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PSL301 > PSL301: Water 8 > Flashcards

PSL301: Water 8 Flashcards

Excretion of waste products; endocrine function

1
Q

UREMIA

A

a raised level in the blood of urea and other nitrogenous waste compounds that are normally eliminated by the kidneys
= advanced kidney failure

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2
Q

clinical symptoms of uremia

A
  • severe fatigue & weakness
  • poor appetite, nausea, vomiting
  • edema in feet, ankles
  • itchy skin
  • disturbed mental functions
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3
Q

Telltale biochemical marker of uremia

A

very high serum creatinine & urea levels (GFR < 10%)

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4
Q

What are the waste products excreted by urine?

A

mainly products of protein metabolism

  • urea
  • creatinine
  • uric acid (urate)

many other small molecules excreted in small amounts

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5
Q

most abundant waste in urine

A

urea

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6
Q

amount of waste found in urine depends on…

A

how much protein is eaten

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7
Q

each urea has __ nitrogens

A

2

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8
Q

Waste products in urine are readily ____ and minimally ___

A

filtered;

reabsorbed

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9
Q

___ is generated from AA breakdown

A

ammonia

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10
Q

ammonia is highly…

A

toxic

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11
Q

to combat toxic effects of ammonia, it is converted to ___ in the ____. This is then excreted in the urine.

A

urea;

liver

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12
Q

steps of urea generation from ammonia

A
  1. ammonia + CO2 -> carbamoyl phosphate
    • L-ornithene -> citrulline
    • L-aspartate -> arginosuccinate
  4. -> L-Fumarate + L-Arginine
  5. L-Arginine + H2O -> Urea + L-ornithene
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13
Q

enzyme: CO2 + NH3 -> carbamoyl phosphate

A

carbamoyl phosphate synthase

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14
Q

enzyme: carbamoyl phosphate + L-ornithene -> citrulline

A

ornithine carbamoyltransferase

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15
Q

enzyme: citrulline + L-aspartate -> arginosuccinate

A

arginosuccinate synthase

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16
Q

enzyme: arginosuccinate -> L-Fumarate + L-Arginine

A

argininosuccinate lysase

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17
Q

enzyme: L-Arginine + H2O -> Urea + L-ornithene

A

arginase

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18
Q

creatinine is generated from…

A

phosphocreatine -> creatine -> creatinine

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19
Q

PHOSPHOCREATINE

A

storage compound for energy in muscle

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20
Q

how many molecules of nitrogen does each creatinine molecule have?

A

2

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21
Q

enzyme: phosphocreatine -> creatine

A

creatine kinase

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22
Q

Uric acid is generated from…

A

nucleic acid break down

- uric acid = nitrogenous metabolite of purines

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23
Q

high concentrations of uric acid causes…

A

gout (type of arthritis)

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24
Q

gout typically occurs in the ___. It is caused by…

A

foot/ankles;

urate crystal deposition in joint fluids -> inflammation -> joint becomes swollen/tender/painful

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25
Q

enzyme: xanthine -> uric acid

A

xanthine oxidase

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26
Q

what is used to treat gout? why?

A

xathine oxidase inhibitors;

xathine oxidase is the enzyme that produces uric acid

27
Q

some human studies suggest that a 60% GFR may be associated with…

A

increased risk of death from cardiovascular disease

28
Q

___ and ___ are not toxic. The toxicity of low GFR is due to…

A

urea;
creatinine;
the small molecules that builds up in blood

29
Q

endocrine functions of the kidney

A
  1. renin
  2. erythropoietin
  3. vitamine D metabolism
30
Q

renin is synthesized & secreted by…

A

cells of afferent arteriole

31
Q

effect of renin on Na

A

increase Na reabsorption

  • ANG II (directly)
  • aldosterone (indirectly)
32
Q

effect of renin on water

A

keeps water inside body

  • thirst
  • vasopressin
33
Q

effect of renin on GFR

A
  • constricts efferent arteriole to increase glomerular capillary pressure
  • increase GFR
  • balances out decreased GFR from hypotension
34
Q

___ is synthesized by ___ at border of medulla and cortex where O levels are low

A

glycoprotein;

pericytes

35
Q

where are pericytes located, and what are they used for?

A

located at border of kidney medulla & cortex, used to make glycoprotein

36
Q

Why are pericytes located at the border of the medulla and cortex?

A
  • O2 are low there
  • very sensitive to O levels
  • decreased O stimulates secretion of EPO
37
Q

2 conditions which cause secretion of EPO

A
  1. anemia

2. hypoxemia

38
Q

function of EPO

A

increase RBC production in bone marrow

39
Q

EPO is a popular drug for…

A

long-distance athletes, where O2 is a limiting factor to success

40
Q

function of vit D

A

increase absorption of dietary calcium from gut

41
Q

how to activate vit D from diet or skin?

A

1) 25-hydroxylation in liver (can be stored here)

2) 1-hydroxlation in kidney

42
Q

what is the final active hormone of vit D?

A

1,25-(OH)2 vit D3

= calcitriol

43
Q

which vitamin D activation step is regulated? Which isn’t?

A

regulated: 1-OHase in kidney
unregulated: 25-OHase in liver

44
Q

effect of PTH on calcium

A

Increase serum Ca

  • break down bone
  • reabsorption by kidney
  • increase rate at which vit D is converted to calcitriol (activity of 1-OHase)
45
Q

what happens to vit D conversion if the kidney is damaged?

A
  • no 1-OHase
  • low Ca absorption from gut
  • low serum Ca
  • stimulate high PTH
46
Q

most common causes of uremia

A
  1. diabetes (30-40%)

2. high BP

47
Q

uremia: why fatigue & weakness?

A

Low EPO secretion by kidneys

  • less RBC
  • reduced O carrying capacity of blood

Waste products reduce muscle function

48
Q

uremia: why hypertension?

A

kidney can’t excrete Na+ as well (damage, reduced GFR)

  • Na+ retained in blood
  • pull water into blood as well
49
Q

uremia: why edema?

A

kidney can’t excrete Na+ as well (damage, reduced GFR)

  • Na+ in ECF
  • expanded ECF = edema
50
Q

uremia: why high levels of urea, creatinine, urate?

A

low GFR can’t process all the waste fast enough

51
Q

what allows us to rule in chronic kidney disease / severe kidney failure?

A

high levels of urea & creatinine in serum

- if this is not present, we can rule out CKD

52
Q

uremia: why hyperkalemia?

A
  • impaired excretion of K by damaged kidney

- low GFR

53
Q

How to treat hyperkalemia?

A

IV insulin

- moves K+ into cells

54
Q

uremia: why metabolic acidosis?

A

impaired ammonium excretion by damaged kidney

- can’t buffer H+

55
Q

low GFR = metabolic ___

A

acidosis

56
Q

uremia: why loss of appetite?

A

Low GFR => metabolic acidosis

  • continued food (protein) intake -> acid
  • acid binds to all available bicarb
  • kidney can’t make ammonium to keep up with acid from diet
  • feels sick & unwell
  • negative effects on bone health
57
Q

uremia: why low Ca, high PTH?

A
  • kidney can’t make calcitriol
  • reduced absorption from gut -> hypocalcemia
  • parathyroid responds to low Ca
  • lots of PTH
  • excess reabsorption of bone -> fragile
58
Q

increased PTH secretion due to low low calcitriol is ____ hyperparathyroidism

A

secondary

59
Q

untreated uremia leads to..

A

coma, death

60
Q

treatment for uremia

A
  • kidney dialysis

- kidney transplant

61
Q

hypernatremia implies an decrease in ___ volume

A

intracellular

62
Q

hyponatremia implies an increase in ____ volume

A

intracellular

63
Q

urine concentration requires…

A
  1. thick ascending limb function

2. vasopressin action on collecting duct

PSL301 (29 decks)

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