
  12. an open space into which collecting ducts drain urine into ureter
    pelvis of human kidney
  13. carries urine from kidney to urinary bladder
  14. temporarily stores urine
    urinary bladder
  15. passes urine to exterior from bladder
  16. basic unit of the kidney
  17. hydrostatic pressure of blood in ________ results in ultrafiltration into surrounding space of Bowman's capsule
  18. a) secretion of hydrogen ion, ammonium and toxins from blood into lumen of tubule
    b) reabsorption of sodium, chloride, bicarbonate, sugar, amino acids, and water back into the blood
    proximal convoluted tubule
  19. a) concentration of salt in urine increases towards bottom of loop
    b) concentration gradient results from countercurrent mechanism plus the active secretion of sodium from ascending portion of the loop
    c) results in concentration gradient towards the bases of the renal pyramids
    loop of Henle
  20. 1) transport epithelium freely permeable to water but not to salt and other solutes
    2) water diffuses out of tubule because interstitial fluid hyperosmotic to fluid in tubule
    descending limb of loop of Henle
  21. 1) transport epithelium permeable to salt but not to water
    2) thin segment: NaCl diffuses out of tubule into interstitial fluid
    3) thick segment: NaCl actively pumped out of tubule into interstitial fluid
    ascending limb of loop of Henle
  22. 1) aldosterone = hormone from the adrenal glands
    2) stimulates reabsorption of sodium ion and secretion of potassium ions
    3) ultimately leads to increasing water reabsorption and increasing blood pressure 4) also regulates plasma pH by secreting hydrogen ion and reabsorbing bicarbonate
    5)important in the regulation of sodium and potassium ion concentrations in the blood
    distal convoluted tubule
  23. a) run parallel to loops of Henle and the concentration gradients in the renal pyramids
    b) tendency is for urine to lose water through collecting duct walls
    c) by regulating permeability of collecting duct walls to water, can regulate concentration of urine
    collecting ducts
  24. a. produced in hypothalamus and stored in the posterior pituitary gland
    b. hypothalamus responds to increased osmolarity of the blood
    c. ADH increases permeability of walls of collecting ducts which conserves water losses
    d. involves negative feedback
    e. alcohol inhibits release of _____ leading to dehydration
    antidiuretic hormone (ADH or vasopressin)
  25. a. specialized tissue located in the afferent arteriole
    b. part of the renin-angiotensin-aldosterone system (RAAS)
    c. releases enzyme renin when blood pressure in afferent arteriole drops
    d. renin converts angiotensinogen to angiotensin II which produces the following effects
    1) general arteriole constriction
    2) stimulates proximal tubule to reabsorb more water & NaCl
    3) causes adrenal glands to release aldosterone which results in Na+ and water reabsorption by the distal tubules
    4) net effect is to increase blood volume and blood pressure
    juxtaglomerular apparatus
  26. a. produced from the walls of the heart atria in response to increase in blood volume and pressure
    b. inhibits the release of renin by JGA
    atrial natriuretic factor (ANF)
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Biology 172 Exam 2 Osmoregulation and excretion
Biology 172 Exam 2 Osmoregulation and excretion
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