Decreased GFR, Anuria, Polyuria

Question 1

what is the pressure in the glomerular capillaries like compared to other capillaries?

Answer 1

higher hydrostatic pressure

Question 2

is the efferent or afferent arteriole of wider diameter?

Answer 2

afferent arteriole

Question 3

what pressure increases in the efferent arteriole?

Answer 3

oncotic pressure

Question 4

what is the bowmans capsular oncotic pressure?

Answer 4

zero normally

Question 5

net filtration pressure=

Answer 5

difference between glomerular hydrostatic pressure and opposing forces (plasma oncotic pressure and pressure in bowmans capsule)

Question 6

hydrostatic pressure in the capillaries and renal blood flow are under physiological regulation. what happens to capillary pressure, renal blood flow, and glomerular filtration rate if the afferent arteriole is constricted?

Answer 6

all three are decreased

Question 7

what happens to capillary pressure, renal blood flow, and glomerular filtration rate if the efferent arteriole is constricted?

Answer 7

capillary pressure increases
renal blood flow decreases
glomerular filtration rate increases

Question 8

what are decreases in glomerular filtration rate often due to?

Answer 8

tubular problems
less often glomerular disease

Question 9

what structure is responsible for tubuloglomerular feedback?

Answer 9

macula densa

Question 10

how is the glomerular filtration rate held relatively constant?

Answer 10

intrinsic autoregulatory mechanisms
extrinsic hormonal and neural mechanisms

Question 11

what can the sympathetic nervous system do to regulate glomerular filtration rate?

Answer 11

sympathetic nerves can constrict afferent arteriole: decreases GFR
can stimulate renin secretion which helps to restore GFR

Question 12

what normalizes glomerular filtration rate in the face of sympathetic nervous system response?

Answer 12

angiotensin II

Question 13

what physiologic changes trigger vasoconstriction of afferent arterioles and thus a decrease in glomerular filtration rate?

Answer 13

increased blood pressure
increased flow rate
increased NaCl in distal tubule

Question 14

what substances increase glomerular filtration rate?

Answer 14

angiotensin II
atrial natriuretic peptide
nitric oxide
prostaglandins E2 and I2

Question 15

what are some substances that decrease glomerular filtration rate via vasoconstriction?

Answer 15

norepinephrine
epinephrine
endothelin

Question 16

what things control renin secretion?

Answer 16

macula densa and tubuloglomerular feedback
sympathetic nervous system
afferent arteriolar pressure

Question 17

what are some key components of a normal renal tubular cell?

Answer 17

microvilli increase surface area for transporters
tight junctions help to control transport
Na/K ATPase in basal membrane establishes Na gradient
hemidesmosomes attach cells to basement membrane

Question 18

what are some cytoskeleton alterations in acute kidney injury?

Answer 18

ischemia and toxins cause decrease ATP: actin cannot polymerize into filaments
loss of apical microvilli and brush border
loss of tight junctions

Question 19

what does loss of tight junctions in a renal tubular cell lead to?

Answer 19

fluid moving from lumen into interstitial space: backleak leads to decreased urine output

Question 20

loss of polarity can result in Na/K ATPase moving from basal membrane to apical membrane. what will be the result?

Answer 20

increase sodium in filtrate, leading to vasoconstriction of afferent arteriole
macula densa
why we see a plummet in GFR with AKI

Question 21

loss of tight junctions allows redistributions of membrane proteins and ___________________ diffuses to apical membrane

Answer 21

Na/K ATPase

Question 22

what can decreased ATP production lead to?

Answer 22

cellular obstruction of tubules

Question 23

what does decreased Na/K ATPase activity lead to?

Answer 23

Na remains in cells
cell swells as water follows

Question 24

what does an increase in intracellular calcium do?

Answer 24

activates proteases and phospholipases
further cell damage

Question 25

what does increased intracellular calcium lead to?

Answer 25

cells slough and form cellular casts

Question 26

do some nephrotoxins cause tubular obstruction through crystal formation?

Answer 26

yes

Question 27

what toxin causes calcium oxalate monohydrate crystals?

Answer 27

ethylene glycol

Question 28

what is one thing ethylene glycol is in?

Answer 28

antifreeze

Question 29

what are some oxalate containing plants?

Answer 29

pigweed halogeton sour grass/shamrock sorrel/rhubarb

Question 30

what does melamine/cyanuric acid cause?

Answer 30

intratubular crystals causing obstructive injury

Question 31

what is the difference in appearance of calcium oxalate monohydrate and calcium oxalate dihydrate crystals?

Answer 31

monohydrate: picket-fence, pointed ends dihydrate: square, flat pyramids or crossed squared

Question 32

what do sulfonamides cause?

Answer 32

tubular obstruction crystals bind to plasma membrane proteins

Question 33

do crystals cause irritation to the bladder?

Answer 33

no

Question 34

what can large numbers of crystals do?

Answer 34

predispose to stone formation

Question 35

does the presence of crystals indicate presence of a stone?

Answer 35

no

Question 36

what do casts indicate?

Answer 36

renal damage

Question 37

what does a cast form in response to?

Answer 37

increased protein or electrolytes

Question 38

what is a hyaline cast?

Answer 38

tamm-horsfall mucoprotein alone

Question 39

what usually causes hyaline casts?

Answer 39

proteinuria

Question 40

can casts plug tubules?

Answer 40

yes

Question 41

what are microscopic lesions of acute tubular injury usually?

Answer 41

subtle

Question 42

what microscopic lesions can you see with acute tubular injury?

Answer 42

loss of brush border vacuolated cells dilated tubules release cytoplasmic blebs into tubular lumen cells detach from basement membrane edematous interstitium

Question 43

does the clinical syndrome correspond with histopathologic findings?

Answer 43

no

Question 44

why does tubular stress trigger a decrease in glomerular filtration rate to reduce workload?

Answer 44

preservation of oxygen tension in medullary area up-regulation of tubular cellular survival factors

Question 45

what would happen without tubuloglomerular feedback with tubular stress?

Answer 45

catastrophic loss of sodium and circulating volume

Question 46

what happens occasionally with severe toxicity?

Answer 46

acute tubular necrosis

Question 47

what can reduce the length or size of the capillary bed and therefore decrease glomerular filtration rate?

Answer 47

loss of nephrons decreased glomerular permeability

Question 48

what can loss of nephrons be caused by?

Answer 48

neoplasia inflammation fibrosis

Question 49

what are histologic findings like with chronic renal disease?

Answer 49

more dramatic than with AKI

Question 50

what can happen in chronic glomerular disease that decreases the glomerular ultrafiltration coefficient?

Answer 50

changes in glomerular wall possible decreases in endothelial cell fenestrations possible capillary constriction/collapse

Question 51

why do we often see a much less severe drop in GFR in animals with CRD than in those with AKI?

Answer 51

AKI affects all of the glomeruli or large swaths: no time for compensation CRD affects individually, so neighbors can help

Question 52

why do animals with chronic renal disease often present with polyuria and polydipsia? as opposed to acute kidney injury which presents with anuria/oliguria

Answer 52

loss of urine concentrating ability

Question 53

what are reported values of glomerular filtration rate in healthy dogs?

Answer 53

1.56 to 2.96 mL/min/kg

Question 54

what does the loop of henle do?

Answer 54

uses Na and Cl to create a hypertonic medullary interstitium

Question 55

_____________ is greater in the inner medullar than in the outer

Answer 55

osmolarity

Question 56

what is the thin descending limb permeable to?

Answer 56

water essentially impermeable to small solutes such as NaCl and urea

Question 57

what is the thin ascending limb permeable to?

Answer 57

NaCl impermeable to water

Question 58

where is urea reabsorbed?

Answer 58

proximal convoluted tubule distal convoluted tubule collecting duct

Question 59

what is the effect of the loop of henle?

Answer 59

hypertonic interstitium progressively more hypertonic as you go deeper into medulla filtrate entering distal tubule is hypotonic

Question 60

what maintains the gradient?

Answer 60

vasa recta

Question 61

how does antidiuretic hormone work?

Answer 61

inserts aquaporins into collecting ducts and water passively moves out of filtrate

Question 62

what does angiotensin II lead to?

Answer 62

increased aldosterone which increases blood volume and vasoconstriction of systemic arterioles

Question 63

how can the sympathetic nervous system override autoregulation?

Answer 63

constrict afferent arteriole stimulate renin secretion which helps to restore GFR

Question 64

angiotensin II preferentially constricts ______________ arterioles more than ______________ arterioles

Answer 64

efferent afferent

Question 65

what do increased blood pressure, flow rate, or NaCl in the distal tubule trigger?

Answer 65

vasoconstriction of afferent arterioles

Question 66

what hormones lead to increased GFR?

Answer 66

angiotensin II atrial natriuretic peptide nitric oxide prostaglandins E2 and I2

Question 67

does increased or decreased pressure in the afferent arteriole lead to increased renin production?

Answer 67

decreased

Question 68

gorging on halogeton can cause _______________________ in sheep and horses

Answer 68

renal problems

Question 69

what do cattle and pigs get from ingesting pigweed?

Answer 69

nephrotoxin, oxalates, and nitrates acute nephrosis and heart failure

Question 70

what does tamm-horsfall mucoprotein normally do?

Answer 70

protects tubular cells and contributes to permeability barrier

Question 71

what does tubular stress trigger?

Answer 71

decrease in GFR to reduce workload: preserves oxygen tension in medullary area (relative hypoxia) and up-regulates tubular cellular survival factors

Question 72

what will decrease the filtration coefficient?

Answer 72

loss of nephrons decreased glomerular permeability

Question 73

what can cause loss of nephrons?

Answer 73

neoplasia inflammation fibrosis

Question 74

how does the filtration coefficient decrease with chronic glomerular disease?

Answer 74

changes in glomerular wall possible decreased in endothelial cell fenestrations possible capillary constriction/collapse

Question 75

what does aldosterone regulate?

Answer 75

Na retention

Question 76

what contributes to the polydipsia/polyuria with CRD?

Answer 76

increased solute load per functional nephron altered function of countercurrent mechanism impaired renal responsiveness to ADH