Elements of Renal Function

Question 1

what are some waste products that the kidneys remove

Answer 1

urea, creatinine, acid, bilirubin, other stuff

Question 2

where is EPO made

Answer 2

kidneys

Question 3

what is EPO made in response to

Answer 3

low PO2

Question 4

what causes drops in PO2

Answer 4

anemia caused by blood loss, arterial hypoxia, inadequate renal flow

Question 5

what is calcitriol and where is it made

Answer 5

active Vit D; kidneys

Question 6

where does gluconeogenesis occur

Answer 6

mostly liver but a substantial amount can happen in kidneys

Question 7

the cortex contains what

Answer 7

renal corpuscles, coiled blood vessels, and coiled tubules

Question 8

the medulla contains

Answer 8

straight blood vessels and straight tubules

Question 9

the microcirculation of the kidneys is comprised of how many capillary networks and how are they arranged

Answer 9

2; in series

Question 10

what are the capillaries of the kidney

Answer 10

glomerular and peritubular

Question 11

what does the glomerular capsule prefer

Answer 11

filtration

Question 12

what does the peritubular capillary prefer

Answer 12

absorption

Question 13

what are the Pc of the glomerular and peritubular capillaries

Answer 13

~60 mm Hg; ~13 mm Hg

Question 14

long medullary peritubular capillaries are often called

Answer 14

vasa recta

Question 15

where is renal blood flow highest

Answer 15

cortex then outer medulla then inner medulla

Question 16

when do we start losing nephrons

Answer 16

10% each decade beyond 40

Question 17

what is the main process of the glomerulus

Answer 17

filtration via starling forces

Question 18

what is the main process of the proximal tubule

Answer 18

reabsorption of the largest fraction of glomerular filtrate

Question 19

what is the main process of the loop of henle

Answer 19

controlling urine concentration and secreting Tamm-Horsfall glycoproteins

Question 20

what is the main process of the distal tubule/collecting ducts

Answer 20

fine control of salt and water secretion

Question 21

How do you calculate renal clearance C_x

Answer 21

C_x=Urine concentration of X * urine volume/ concentration of X in plasma

Question 22

How do you calculate glomerular flow rate

Answer 22

GFR = urine concentration of inulin*urine volume/plasma concentration of inulin

Question 23

How do calculate clearance ratio

Answer 23

Clearance of X / clearance of inulin

Question 24

How do you calculate renal plasma flow

Answer 24

RPF = (urine concentration of PAH * urine volume)/ (renal artery PAH concentration - renal vein concentration of PAH)

Question 25

What is the issue with effective renal plasma flow

Answer 25

Underestimates RPF by 10%

Question 26

What is effective renal plasma flow also equal to

Answer 26

Clearance of PAH

Question 27

How do you calculate the Glomerular Filtration Rate

Answer 27

GFR = urine concentration of inulin * urine volume / plasma concentration of inulin

Question 28

What does glomerular filtration rate also equal

Answer 28

Clearance of inulin

Question 29

How do you calculate filtration fraction

Answer 29

FF - GFR / RPF

Question 30

How do you calculate filtered load

Answer 30

Filtered load = GFR * plasma concentration of X

Question 31

How do you calculate excretion rate

Answer 31

Excretion = urine volume * urine concentration of x

Question 32

How do you calculate reabsorption or secretion rate

Answer 32

Filtered load - excretion If > 0 then net reabsorption If < 0 then net secretion

Question 33

What are the 3 ways that sympathetic can increase BP

Answer 33

1. α1 activation with more constriction on afferent arterioeles 2. Stimulating juxtaglomerular cells to release renin through β1 receptors 3. Na-K ATPase incereasing reabsorption of Na from α1 activation on tubular epithelial cells

Question 34

How do you calclulate urinary excretion

Answer 34

Urinary excretion = amount filtered - amount reabsorbed + amount secreted

Question 35

How do you calculate tubular reabsorption

Answer 35

Tubular reabsorption = glomerular filtration - urinary excretion + amount secreted

Question 36

If excretion > filtration then what has happened

Answer 36

Tubular excretion

Question 37

How do you calculate V

Answer 37

Urine volume/time Generally in mL/min

Question 38

What is renal clearance

Answer 38

The rate at which substances are removed from plasma It is measure as the volume of plasma cleared of a substance by the kidneys per unit of time

Question 39

Clearance is a ___________ rate

Answer 39

Flow

Question 40

What is the glomerular filtrate

Answer 40

Volume of plasma filtered into the combined nephrons of both kidneys per unit time Also the fluid that goes into Bowman’s space

Question 41

When would we expect protein and cells in glomerular filtrate

Answer 41

In the event of damage

Question 42

How do you calculate filtration fraction

Answer 42

GFR/RPF

Question 43

What does Kf depend on

Answer 43

Permeability and surface area

Question 44

What is the main influence of filtration fraction

Answer 44

Influenced by blood pressure

Question 45

How does the filtration fraction relate to the oncotic pressure in the peritubular capillaries

Answer 45

As it increases there is less water in the capillaries so the oncotic pressure increases

Question 46

How does renal artery stenosis or severe hemorrhage affect FF

Answer 46

Decreased RBF so GFR must increase to maintain homeostasis GFR/RBF where GFR goes up and RBF goes down

Question 47

What is the difference between filtered load and filtration fraction

Answer 47

Filtered load is the amount of substance in the blood filtered in unit time Filtration fraction relates to blood flow

Question 48

How do you calculate filtered load

Answer 48

GFR X PNa

Question 49

What is normal GFR

Answer 49

125 mL/min

Question 50

When can renal clearance be used to estimate GFR

Answer 50

1. Substance can be freely filtered 2. Substance can’t go out of or into the tubules 3. Can’t be synthesized, metabolized, or accumulated in the kidney 4. Physiologically inert

Question 51

What do we normally use to look at GFR

Answer 51

Inulin or creatinine

Question 52

What is the issue with using inulin

Answer 52

We have to infuse it

Question 53

Why do we normally use creatinine clearance for GFR

Answer 53

Body makes it naturally and production = excretion

Question 54

What is an issue with creatinine and GFR

Answer 54

Some (10%) is secreted in the tubules

Question 55

What is the relationship between plasma creatinine concentration and GFR

Answer 55

Inversely proportional

Question 56

What do we use to isolate renal issue location

Answer 56

BUN/creatinine

Question 57

How do we determine pre-renal, post-renal, or intrarenal diseases

Answer 57

>20:1 10-20:1 <10:1

Question 58

What are some pre-renal diseases

Answer 58

Hypovolemia, dehydration, reduced renal perfusion, and high protein

Question 59

What are post-renal issues

Answer 59

Ureter backup

Question 60

What are some intrarenal issues

Answer 60

Liver disease and low protein diet

Question 61

The normal formula over/under-estimates creatinine clearance

Answer 61

Over

Question 62

What is used to estimate renal plasma flow

Answer 62

PAH

Question 63

Where is most PAH filtered out of the blood

Answer 63

Peritubular capillary which is why it is used to estimate RBF