Lecture 14 Body Fluids Flashcards
Layers of the filtration barrier
endothelium
basement membrane
podocytes
Endothelium of filtration barrier
part of the capillaries, first layer of filtration barrier
fenestrae with negative charges
basement membrane of filtration barrier
composed of collagen and proteoglycan fibers with strong negative charges
meshwork formed by collagen and proteoglycan makes a filtration
podocytes of filtration barrier
create a filtration slit with negative charges
albumin in urine
albumin is the most popular protein in blood, presence would indicate damage and infection in the filtration barrier
blood cells aren’t supposed to pass
Globular filtration rate is determined by
balance of hydrostatic and colloid osmotic forces acting across the capillary membrane
basically starling forces
capillary filtration coefficent
product of permeability and filtering surface area of the capillaries (K1)
depends on the number and size of the pores in the capillary
what is the average GFR per day?
125 mL/min
180 L/day
what are some diseases that effect the lower glomerular capillary filtration coefficient
chronic uncontrolled hypertension and diabetes mellitus
define minimal change nephropathy
loss of negative charge in the basement membrane
define hyronephrosis
dissension and dilation of renal pelvis and calyces
GFR equation
GFR = K1 x Net Filration pressure
GFR = K1 x (P g -P b - Pi g + Pi b)
relationship between K1 and GFR
directly proportional
increase in K1 increases GFR
decrease in K1 reduces GFR
factors that influence glomerular capillary colloid osmotic pressure
arterial pressure colloid osmotic pressure
filtration fraction
factors that increase glomerular colloid osmotic pressure
increasing filtration fraction
variables that determine glomerular hydrostatic pressure
arterial pressure
afferent arteriolar resistance
efferent arteriolar resistance
arterial pressure impact on glomerular hydrostatic pressure
increase in AP causes increase in Pg which increases GFR
afferent arteriolar resistance
blood isn’t coming in
increase in AAR causes decrease in Pg which decrease GFR
efferent arteriolar resistance
clamping off the efferent arteriole – blood is still coming in but not going out
increase in EAR causes increase in Pg which increases the GFR
Where does most of the O2 consumed by the kidneys become used?
active reabsorption of Na
utilizing ATP to absorb Na
Do kidneys or brain have more blood flow?
kidneys have 7x blood flow but only 2x oxygen consumption
activation of renal sympathetic nerves…
constricts the renal arterioles
decreases renal blood flow and GFR
innervation of blood vessels in the kidney
sympathetic
hormones that control GFR consistency (7)
norepinephrine and epinephrine endothelin angiotensin ii endothelial derived nitric oxide prostaglandins bradykinin
norepinephrine and epinephrine
from adrenal medulla
parallels the sympathetic nervous system
endothelin
released by damaged vascular endothelial cells of kidneys and other tissues
contribute to renal vasoconstriction (decrease gFR)
contributed to hemostasis if blood vessel is severed
plasma levels will increase in certain disease states associated with vascular injury (toxemia or pregnancy, acute renal failure, chronic uremia)
angiotensin II
preferentially constricts efferent arterioles
formed in situations associated with decreased arterial pressure or volume depletion (increases GFR via efferent arterials)
afferent arterioles seem to be protected against angiotensin II (release vasodilators via prostaglandins and NO)
nitric oxide
via endothelial cells
helps maintain renal vasodilation
prostaglandins and bradykinin
vasodilators may offset effects of sympathetic and angiotensin II vasoconstrictor effects (esp. afferent arterioles)
auto regulation
relative constancy of GFR and renal blood flow
maintains a relatively constant GFR
allows precise control of renal exertion of water and solutes
prevents large changes in GFR and renal extortion that would occur with change in blood pressure
two components of tubuloglomerular feedback mechanism
afferent arteriolar feedback mechanism
efferent arteriolar feedback mechanism
juxtaglomerular complex
macula densa in distal tubule (reads [NaCl])
juxtaglomular cells in afferent and efferent arterioles
decrease in GFR causes a slow rate in loop of Henle therefore
increased reabsorption of sodium and chloride ions in ascending limb
decrease in sodium chloride at macula dense
decrease in [NaCl] results in a signal from macula dense
decreases resistance to blood in afferent arterioles
increase renin release from JG cells
increase angiotensin II
increase efferent arteriolar resistance
