Renal function

Question 1

Kidney function

Answer 1

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

Question 2

Filtration

Answer 2

plasma is filtered from blood

Question 3

Average person renal blood flow

Answer 3

600mL/min

Question 4

Glomerulus

Answer 4

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

Question 5

Capillary endothelial cells

Answer 5

in kidneys they have larger openings (fenestrated) is nonselective

Question 6

Basement membrane

Answer 6

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

Question 7

podocytes

Answer 7

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

Question 8

hydrostatic pressure

Answer 8

60mmHg

Question 9

capsular hydrostatic pressure

Answer 9

20mmHg

Question 10

blood colloidal pressure

Answer 10

30mmHg

Question 11

Juxtaglomerular cells

Answer 11

specialized cells at afferent arteriole that regulates pressure

Question 12

macula densa

Answer 12

specialized cells at distal tubule that work with the juxtaglomerular cells

Question 13

juxtaglomerular apparatus

Answer 13

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

Question 14

angiostensin II

Answer 14

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

Question 15

aldosterone

Answer 15

hormone regulating sodium reabsorption in distal tubule

Question 16

ADH

Answer 16

hormone regulating water reabsorption in collecting duct

Question 17

reabsorption

Answer 17

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

Question 18

Passive reabsorption

Answer 18

substances being moved with the gradient of concentration/charge

Question 19

Active reabsorption

Answer 19

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

Question 20

Where is water reabsorbed?

Answer 20

Descending Loop of henle

Question 21

Where is urea reabsorbed?

Answer 21

Proximal tubule and ascending loop of henle

Question 22

Plasma concentration

Answer 22

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

Question 23

countercurrent mechanism

Answer 23

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

Question 24

Secretion

Answer 24

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

Question 25

Clearance test GFR

Answer 25

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

Question 26

Average GFR

Answer 26

120 mL/min

Question 27

Perfect substance for GFR testing

Answer 27

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

Question 28

Creatinine

Answer 28

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

Question 29

Advantages and disadvantages of creatinine

Answer 29

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

Question 30

Radioisotopes

Answer 30

exogenous, invasive and expensive way to measure GFR

Question 31

Beta-2-macroglobulin

Answer 31

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

Question 32

Cystatin C

Answer 32

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

Question 33

Estimated GFR formula names

Answer 33

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

Question 34

Reabsorption test

Answer 34

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

Question 35

Diabetes insipidus concentration test

Answer 35

infusion of AHD to measure the urine plasma osmolarity ratio.

Question 36

Neurogenic diabetes insipidus

Answer 36

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

Question 37

Nephrogenic diabetes insipidus

Answer 37

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

Question 38

Free water clearance

Answer 38

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

Question 39

Secretion clearance test

Answer 39

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

Question 40

Oral ammonium chloride test for secretion

Answer 40

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

Question 41

Renal tubular acidosis

Answer 41

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