Physiological correlates of renal disease II

Question 1

the PCT is permeable to:

Answer 1

• water

- salt

Question 2

what is the osmolarity in the PCT in comparison to plasma?

Answer 2

isoismotic

Question 3

how is the permeability of the collecting duct described?

Answer 3

variable permeability according to hormonal control

Question 4

what are the two requirements for forming a concentrated urine?

Answer 4

• high osmolarity of renal medullary interstitial fluid

- high level of ADH

Question 5

the ascending loop is permeable to:

Answer 5

salt

Question 6

what structure serves as a counter current exchanger in order to minimize washout of solutes from the interstitium?

Answer 6

vasa recta

Question 7

what is the role of the vasa recta?

Answer 7

serves as counter current exchanger to minimize washout of solutes from the interstitium

Question 8

as you go deeper into the interstitium, how does osmolarity change?

Answer 8

higher osmolarity

Question 9

why is the counter current exchange system necessary?

Answer 9

necessity to maintain osmolarity in the medulla

Question 10

how does an increase in fluid osmolarity and plasma sodium concentration affect osmoreceptor cells?

Answer 10

osmoreceptor cells shrink

Question 11

what causes osmreceptor cells to shrink?

Answer 11

increase in fluid osmolarity and plasma sodium concentration

Question 12

after osmoreceptor cells shrink, what occurs in the hypothalamus? which nucleus?

Answer 12

release of ADH from supraoptic nucleus

Question 13

the degree of dilution or concentration of the urine is controlled by what hormone?

Answer 13

ADH

Question 14

an increase in plasma ADH has what effect on distal tubules and collecting ducts?

Answer 14

water permeability increases

Question 15

fluctuation in NaCl delivery to the distal tubule is sensed by what structure?

Answer 15

juxtaglomerular apparatus

Question 16

what controls the GFR by a feedback mechanism acting on the renal arteriolar resistance?

Answer 16

juxtaglomerular apparatus secondary to fluctuation in NaCl delivery to the distal tubule

Question 17

what comprises the juxtaglomerular complex? where are these components located?

Answer 17

• macula densa (initial distal tubule)

- juxtaglomerular cells (wall of arterioles)

Question 18

what are two functions of the macula densa?

Answer 18

• sense the delivery of salt

- decide how much renin is released

Question 19

what type of adrenergic innervation stimulates renin release?

Answer 19

B1

Question 20

angiotensin II formation is regulated by changes in ________

Answer 20

BP

Question 21

how does angiotensin II affect sodium and water reabsorption? how does it do this?

Answer 21

• increases sodium and water reabsorption
• constricts efferent arterioles
• directly stimulates sodium tubular reabsorption
• stimulates aldosterone secretion

Question 22

where does aldosterone act? what is its role?

Answer 22

• cells of cortical collecting tubule

- increases sodium reabsorption and potassium secretion

Question 23

levels of what compounds affect the level of aldosterone? what are these levels specifically?

Answer 23

• high Na decreases plasma aldosterone

- high K increases plasma aldosterone

Question 24

an increase in activity of renal sympathetic nerves results in an increase of sodium and water reabsorption due to what three factors?

Answer 24

• reduction in GFR by constriction of renal arterioles
• increase in tubular sodium reabsorption
• increase in renin release and angiotensin II formation, further stimulating tubular sodium reabsorption

Question 25

definition: renal clearance

Answer 25

volume of plasma that is completely cleared of the substance by the kidney per unit of time

Question 26

what are the uses of renal clearance?

Answer 26

- quantify the rate at which blood flow through the kidneys | - basic kidney function

Question 27

what is the best overall index of kidney function?

Answer 27

GFR

Question 28

what is the renal clearance equation?

Answer 28

C = (V x U) / P ``` C = clearance V = urine flow rate U = urine concentration of x P = plasma concentration of x ```

Question 29

what is inulin? what is its clinical use?

Answer 29

- polysaccharide molecule not produced by our body | - used to assess GFR

Question 30

what is the clniical significance of creatinine?

Answer 30

cleared from body entirely by glomerular filtration

Question 31

if a substance is completely cleared from the plasma, the clearance rate of that substance is equal to what measurement?

Answer 31

total renal plasma flow

Question 32

definition: filtration fraction

Answer 32

fraction of renal plasma flow (RPF) that is filtered into bowman's capsule at the glomerulus

Question 33

what is the equation for GFR in terms of RPF and FF?

Answer 33

GFR = RPF x FF

Question 34

how does HTN exacerbate kidney injury?

Answer 34

alteration of renal hemodynamic and tubular reabsorption

Question 35

what type of kidney lesions promote HTN? what are 3 examples of these?

Answer 35

- lesions that reduce the ability of the kidney to excrete sodium and water - increased renal vascular resistance - decreased glomerular capillary FF - excessive tubular sodium reabsorption

Question 36

what is acute kidney injury (acute renal failure) in the context of time frame, GFR, and sequelae?

Answer 36

- syndrome that results in a sudden decrease in kidney function or damage from few hours to few days - rapid decline in GFR accompanied by accumulation of waste products in the blood and inability to maintain fluid and electrolyte balance

Question 37

what is the cause of pre-renal AKI?

Answer 37

kidney hypoperfusion

Question 38

what is the cause of renal AKI?

Answer 38

- vessel and glomerular injury - tubular epithelial injury - renal interstitial injury

Question 39

what are the 4 sites of renal AKI?

Answer 39

- vascular - glomerular - tubular - interstitial

Question 40

what is the cause of post-renal AKI?

Answer 40

urinary tract obstruction

Question 41

what are the physiological consequences of AKI?

Answer 41

- water and sodium overload (edema, HTN) - hyperkalemia - metabolic acidosis - anuria (severe AKI)

Question 42

what is the cause of chronic kidney failure?

Answer 42

disorders of blood vessels, glomeruli, tubules, renal intersitium, and lower urinary tract