Renal 1: Glomerular Filtration Flashcards
the functional unit of the kidney where urine is formed
nephron
urine is initially formed by filtration of ___
blood
filtration occurs at the ___ due to ___ differences between urine and bloood
glomerulus; pressure
the ___- is regulated to control the rate of urine production
GFR
clearance is a measure of
how effectively a substance is removed from th eblood by the kidenys
___ can be used to estimate GFR
clearance
the human body is a ___ system (open / closed)
open
the kidneys excrete ___, ___ and ___
water; electrolytes (Na, K, Cl, HCO3, H, Ca, P) and wastes
the kidneys regulate body fluid ___, ___, ___ and ___
volume, composition, osmolarity, pH
is water loss to the skin and lung regulated ?
no
what are the 3 ways the body gains water?
metabolic water, ingested foods and ingested liquids
blood enters the kidney by the __
renal artery
blood exits the kidney by the __
renal vein
urine exits the kidney by the ___
ureter
urine is formed in the __
renal corpuscle
t/f the urine has close contact with blood in the bowmans capsule / glomerulus
t
what are the 3 layers of glomerular filtration barrier?
- fenestration (pore) of the glomerular endothelial cell
- basement membrane of glomerulus
- slit membrane between pedicels
substances are filtered on the basis of ___ and ___
size and charge
what size passes best in filtration?
small
what charge passes best in filtration?
positive
podocytes are also known as ___ cells
mesengial
t/f filtrate must pass through the barriers of the bowman/s capsule in series
true
is the perfusion high or low in the glomerulus?
high
RPF / RBF stand for
renal plasma flow and renal blood flow
the filtration fraction
GFR over renal plasma flow
__-% of what is filtered is reabsorbed
99
___% of what is filtered is excreted
1
what are the 4 pressures in the bowman’s capsule (glomerulus) that contribut e tp net filtration pressure? Are these inward or outward?
- glomerular capillary hydrostatic pressure (out)
- bowman’s space hydrostatic pressure(in)
- Plasma colloid osmotic pressure (in)
- bowmans space colloid osmotic pressure (out)
bowmans space colloid onconic pressure is __mmhG
0
__- and __ are forces the favour filtration
- glom capillary hydrostatic pressure
2. bowman’s space colloid osmotic pressure
___ and ___ are forces that oppose filtration
bowmans space hydrostatic pressure
plasma colloid osmotic pressure
what is the greatest filtration pressure?
glomerular hydrostatic pressure
what are the effects on glomerular pressure and filtration rate if there is vasoconstriction of the segment before the glomerulus? (afferent)
both reduced due to lower blood flow
what are the effects on glomerular pressure and filtration rate is there is vasoconstriction of the segment after the glomerulus? (efferent)
both increase due to reduced ability of blood to leave the glomerulus
___ determines GFR, but ___ and ___ are constant during changes in blood pressure due to ___
PGC; GFR and RBF; autoregulation
what are the 2 mechanisms for autoregulation?
- myogenic mechanism
2. tubulogenic feedback
explain the process of myogenic mechanism
pressure increases –> raise RBF and GFR –> smooth muscle stretch –> smooth muscle cell contration –> increased afferent arteriole resistance –> decreased RBF and GFR
in the tubulogenic mechanism of autoregulation, the ___ region of the distal tubule provides feedback to the glomerulus of the ___ nephron
macula densa; same
the macula densa comes very close to the ___ of the same nephron
afferent arteriole
describe the process of tubulogenic autoregulation
increased pressure –> increased GFr, RBF
–> flow, NaCl sensed by the macula densa –> signal to the JgA –> increased afferent arteriole resistance –> decreased RBf and GFr
chronic kidney disease affects __-% of canadians
12
progressive loss of kidney function results in a decrease in ___
GFR
t/f gfr is used to measure the health and function of kidney
t
how do we calculate renal clearance?
Cx = concentration of X in urine x urine flow rate all divided by plasma x
if Cx < GFR, X is __
reabsorbed
if Cx > GFR, X is ___
excreted
is there absorption or secretion of creatinine? what does this mean?
no; what is filtered is amount excreted (can measure function of GFR)
how do we calculate CrCl (GFR)?
GFR = Ucr x volume of urine all divided by plasma cr
normal creatinine clearance is
80-120 ml/min
CLcr in renal disease is __
<60 ml/min
CLcr in kidney failure is __
<15 ml/min
