PSL301: Water 8 Flashcards Preview

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Flashcards in PSL301: Water 8 Deck (63):
1

UREMIA

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

2

clinical symptoms of uremia

- severe fatigue & weakness
- poor appetite, nausea, vomiting
- edema in feet, ankles
- itchy skin
- disturbed mental functions

3

Telltale biochemical marker of uremia

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

4

What are the waste products excreted by urine?

mainly products of protein metabolism
- urea
- creatinine
- uric acid (urate)

many other small molecules excreted in small amounts

5

most abundant waste in urine

urea

6

amount of waste found in urine depends on...

how much protein is eaten

7

each urea has __ nitrogens

2

8

Waste products in urine are readily ____ and minimally ___

filtered;
reabsorbed

9

___ is generated from AA breakdown

ammonia

10

ammonia is highly...

toxic

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

urea;
liver

12

steps of urea generation from ammonia

1. ammonia + CO2 -> carbamoyl phosphate
2. + L-ornithene -> citrulline
3. + L-aspartate -> arginosuccinate
4. -> L-Fumarate + L-Arginine
5. L-Arginine + H2O -> Urea + L-ornithene

13

enzyme: CO2 + NH3 -> carbamoyl phosphate

carbamoyl phosphate synthase

14

enzyme: carbamoyl phosphate + L-ornithene -> citrulline

ornithine carbamoyltransferase

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enzyme: citrulline + L-aspartate -> arginosuccinate

arginosuccinate synthase

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

argininosuccinate lysase

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

arginase

18

creatinine is generated from...

phosphocreatine -> creatine -> creatinine

19

PHOSPHOCREATINE

storage compound for energy in muscle

20

how many molecules of nitrogen does each creatinine molecule have?

2

21

enzyme: phosphocreatine -> creatine

creatine kinase

22

Uric acid is generated from...

nucleic acid break down
- uric acid = nitrogenous metabolite of purines

23

high concentrations of uric acid causes...

gout (type of arthritis)

24

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

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

25

enzyme: xanthine -> uric acid

xanthine oxidase

26

what is used to treat gout? why?

xathine oxidase inhibitors;
xathine oxidase is the enzyme that produces uric acid

27

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

increased risk of death from cardiovascular disease

28

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

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

29

endocrine functions of the kidney

1. renin
2. erythropoietin
3. vitamine D metabolism

30

renin is synthesized & secreted by...

cells of afferent arteriole

31

effect of renin on Na

increase Na reabsorption
- ANG II (directly)
- aldosterone (indirectly)

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effect of renin on water

keeps water inside body
- thirst
- vasopressin

33

effect of renin on GFR

- constricts efferent arteriole to increase glomerular capillary pressure
- increase GFR
- balances out decreased GFR from hypotension

34

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

glycoprotein;
pericytes

35

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

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

36

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

- O2 are low there
- very sensitive to O levels
- decreased O stimulates secretion of EPO

37

2 conditions which cause secretion of EPO

1. anemia
2. hypoxemia

38

function of EPO

increase RBC production in bone marrow

39

EPO is a popular drug for...

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

40

function of vit D

increase absorption of dietary calcium from gut

41

how to activate vit D from diet or skin?

1) 25-hydroxylation in liver (can be stored here)
2) 1-hydroxlation in kidney

42

what is the final active hormone of vit D?

1,25-(OH)2 vit D3
= calcitriol

43

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

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

44

effect of PTH on calcium

Increase serum Ca
- break down bone
- reabsorption by kidney
- increase rate at which vit D is converted to calcitriol (activity of 1-OHase)

45

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

- no 1-OHase
- low Ca absorption from gut
- low serum Ca
- stimulate high PTH

46

most common causes of uremia

1. diabetes (30-40%)
2. high BP

47

uremia: why fatigue & weakness?

Low EPO secretion by kidneys
- less RBC
- reduced O carrying capacity of blood

Waste products reduce muscle function

48

uremia: why hypertension?

kidney can't excrete Na+ as well (damage, reduced GFR)
- Na+ retained in blood
- pull water into blood as well

49

uremia: why edema?

kidney can't excrete Na+ as well (damage, reduced GFR)
- Na+ in ECF
- expanded ECF = edema

50

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

low GFR can't process all the waste fast enough

51

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

high levels of urea & creatinine in serum
- if this is not present, we can rule out CKD

52

uremia: why hyperkalemia?

- impaired excretion of K by damaged kidney
- low GFR

53

How to treat hyperkalemia?

IV insulin
- moves K+ into cells

54

uremia: why metabolic acidosis?

impaired ammonium excretion by damaged kidney
- can't buffer H+

55

low GFR = metabolic ___

acidosis

56

uremia: why loss of appetite?

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

uremia: why low Ca, high PTH?

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

58

increased PTH secretion due to low low calcitriol is ____ hyperparathyroidism

secondary

59

untreated uremia leads to..

coma, death

60

treatment for uremia

- kidney dialysis
- kidney transplant

61

hypernatremia implies an decrease in ___ volume

intracellular

62

hyponatremia implies an increase in ____ volume

intracellular

63

urine concentration requires...

1. thick ascending limb function
2. vasopressin action on collecting duct