Renal function Flashcards

1
Q

Kidney function

A

remove waste, control nutrient loss, essential to water and electrolyte balance and acid base balance.

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2
Q

Filtration

A

plasma is filtered from blood

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3
Q

Average person renal blood flow

A

600mL/min

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4
Q

Glomerulus

A

substances <70 kilodaltons pass through (selective by size) ultrafiltrate of blood. Normally only glucose and ions can pass through filter.

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5
Q

Capillary endothelial cells

A

in kidneys they have larger openings (fenestrated) is nonselective

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6
Q

Basement membrane

A

only lets things <4nanometers. has a net negative charge so only positive ions can pass.

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7
Q

podocytes

A

epithelial cells, inner lining of Bowmans capsule. are woven together to make filtration slits. Phagocytose any molecules that get stuck in filtration barrier

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8
Q

hydrostatic pressure

A

60mmHg

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9
Q

capsular hydrostatic pressure

A

20mmHg

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10
Q

blood colloidal pressure

A

30mmHg

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11
Q

Juxtaglomerular cells

A

specialized cells at afferent arteriole that regulates pressure

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12
Q

macula densa

A

specialized cells at distal tubule that work with the juxtaglomerular cells

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13
Q

juxtaglomerular apparatus

A

the two cells work together and respond to change in blood pressure (generally from sodium)

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14
Q

angiostensin II

A

increases sodium reabsorption to increase water reabsorption, causes an increase in blood pressure. Sends thirst signals to the brain and encourages aldosterone and ADH secretion

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15
Q

aldosterone

A

hormone regulating sodium reabsorption in distal tubule

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16
Q

ADH

A

hormone regulating water reabsorption in collecting duct

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17
Q

reabsorption

A

useful material the body needs returns to the blood from the filtrate

18
Q

Passive reabsorption

A

substances being moved with the gradient of concentration/charge

19
Q

Active reabsorption

A

moving against the gradient, takes energy and usually is done through carrier proteins/receptors

20
Q

Where is water reabsorbed?

A

Descending Loop of henle

21
Q

Where is urea reabsorbed?

A

Proximal tubule and ascending loop of henle

22
Q

Plasma concentration

A

point at which active transport stops and things are excreted in the urine

23
Q

countercurrent mechanism

A

selective urine concentration process in the ascending and descending LOH. Osmolarity increases as you reach the bottom of the loop which forces the water to flow out

24
Q

Secretion

A

movement of metabolic waste products too large for the filter from the capillaries into the tubules. Regulation of acid/base balance

25
Q

Clearance test GFR

A

measures the rate in which kidneys can remove a filterable substance from the blood.

26
Q

Average GFR

A

120 mL/min

27
Q

Perfect substance for GFR testing

A

something that is only filtered, is stable and consistent in the plasma and is not diet dependent

28
Q

Creatinine

A

most common for GFR testing, measure levels in plasma sample and in 24 hr urine sample

29
Q

Advantages and disadvantages of creatinine

A

Adv: endogenous, produced at a constant rate and has automated testing
Disadv: some is secreted as well as filtered, medical interference possible, varies with muscle mass and requires 24hr sample

30
Q

Radioisotopes

A

exogenous, invasive and expensive way to measure GFR

31
Q

Beta-2-macroglobulin

A

endogenous and testable, but can not be used on patient with immunogenic disease

32
Q

Cystatin C

A

Endogenous, produced at a constant rate and recommended for people unable to accurately do a 24 hr sample. shed from nucleated substances, is fairly new

33
Q

Estimated GFR formula names

A

Cockroft-gault=age, weight and serum creatinine sample
MDRD=age, race and serum creatinine sample

34
Q

Reabsorption test

A

concentration tests, done after fluid deprivation for 12-16 hours. The urine sg should be >1.025 and the osmolarity should be >800

35
Q

Diabetes insipidus concentration test

A

infusion of AHD to measure the urine plasma osmolarity ratio.

36
Q

Neurogenic diabetes insipidus

A

urine/plasma ratio >3:1. Shows deficiency in ADH

37
Q

Nephrogenic diabetes insipidus

A

Urine/plasma ratio <3:1, shows inability to respond to ADH

38
Q

Free water clearance

A

ability of kidney to respond to state of hydration.
Positive value=hydration
Negative value=dehydration

39
Q

Secretion clearance test

A

measures renal blood flow. PAH, is exogenous, binds to plasma and is secreted into proximal tubule.

40
Q

Oral ammonium chloride test for secretion

A

measure acid base balance ability of secretion. Administered over 3 days, if urine pH is higher than 5.3 then the secretion abilities are abnormal

41
Q

Renal tubular acidosis

A

inability of the kidneys to produce an acidic urine in the presence of metabolic acidosis, impaired tubular secretion of H+ ions