urology

Question 1

parts of kidney

Answer 1

cortex
minor + major calyx => ureter
medulla
renal artery + vein

Question 2

renal blood supply

Answer 2

renal artery => segmental arteries => interlobar => arcuate => interlobular => afferent arteriole => glomerulus

efferent arteriole => peritubular capillaries => interlobular vein => arcuate => interlobar => renal

Question 3

Detrusor

Answer 3

contracts to build pressure in the urinary bladder to support urination

Question 4

Trigone

Answer 4

stretching => signals brain about need for urination

Question 5

internal vs external sphincter of bladder

Answer 5

int = involuntary => SM

ext = voluntary => striated

Question 6

PCT cells

Answer 6

lots of mito => transport of water, salts, glucose, ions, bicarbonates

Question 7

loop of henle - thick vs thin

Answer 7

thin (desc+asc) => low mito => passive absorption of h20 + nacl

thick (asc only) => mito rich => active salt absorption

Question 8

DCT

Answer 8

mito rich
active reabsorption of salt and ions

Question 9

CD cells

Answer 9

intercalated = mito rich
principal cells = not

Question 10

superficial vs juxtamedullary nephron

Answer 10

superficial => BC towards outer cortex + short LOH (til outer medulla) => more

JM => BC towards cortex/medulla border + long LOH (til inner medulla) => less

Question 11

macula densa

Answer 11

in dct

GFR regulation via tubulo-glomerular feedback mechanism

Question 12

jxtaglomerular cells

Answer 12

afferent arteriole

renin secretion for regulating BP

Question 13

how is glomerular filtration passive

Answer 13

fluid ‘driven’ through semipermeable glomerular capillaries into Bowman’s capsule space by hydrostatic pressure of the heart

Question 14

g-filtration barrier

Answer 14

size and charge dependent

highly permeable to fluids + small solutes
impermeable to cells + proteins

Question 15

what can pass through fenestrae

Answer 15

water, ions and small proteins

Question 16

why very few proteins cross GMB

Answer 16

lined with negatively charged proteins that repel negative substances in blood => can’t enter BC

Question 17

slit diaphragm

Answer 17

between epithelial podocytes of BC
finger-like projections with small spaces in between
water and small solutes pass through

Question 18

net ultrafiltration pressure (Puf)

Answer 18

HPgc - HPbw - OPgc

(hydrostatic/oncotic pressures of glomeurlar capillaries/bowmans capsule)

Question 19

why is oncotic pressure in bowman’s capsule ignored in Puf calc

Answer 19

only small molecules present in BC → exert negligible pressure

Question 20

GFR

Answer 20

amount of fluid filtered from the glomeruli into BC per unit time (mL/min)

sum of filtration rate of all nephrons

Question 21

Kf

Answer 21

ultrafiltration coefficient

(dependent on membrane permeability and surface area available for filtration)

Question 22

GFR using Kf

Answer 22

GFR = Kf x Puf

Question 23

GFR regulation via myogenic mechanism

Answer 23

arterial pressure increases = afferent arteriole stretches
contracts => resistance rises
blood flow reduces = GFR stays same

Question 24

GFR regulation via tubulo-glomerular feedback mechanism

Answer 24

increased GFR = increased NaCl in Loop of Henle
detected by macula densa = increased ATP & adenosine discharging
afferent arteriole constricts => GFR stabilises (and vice versa)

Question 25

renal clearance

Answer 25

no:litres of plasma that are completely cleared of the substance per unit time

Question 26

renal clearance calculation

Answer 26

(conc of substance in urine x rate of urine production) / conc of substance in plasma

Question 27

calculate GFR using clearance

Answer 27

both equal when substance is freely filtered + no resorption/seceretion

amount filtered at BC = amount excreted

e.g inulin/creatinine

Question 28

renal plasma flow

Answer 28

amount of blood arriving at kidney per unit time => same for all

Question 29

calculate RPF usine renal clearance

Answer 29

both equal when amount of substance entering kidney = amount excreted

all filtered + secreted (none left in plasma)

e.g PAH - para amini hippurate

Question 30

filtration fraction (+calc)

Answer 30

ratio of amount of plasma filtered + amount arriving at afferent arteriole

GFR/RPF

Question 31

substances reabsorbed throughout kidney (main)

Answer 31

early PCT => Na + HCO3-
late PCT => glucose

desc LOH => H2O passively
thin asc LOH => NaCl passively
thick asc LOH => NaCl actively

early DCT => NaCl + Ca2+

late DCT + CD:
principal cell => Na+ (maintain BP)
alpha intercalated => HCO3- (increases alkalinity)
beta intercalated => H+ (increases acidity)

Question 32

issues with using inulin in GFR calc

Answer 32

must be transfused
time consuming
tedious
short duration to measure means bladder catheterisation is necessary

Question 33

51 CrEDTA

Answer 33

same properties as inulin but emits radiation

inject => measure plasma activity + monitor disappearance

Question 34

why creatinine is used in GFR calculations

Answer 34

endogenous - from creatine metabolism

released into blood at constant rate so plasma concentration = stable

Question 35

diabetes mellitus vs insipidous in urinanalysis

Answer 35

M: glucose
I: low specific gravity

Question 36

nephrotic vs nephritic syndrome in urinanalysis

Answer 36

nephrotic => protein
nephritic => blood

Question 37

liver disease urinanalysis

Answer 37

billirubin/urobillinogen

gallstones for B/haemolysis for U also