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BMS 752 (Medical Physiology) > Renal Phys > Flashcards

Renal Phys Flashcards

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USMLE® Step 1 flashcards
1
Q

what is the correct order of blood flow through vessels inside the kidney

A

afferent arterioles

glomerulus

efferent arterioles

pertubular capiliarries

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2
Q

patient presents with chronic kidney disease. What lab value would indicate the greatest absolute decrease in GFR?

A

a rise in plasma creatinine levels from 1mg/dl to 2mg/dl

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3
Q

which of the following is NOT a component of the filtration barriers in the glomerulus

  1. podocytes
  2. basement membrane
  3. capillary endothelium
  4. all of the above are part of the filtration barrier of the glomerulus
A

4, they are all barriers

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4
Q

if a drug causes vasoconstriction of the efferent arteriole _with no effec_t on the afferent arteriole, what is the expected trend in GFR and RBF compared to normal

A

GFR will increase and RBF will decrease

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5
Q

what is a condition that will allow GFR and RBF to not be related in parallel

A

renal response to atrial natruetic peptide

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6
Q

which of the following is NOT true in regards to atrial and brain natruretic peptide

  1. produced in the ventricles
  2. increases cardiac output
  3. serum BNP is a valuable index of cardiac stretch
  4. promotes sodium extretion
A

2, increases cardiac output

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7
Q

what is is the effect of renal artery stenosis due to atherosclerosis on renal function and blood pressure

  1. An increase in blood pressure due to stimulation of the rennin-angiotensin-aldosterone system which in turn will initially cause a transient increase in GFR
  2. reabsorption of sodium and water resulting in an increase in preload that can increase BP
  3. After the initial period, a further increased constriction of the afferent andefferent arterioles ensues which results in the retention of fluid and an increase blood pressure
  4. all of the above results from renal artery stenosis
A

4, all of the above

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8
Q

which of the following is not true regarding regulation of serum potassium

  • *a**. Insulin promotes the intake of potassium ion into tissues such as skeletal muscle.
  • *b**. Addisons disease can result in a decrease levels of serum potassium due to a decrease aldosterone levels.
  • *c**. Epinenphrine acting on the β 2 receptor promotes potassium uptake into cells.
  • *d**. Exercise increases the release of potassium from working muscles and the degree of hyperkalemia is dependent on the intensity of exercise.
A
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9
Q

what condition would you expect to be present in a patient with the following symptoms

pH 7.34, PCO2 46mmHg, Resp Rate 15, HCO3 25 meq/L

A

respiratory acidosis that is being compensated by the renal system

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10
Q

which of the following is NOT a partial compensation for fluid loss

a. A retention of water from the kidney that can actually in some case cause a hypo-osmotic plasma (< 290 mOsm/kg H 2 O)

b. The increase in sympathetic nervous stimulation of the kidney acting on Beta receptors on the JG cells increase the release of rennin and thus angiotensin II

c. An increase in the permeability of the collecting duct to urea to facilitate the osmotic gradient in the interstitial fluid of the kidney

d. A massive vasoconstriction occurs that essentially block blood flow to the kidneys in order to shunt blood to more important organs such as heart and brain.

A

d, A massive vasoconstriction occurs that essentially block blood flow to the kidneys in order to shunt blood to more important organs such as heart and brain.

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11
Q

which of the following about aldosterone is NOT true

  • *a**. High serum K+ levels increase the secretion of aldosterone by action on adrenal cells
  • *b**. Low sodium in the tubular fluid increases indirectly stimulate aldosterone by the secretion of renin
  • *c**. Aldosterone stimulates the secretion of hydrogen ion by intercalated cells in the collecting ducts
  • *d**. None of the above, all are true about aldosterone.
A

d, all of the above are true

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12
Q

what is the action of hydrochlorothiazide that helps control blood pressure

A

decrease in intravascular fluid that will decrease the amount of preload to the heart to decrease stroke volume and cardiac out put

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13
Q

what are some buffered forms of hydrogen formed in the renal tubules that are in urine

a. Titratable acid such as phosphate (monobasic)
b. Water a byproduct of the addition of hydrogen and biocarbonate through action with carbonic anhydrase
c. Ammonium ion by the addition of the hydrogen ion to ammonia generated by the catabolism of glutamine
d. All of the above are forms of the hydrogen ion in excreted urine

A

d. All of the above are forms of the hydrogen ion in excreted urine

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14
Q

which of the following will cause a decrease in renin secretion from the kidney

a. Decreased fluid and solute delivery to the macula densa
b. Hemorrhage
c. Intervenous infusion of isotonic saline
d. Narrowing of the renal artery

A

c. Intervenous infusion of isotonic saline

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15
Q

which of the following are potential sites for K+ secretion in the nephron

a. Proximal tubule

b. Ascending loop of Henle
c. Distal convoluted tubule and collecting duct
d. Proximal convoluted tubule and distal convoluted tubule

A

c. Distal convoluted tubule and collecting duct

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16
Q

Gitelman’s syndrome is a genetic defect that affects the thiazide sensitive Na + /Cl - symporter in the distal convoluted tubule.

Which of the following would be observed in these patients?

a. Salt wasting
b. Hypokalemia
c. Hypocalcuria
d. All of the above would be observed in a patient with Gitelman’s syndrome

A

d. All of the above would be observed in a patient with Gitelman’s syndrome

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17
Q

what causes a detrimental accumulation of fluid by the kidneys in response to decreased ejection fraction in kidney faiilure

A

heart failure will cause a decrease in BP, which will trigger baroreceptors in the vasculature and kidneys, resulting in a decreased RBF and GFR to increase BP

this overrides the signals from the kidney that would elimiinate fliud

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18
Q

What are the generalized functions of the kidney

A

excretion of waste

regulation of fluid volume and content

balance electrolytes

react to changes in pH along with resp

Produce and secrete hormones

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19
Q

why would a failing kidney change the theraputic window of a drug

A

because unless the kidneys can excrete the drug it can stay in the blood and increase the amount circulating

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20
Q

what types of waste products are excreted by the kidneys

A

urea

uric acid

creatinine

metabolites of hormones (vitamins)

bilirubin

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21
Q

what are ions that can be excreted into urine

A

Na

K

Cl

HCO3

H+

Ca

P

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22
Q

what is the role of the kidneys in regulating pH

A

during acidosis the kidneys will hold on to HCO3

during alkalosis the kidneys will excrete HCO3

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23
Q

how would the lung react to decreased blood pH?

how would the kidneys

A

increasing respirations to blow off CO2

decreasing secretion of HCO3

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24
Q

how is the kidney a source of drug interaction

give an example

A

certain drugs can cause the preferential secretion of acids or bases

diuretics can increase the secretion of aspirin, an acid, and decrease secretion of basic drugs like amphetamines

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25
Q

how is a positve ion balance maintained in the body

negative

A

positive = excretion < intake

negative = excretion > intake

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26
Q

what three organs work to maintain blood pH

A

lungs, kidneys, liver

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27
Q

what are the three hormones secreted by the kidneys

A

renin, calcitrol, erythropoietin

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28
Q

what is the function of renin

A

renin promotes the production of angiotensinogen from the liver, which is converted to angiotensin in the kidneys

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29
Q

wjhat is the function of angiotensinogen

A

regulated BP and Na/K balance

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30
Q

what is the function of calcitrol

where is it produced

A

allows for normal absorption of Ca from the GI tract and deposiiton of Ca in bone

it is converted from vitamin D in the proximal tubules

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31
Q

what hormone opposes the function of calcitrol

A

PTH

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32
Q

what does EPO do

A

increases red blood cell production

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33
Q

aside from production of hormones, what other important endocrine function does the kidney play

A

ir regulates clearance of hormones which can indirectly influence endocrine function

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34
Q

how can hypersecetion of PTH effect other systems

A

hyperseceretion of PTH can increase the amount of PTH produced, which can cause more calcium to be released

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35
Q

what is the functional unit of the kidney

A

the nephron

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36
Q

what structures are contained in the nephron

A

renal capsule

proximal tubule

loop of henle (distal, ascending, thick)

distal tubule

collecting system

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37
Q

two types of nephrons

A

superficial

juxamedullary

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38
Q

what surrounds the nephron

A

peritubular capillaries

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39
Q

what is the function of the peritubular capillaries

A

deliver substances and O2 to the nephron and allow for reabsorption

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40
Q

three differences between superficial and juxtamedullay nephrons

A

JM nephrons have a long loop of henle

their primary job is to concentrate or dilute urine

has vasa recta

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41
Q

why do JM nephrons have a long loop of Henle

A

to take advantage of countercurrent ion regulatioin

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42
Q

why is there a brush boarder in nephron cels

A

to increase surface area and allow for more Na/K pumps

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43
Q

where does 70% of the absorption in the nephron happen

A

the proximal tubule

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44
Q

what happens in the thick loop of henle

A

temm-horsfall proteins are secreted

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45
Q

what to tamm horsfall proteins do

A

normally they are a defense against bacteria in the nephron, but the also form casts that can trap substances

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46
Q

two types of collecting tubule cells

A

principle cells

intercalated cells

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47
Q

what differentiates principle cells from intercalated cells

A

moderate invaginations of the basolateral membrane

main function is the the reabsorption of NaCl and secretion of K

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48
Q

what is the primary function of intercalated cells

two types of intercalated cells and their function

A

regulation of acid base balance

alpha (reabsorbs HCO3 in acidosis)

beta (reabsobs H+ in alkalosis)

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49
Q

why do intercalated cells have a lot fo mitochrondria

A

the need lots of ATP the run the H+ ATPase that they use to fuel cell transport and regulate acid-base balance

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50
Q

what is the function of the renal corpuscle

A

produces ultra-filtrate from blood in the glomerular capilaries that ends up in the glomerular space

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51
Q

what is the structure of the renal corpuscle

A

fenestrated capillaries surrounded by podocytes

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52
Q

what covers the epithelial cells of the renal corpuscle

what disease process might effect this layer and how

A

a basement membrane

can be thickened by DM

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53
Q

what are the three anatomical strucutures of the filtration barrier in the renal corpus

A

fenestrated epithelium

basement membrane

podocyte from bowmans capsule

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54
Q

name three structures that are not normally allowed through the filtration barrier of the nephron

A

RBCs

WBCs

platelets

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55
Q

what stops the filtration of very large anionic molecules (proteins) through the filtration barrier

A

expression of negatively charged glycoproteins on the endothelial cells

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56
Q

what is the function of NO in the capillaries

what about endothelian 1

A

NO is a vasodilator

endothelian is a vasoconstrictor

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57
Q

when proteins are allowed to pass through holes in capillaries, what stops them from passing through the basement membrane

A

the fact that fenistrations in the basement membrane are too small to allow them to pass (25-65 nm)

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58
Q

what is the function of a podocytes

A

they wrap around capillaries and glomerular capsule to produce filtration slits that filter blood

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59
Q

glycosylation

how would you assess this in a patient

A

a reaction in the glycoproteins on the basement membrane that decreases their ability to repel anionic proteins

HbA1c levels or fasting glucose, along with albumin in the urine

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60
Q

what determines the composition of ultrafiltrate

A

the characteristics of the glomerular filtration barrier (endothelium, basement membrane, podocytes)

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61
Q

molecules below what size are freely filtered in the nephon

what size will prohibit free filtration

A

<20 angstroms

>42 angstroms

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62
Q

why are cations more likely to be filtered than anions

A

because the glycoproteins on the basement membrane are negatively charged, so anions would be repelled and cations would be attracted

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63
Q

what are mesangial cells

A

smooth muscle cells that remove proteins and trapped residues from the basement membrane to keep the filter from getting clogged

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64
Q

five specific functions of mesangial cells

A

provides structural support to the glomerular capillaries

secretes extracellular matrix

acts as a phagocyte

secretes prostaglandins and pro-inflammatory cytokines

influences GFR by regulating blood floow

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65
Q

how can mesangial cells influence filtration

A

by changing the surface area for diffusion

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66
Q

why would renal failure cause anemia

A

because mesangial cells in the kidney produce EPO, and as the kidneys fail those cells loose their secretory capacity

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67
Q

what is the primary function of the juxaglomerular apparatus

A

regulation of filtration rate and renal blood flow by detecting the amount of NaCl in filtrate and changes in renal blood pressure

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68
Q

where is the juxaglomerular apparatus found

what are three cells found there

A

between the distal tubule and the afferent arteriole

macula densa

extraglomerular messangial cells

renin/angiotensin producing cells

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69
Q

where is are the macula densa found

what is their function

A

superior border of the thick loop of henle

detects NaCl concentration in the distal tubule

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70
Q

where are the extraglomerular messnagial cells found in the juxtaglomerular apparatus

what is their function

A

near the macula densa

their function is unknown

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71
Q

where are the renin/angiotensin cells in the juxtaglomerular apparatus

what is their function

A

near the afferent tubule

secretion of hormones into the blood based on renal blood pressure

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72
Q

why is innervation of the kidney necessary

A

to regulate RBF, GFR, salt and H2O reabsorption

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73
Q

what provides sympathetic innervation to the kidnets

A

the celiac plexus through the aorticorenal ganglia

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74
Q

T/F there is significant parasympathetic innervaion to the kidney

A

false, there is none

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75
Q

what two neurotransimitters are secreted by the sympathetic neurons of the kidney

A

norepinephrine and dopamine

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76
Q

what structures are innervated by sympathetic nerves in the kidney

A

renin producing glandular cells

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77
Q

what are three functions of norepinephrine on the kidney

A

increase in renin production (beta adrenergic receptors)

increase in NaCl and water reabsorption

vasoconstriction via alpha adrenergic pathways

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78
Q

what are the two effects of dopamine in the kidney

A

naturesis

vasodilation

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79
Q

what is the function of vagus nerve fibers in the kidney

A

unknown, possibly afferent fibers

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80
Q

what does sympathetic innervation of the kidneys react to the produce vasoconstriction of renal blood vessels

if vasoconstriction is excessive, what can happen

A

decrease in renal blood flow

acute tubular necrosis

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81
Q

how does the sympathetic innervation of tubular cells create “natures little IV”

this is important in what speficic disese process

A

by increasing NaCl absorption

shock

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82
Q

what will the effect of sympathetic innervation be on renin producing cells

what are two consequences of that

A

increases renin secretion

increase in systemic BP

increase in K secretion in urine

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83
Q

why does there need to be high hydrostatic pressure in the glomerular capillaries

A

because there need to be pressure to push all the filtrates out of blood

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84
Q

why is important that the peritubular capillaries be have low hydrostatic pressure compared to the glomerular capilaries

A

because the peritubular capilaries need to reabsorb and then secrete substances based on need

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85
Q

explain this formula

Ex = Fx - Rx + Sx

A

excretion rate of a substance is equal it is filtration rate minus the reabsorption rate plus the secretion rate

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86
Q

T/F there are no cellular elements and very little protein typically found in ultrafiltrate

A

true

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87
Q

what forces control the production of ultrafiltration

A

starling forces

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88
Q

what are the starling forces

A

hydrostatic pressure in the artery

osmotic pressure in the artery

hydrostatic pressure in the tubule

osmotic pressure in the tubule

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89
Q

of the starling forces, which is the primary driving force behind filtration

A

hydrostatic pressure in the arteries

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90
Q

what are the starling forces that oppose filtration

A

hydrostatic pressure in the tubule

osmotic pressure in the the capillary

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91
Q

why is the osmotic pressure of the bowmans capusle typically a nonfactor in filtration

A

because there should be relatively little protein the space

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92
Q

explain this forula

PUF = PGC - (PBS + πGC)

A

the pressure of ultra filtrate is equal to the hydrostatic pressure of the glomerular capilaries minus the sum of the pressure in bowmans space and the osmotic pressure of the glomerular capillary

93
Q

what happens to PGC and πGC as the ultrafiltrate passes through the nephron

why is this relevant

A

PGC decreases

pi GC increases

promotes reabsorption in the peritubular capillaries

94
Q

describe the equation

GFR = Kf * PUF

A

the glomerular filtration rate is equal to the product of hydraulic conductivity and surface area (Kf) times the pressure of ultrafiltrate

95
Q

what is the typical GFR

how much of that volume is reabsorbed

A

125 mL/min

99%

96
Q

four important factors in determining GFR

A

Starling forces

permability of the glomerular capilary

surface area of the capilaries

plasma flow rate

97
Q

four factors that will increase GFR

A

increase in arterial BP

vasodilation of the afferent arteriole

vasoconstriction of the efferenet arteriole

increase renal blood flow

98
Q

three main ways the pressure in the glomerular capsule (PGC) can be altered

A

changing the resistance in the afferent arteriole

changing the efferent arteriole resistance

changing the renal arteriole pressure

99
Q

two ways to alter afferent arteriole resistance with their effects

A

decreased resistance through dilation: increase PGC and GFR

increased resistance through constriction: decreased PGC and GFR

100
Q

two ways altering efferent arteriole resistance can effect PGC

A

decreased resistance throght dialtion: decreased PGC and GFR

increased resistnace through constriction: increased PGC and GFR

101
Q

two ways altering renal arteriolar pressure will change PGC

A

increased BP leads to a transient increase in PGC and GFR

decreased BP leads to transient decrase in PGC and GFR

102
Q

how can the kidneys regulate blood pressure

A

regulate water and Na reabsorption

producing renin for the RAA cycle

103
Q

what will the kidney do in response to hypotension

A

decrease GFR to conserve water

104
Q

what will increase RBF

what will decrease RBF

which of the two trumps the other

A

vasodilation

vasoconstriction

vasoconstriction

105
Q

five reasons why RBF is important

A

Indirectly determines GFR

modifies the rate of solute and water reabsorption be proximal tubule

participates in the concentration and dilution of urine

delivers O2, nutrients, and hormones to renal cells

delivers substrates for excretion

106
Q

what would be the result of decreased renal blood flow from cardiogenic shock

A

acute tubular necrosis if enough cells are destroyed which can escalate into renal failure

107
Q

define clearance of a solute

A

the virtual volume of blood plasma volume per unit of time inflow needed to supply the amount of solute that appears in the renal veins or in the urine

108
Q

why is the amount of solute in the renal veins less important than the amount removed from blood

A

because solute in the veins is recycled

109
Q

explain this equation

Q = deltaP/R

A

renal blood flow equals the mean arterial-venous pressure to the organ divided by the resistance through the organ

110
Q

why is the clearance of P-aminohippurate of note

A

clearance of PAH almost equals renal plamsa flow, and RPF = RBF

111
Q

how is PAH used to test renal blood flow

A

PAH IV is given

PAH is filtered almost completely bt the kidney

the clearance of PAH divided by the extraction of PAH is an indirect measure of the RPF

112
Q

explain this equation

RPF = CPAH/EPAH

A

renal plasma flow

113
Q

what is the relationship between RBF and RPF

A

RBF = RPF/1-hematocrit

114
Q

what is normal resting renal blood flow

what is that in percent of cardiac output

A

1.2L/min

around 20-25%

115
Q

normal resting plasma flow

A

650 mL/min

116
Q

what is the RPF in a normal adult

A

600-700ml/min

117
Q

between what MAP does renal blood flow remain constant

what happens to GFR in this range

A

80-180

it remains basically the same

118
Q

in what ways is autoregulation of renal blood flow maintained

A

changes in vascular resistance in the afferent and efferent arterioles

119
Q

two mechanisms responsible for autoregulation of renal blood flow

A

myogenic response to arterial pressure

tubuloglomerular feedback

120
Q

what does tubuloglomerular feed back respond to

A

changes in NaCl in the intertubular fluid

121
Q

what structure is effected by mygoenic and tubuloglomerular feed back

A

the radius of the afferent tubules

122
Q

describe the sequence of autoregulation inresponse to increased GFR (8)

A
  1. GRF increase
  2. increase flow through the tubule
  3. flow past the macula densa increases
  4. paracrine stimulation from macula to afferent arteriole
  5. afferent arteriole constricts
  6. increased resistnace
  7. decreased hydrostatic pressure in the glomerulus
  8. decreased GFR
123
Q

describe the process of tubuloglomerular feedback in repsonse to high GFR

A

NaCl increase is detected by the macula densa

macula releases ATP and adenosine

signaling to the afferent arterioles to constrict

constriction decreases GFR

124
Q

what will happen if there is a decrease in ATP and adenosine

how does this change in the presence of NO

what about angiotensin II

A

vasodilation of the afferent arteriole

NO will decrease vasoconstriction caused by ATP and adenosie

Angiotensin II will increase the vasoconstrictive effects of adenosine

125
Q

what are two things that can modulate autoregulation

A

sympathetic tone and hormones

126
Q

what is the effect of sympathetic tone if the content of the extracellular fluid is nomal

A

there is minimal effect

127
Q

what is the effect of norepinehprine and dopamine on the kidney

what will be the effect

A

vasoconstrcitons through alpha adenoreceptors on the afferent arterioloe

dcreased in RBF and GFR

128
Q

what is the function of renalase

why is this important

A

degrade catecholamines and allow them to be removed from the kidney

it stops vasocontrictions from dopamine and NE

129
Q

three vasoconstrictors in the kidney

A

SNS

angiotensin II

endothelian

130
Q

what does the SNS respond to produce vasoconstriction of the kidney

what is the effect on GFR and RBF

A

decreased extracellular fluid volume

both will decrease

131
Q

what are the SNS hormones that will vasoconstrict

what wll reverse their effect

A

Epi and NE

renalase

132
Q

what stimulus will increase NO production

what is the effect

A

increased shear stress, histamine, bradykinin

increased in GFR, increase in RBF

133
Q

what is the effect of NO on the action of angiotensin II, NE, and Epi

A

it will decrease the amount of vasoconstriction

134
Q

what stimulus will produce bradykinin

what will the effect be on GFR and RBF

A

increased prostafglandins and decreased acetylchloline

increase in both

135
Q

what effect will the increase of bradykinin have on the release of NO and prostaglandins

A

it will stimulate the release of both, which will further incrased GFR and RBF

136
Q

what will stimulate the release of natriuretic peptide

what will the effect be on GFR and RBF

A

increase GFR, no effect on RBF

137
Q

what would increased levels or atrial and brain natruiretic peptide be indicative of

A

congestive heart failure

138
Q

what is the function of atrial natriuretic peptide

A

it attempts to decrease fluid volume in response to excessive stretch in the atria

139
Q

what stimulus will release angiotensin II

what will the efect be on GFR and RBF

A

decreased extracellular volume

decreased GFR and RBF

140
Q

what will the effect of angiotensin II be on BP and ECFV

A

will constrcit the afferent and efferent arterioles to increase them both

141
Q

wha stimulus with stimulate the release of endothelian

what is the effect on GFR and RBF

how does it accomplish this

A

increased tensions in the vessel wall, angiotensin, decreased ECFV

decrease in both

constriction of the efferent and afferent arterioles

142
Q

four vasodilators of the kidney

A

prostaglandins

NO

bradykinin

natriuretic peptides

143
Q

what is the function of adenosine in the kidneys

what is its effect on GFR and RBF

A

vasoconstriction

decrease in both

144
Q

what will the effect of ATP in the interstitial fluid be

A

in tubuloglomerular feedback it constricts afferent arterioles to decrease GFR and RBF

in some conditions it can stimulate NO and increase GFR and RBF

145
Q

where is atrial natriuetic peptide produced

BNP?

A

the atria

the ventricles

146
Q

what stimulus will cause the secretion of ANP and BNP

A

stretch in the atria

147
Q

what is the difference in ANP and BNP, aside from where they are produced

A

ANP has a higher affinity, BNP is longer lived

148
Q

four functions of ANP/BNP

A

decreased vascular resistance

decreased central venous pressure

increased natriuresis

decreased cardiac output

149
Q

why would BNP be a good test for CHF

A

increased stretch on the vessel walll will increase BNP production

BNP as a long half life

150
Q

how does BNP/ANP increase GRF

A

dilation of the afferent arterioles

constriction of the efferent arterioles

increase in glomerular hydrostatic prssure

151
Q

what is the effect of theraputic doses of glucocorticoids have on GFR and RBF

A

increases both

152
Q

what is the effect of histamine on RBF

A

increase RBF through decreasing resistance in the afferent and efferent arterioles

153
Q

what is the effect of dopamine on RBF

A

increases

154
Q

explain this formula

Cx = (Ux * V)/Pax

A

clearance of a substance is equal to the amount in urine times the volume of urine per day divided by the arterial concentration

155
Q

how is clearance corrected for body size

A

clearnance * 1.73m2/body surface area in m2

156
Q

four criteria to determine if a substance can be used to calculate GFR

A

freely filtered

no absorbed or secreted

not metabolized or produced by the kidney

does not alter GFR

157
Q

what is the gold standard substance to determine GFR

is it commonly used in clinic? why?

A

inulin

because it has to be IV injected

158
Q

explain this formula

clearance ratio = Cx/Cinulin

A

the clearance ratio of substance x is equal to the clearance ratio over clearance of inulin

159
Q

what would it mean if a substance had clearance ratio of 1

less that one

greater than one

A

the substance is filtered and not reabsorbed

the substance could not be filtered or is filtered then reabsorbed

the substances is filtered and secreted

160
Q

why is creatinine used to determine GFR

A

freely filtered at a reletively stead concentration of 1mg/dL

almonst non is reabsorbed, secreted, or metabolized by the nephron

161
Q

what percent of plasma is shunted and not filtered through the glomerulus

A

15-20%

162
Q

what is the filtration fraction

how is it calculated

A

the portion of blood that is shunted away from the glomerulus

GFR/RBF

163
Q

what are normal GFR values for males and females

A

125 ml/min

110 ml/min

164
Q

what GFR value would be considered kidney failure

kidney disease

normal

A

0-15 ml/min

15-60

60-120

165
Q

what would a creatinine plasma level of = 1.2 indicate

1.3-1.6

>/= 1.7

A

normal

borderline or increased creatinine due to muscle mass

renal disease

166
Q

what would albumen or glucose in the urine indicate

A

diabetic neuropathy

167
Q

PAH clearance is equal to what

A

RPF

168
Q

inulin clearance is equal to what

A

GFR

169
Q

what is the basic process of urine formation

A

ultrafilatration of plasma

reabsorption of water and solutes

secretion

excretion

170
Q

where does most of the action happen in the kidney

A

in the PCT

171
Q

67% of what substances filtered by the nephron are reabsorbed in the PCT

A

H2O, Na, Cl, K, others

172
Q

nearly all of what two substances is reabsorbed in the PCT

A

glucose and AA

173
Q

what pump on the basolateral membrane is the primary actor for reabsorption in the PCT

A

Na K pump

174
Q

where in the PCT is Na absorbed

HCO3

CL

A

the first 1/2

first 1/2

last 1/2

175
Q

what is the function of phosphate that is filtered and remains in urine

A

buffering pH

176
Q

where is the majority of Cl reabsorbed in the PCT

A

the DCT

177
Q

what pump reabsorbs Na in the 1st 1/2 of the PCT

What is a secondary effect of this

A

Na/H+

places HCO3 into the interstitium

178
Q

what are four apical symporters found in the 1st PCT

A

Na/glucose

Na/AA

Na/Pi

Na/Lactate

179
Q

what is the main symporter found at the BL membrane in the first half of the PCT

why is it important

A

Na/K

it maintains the Na gradient

180
Q

how are Na and Cl transported across the cell membrane in the 2nd PCT

A

transcellular and paracellularly

181
Q

why is Cl transported instead of organic anions or HCO3

A

because most of the proteins and HCO3 have already be reabsorbed

182
Q

what is the transcellular route of Na reabsorption in the 2nd PCT

A

parallel operation of Na/H antiporter and Cl anion antiporter

183
Q

how is Na pumped cross the basolateral membrane in the 2nd PCT

CL

A

Na K pump

Cl/K symporter

184
Q

what stops cesllls in the PCT from brust

A

Na K pump

185
Q

where is most of the H2O absorbed

A

PCT

186
Q

Where is most of the glucose absorbed

A

PCT

187
Q

where are the most of the proteins absorbed in the kidney

A

PCT

188
Q

what would glucose in the urine indicate

A

hyperglycemia, failure of glucose reabsorption

189
Q

what would albumin in the urine indicate

A

high pressure, kidney failure

190
Q

if protein is filtered where is it reabsorbed in the kidney

A

the proximal tubule

191
Q

by what means of cellular transport are proteins reabsorbed

what happens to them once they are reabsorbed

A

endocytotis

they are digested and leave the cell via the basolateral membrane

192
Q

why can urinalysis detect certain drugs

A

because some substances are secrete into the PCT and not reabsorbed

193
Q

what is the process of exretion of organic anions into the tubules

A

intracellular ketogluterate is exchanged into the tubular fluid for OA with OAT1, 2, 3

ketoglutarate in the tubule fluid is exchanged with OA by OAT4 and MRP2

194
Q

what enzymes are repsonsible for moving OAs into tubular cells from blood

what enzymes are responsible for moving OAs into tubular fluid

what is the common factor in each

A

OAT1, 2, 3

MRP2 and OAT4

OAT enzymes are ketogluterate antiporters

195
Q

what is the process for excretion of organic cations

A

OCT enzymes transport OC from blood

OC/H+ antiporter and MDR1 transport them out

196
Q

where are the rate-limiting enzymes in the process of organic cation secretion

A

on apical membrane (OC/H and MDR1)

197
Q

what are three factors that can stimulate the action of rate-limiting enzymes in secretion of organic cations

A

PKA, PKC, androgens

198
Q

what two substance are reabsrbed in the loop of henle, along with the percent of what is in filtrate

A

25% of filtered NaCl

15% of filtered H2O

199
Q

where does reabsorpton of NaCl happen in the loop of henle

where does it not occur

A

the thick and thin loops

no the descending limb

200
Q

where does H2O reabsorption happen in the loop of henle

what cellular protein is responsible for this

A

exclusively in the thin descending loop of henle

aquaporin 1

201
Q

T/F the descending limb of henle is impermable to water

A

false, the ascending limb is impermeable

202
Q

what is the driving force behind the absorption of water in the descending loop of henle

A

the gradient created by absorption of NaCl in the ascending loop

203
Q

what type of cellular transport is used for NaCl reabsorption in the ascending loop

what happens to NaCl in the tubule as it approaches the macula densa

A

passive transport

it diffuses out of the tubule into the interstitium

204
Q

what happens to the osmolality of the tubular fluid as it moves towards the macula densa

what morphological feature allow for this to happen

A

it decreases and NaCl is actively pumped out

the loop of henle gets thicker to accomodate more mitochondria to fuel Na/K pumps

205
Q

what enzymes are responsible for pumping Na out of the blood in the ascending loop of henle

what about Cl

A

Na/K pump

Cl/K symporter

206
Q

what enzymes are responsible for the movement of Na and K out of the tubule in the ascending loop of henle

A

Na and K move with Na/K/2Cl symporter

Na alone is by Na/H antiporter

207
Q

why is the Na/K pump necessary to the reabsorption of solute in the thick loop of henle

A

it maintains a low intracellular Na gradient to fuel transport from the tubule

208
Q

what happens to the the charge of tubular fluid as it passes through the thick loop of Henle

why is this important

A

it acquires a positive charge

the voltage is important for the reabsorption of cations like magnesium

209
Q

what substances are absorbed in the distal tubule and collecting duct

A

NaCl (8%)

variable amounts of H, K, and H2O inreaction to dehydration, alkalosis, or acidosis

210
Q

what is absorbed in the intial distal loop of henle

what is this strucutre impermable to

A

Na, Cl, and Ca

impermeable to H2O

211
Q

what enzyme is active in the intital segment of the DCT at the apical membrane

BL membrane

A

Na/Cl symport

Na/k pumps, Cl passive transport channels

212
Q

what substance is not absorbed in the DCT

what is the consequence of this

A

Na contentration decreases

213
Q

what are two cell types in the DCT

what are their functions

A

principle and intercalated

principle reabsorb NaCl and H2O, secrete K into tubule

incalated cells secrete H+ or HCO3 for acid base balance

214
Q

how does Na move out of the later segments of the DCT

what is the driving force behind this movement

what other ion does the effect

A

diffusion through ENaC channel

negative charge inside the DCT cell

it sets up a gradient for Cl paracellular transport

215
Q

what is the action of intercalated cells and principle cells on K

A

principle cells uptake K from the BL via Na/K, then it is secreted through passive diffusion

Intercalated cells reabsorb K from the tubule via H+/K ATPase

216
Q

what is the normal pH of urine

what causes this

A

5.5

H+/K ATPase antiport excnages H in the tubule for K in the cell

217
Q

what mediates H2O absorption in the later DCT

A

the effect of ADH on APQ2 on the apical and APQ3 and 4 on the BL membrane

218
Q

what is the effect of ADH on the later DCT

A

decreased ADH will down regulate APQ’s on the apical and Bl membranes, causing decreased H2O reabsorptiond and diuresis

219
Q

what is the location of dysfunction barter syndrome

what is the mechanism

A

ascending loop of henle

problems withthe Na/K/2Cl pump

220
Q

what diuretic would mimc barter syndrome

what would the pathologic effects be

A

lasix (inhibition of Na/K/2Cl symporter)

salt wasting, metabolic acidosis

221
Q

what is the location of dysfunction in Gitelman syndrome

what is the mechaniism

A

intitla DCT

failure of the Na/CL symporter

222
Q

what diuretic would mimic gitelman syndrome

what would be the pathlogical effects of this

A

thaizaide

hypocaluria

223
Q

where is the location of dysfunctionin liddle syndrome

what is the mechanism

A

later DCT

hyperactive ENaC

224
Q

what diuretic would mimic liddle syndrome

what would the pathologcial effects be

A

amiloride (inhibits ENaC)

metabolic acidosis

225
Q

what diuretics act on the PCT

A

acetazolamide

manitol

226
Q

what diuretics act on the DCT

A

thiazides

227
Q

what diuretics act on the thick asceening loop of henle

A

furosemide and bumetanide

228
Q

what diuretics work on the collecting duct

A

amiloride and triamterene

BMS 752 (Medical Physiology) (13 decks)

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