Renal system1 of 2

Question 1

The urinary system has many functions describe the the 5 main ones, use the clues below.

1. Regulate
2. excrete
3. blood pressure
4. RBC production
5. prohome

Answer 1

1. Regualtion of balance between water and electrolytes and acid base balance
2. excretion of metabolic waste products and foreighn substance (including drugs) along with excess water and electrolytes in the urine
3. secretion of renin, a protease important for regulation of blood pressure.
   
   1. acts by cleaving cirulating angiotensinogen to angiotensin 1
4. secretion of erythropoietin, a glyco protein growth factor that stimulates erythrocyte productin tin red bone marrow when the blood O2 level is low
5. conversion of sterior prohormone vitamin D, initially produced in the skin, to active form 1,25-dihydroxyvitamin D3 or cacitrol

Question 2

label the gross anatomy of the kidney

Answer 2

Question 3

what is the functional unit of the kidney?- list and describe the 2 components

Answer 3

uriniferious tubules

1. nephron
   
   1. collects a filtrate of blood and modifies the filtrate by adding nitrogenous waste to it and reabsorbing componenets from it
2. collecting duct
   
   1. absorbs water from the filtrate, creating hypertonic urine that is conveyed to the calyces

Question 4

what are the functionally and histologically distinct regions involved with the nephron

Answer 4

nephron

1. renal corpuscle
2. proximal convuluted tubule
3. loop of henle
4. distal convoluted tubule
5. collecting tubules,
   
   1. a short minor part linking the nephron to the collecting ducts
   2. connecting tubules from various nephrons join to form collecting tubules, which then merge to form collecting ducts

Question 5

What are the two embryologically distinct regions of the uriniferous tubule?

Answer 5

nephron and the collecting tubule/duct

1. nephron
   
   1. renal corpuscle
   2. PCT
   3. loop of henle
   4. DCT

Question 6

Describe the twyp of nephrons

Answer 6

2 categories based on their location and length of their loop of henle

1. juxtamedullary nephron
   
   1. long loops of henle
   2. extend deep into the medulla. These are specialized to maintain the hypertonic gradient of the medulla
2. cortical nephrons
   
   1. have short loops of henle
   2. do not extend far into the medulla
   3. are about seven times more numerous than the hustamedullary nephron

Question 7

what is the 1st subdivision of a nephron? (two names) discuss and describe components

Answer 7

renal corpuscle aka malpighian corpuscle

1. responsible for filtration of blood plasma
2. structures
   
   1. bowman capsule
      
      1. invests a tuft of fenestrated capillaries called glomerulus
      2. two layers
         
         1. visceral
            
            1. attached to the capillary glomerulus and lined by epithelial cells called podocytes
               
               1. podocytes rest on a basal lamina
         2. parietal
            
            1. lined by simple squamous epithelium, resing on the basal lamina
            2. continuous with the simple cuboidal epithelium of PCT
         3. two layers generate bowmans space
            
            1. contains the plasma ultra filtrate
            2. generates the urinary pole- continuous with the lumen of the PCT
   2. glomerulus
      
      1. convoluted tuft of fenestrated capillary, situated between 2 arteriorles
         
         1. arterioles
            
            1. afferent - carries blood into the glomerulus
         2. efferent
            
            1. the vessel by which blood exits the glomerulus
      2. increased hydrostatic pressure in these arterioles favors the movement of plasma across the glomerular filter

Question 8

flattened stellate cells on the visceral layer? function?

Answer 8

podocytes

1. flattened stellate cells develooped from the visceral layer that completely envelops the capillaries
2. primary processes radiate from the cell and five rise to secondary processes.
   
   1. these eventually terminate in fine, finger like extensions pedicles that interdigitate with pedicles of other podocytes

Question 9

in addition to endothelial cells and podocytes, the renal corpuscles also contain. Describe location and function(4)

Answer 9

mesangium=mesangial cells and mesangial matrix

1. function
   
   1. physical support of capillaries with in the glomerulus
   2. adjusted contractions in response tto blood pressure changes,
      
      1. helps maintain an optimal filtration rate
   3. phagocytosis of protein aggregates adhering the glomerular filter
      
      1. antigen-antibody complexes
   4. secretion of several cytokines
      
      1. prostaglandins and other factors important for immune defense and repair of glomerulus

Question 10

dientify and describe the poles of the renal corpuscle

Answer 10

1. urinary pole
   
   1. continuous with the lumen of the PCT
2. vascular pole
   
   1. the area of glomerulus from which both afferent and efferent arterioles arise

Question 11

describe glomerlular filtration

Answer 11

filtration occurs through the glomerular filter, which is composed of 3 major componenents:

1. fenestrated capillary endothelium-coarse
   
   1. fenestrated cells allow coarse filter
      
      1. this allows non cellular formed elements to pass
      2. 70-90nm
2. basement membrane-charged
   
   1. type 4 collagen, laminin
   2. juxtaposed between the pedicles and capillary endothelium
   3. heparin suphate proteoglycan makes the basement negatively charged
      
      1. serves as an electrstatic barrier, preventing same charged particles from being filtered
3. podocyte filtration slit-fine
   
   1. spaces about 25nm in diameter interdigitating pedicles
   2. slit diaphragm- specialized junctions composed of nephrins , glycoproteins and proteoglycans
   3. restric small proteins and organic anions

Question 12

of the glomerular filtration barrier, which is considered the primary?

Answer 12

the basement membrane is considered the primary filter (glomerular ultra filter)

Question 13

blood plasma minus large molecules

Answer 13

filtrate

Question 14

damage to glomerular filter occus in a number of disease state which can generate into

Answer 14

nephrotic syndrome

Question 15

summarize the initial filtration of blood in the kidneys

Answer 15

1. the whole blood is in the capillary lumen
2. filtrate is formed by passing through the fenestrated capillary endothelium, basement membrane and the podocyte filtration slits
3. the basement membran is the primary filter (glomerular ultra filter)
4. the filtrate collects in the bowman’s space
   
   1. filtrate = blood plasma minus large molecules

Question 16

what is the most common cuase of renal failure in affluent countries? Explain the disease and normal state

Answer 16

diabetic nephropathy, which is associated with proteinuria.

1. normally
   
   1. glomeruli balance deposition and removal of mesangial matricx very tightly.
2. diabetic glomerulosclerosis =
   
   1. thickening of the
      
      1. mesangial basement membrane
      2. mesangial matrix
   2. This is in response to the increase in transforming growth factor beta = inducing increased deposition of mesangial matrix in response to hypreglycemia and a different matrix deposition

Question 17

what is the 2nd subdivision of the nephron?

Answer 17

proximal convoluted tubule

Question 18

describe the content and function of the PCT

Answer 18

• content
  
  • Simple cuboidal epithelium lines the PCT
  • Brush border
    
    • layer of microvilli on apical surface of simbple cuboidal cells
      
      • increases capacity of glomerular filtrate reabsorption
  • stain easily due high [mitochondrial]
    
    • high energy cells
• function
  
  • reabsorbs
    
    • all glucose
    • 75% of H20 and NACl
    • small proteins via pinocytosis
    • HCO3- (bicarbonate)
  • secretes
    
    • NH4+ (ammonium ions)
      *

Question 19

PCT are highly dependent on what enzyme in the basolateral membrane? What about the brush border? (be sure to undertnand the gradients used in each)

Answer 19

The NaCl, water and glucose reabsorption are higly dependent on the Na+K+ ATPase found in the basolateral membranes

1. pump protein activly transports Na out of the cell, Cl- follwos to maintain electrical neutrality and water follows for osmotic equilibrium

brush border

1. Na+ glucose transporter located in the brush border membrane uses the Na + gradient

Question 20

There are 4 important pumps and 1 important enzyme associated with the PCT? explain function of each

Answer 20

both are located in the PCT

1. Na+K+ ATPase-most important(all other enzymes rely on this gradient)
   
   1. basolateral membranes
   2. NaCl, water and glucose are reabsorbed
   3. uses the most energy- hence lots of mitochondria
2. Na+ glucose transporter
   
   1. brush border membrane
   2. RELIES ON THE Na+ GRADIENT GENERATED BY Na+K+ATPase TO DRIVE GLUCOSE INTO THE CELL
3. NaH+ exchanger
   
   1. brush border membrane
   2. as HCO3 is filtered out, it must be reabsorbed to maintain pH
      
      1. ~85% is reabsorbed here
   3. RELIES ON THE Na+ GRADIENT GENERATED BY Na+K+ATPase TO DRIVE H+ INTO THE TUBULE LUMEN where it combines with HCO3- to form H2CO3
4. Na+NH4+ exchanger
   
   1. brush border membrane
   2. RELIES ON THE Na+ GRADIENT GENERATED BY Na+K+ATPase TO DRIVE NH4+ OUT OF THE CELL and into the filtrate
   3. contributes to lipid-soluble NH3 to the filtrate by diffusion across the epithelial membrane
5. carbonic anhydrase
   
   1. brush border membrane
   2. contributes to the formation of H2CO3, from H20 and CO2

Question 21

what is the 3rd subdivision of the nephron?

Answer 21

loop of henle

Question 22

define the features in the loop of henle. construct and functions

Answer 22

1. descending limb
   
   1. arises fro mPCT
   2. no brush border
   3. in kidney outer medulla
   4. lined with
      
      1. simple squamous epithelium
   5. HIGHLY permeable to WATER
   6. LOW permeability to SOLUTES
2. ascending limb
   
   1. lined by
      
      1. simple cuboidal epithelium
   2. originates after the curve in the loop of Henle
   3. impermeable to water
   4. HIGHLY permeable to solutes
   5. LOW permeability to water
   6. Na+K+ATPase pump found here
      
      1. FACILITATES ABSORPTION OF SOLUTES

Question 23

reducing osmolalitty of the intersitital fluid of the medulla leads to ___

Answer 23

diuretics like furosemide (Lasix) inhibits the absorption of NaCl and increases urinary excretion of both NaCl and water by reducing osmolality of the interstitial fluid of medulla

Question 24

Which portion of the nephron activly reabsorbs NaCl but is impermeable to urea? Describe the fluid leaving this area.

Answer 24

distal collecting tubule

NaCl absorption is under the effect of aldosterone.

in the absence of ADH the tubules are impermeable to water( NaCl is reabsored w/o H2o) and the osmolality is reduced. the fluid leaving this area and entering into the collecting ducts is HYPO-OSMOTIC with respect to the plasma

Question 25

Question 26

what is extremely important for the production of hypertonic urine? explain

Answer 26

count-current exchange along the loop of henle

Question 27

what happens to the osmolality of the tubular fluid in the presence of ADH?

Answer 27

in the presence of ADH water diffuses into the interstitium and the osmolality of the tubular fluid increases and urine concentration begins. increase in uptake of water from the medullary collecting tubule

Question 28

where can reabsorption of NH4+ occur?

Answer 28

loop of henle

Question 29

flow and function of the vasa recta

Answer 29

the vasa recta are a capillary network tha remove, in a flow dependent manner, excess of water and solutes continuously added to the interstitium by the nephron segments

Question 30

What is the 4th subdivision of the nephron? describe location and cell layer

Answer 30

distal convoluted tubule

1. tortuous tubule that arises from the thick ascending limb after it penetrates the cortex
2. lined by simple cuboidal epithelium
   
   1. cuboidal cells are shorter as compared to PCT epithelial cells and lack a brush border

Question 31

DCT

1. plasma membrane, compare to PCT
2. important cell type
3. membrane enzyme
4. function

Answer 31

1. plasma membran of basolateral domain is folded and contains mitochondria, similar to PCT
2. macula densa
   
   1. modified cells of DCT
   2. located adjacent to renal corpuscle at the vascular pole
   3. apear as thin columnar and tightly packes
   4. these are theCHEMORECEPTORS sensitive to Na+ levels of the DCT filtrate
3. Na+K+ATPase
   
   1. activity on basal surface of epithelial cells, provides tha DCT with the means to reabsorb nearly all remaining filtrate NaCl
4. distal portion of DCT and collecting duct
   
   1. normally are not permeable to water , but become in the presence of
      
      1. ADH
      2. VASOPRESSIN

Question 32

what pole are macula densa cells found?

Answer 32

Vascular pole

Question 33

what is the 5th subdivision of the nephron?

Answer 33

colelcting tubules

Question 34

continue from DCT. What is the epithelium?

Answer 34

collecting tubutles

-simple cuboidal w/o brush border

1. cell types
   
   1. principal cells
      
      1. the only ones seen in the medullary portion
   2. intercalated cells
      
      1. only seen in the cortical portion

Question 35

formed by the merger of collecting tubules. where does it begin and continue?

1. two cell types

Answer 35

collecting ducts- begins with the medullary rays in the cortex and continues through to medulla

1. cell types
   
   1. principal cells- in the medulla
      
      1. function- two conditions
         
         1. presence of ADH
            
            1. critical to water reabsorption from the filtrate
            2. can also reabsorb Na+
            3. can also secrte K+
         2. no ADH = hypotonic urine is produced
            
            1. impermeable
      2. controlled by
         
         1. ADH- releasd from the pituitary
         2. basolateral Na+K+AtPase
            
            1. responsible for NA+ reabsorption from the filtrate and K+ secretion into the filtrate.
   2. intercalated cells- in cortex and medulla
      
      1. function- regulate the pH
         
         1. microvilli- abundant in mitochondria
         2. secrete H+ or HCO3-
         3. absorb K+

Question 36

dehydration leads to the conservation of water, explain

Answer 36

ADH is released fro mthe pituitary gland, by dehydration

ADH travels to the principal cells of the collecting ducts(in the kidneys) and increases the permability of water

generating hypertonic urine

Question 37

secrete either H+ or HCO3-

what are they and where?

Answer 37

intercaleted cells

1. in the collecting ducts (closer the the DCT, not found in the medullary portions)
2. secrete either H+ or HCO3- , regulating acid base balance
3. reabsorb K+

Question 38

straight collecting ducts in the inner medulla

1. formed by
2. lined by
3. flow into

Answer 38

papillary ducts of bellini

1. each formed by the merger of several smaller collecting ducts
2. lined by simple tall columnar cells
3. empty into minor calyces

Question 39

present on each renal papilla and consists of about 25 pores.

1. what does it represent?

Answer 39

area cribrosa

1. present on each renal papilla and consists of about 25 pores that represent the end of papillary ducts
2. empty into the minor calyces, then into the major calyces
3. there are two major calyces which drain into the ureter.

Question 40

how many major calyces drain into the ureter?

Answer 40

two major calyces drain into the ureter

Question 41

what is the location and function of

PCT

Answer 41

1. cortex
2. reabsorption of
   
   1. all organic nutrients
   2. most water
   3. electrolytes
   4. secretion of organic anions and cations
      
      1. H+ and NH4- (respectivly)

Question 42

what is the location and function of

loop of henle thin limb

Answer 42

1. medulla
   
   1. passive reabsoprtion of
      
      1. Na+
      2. CL-

Question 43

what is the location and function of

loop of henle Thin ascending limb

Answer 43

1. medulla nd medullary rays
2. active reabsorption of various electrolytes

Question 44

what is the location and function of

DCT

Answer 44

1. cortex
2. reabsorption of electrolytes

Question 45

what is the location and function of

collecting system: peincipal cells

Answer 45

1. medullary rays and medulla
2. regulated reabsorption of water and electrolytes
   
   1. regulated secretion of K+

Question 46

what is the location and function of

collecting system: intercaleted cells

Answer 46

1. medullary rays
2. reabsorption of K+ (low K diet)
3. help maintain acid-base balance

Question 48

label the following numbers

Answer 48

Question 49

what is another name for ADH? where does it act?

Answer 49

Vasopressin