Early tubular segments
(Page 3.) Does most reabsorption occur in the early tubular segments or later tubular segments?
b/c the membrane permeabilities are relatively fixed in the early tubular segments
(Page 3.) Why does most reabsorption occur in the early tubular segments as opposed to the later tubular segments?
Later tubular segments
3. (Page 3.) Does fine-tuning of the filtrate occur to a greater extent in the early tubular segments or later tubular segments?
Intercalated cells & principal cell
4. (Page 4.) What are the names of the two types of epithelium found in the collecting ducts?
Help balance of blood pH by secreting hydrogen ions into the filtrate
5. (Page 4.) What is the function of the intercalated cells in the collecting ducts?
To perform hormonally regulated water & sodium reabsorption & potassium secretion
6. (Page 4.) What is the function of the principal cells in the collecting ducts?
aldosterone: adreanal gland; antidiuretic hormone (ADH): pituitary gland
8. (Page 5.) What two hormones control the permeability of principal cells? Where are each of these hormones secreted from?
low blood osmolarity, low blood volume, and angiotensin II
10. (Page 5.) What triggers the release of aldosterone?
increases
11. (Page 5.) What happens to sodium ions and potassium ions in the collecting ducts when there is an increase in aldosterone?
Quickly inserts luminal water channels, thus increasing water permeability
16. (Page 6.) What is the effect of ADH on principal cells of the collecting ducts?
It decreases osmolarity
18. (Page 6.) What is the effect of ADH on interstitial osmolarity?
water
19. (Page 7.) What is lost by the body during dehydration due to perspiration?
ADH - increase reabsorption; body fluid is conserved
20. (Page 7.) What hormone is released during dehydration due to perspiration? What is its effect?
decreases
21. (Page 7.) What happens to urine volume as a result of ADH during dehydration?
decreases
22. (Page 7.) What happens to the secretion of ADH during overhydration?
It increases
23. (Page 7.) What happens to urine volume in overhydration when ADH levels are low?
any drug that elevates the rate of urination
25. (Page 7.) What is a diuretic?
a. Body water decreases (dehydration). b. Blood osmolarity increases (results from fluid loss). c. ADH release from the pituitary increases to counter effects of dehydration. d. Water permeability of the collecting ducts increases (water reabsorbtion from
26. (Page 7.) When there is an increase in dehydration, are the following increased or decreased?
Low levels b/c the hormones promote both Na+ and water reabsoprtion
30. (Page 9.) Under conditions of normal hydration is the filtrate osmolarity in the CCD (cortical collecting duct) low or high? Why?
a. PCT 65% b. descending Loop of Henle 15% c. ascending Loop of Henle unchanged d. cortical collecting duct 15% e. Under normal hydration, what percentage volume of fluid enters the medullary collecting duct? 5%??
31. (Page 10). Under normal hydration, what percentage volume of fluid is reabsorbed in the following areas of the nephron:
ADH
32. (Page 10). What hormone regulates the final amount of water reabsorbed in the medullary collecting duct?
Sodium
36. (Page 11.) In the medullary collecting duct, ADH influences the reabsorption of both water and ____.
It raises to 40%
37. (Page 11.) As urea leaves the medullary collecting duct and travels into the interstitium, what happens to the osmolarity of the interstitium?
Urea would passively re-enters the filtrate in the loop of Henle and re-circulates back to the collecting ducts. It may then again diffuse into the interstitum or pass into the renal pelvis as a component of urine.
38. (Page 11.) What happens to the urea that enters the interstitium?
99%
40. (Page 12.) In normal conditions what percentage of the glomerular filtrate is reabsorbed during its passage through the tubules and ducts?
Thin descending loop of Henle, cortical collecting duct, medullary collecting duct
41. (Summary) In which two regions of the tubule does the filtrate become more concentrated?
Thick ascending loop of Henle
42. (Summary) In which region of the tubule does the filtrate become more dilute?
PCT, thin descending loop of Henle, cortical collecting duct, medullary collecting duct
43. (Summary) In which region of the tubule does the volume of filtrate change?