Renal Flashcards

Question

how is chloride reabsored

Answer 1

as Na and HCO3 are reabsorbed and water follows, Cl conc increases passively diffuses down conc gradient also co-transporter

Answer 2

carbonic anhydrase, combines H+ and bicarbonate to H2CO3 to make H20 and CO these can diffuse across back into plasma

Answer 3

50% is reabsorbed by passive diffusion due to other things being reabsorbed and conc rising

Answer 4

70% PCT 15% LoH variable = collecting ducts

Answer 5

hair pin like structure with countercurrent mechanism fluid flows down descending and up ascending 2 types of nephrons = juxtamedullary (15% to deep medulla) and cortical (85% - only junction of cortex and medulla) descending = impermeable to solute, permeable to water. thin ascending limb = impermeable to water, permeable to solule TAL = permeable to ions and impermeable to water this aids its mechanism in creating high osmoltic pressure in depths of medulla and hence water conservation.

Answer 6

active transport of solutes out of TAL - Na/K basolateral, Na/2Cl/K luminal, K+ channels basolateral etc creates high osmotic pressure in interstium water leaves the DL as descending travels further down, less water to dilute and thus interstitial fluid increases in osmotic pressure increases conc of solute within DL this is fed back round to TAL which is impermeable to water and now has high conc solutes delivered for further AT the hairpin arrangement creates a countercurrent mechanism which creates very high concs in depths of medulla. 1400mOSm /L at deepest point. this allows for efficient water reabsorption by collecting duct in times of dehydration.

Answer 7

TAL has pumped out fluid so dilute 100mOSmol/l enters DCT

Answer 8

capillaries emerging from efferent arterioles hairpin structure following LoH this hairpin arrangement and low flow means solutes are not washed away as equilibrium is reached. however O2 is still supplied

Answer 9

vasoconstriction of vasa recta, slows down flow allowing time to equilbrate and hence maintaining medullary concentrations hence aids fluid absorption some drugs will oppose this e.g. ARBs, ACEi

Answer 10

further reabsorption of solute - Na/ HCO3, K impermeable to water so delivers hypotonic solution to collection duct for control of water regulation also contains macula densa - part of juxtamedullary apparatus and communicates with afferent arterioles.

Answer 11

role in water reabsorption and homeostasis of osmotic pressure And also in Na reabsorption **OSMOTIC HOMEOSTASIS:** Dilute fluid enters collecting duct collecting duct passes through medulla if aquaporins are present, reabsorption of water is allowed by the high osmotic gradient created by LoH if aquaporins are not present, dilute urine is excreted this is regulated by ADH urea recycling also plays a role here. **NA REABSORPTION** collecting duct also plays a role in sodium homeostasis under influence of aldosterone.

Answer 12

sensors - control centre - effectors with the hypothalamus and collecting ducts of the kidneys playing a central role in this Sensors * paraventricular and supraoptic nucleus of anterior hypothalamus * detect changes to osmotic pressure Control centre * hypothalamus sends impulses to posterior pituitary and ADH is secreted, also sends impulses to initiate thirst Effector * ADH travels in blood * receptors V2 on collecting ducts * GPCR - Gs - cause vesicles containing aquaporin to fuse with luminal membrane * (Aquporin channels already on BL membrane) * now water can flow down osmotic gradient into the renal interstitium and absorbed by capillaries

Answer 13

280-290mOsm/Kg H20

Answer 14

produced in hypothalamus (supraoptic) travels down by axonic transport stored in vesicles of posterior pituitary

Answer 15

stimulus = high osmolarity , ATII (volume depletion), sympathetic NS, opioid receptors, emotions (pain, stress), other drugs nicotine

Answer 16

osmolarity homeostasis - collecting duct vasoconstriction - helps with volume depletion role in clotting (desmopressin releases vWF), platelet aggregation neurotransmitter - release of ACTH

Answer 17

human cells are subject to osmotic pressure. in hypotonic solutions, water will enter cells and they can burst and in hypertonic they can shrink/ dehydrate in the brain oedema in a constricted space can result in increase ICP and reduced perfusion and ischeamia

Answer 18

urea is an active osmole ADH causes urea channels on collecting duct urea leaves collecting ducts, increases osmolarity of interstitium further, aiding further water reabsorption in times of dehydration it is recycled by descending limb

Answer 19

excess ADH * SiADH - lung tumours, traumatic brain injury * low plasma osmolarity, concentrated urine. hyponatraemia no ADH * neurogenic diabetes insipidus * dilute urine 23L/day * high osmolarity, high sodium plasma conc * caused by traumatic brain injury, SAH, brain tumour insensitivity to ADH * nephrogenic diabetes insipidus e.g. lithium, congential , CKD * dilute urine 23L/day * high osmolarity, high sodium plasma conc

Answer 20

diagnosis = low osmolarity (less than 280) , low sodium ( less than 135), euvolaemic treatment - lithium, demeclocycline , fluid restriction

Answer 21

urine production > 3L/day (usually much more) sodium >145 osmolarity >305 desmopressin and fluids

Answer 22

since sodium is the main osmotically active solute, mostly via chnages to Na conc Neuronal sympathetic NS / baroreceptors Hormonal: RAAS ANP/ BNP osmolarity and ADH other: direct passive influence - more ECF, more GFR, higher excretion rate. more ECF, less reabsorption via peritubular capillaries psychological and social factors -e.g. diet, fluid intake

Answer 23

tindirect * clearance of inulin - inulin is a polysaccharide that is freely filtered and not bound by plasma proteins, not reabsorbed or secreted or metabolised * it is infused into a patient and clearance of it is measured * this is accurate however time consuming and impractical indirect / estimation * using creatinine and cockcroft and gault equation which takes into account age, weight and gender to estimate GFR * there is also the modification of diet in renal disease (MDRD) equation and the CKD EPI equation * this is easier as creatinine is a natural byproduct of muscles so no need for an infusion however creatinine is secreted so not completely accurate and will over estimate GFR.

Answer 24

freely filtered not metabolised not reabsorbed not secreted inert doesnt influence GFR itself

Answer 25

some is secreted so overestimation of GFR amount produced depends on body muscle amount - so can vary from gender to race to individual.

Answer 26

plasma clearance of PAH (para-amino-hippuric acid) as a modification of FICKs principle i.e. flow to an organ is equal to uptake or excretion of a substance divided by the A-V conc difference PAH is used because it is almost completely removed by kidneys by filtration and secretion and not used by any other organ When PAH is infused into the bloodstream, nearly all of it is removed from the plasma by the kidneys during a single pass through the renal circulation under normal physiological conditions. Thus, the clearance of PAH is nearly equal to renal plasma flow (RPF), which can be further converted to RBF. clearance of PAH = estimation of Renal PLASMA flow can work out the renal blood flow from this by knowing the haematocrit value.. RBF = RPF / 1-Hct

Answer 27

volume of plasma cleared of a drug / substance per unit time calculated by = (urine conc x urine flow) / plasma conc it combines all methods of clearance by kidneys e.g. filtrations/ secretion.

Answer 28

osmolarity = the number of osmoles per kg of solvent osmolarity = the number of osmoles per L of solvent - temp dependant as volume changes with temp so less accurate.

Answer 29

1 mole of osmotically active particles where 1 mole is the same number of particles as there are atoms in 12g of C12 = 6.022x10.23 OR 1 osmole = amount of solute that exerts osmotic pressure of 1atm when placed in 22.4L of solution at 0 degrees.

Answer 30

the pressure required to prevent water travelling via osmosis from area of low to high concentration.

Answer 31

solvent = a substance capable of dissolving another solute e.g. water solute = a substance that dissolves into a solvent e.g. NaCl

Answer 32

tonicity is the osmotic pressure of one substance compared to another reference point e.g. hypotonic means it has less osmotic pressure compared to the other solution.

Answer 33

2x (NA + K )+ glucose + urea (osmolality may be different ie. osmolar gap) also via vant hoff equation - number of osmoles PV = nRT. rearrange for P to be pressure

Answer 34

osmolality - osmolarity usually less than 10 increases with increased levels of other osmotically active particles e.g. mannitol, alcohol, methanol (other than glucose, urea, sodium etc)

Answer 35

a form of osmotic pressure exerted by presence of proteins

Answer 36

vasodilation of afferent arteriole to maintain GFR involved in signalling from macula densa when GFR is low to maintain it.

Answer 37

proportion of plasma being filtered by glomerulus GFR / Plasma flow rate x 100 i.e a % usually around 20%

Answer 38

Blood pressure - hypovolvaemia, sepsis local vasoconstriciton / dilation of afferent/ efferent - hence local mediators (prostaglandins) but also hormones and sympathetic NS changes to oncotic pressure - hypoalbuminaemia

Answer 39

osmometer uses collagative properties usually freezing point sample is supercooled to -7 degrees (using peltier effect - absorption of heat at 2 dissimilar metals), then stired to trigger freezing, freezing point recorded. the more osmoles, the lower the freezing point THis will measure OSMOLALITY (rather than osmolarity)

Answer 40

Extracellular and intracellular Intracellular = 2/3 extracellular =1/3 extracellular further divided into interstitial (3/4) and plasma (1/4) in total 42L ICF = 28L ECF =14L

Answer 41

age (higher in neonates, less in elderly) gender, ethnicity muscle mass vs fat - fat constains less pregnancy

Answer 42

in neonates TBW = 80% adults TBW =60% of weight fat is higher in adults

Answer 43

ECF = Inulin - crosses endothelium but doesnt go intracellularly. plasma = radioactive albumin red cell mass = radioactive Hb TBW = dueterium oxide - crosses all compartments worked out via concentration and dose given to work out volume.

Answer 44

no direct measurement take away others e.g. Total water - ECF therfore using dueterium oxide and inulin

Answer 45

no direct way ECF - Plasma

Answer 46

determines ECF volume as most dominant extracellular cation determines osmolarity important for membrane potentials and generation of AP.

Answer 47

1-2mM /kg /day

Answer 48

sweat faeces urine

Answer 49

bowmans capsule - same as plasma = 135 -145 in descending limb water leaves = increase in conc by end of asending limb = active transport, low sodium entering collecting ducts depends on ADH

Answer 50

hypo Na - headache, N&V - confusion, seizures, hyper - thirst - weakness - dry mucus membranes - seizures etc

Answer 51

slowly risk of central potine myelinosis

Answer 52

major intracellular cation determines resting membrane potentials important in action potentials - repolarisation important in regulation of cellular processes

Answer 53

3.5 to 5mM

Answer 54

reduced intake - diet, laxatives and poor absorption increased losses - renal tubular disease, diuretics , cushings, increased aldosterone intracellular shifts - insulin, salbutamol, adrenaline

Answer 55

less than 2.5 less than 3.5 = mild less than 3 = moderate

Answer 56

CVS - arrythmia (flat T, long PR, Long QT, torsades) muscle - weakness, ventilatory failure GI - ileus

Answer 57

excess intake - bananas, IV potassium reduced output - K+ sparing diuretics, addisons, CKD intracellular... haemolysis / rhabdomyolysis / burns MH sux after denervation

Answer 58

above 6.5mM mild 5.5 to 6 moderate 6 to 6.5

Answer 59

secreted into tubules filtrate flow dependant

Answer 60

CVS - arrhythmias - tall T , flat P , prolonged PR, sine wave, VF muscle weakness malaise

Answer 61

high K+ outside depolarises membrane, less negative resting potential, more excitable cell as per nernst equation

Answer 62

A B C calcium gluconate 10% - protect the heart (or CaCl2) salbutamol nebs Insulin 10 units actrapid+ dextrose 50ml 50% sodium bicarb if metabolic acidosis RRT other - calcium resonium - bind and prevent absorption

Answer 63

0.7 to 1mM

Answer 64

loss - diarrhoea, diuretic reduced intake - diet

Answer 65

nausea, anorexia muscle cramps, lethargy later - tetany, muscle spasms, seizures , ECG changes (QT prolongation) anatogonises Ca - hypocalcaemia - hyperexcitable e..g trousseaus sign and chvostek sign

Answer 66

mostly intracellular 2nd most abundant intracellular after potassium soft tissues, muscle and bone

Answer 67

often low K and low Mg are seen together due renal losses low K can rarely be corrected with low mg correct Mg first Mg promotes K loss by kidneys and Mg blocks Na/K ATPase - hence poor uptake of K into cells

Answer 68

cortisol release causes Na reabsorption, K loss via kidneys

Answer 69

high Na delivery to macula densa - ATP and adenosine release - inhibits renin low Na - prostaglandins released - vasodilation of afferent and renin release.

Answer 70

different perspective of how acids and bases are regulated in the body compared to the henderson hasselbach model. it uses relationship between ions, water dissociation, and the principles of electroneutrality. 3 components * Strong ion difference - difference of strong cations and anions e..g Na + , Cl- * weak acids and bases levels * pCO2 if there are more cations (Na) compared to Anions (Cl) i.e. a large strong ion difference --> promotes acidity as it promotes the dissociation of H20 e.g. after vomitting , loss of Cl, increases the SID. promotes dissociation of H20. to balance loss of Cl, H+ must be lost. hence alkalosis.

Answer 71

20-30ml/kg 1-2mM/kg Na 1mM / Kg K 50g-100g glucose

Answer 72

overload electrolyte disturbance / acidosis

Answer 73

crystalloid - sollution containing inorganic ions dissolved in water - hartmans, 0.9% saline , dex saline may be isotonic, hypotonic, hypertonic colloid - suspension of particles unable to pass through semipermeable membrane and hence remain intravascular. can also be defined as a mixture in 2 phases dispersed amongst one another. can be naturally occuring (albumin) or synthetic (gelatin).

Answer 74

cystalloids - cheap, long shelf life, low ADR profile. many uses in resusitation, maintainance etc and correction of electolytes. However risk of electrolyte abnormalities, overload and acidosis. colloids - better at increasing intravascular volume and therefore less risk of peripheral oedema and small amount required to have same effect. however expensive, more ADRs (anaphylaxis)

Answer 75

0.9% saline = 154mM Na and 154mM Cl, pH 5, osmolarity 300 hartmans = 131 Na, 111 Cl, 5K, 2 Ca, pH 6.5, lactate buffer, osmolarity 280

Answer 76

similar to hartmans, however ph 7.4. no lactate instead acetate and glucaonate

Answer 77

hyperchloraemic acidosis

Answer 78

similar to hartmans but no lactate caused metabolic acidosis lactate added to solution to buffer this = ringers lactate/ hartmans

Answer 79

liver disease lactate not metabolised and cause cause acidosis

Answer 80

HAS = human albumin solution 4% or 20% Starches - no longer used due to safety concerns Dextrans 40 or 70 Gelatins (type of collagen) e.g. gelofusine - suspended in crysatalooid solution excreted unchanged in kidney blood products are also classed as colloids - Cyroprecipitate, packed red cells, FFP

Answer 81

naturally occuring protein molecule normally synthesised by liver. HAS is a solution of albumin from donor blood. available in 4.5% and 20% solutions large protein with 69KDa MW and negatively charged and thus exerts oncotic pressure. often given in those with ascites, severe sepsis. it is costly, associated with coagulopathies and can cause allergy

Answer 82

all anaphylaxis risk especially with gelatins coagulopathies, itching, flushing , renal dysfunction

Answer 83

0.9% saline hartmans 0.18% saline + 4% dextrose 5% dextrose

Answer 84

initially doesnt change until fluid moves from interstitium to plasma or fluids are given IV then will fall.

Answer 85

haemorrhage burns vomitting/ diarrhoea diuretics insensible - fever

Answer 86

level of dehydration / fluid loss - clinically via lactate, urine output, mucus membranes, HR/tachy, fluid balance chart then responsivness by.. 1. leg raising - tilt bed by 45 degrees, if haemodynamic improvement e.g. BP, HR, swing on art line reduced then likely fluid deplete. if condition deteriorates potentially overloaded 2. fluid challenge - bolus and look for improvements 3. respiratory swing - i.e. on arterial line, PPV can be analysed. only reliable in ventilated

Answer 87

1L of saline = isotonic solution. Na cannot cross plasma membranes, so stays mostly extracellular. 1/4 plasma 3/4 interstitium 1L dextrose = glucose metabolised = hypotonic, enters cells. less than 10% stays in plasma

Answer 88

a rapid decline in kidney function over hours to days resulting in increase in creatinine and urea reduction in GFR defined by serum creatinine >26.5mM in 48hrs or >1.5x baseline OR urine output less than 0.5ml/kg/hr for 6 hrs is classified into 3 stages KDIGO 1. serum creatinine 1.5 to 1.9 x baseline 2. serum creatinine 2 to 2.9 x baseline (or UO less than 0.5 for more than 12 hr) 3. serum creat more than 3 x (or UO less than 0.3 for 24 hrs or anuria for 12 hours

Answer 89

pre renal * sepsis, haemorrhage, renal artery stenosis, NSAIDs or ACEi * poor CO - HF renal * glomerular - nephritic and nephrotic syndromes * acute tubular necrosis, drug toxicity (gold, penicillamine, gentamicin) * vasculitis post renal * stone, tumour, prostate BPH

Answer 90

increase waste - urea , drug half lives electrolyte disturbances - hyperkalaemia, hyponatraemia acidosis hypertension + overload - RAAS activated as kidneys are being underperfused, so think BP is low.

Answer 91

identify risk - stop nephrotoxic e.g. metformin stopped when in hospital and ACEi and NSAIDs fluids / avoid dehydration monitor UEs maintain good BP intra op

Answer 92

fluids manage cause - pre, renal, post e.g. may need to relieve obstruction treat complications - acidosis, hyperkalaemia, overload may require dialysis adjust drug doses / stop nephrotoxins

Answer 93

AEIOU Acidosis - severe metabolic acidosis electrolytes - refractory hyperkalaemia Intoxication - salicylates Overload - refractory pulmonary oedema uraemia - with complications such as pericarditis/ encephalopathy

Answer 94

transplant peritoneal dialysis haemodialysis - arteriovenous or venovnous may be continous or intermittent - intermittent less haemodynamic stability as achieving larger fluid shifts in shorter space of time. continous therapies could be haemodialysis or ultrafiltration or haemodilation 5 types CAVHD = cont arteriovenous haemodialysis CVVHD = cont venovenous haemodialysis CAVH = cont AV haemfiltration CVVHDF = cont venovenous haemofiltration SCUF = slow continuous ultrafiltration

Answer 95

ultrafiltration - uses hydrostatic pressure across a filter to push solvent across this filter. good for treating fluid overload. dialysis - blood and dialysate pass eachother separated by a semipermeable membrane. diffusion occurs across this. the composition of dialysate is chosen depending on need.

Answer 96

haemodynamic instability - wouldnt tolerate intermitted i.e. critically ill raised ICP high volume required to be removed risk of disequilibrium syndrome

Answer 97

longer time for immbility more labour intensive and expensive needs continous anti-coag

Answer 98

set filtration fracture, clearance rate and blood flow prescribe the citrate or heparin

Answer 99

citrate - limited to machine, not patient, need to monitor Ca levels heparin - will anticoag patient too (may or may not be useful)

Answer 100

access related - infection, thrombosis, bleeding circuit related = clotting anticoag related = HIT, bleeding, hypocalcaemia diaysis related = fluid shifts (hypotension, electrolytes)