Renal, Renal Physiology

Front 1

what is the primary, general function of the kidney?

Back 1

to keep the composition and volume of the blood plasma constant

Front 2

what are the endocrine functions of the kidney?

Back 2

secrete angiotensin and erythropoetin

Front 3

give the break down of the % body weight that total fluid, intracellular fluid, and extracellualr fluid comprise?

Back 3

60% = total fluid
40% = intracellular fluid
20% = extraceullar fluid

Front 4

what method can be used to directly measure the sizes of fluid compartments?

Back 4

indicator-dilution technique

Front 5

what is the formula used for indication-dilution technique to determine the volume of different compartments?

Back 5

V = n/C

V=volume
n=amount of indicator
C=concentration of indicator

Front 6

indicators for measuring total body water include?

Back 6

1. THO
2. D2O
3. Antipyrin

Front 7

indicators for measuring ECF include?

Back 7

Inulin <--- most important
sucrose
mannitol
sulfate
chloride
sodium

Front 8

indicators used to measure plasma volume include?

Back 8

1. Evan's blue
2. RISA-(I^131)
3. Cr^51-erythrocytes

Front 9

what type of indicator is optimum for measuring total body water?

Back 9

one that acts the same as water and can enter all fluid compartments just like water

Front 10

what type of indicator is optimum for measuring ECF?

Back 10

one which is impermeable to cells (enters all areas but the intracellular fluid compartment)

Front 11

what type of indicator is best for measuring ICF?

Back 11

Trick!!! intracellular fluid cannot be measured directly

Front 12

what type of indicator is best for measuring plasma volume?

Back 12

one which is impermeable to vessel endothelium or which is bound to plasma proteins

Front 13

what accounts for most of the ICF anions?

Back 13

fixed negative charges on proteins and nucleic acids

Front 14

what is the main source of anions in the ECF?

Back 14

chloride

Front 15

describe the osmolarity between the different fluid compartments?

Back 15

largely the same between all compartments because most cells are very permeable to water

Front 16

in which compartments would you find an large Na+ concentration?

Back 16

ISF/Plasma

Front 17

in which compartments would you find a large K+ concentration?

Back 17

ICF

Front 18

in which compartments would you find a large Cl- component?

Back 18

ISF/Plasma

Front 19

what is the general osmolarity between the fluid compartments?

Back 19

~283

Front 20

Pfill = ?

Back 20

Pfill = (Pcap-Pisf) - (∏cap-∏isf)

Front 21

what is the total body filtration rate, the total body absorption rate, and the lymph flow rate?

Back 21

20, 18, 2 ml/min

Front 22

how does nephrotic syndrome cause edema?

Back 22

loss of proteins results increased oncotic pressure in the ISF causing filtered water to stay in the ISF.

Front 23

what is the effect of adding purely water to plasma?

Back 23

it dilutes into all fluid spaces and increases their volume in proportion to their original size (ISF get 1/3 of water added and ICF gets 2/3)

Front 24

what happens when isotonic saline (9g/L) is added?

Back 24

it Na+ cannot enter the ICF so water is only added to the ECF compartments - dilution of plasma proteins will cause much of the water to stay in the ISD

Front 25

how can one insure that added volumes of fluid will not enter cells or the ISF, but will instead stay in the plasma fluid space?

Back 25

add colloids which will increase the plasma oncotic pressure along with saline solution

Front 26

in a 70 kg individual, total body water equals how many liters?

Back 26

42

Front 27

Name the major portions of the nephron starting from the glomeruli and ending collecting duct?

Back 27

glomerulus -> proximal tubule -> loop of Henle -> distal tubule -> collecting ducts

Front 28

what are the parts of the proximal tubule?

Back 28

1. proximal convoluted tubule
2. proximal straight tubule

Front 29

what are the parts of the loop of Henle?

Back 29

1. descending thin limb
2. ascending thin limb
3. ascending thick limb

Front 30

what are the parts of the distal tubule?

Back 30

1. distal convoluted tubule
2. connecting tubule
3. initial cortical collecting duct

Front 31

what are the parts of the collecting duct?

Back 31

cortical, inner medullary, outer medullary tubules

Front 32

what is the surface area of the body including GI, lung, and genitourinary tract?

Back 32

75 m^2

Front 33

what percentage of the blood to to the kidney goes to the cortex?

Back 33

93%

Front 34

what keeps plasma proteins from exiting the the blood flow and entering the nephron?

Back 34

negatively charge basal lamina repels the postively charge plasma proteins

Front 35

what is allowed past the basal lamina?

Back 35

things smaller than 3.5 nm and positively charged... or anything if it is small enough

Front 36

of the 120ml per min. filtered into the nephron, how much is returned to the plasma in the tubules?

Back 36

119 ml, meaning only about 1ml per min of urine is produced by the kidney each minute

Front 37

what is the net filtration pressure in the glomeruli?

Back 37

+9 mm Hg

Front 38

of the 25% of blood flow entering the kidney how much is actually filtered?

Back 38

20%

Front 39

what is the equation for filtration fraction?

FF = ?

Back 39

FF = GFR / renal plasma flow

Front 40

why does slowing renal blood flow actually increase filtration?

Back 40

normally the blood is moving through faster than the cappilary hydrostatic pressure (Pc) can eqilibrate with the capillary oncotic (πc) and Bowmans space pressure (Pb) (Net filtration = Pc - (Pb + πc)

With slow flow, net filtration becomes zero because there is time to remove the maximum amount of fluid possible

Front 41

describe the effect of increasing efferent arteriolar resistance on GFR?

Back 41

initially increases GFR then as RPF drops GFR drops off

Front 42

what is the BP range in which GFR can remain relatively steady?

Back 42

80-180 mmHg

Front 43

what is the Bayliss relfex?

Back 43

the arterioles in the kidney constrict when stretched (increased BP)

Front 44

in addition to the stretch reflex in the kidney arterioles, ___ also controls renal perfusion?

Back 44

macula densa

Front 45

what causes the macula densa to want to reduce GFR?

Back 45

increased Na+ osmolarity

Front 46

why would the kidney want to produce renin when local control by the macula densa does not reduce distal tubule Na+?

Back 46

renin increases aldosterone production causing increase Na+ reabsorbtion

There of course is the other compenent to renin release which is activation of Angiotensin system which will increase BP systemically

Front 47

what is the equation we need to use for solving the effects that different fixes have on the blood (adding more water, solutes, or saline)?

Back 47

major concern is keeping added fluid out of the cells so to determine volumes in each compartment use the equation

(C fix)(V fix) = (V blood loss)(C blood loss)

Then once the volume of a given compartment is found divide the blood loss volume/concentration by the fixed volume/concentration

Front 48

Using hydrolic conductivity (Lp), area (A), change in hydrostatic pressure (Delta P), and change in oncotic pressure (Delta π) how would you calculate GFR?

Back 48

GFR = LP A (delat P – delta π) = Kfil x Pfil

Front 49

how much filtrate is produced per minute in the kidney?

Back 49

125 ml/min (180L per day)

Front 50

how can GFR be calculated using Ucreatinine, Pcreatinine, and UFR?

Back 50

GFR = (Ucreatinine/Pcreatinine) (UFR)

Front 51

what is the formula for determining plasma solute excretion (Cx)?

Back 51

Cx = (Ux/Px) (UFR)

in other words if x is completely filtered and niether secreted or reabsorbed, Cx = GFR

Front 52

how much of the filtrate is absorbed in the proximal tubule?

Back 52

2/3

Front 53

at the end of the proximal tubule, how much greater should the tubular fluid be than the plasma fluid?

Back 53

1/3 aka 2/3 should have been absorbed

Front 54

what is the osmotic gradient when comparing the renal tubule to the surrounding lateral space? What pressure difference does this translate into?

Back 54

5-10 mOsM difference --> 100-200 mmHg driving pressure to take water out of tubule and deposit in lateral space

Front 55

how does the kidney ensure that all the glucose is reabsorbed?

Back 55

there are many Na+/Glucose and 2Na+/Glucose cotransporters

Front 56

Draw the mechanism by which bicarb (HCO3-) is reabsorbed

Back 56

.

Front 57

what percentage of HCO3- is reabsorbed?

Back 57

93%

Front 58

where does HCO3- reabsorbtion occur?

Back 58

proximal tubule

Front 59

what is the effect of renal diabetes mellitus?

Back 59

reduces the maximum reabsorption capacity of the proximal tubule

Front 60

what effect does parathyroid hormone have in phosphate absorption?

Back 60

when it is present it results in the removal of Na+:PO4- cotransporter from the apical membrane increasing PO4- excreted in the urine

Front 61

what is used to measure the maximum excretion possible for any solute?

Back 61

PAH (maximally filtered and secreted, but none is absorbed)

Front 62

is the amount of PAH excreted the same as that of the renal blood supply of PAH?

Back 62

no, even though it is rapidly filtered and secreted, the total PAH availible for excretion is not totally excreted

Front 63

what are the two types of nephrons and what distinguishes them from each other?

Back 63

1. superficial nephrons - short loop of Henle, located upper/middle in cortex
2. juxtamedullary nephrons - long loop of Henle, located in lower cortex and loop extends deep into medulla

Front 64

what are the two types of cells located in the loop of Henle?

Back 64

1. macula densa cells
2. intercalated cells

Front 65

where does furosemide work?

Back 65

at the Na+:2Cl-:K+ in the intercalated cells of the thick ascending limb of the loop of Henle

Front 66

how much of the tubular fluid is absorbed through the intercalated cells in the loop of Henle?

Back 66

very little, there are no aquaporins

Front 67

Describe solute absorption in the thick ascending limb?

Back 67

.

Front 68

Draw solute exchange which occurs in cells of the early distal tubule

Back 68

.

Front 69

Draw solute exchange as it happens in the principle cells of the late distal tubule.

Back 69

.

Front 70

Draw the solute exchange which occurs in the Type A Intercalated cells of the late distal tubule?

Back 70

,

Front 71

Draw the solute exchange which occurs in the Type B intercalated cells located in the late distal tubule?

Back 71

.

Front 72

what stimulates water reabsorption in the principle cells of the late distal tubule?

Back 72

Vasopressin causes aquaporins to be inserted into apical membrane

Front 73

what is the normal water input?

Back 73

2L

Front 74

how does water leave the body? (3)

Back 74

1. .1 L stool
2. .5 L insensible loss
3. 1.4 L in urine

Front 75

During maximum diuresis how much urine is produced per day?

Back 75

17L

Front 76

During maximum antidiuresis how much urine is produced per day?

Back 76

.7L

Front 77

what is the max diuresis per min? what is the min?

Back 77

12 ml/min, .5ml/min

Front 78

what is the osmolarity of urine during max diuresis? what about max antidiuresis?

Back 78

50-60 mOsM, ~1200 mOsM

Front 79

what causes the insertion of aquaporins in the principle cells of the late distal tubule and collecting ducts in response to water deprivation?

Back 79

ADH

Front 80

what are the 4 effects of ADH (vasopressin) on the production of urine?

Back 80

1. increases apical membrane H2O permeability in late distal tubule and collecting duct
2. increases urea permeability for inner medullary collecting duct
3. stimulates NaCl absorption in TALH
4. increases blood flow to juxtamedullary glomeruli

Front 81

whats the thirst threshold in regards to plasma osmolarity?

Back 81

294 (normal = 280-296)

Front 82

if a person presents with high plasma osmolarity with low plasma ADH what is the underlying cause?

Back 82

Lack of ADH release cause by diabetes insipidus

Front 83

if a person presents with high plasma osmolarity with high plasma ADH what is the underlying cause?

Back 83

Lack of V2 receptor or AQP2 in distal tubule and collecting ducts

Front 84

how is osmolar clearence (Cosm) determined? (equation)

Back 84

Cosm = (Uosm/Posm)(UFR)

Front 85

how is the free water clearence (Cw^free) determined? (equation)

Back 85

Cw^free = UFR-Cosm

Front 86

what is the difference between Cosm during diuresis as compared to antidiuresis?

Back 86

it is exactly the same because as UFR increases, the osmolarity of the urine drops and as UFR drops, the osmolarity increases

Front 87

what percentage of the filtered load do the proximal tubule and the TALH reabsorb?

Back 87

92%

Front 88

what is a normal range for Cosm?

Back 88

1.7-7.0 ml/min

Front 89

what causes the production of ADH?

Back 89

1. decrease ECF volume
2. increased plasma K+ concentration

Front 90

describe the two actions of angiotensin II?

Back 90

1. immediate vasoconstriction
2. later increases in ADH production

Front 91

if Na+ levels are increased and there is volume expansion, what is released and what is the result?

Back 91

ANP is released causing decreased Na+ absorption in the distal tubule = increases Na+ excretion and reduces volume

Front 92

if the macula densa senses long term NaCl what happens?

Back 92

it increases renin excretion

Front 93

hyperkalemia stimulates the release of this hormone which in turn causes what effects?

Back 93

Aldosterone causes increased K+ secretion from distal tubules

Front 94

what is the normal percentage of filtered K+ excreted every day?

Back 94

40% (300 mmol/day

Front 95

under the effects of aldosterone, how much K+ can be secreted every day?

Back 95

up to 200% of the filtered load

Front 96

in hyokalemic states, how much K+ will be absorbed?

Back 96

all but 1%

Front 97

draw an intercalated cell in regards to K+ absorption?

Back 97

.

Front 98

what are the 3 types of diuresis?

Back 98

1. water
2. osmotic
3. natriuretic

Front 99

what causes water diuresis?

Back 99

lack of ADH

Front 100

what causes osmotic diuresis?

Back 100

diabete mellitus

Front 101

what causes natriuresis?

Back 101

inhibition of Na+ reabsorption

Front 102

Where does this diuretic work?

Acetazolamide

Back 102

proximal tubule

Front 103

Where does this diuretic work?

Furosemide

Back 103

TALH

Front 104

Where does this diuretic work?

Thiazide

Back 104

distal tubule

Front 105

Where does this diuretic work?

amiloride

Back 105

distal tubule and collecting duct

Front 106

What is the mechanism of action for this diuretic?

Acetazolamide

Back 106

inhibits carbonic anhydrase thereby increasing the osmolarity and H2O excreted

Front 107

What is the mechanism of action for this diuretic?

Furosemide

Back 107

inhibits Na+:K+:2Cl– : cotransporter reduces medullary gradient suppresses tubuloglomerular feedback

Front 108

What is the mechanism of action for this diuretic?

Thiazide

Back 108

inhibits Na+:Cl– cotransporter

Front 109

What is the mechanism of action for this diuretic?

amiloride

Back 109

inhibits Na+ channel (ENaC)