Lect 3 - Block 3 - Glomerular Filtration Flashcards
Filtered load is _________ x __________
It is the quantity of a compound that enters Bowman’s capsule each minute
GFR x filtrate concentration
Blood flow through kidney:
Renal artery, arterial branches, interlobular artery, afferent arteriole, glomerular capillary, efferent arteriole, peritubular capillary, venous branches, renal vein
Filtration fraction
GFR/renal plasma flow = filtration fraction
Percent of plasma which is filtered by the renal glomerulus and enters Bowman’s capsule
Usually about 20% of total RPF
Tubular system order of flow
Bowman’s capsule, proximal tubule, loop of Henle (thin descending, thin ascending, thick ascending), distal tubule, cortical collecting duct, medullary collecting duct, renal papilla, ureter, bladder, urethra
2 tipos de néfrons
Juxtamedullary nephrons
Cortical nephrons
Ultrafiltrate first enters where?
Bowman’s capsule
Glomerular capillaries get what percent of cardiac output?
20-25%
1200-1300mL/min
2 capillary beds of the kidney
Glomerular: 1300mL/min
Peritubular capillaries
Cortex: 1000mL/min
Outer medulla: 240mL/min
Vasa recta to inner medulla: 60mL/min
Cortex and outer medulla get most do the peritubular capillary blood flow
Plasma is what percent of blood?
55% (other 45% are RBC’s)
Renal Plasma Flow (RPF) =
RBF(1-hematocrit) = RBF
600-700mL/min (both kidneys)
GFR is normally
125mL/min (120-140 - both kidneys)
Urine production rate is normally about _______, and ranges from _____ to _____
1mL/min, ranges from 0.4 to 20mL/min
Filtration fraction is ______ if preglomerular resistance changes
Filtration fraction is ______ if postglomerular resistance changes
constant
altered
Kidneys use autoregulation for blood pressure. The normal BP range is from ___to___mmHg, and changes in BP within this range (do/don’t) alter renal blood flow or GFR.
80-150mmHg
changes in this range don’t alter renal blood flow or GFR
Kidney blood flow control - autoregulation
1.
2.
3.
- Tubuloglomerular feedback
- Myogenic
- Prostaglandins
Kidneys shut down at blood pressures less than ____mmHg
50mmHg
Blood flow (is/isn’t) controlled by metabolism in kidneys
isn’t
Even though GFR doesn’t change with blood pressure, the rate of urine formation is directly tied to arterial blood pressure. This is called ______ ________, where increase in arterial pressure causes an increase in the rate of urine production
pressure diuresis
Sympathetic innervation of kidneys
1.
2.
3.
- mostly afferent arterioles, some efferent
- Justaglomerular cells (renin secretion)
- Tubule (Na+ reabsorption)
Hydrostatic pressure from across glomerular capillary starts at ____ and ends at _____
50, 40
colloid osmotic pressure in glomerular capillary changes from ____ to ____
25, 30
Hydrostatic pressure of Bowman’s capsule is ____
10mmHg
Net filtration pressure across glomerular capillary is _____
10mmHg outward (15 at afferent arteriole side, 0 at efferent arteriole side)
Filtration is dependent on 5 things
- permeability
- capillary hydrostatic pressure
- filtrate oncotic pressure
- plasma oncotic pressure
- filtrate hydrostatic pressure
(filtrate oncotic pressure is normally 0, because large oncotic proteins are not filtered)
pressao efetiva de ultrafiltracao=peuf
Oncotic pressure due to presence of proteins in plasma (increases/decreases) as fluid flows through the glomerular capillaries
Increases
Afferent arteriole is changed by ________
sympathetics
Efferent arteriole is changed by ________
angiotensin II
tubuloglomerular feedback
Protein oncotic pressure is changed by _______
plasma protein concentration
barrier integrity
Renal blood flow:
afferent constriction causes ___RBF, ___GFR, ___Peri Reabs
decrease RBF, decrease GFR, increase Peri Reabs
Renal blood flow:
efferent constriction causes ___RBF, ___GFR, ___Peri Reabs
decrease RBF, increase GFR, increase Peri Reabs
Renal blood flow:
afferent dilation causes ___RBF, ___GFR, ___Peri Reabs
increase RBF, increase GFR, decrease Peri Reabs
Renal blood flow:
efferent dilation causes ___RBF, ___GFR, ___Peri Reabs
increase RBF, decrease GFR, decrease Peri Reabs
3 layers filtrate passes through from glomerular capillaries to Bowman’s capsule
barreira de filtracao
- Capillary endo (fenestrated), keeps RBC’s out ENDOTELIO
- Basement membrane, has a “-“ charge, keeps proteins out MBG
- Bowman’s capsule epi. small holes that do more filtering of big particles=estruturas podocitarias
resitencia por tamanho e carga eletronegativa
3 things that are freely filtered
H2O, NaCl, Glucose
Inulin is used to measure _____ and is filtered at about 90%
GFR
____ charged particles are easier to filter through the basement membrane into Bowman’s capsule
Positively
The loss of negative charge in the basement membrane in the kidney is a consequence of this long-term disease.
Diabetes, due to glycosylation of the basement membrane proteins
The loss of negative charge in the basement membrane in the kidney is a consequence of this infection.
Post streptococcal glomerulonephritis, where antibodies created in response to strep infection attack the glomerular basement membrane
GFR is maintained even though the number of nephrons is lost in chronic kidney disease. This is because the remaining nephrons…
have a compensatory increase in glomerular filtration rate
The body can tolerate a loss of 1/2 of the nephrons and still maintain ____% of GFR
90%
Administering an ACE inhibitor will cause a(an) ____ in GFR and a _____ in filtration fraction. This is because the ____ arteriole is dilated
decrease, no change, efferent
During malignant hypertension, administering an ace inhibitor will __________ GFR. This is due to dilation of the ________ arteriole
Decrease, efferent
