L17: Micturation & Glomular Filtration Flashcards
sensory signals from bladder stretch receptors are conducted ________ back to bladder via _______ nerves.
reflexively
parasympathetic
reflex contractions will ____ ________ when the bladder is half full
stop spontaneously
as the bladder continues to fill micturition reflexes will ?
occur more often and more intense
higher brain centers, in the _____, keep urination partially ________ until it is a desired event.
pons
partially inhibited
when it is time urinate, what helps facilitates reflexes and relax external sphincters.
cortical centers
how do nephrons regulate arterial pressure long term
excrete variable amounts of Na and water
how do nephrons regulate arterial pressure short term
secrete hormones and vasoactive factors such as renin
how do nephrons regulate acid-base balance
by excreting acids to regulate body fluid buffer stores
and
eliminate wastes created by protein metabolism - urea
list the 3 processes done by nephrons that determine urine composition
filtration
reabsorption
secretion
urinary excretion rate =
filtration rate - reabsorption rate + secretion rate
what are the major components of glomerular filtrate
water
ions
glucose
urea
filtration fraction =
GFR/renal plasma flow
define filtration fraction
if it = 0.2
then means 20% of plasma flowing thru kidney is filtered
low molecular weight substances are not freely filtered since ?
they are partially bound to proteins
what are the 3 components of the filtration barrier
endothelium
basement membrane
podocytes
filtration barrier endothelium
have fenestrae and negative charges
filtration barrier BM
collagen
proteoglycan fibers
strong negative charges
filtration barrier podocytes
negatively charged
2 factors that determine GFR
- balance of hydrostatic and colloid osmotic forces acting on capillary membranes
- capillary filtration coefficient
define capillary coefficient
= K1
the product of permeability and filtering surface area of capillaries
normal GFR
125 mL/min
or
180 L/day
diseases that lower glomerular capillary filtration coefficient
chronic uncontrolled hypertension
diabetes mellitus
define minimal change nephropathy
loss of negative charges on the BM
define hydronephrosis
distension and dilation of renal pelvis and calyses
express GFR in starling forces
GFR = K1 x net filtration pressure
GFR = K1 x (60-18-32+0)
relate K1 to GFR
K1 = GFR/net filtration pressure
K1 is _____ related to GFR
directly
increase k1 = increased GFR
and vice versa
2 factors that effect glomerular capillary colloid osmotic pressure
arterial plasma colloid osmotic pressure
filtration fraction
what increases GCCOP
increasing filtration fraction
3 variables that determine glomerular hydrostatic pressure
arterial pressure
afferent & efferent arteriole resistance
kidney blood flow is ___ as much as brain flow, but has ___ the O2 consumption. what is this related to ?
7x, 2x
related to high rate of active Na absorption
renal blood flow formula
(renal artery press. - renal vein press.) / total vascular resistance
all BVs of kidneys are innervated by ?
sympathetic system
strong action of _____ nerves to kidneys will result in ?
- -constriction of renal arterioles
- -decreased renal blood flow and GFR
moderate nervous stimulation has ____ effect on kidneys
little effect
norepinephrine and epinephrine are from
the adrenal medulla
angiotensin II control of GFR
constricts efferent arterioles which helps to increase GFR
in what situations in angiotensin II used to control GFR
–when arterial pressure is decreased
or
–volume depletion
why does angiotensin II only effect ______ arterioles?
efferent
afferent arterioles are protected against this due to release of vasodilators
prostaglandins, NO, bradykinin
what is the source of endothelin
it is released by damaged vascular endothelial cells of kidneys
how does endothelin help control GFR
helps w/ renal vasoconstriction to reduce GFR
NO is derived from _____ cells, and helps ?
endothelial cells
helps maintain renal vasodilation
prostaglandin and bradykinin are both _____. and work to offset the effects of ______ .
vasodilators
offset effects of angiotensin II
for the afferent arterioles
define autoregulation
refers to the relative constancy of GFR and renal blood flow
functions of autoregulation
- -maintain constant GFR
- -precise control of renal excretion of water and solutes
- -prevent large changes in GFR and renal excretion
what is the importance of autoregulation
w/o it a slight increase in bp could increase GFR up to 225 L/day
which would increase urination to 46.5 L/day
what are the 2 components of autoregulation feedback mechanism
afferent and efferent arteriolar feedback
the macula densa is found in the
distal tubule
a decreased GFR will increase the reabsorption of what in the ascending limb and decrease what at macula densa?
Na and Cl
NaCl
what is the major storage of renin
juxtaglomerular complex
